Boondocking Newbies

[Tom Cherry]

1 hour ago, Steve P said:

I'm drowning in info... I guess it would have been good to mention that I have 4 AGM batteries for the house, and two larger ones for the chassis.  I also have a Magnum inverter, and the Intellic EMS remote.  If the EMS has an AGM setting, that's what it's on... I can't remember, but I did check it last year.

First....lets get you acclimated.  YES....read this... all.

Second.  SO, you have AGM's.  The FIRST thing to do is to find out how GOOD they are.  That is really simple....  MORE info later.

Third...  The Intellitec EMS has absolutely positively NOTHING to do with the 12 VDC system or the such.  It is a 120 VAC load shedding device.  NOW FWIW.  You know what your ATS (automatic transfer switch) is.  It switches power from shore or genny and to the main panel. There is a 30 Amp breaker on the main panel.  THIS provides power to the Inverter.  The Inverter is what feeds ALL the interior (maybe one in the bedroom) outlets as well as the Microwave.  There are NO Breakers for them.  There is an INTERNAL ATS in the Inverter.  You HAVE (on a Magnum....some others) a "decent" set or bank of House Batteries.  If your House goes DEAD...then you will NOT have any AC outlets or Microwave. The Magnum monitors (via the 30 Amp breaker) the incoming current.  If it see or measures NO current then it starts inverting.  BUT, if there is NO battery or 12 VDC to draw from....it does NOTHING...  BUT if there is also NO Battery power....then the ATS says...  SOMETHING IS WRONG....  And the internal ATS will NOT allow the power for your internal outlets or microwave.  This concept has been know to cause the "OMG....FIND a new HOBBY" syndrome and the FOR SALE sign goes up.  Seriously....most MH work this way.  NOW....keep this in MIND...if your house bank really dies...as in can't be charged.....YOU ARE OUT OF LUCK.  But one simple Jumper Cable can be connected between the Positive of the House to the Positive of the Chassis....BINGO, the Inverter is happy once more....and then you have power.  Temporary....but better than NO INTERNAL power.

NOW....the Magnum Remote is your CONTROL of the AGS.  I was requested to WRITE another paper.  How to use a Magnum.  Here is the link.  It gives specific instructions.  You NEED to read it and understand HOW to set your Inverter...as an improperly set up Inverter will KILL (DESTROY) the AGM's.  Use the AGM2 Setting when you get to the battery type.  THIS IS URGENT AND SHOULD BE DONE NOW.  If you get confused....call Magnum and they will assist you.

OK....now for your NEXT assignment.  You MUST exercise and measure your batteries to see what the REAL State of Charge (SOC) is.  Since you have AGM, you depend on VOLTAGE.  There is a chart in the file Battery 101 that has AGM information as well as Flooded.  SO, you depend on your VOM to tell you what is going on.

.I just answered another person's request as to HOW TO EXERCISE and TEST the SOC of my batteries.  I will send you a PM with what I wrote...and the specifics of it.

BUT....the bottom line....you exercise 3 times....usually let the batteries full recharge over night.  THEN you drain or discharge them.  Then you turn off the House Disconnect....then pull the Jumpers on the House.  Let them sit for maybe 30 minutes or so.  Measure the Voltage.  That tells you HOW low you discharged them.

Then reconnect the Jumpers.  Turn on the House and let them recharge for at least 16 hours.  You will get maybe 90% full charge instantly....as in running your Genny for 3 hours...but for a FULL SOC, you need to let the inverter stay on. 

NOW....before you drain them.....kill the shore.  Then turn on an exhaust fan and a few lights....takes off the surface charge....just a few minutes.  TURN OFF the load.  Turn OFF the Disconnect.....that prevents them from being drained.  THEN remove the Jumpers.  Let them sit for maybe 30 minutes.  Measure the VOLTAGE.  Since you recharged them to "MAX", then compare the voltage to the chart...for the AGM.  That tells you what their POTENTIAL IS.  If they are below 75%....then don't plan on any long term boondocking.  The RULE OF THUMB....75% will allow you to "make do".  Below that....save some money for replacement....as you will eventually drop to below 50% and they will not be reliable. THEN it is your call as to what type to buy...

That is is.... you MUST repeat the exercise 3 times, per Trojan, to actually "rejuvenate" or get them up to their "peak"....based on their internal cell conditions.  When you do the final "100% recharged" and let them sit and measure...that is as GOOD as they will ever be...  

Hope this explains things.  It is NOT unusual for even experienced MH folks to be a little "less than properly educated" on batteries....  Not rocket science....just learning.

Will send you the Private Message that the other member is now using to do his tests....

[Rocketman3]

Here are a few tips (we full-time and boondock most of the time).mak

The Victron Battery Monitors are GREAT! (Smartshunt or BMV712).  Because all the power going back to battery runs through the shunt it is very accurate.  If you plan on doing much boondocking this is required (in my opinion). It gives you the information to make proper decisions.  Also you can figure out how many watts different items use. (For example - which lights are better (lower wattage). One of the most important helps is - should I run the generator and when to shut off the generator.  

Practice Boondocking in your driveway - Spend an evening in the rig with the lights on, etc.

Plan your generator usage. 

If you plan on doing a LOT of boondocking - install a good solar system. (Ours is 1400w).

Get out there and enjoy - then figure out what you need to change to help you enjoy it more.

 

[96 EVO]

1 hour ago, Steve P said:

Clearly, the first few nights, I am not going to sleep well (due to frequent battery checks!).

Ever seen one of those old digital clocks that shine the time onto the bedroom ceiling?

Maybe you could get something like that for your battery voltage 😂!

[Steve P]

41 minutes ago, 96 EVO said:

Ever seen one of those old digital clocks that shine the time onto the bedroom ceiling?

Maybe you could get something like that for your battery voltage 😂!

I'd rather have something Bluetooth that alarms me when the voltage drops, but I have bigger fish to fry before departure  Saturday...

[Tom Cherry]

36 minutes ago, Steve P said:

I'd rather have something Bluetooth that alarms me when the voltage drops, but I have bigger fish to fry before departure  Saturday...

YES....that would be nice....but many of the so called alarms are not that accurate and often deceive and give a false reading...  do the tests...determine the SOC and then you should have confidence....

[waterskier_1]

6 hours ago, Tom Cherry said:

Well now, you've got a LOT of information.  There is NO STANDARD or best way....whatever works for you as well as your needs and the restrictions on where you boondock.  I was asked to write up a paper on batteries....as I often offered advice....so here is the link.

FWIW....and this is MY opinion, however, it is also the opinion of a LOT of seasoned members.  Batteries are like "fine ladies".....and one's tastes will dictate....but also they have some needs, which can become quite high....  SO...This is MY TAKE....  and others may not agree or they have special situations.

Flooded cell batteries, especially the high end or the GOLD STANDARD (Trojan T-105) are the BEST and MOST COST EFFECTIVE battery.  They don't cost that much more than the next level Interstates.  They last a lot longer than the "brands" sold by Batteries Plus.  We have many members, one in particular, that is going on 10 years on a bank.  We all, to get that life, have an accurate hydrometer and VOM and exercise them at least twice a year.  We use Water Miser caps (Amazon) and rarely add more than an ounce to each sell when we test and exercise. I like a wooden gauge...which is outlined, as my old eyes are excellent for a 78 YO Male.  BUT, having a simple dip stick to get the electrolyte level about 60% of the way between the bottom of the well and the plates is easy.  Trojan NOW has a well designed well with a FILL TO HERE mark.  THEY LEARNED.

AGM's are often a second choice.  However, if you GOOF or have an equipment failure, the results can be costly.  They are NOT as robust as the Flooded cells.  YES, they are used on higher end coaches and such and commercial units.  BUT, if you don't exercise them and keep your Inverter charger set for the RIGHT profile...then they can fail prematurely.  We often have topics where "I bought AGM's and they failed quicker than my old flooded..." and the cause is usually lack of exercising and or not knowing HOW to set up or properly charge them.  WHATEVER YOU DO....Trojan recommends NOT Equalizing any BATTERY...Flooded as the last resort.. but IF you equalize AGM's, say good bye and have your credit card ready....not tomorrow, but within a year or two.

Lithium.  Wonderful technology and evolving. Problem is, that unless you have a newer inverter, you may NOT be able to properly charge them. Most of our Lithium experts recommend specific DC to DC chargers and do NOT let the Lithiums charge from the OEM or replacement inverter/chargers.  THAT is a gross and maybe incorrect overview....but for my needs....I don't do that much dry camping....and am satisfied from a performance and price (value) with my Trojans.  IF you need this, then PLEASE DO A LOT OF READING and SEARCHING HERE...we DO have experts...

NOW...the RULE of thumb... and this was and has been a topic at a lot of our Gatherings....regarding Boondocking and especially conversions to residential refrigerators is this.  Convert to ALL LED overheads.  Fluorescents are OK...but some will turn off one fixture if there are 3 in the living area.  Put the home entertainment systems on a power (Surge) strip and TURN THEM OFF THERE....standby sucks up juice. With a normal, good set of 4 flooded cells, you need to only run the Genny 3 or so hours every 24 hours.  The icemaker should be cut off and use the "LOW or ENERGY EFFICIENCY" mode if the res refer has that.  

The rest....  just one comment.  I know folks that do a lot of tailgating.  Purchasing two Honda 2200's would be almost $3500 with the parallel hookups....and the off brands are usually good. Your needs and the surrounding rules or environment should be taken into account.  The cost of running is about the same.  The 7.5 or 8.0 Onan uses, typically, 0.5 GPM.  YES, it will be higher when you are on full charge.  So, figure 2 gallons per 3 hours of charging.  Then compare that to around 3 gallons for the Honda's.  

NOW, if you need FULL TIME POWER and can't exist off of inverted, then that is a different scenario.  Many folks have solar farms on their roofs.  They camp where they can, usually, be in full sun.  But, the cost of them adds up.  

So, it is a dollar evaluation versus needs and looking at alternatives.

I have dry camped for several extended periods at festivals and in NP's, one of which has ODD hours and very restrictive conditions....like no more than 3 hours but you can do it twice a day. I added the Magnum "Auxillary" start harness ($15) and a simple DC 24 hour programmable timer ($25) and started my Genny for 1.5 hours twice a day....and we were STILL free to go out and enjoy the park....so that was a good "investment and solution" for me.

As to the AGS and run down....read the paper.  Generally speaking, folks make a mistake or misunderstand the charts.  When you allow the AGS to start the Genny, you are usually under a load.  The "Under Load" voltage is usually 0.1 to 0.2 VDC LOWER than the RECOVERY or when there is NO LOAD (relatively speaking) on the bank.  So, in reality....you should be able to set the AGS to say 11.8 or so....then the AGS kicks in and you recharge.  Typically 3 to 3.5 hours for a 4 battery bank.  Setting it at 12 VDC actually hurts, from a long range standpoint, the life of a battery.  Better to run the batteries down to 12.0....RECOVERY, not AGS setting which is 50%.  Some say even 11.9 RECOVERY...which would, typically, equate to 11.7 on the AGS.  NEVER lower....as you might NOT have enough juice to crank the genny.

Hope this helps.  I also hope no one takes offense at my summations of the alternatives....this is my understanding and folks that have special needs or such are really creative and knowledgeable....

 

Tom, I think your battery info is about 10 years outdated.  Right now, you can buy a Renogy 200 A-Hr LiFePO4 battery from Renogy (a fairly reputable company, but definitely not the Rolls Royce of LiFePO4 batteries for just slightly more than you can purchase two Trojan T-105 batteries.  I say two, because you need to 6-volt batteries to operate our 12 volt systems.  The T-105's are rated at 225 A-Hrs, and the best cost I can find is $189.00 each - so $378 for two.  that yields $1.68/A-Hr.  The Renogy 200 A-Hr batteries are $369 each.  They are 12 volt so only one is needed.  That yields $1.85/A-Hr.  Note the with the Renogy, you only have 200 A-Hrs vs the T-105 at 225, but all 200 A-Hrs are usable where only 50% or 112.5 A-Hrs are useable with the Trojans.  

I've never heard the term RECOVERY used in determining when to set the AGS to start.  It makes no difference what the "Recovery" voltage might be, unless you are proposing to disconnect all loads before the AGS is allowed to crank the generator.  Not likely.  The loads will be there when the AGS start value is reached, and will remain there while the generator is cranking.  I have never heard that using an AGS affects the depth of discharge (1 - SOC) versus charging with Shore Power.  

There are other considerations when switching to LiFePO4 batteries.  Will the inverter work with them.  Almost all inverters with updates built in the last 20+ years will work.  But you will need a DC-DC Charger if you want to charge from the alternator.  Some don't use one, but many have fried their alternators.  Even if you don't damage your alternator, you don't want 14.4 Volts applied to LiFePO4 batteries for 8 hours while driving down the road (I don't want that applied to my Lead Acid either, so I disabled alternator charging of my house batteries).  

There are many other factors, like freezing temps, that need to be considered when changing to LiFePO4 also.  But the OP really was asking about how to manage his current rig when boon-docking (BD).  I think wholesale replacement of the batteries, generator, and adding solar are outside the scope.  But things like switching to LED lights and choosing the location for a climate where A/C or Heat is not required for 24 hours a day are smart considerations.  

I guess the next step would be for the OP to relate why he wants to BD.  Is it to save money?  Is it because there are no other facilities where he wishes to go?  Getting a feel for how the OP wishes to travel would be more helpful than tossing out lots of suggestions that might not be appropriate to his wishes.

  -Rick N.

28 minutes ago, Tom Cherry said:

YES....that would be nice....but many of the so called alarms are not that accurate and often deceive and give a false reading...  do the tests...determine the SOC and then you should have confidence....

My alarms from my  Victron 700 series are quite accurate.  It isn't the bluetooth or alarms that makes a false reading, but the source of the alarm.  

  -Rick N.

[waterskier_1]

6 hours ago, 96 EVO said:

Your coach being the same MY as mine, I'm going to say there's a better chance your gen get's it's starting power from the house batteries.

Even more reason to follow Ivan's advice and not run your house bank below 12.0v (without a load), or they may not turn over your gen!

Easy way to find out.  Turn off the Chassis Battery Disconnect Switch and try to start the generator.  If it starts, it's starting off the House bank.  If it doesn't start, turn on the Chassis Battery Disconnect Switch and turn Off the House Battery Disconnect Switch.  If it start, it's starting off the Chassis bank.  If it still doesn't start, you have a problem.  It is relatively easy on many Monaco coaches to switch the generator to start off the other set of batteries.  Both Chassis and House Battery circuits have large cables running to the FRB (Front Run Bay).  The generator cable also connects to one of those circuits in the FRB.  Simply remove from one and connect to the other.

  -Rick N.

 

6 hours ago, cbr046 said:

There's always the Boost Switch but for a $100 Gooloo GP4000 you can have the spare of all spares - https://www.amazon.com/GOOLOO-GP4000-Starter-SuperSafe-Portable/dp/B09HJH1S41/

Todd gave it a good review on Project Farms - https://www.youtube.com/watch?v=bMXyoIBJyJA&t=356s

- b

If you have LiFePO4 House batteries, I do NOT recommend trying to Boost to start the main engine.  If you are boosting from the Chassis batteries to start the generator connected to the House batteries, it is less of a concern, if think.  I have disabled my BIRD since I don't want either system connecting to the other.

  -Rick N.

 

4 hours ago, Steve P said:

Clearly, the first few nights, I am not going to sleep well (due to frequent battery checks!).

You can do a "dry run" in your driveway, during the day.  Yes, there will be slightly more lights used in the evening, but then slightly less after you retire, with the possible exception of the furnace. 

  -Rick N.

[96 EVO]

38 minutes ago, waterskier_1 said:

  It is relatively easy on many Monaco coaches to switch the generator to start off the other set of batteries.  Both Chassis and House Battery circuits have large cables running to the FRB (Front Run Bay).  The generator cable also connects to one of those circuits in the FRB.  Simply remove from one and connect to the other.

 

  -Rick N.

I did exactly that several years ago, only my connections were in the rear run bay!

[Steve P]

 

Everyone's insights are tremendously helpful.  I'm just wanting the convenience of overnighting at a Cracker Barrel or similar.   Maybe Harvest Hosts if that goes well.  And after that, who knows, maybe NP / BLM...

GOOD tip Rick N on using the battery disconnects to see what the generator uses for starting !

Tom - I'm still digesting all your advice before I start any battery testing. 

As far as my BIRD, the previous owner said he just used the battery maintainer on the side of the battery compartment to charge the chassis batteries.  It wasn't until a couple months later the solenoid in the BIRD circuit must be bad... although I haven't tested it (too many other projects).

[96 EVO]

Do you own a handheld digital volt meter?

Pretty much a 'must' when you own an RV!

[Steve P]

16 minutes ago, 96 EVO said:

Do you own a handheld digital volt meter?

Pretty much a 'must' when you own an RV!

Two actually, one analog and one digital.  Why do you ask?  I thought the inverter/EMS would give me the voltage readings...

[96 EVO]

Well, when your plugged into shore power, or generator power, put your meter on your chassis batteries.

That well tell you if your BIRD system is working.

The solenoid that connects the two battery banks sometimes needs attention.

[cbr046]

3 minutes ago, Steve P said:

I thought the inverter/EMS would give me the voltage readings...

That's like entrusting your daughter to a 17 yr old with a 700 hp Charger. . . .

- b

[96 EVO]

2 minutes ago, cbr046 said:

That's like entrusting your daughter to a 17 yr old with a 700 hp Charger. . . .

- b

Hey........

I once was that 17yr old with the 700hp El Camino!! 😂!!

[jacwjames]

7 hours ago, Steve P said:

Clearly, the first few nights, I am not going to sleep well (due to frequent battery checks!).

Ah, this is where the  BMV712 shines, it is Bluetooth capable and I can open my display under the cover and confirm what the state of charge is.  

Under the covers I can check the temps on the MicroAir thermostat and then check state of charge.  If SOC is ~75% I can turn on the furnace.  If not I'll reach up from under the covers and start the generator.    In the AM and the LR is colder I'll start the furnace to warm it up and when it cycles off I'll start the generator and fire up the coffee maker then jump under the covers until it is done. 

Technology is great if it works and is useful!!!!

The more I use this tech and gain confidence the more I'm comfortable with relying on it. 

[96 EVO]

26 minutes ago, Steve P said:

Two actually, one analog and one digital.  Why do you ask?  I thought the inverter/EMS would give me the voltage readings...

The Magnum remote panel you have will give you the voltage of your house bank. Not your chassis batteries.

[96 EVO]

37 minutes ago, cbr046 said:

That's like entrusting your daughter to a 17 yr old with a 700 hp Charger. . . .

- b

Spun my mint '69 Olds 442 off the hiway, over a 8' bank, onto two parallel drift logs on the beach!

No damage to myself or my car!

How I survived teenage years I have no idea 😁!!

[Steve P]

23 minutes ago, 96 EVO said:

The Magnum remote panel you have will give you the voltage of your house bank. Not your chassis batteries.

Started to ask why the chassis wouldn't just stay fully charged... then started to wonder what besides the dash radio would drain the chassis batteries, and realized, I don't know -- more to learn!  More reading of the manual.  It's amazing how quickly I forget...

[96 EVO]

Yeah, there's a few phantom draws on your chassis bank.

As long as your BIRD system is operational, won't be an issue!

When you run your generator, they will get topped up!

[kenandjoanne2002]

Boy my head is spinning with all the talk of batteries.  I will not use the "b" word again.  Many years ago a friend introduced me to a 1 to 3 brick propane heater.  The term brick is the number of approx 4" x 10" propane panels in the free standing unit.  Purchase one that is safe for indoor use and plumb it into your onboard propane piping.  We never use our furance while boondocking! pulls the "b" word down too fast.

You can purchase a clamp around electric meter at Lowe's or Home Depot for about $50 (when I bought mine 20 years ago).  Since we boondock the majority of the time I wanted to know what was drawing down my power.  Clamping the meter on the ground post while the wife turned on different items I could see what was actually drawing the most power.  That was very educational. 

To stop the paricite draw from front overhead (vcr, tv, satilite dish, etc) I bought a remote 110v on/off switch (like one would use for turning on/off xmas lights outside) and plugged that remote switch into the main outlet in the overhead panel.  Then into that I used a power strip to pulg in off the item in the overhead.  When boondocking I can kill all power to the overhead saving "b" power.

For all that do want to talk about "batteries" this website should occupy a day or two, Hee Hee.

https://batteryuniversity.com/articles

Happy boondocking, Ken Parsons, 72707 02 Diplomat

 

[Tom Cherry]

17 hours ago, waterskier_1 said:

Tom, I think your battery info is about 10 years outdated.  Right now, you can buy a Renogy 200 A-Hr LiFePO4 battery from Renogy (a fairly reputable company, but definitely not the Rolls Royce of LiFePO4 batteries for just slightly more than you can purchase two Trojan T-105 batteries.  I say two, because you need to 6-volt batteries to operate our 12 volt systems.  The T-105's are rated at 225 A-Hrs, and the best cost I can find is $189.00 each - so $378 for two.  that yields $1.68/A-Hr.  The Renogy 200 A-Hr batteries are $369 each.  They are 12 volt so only one is needed.  That yields $1.85/A-Hr.  Note the with the Renogy, you only have 200 A-Hrs vs the T-105 at 225, but all 200 A-Hrs are usable where only 50% or 112.5 A-Hrs are useable with the Trojans.  

I've never heard the term RECOVERY used in determining when to set the AGS to start.  It makes no difference what the "Recovery" voltage might be, unless you are proposing to disconnect all loads before the AGS is allowed to crank the generator.  Not likely.  The loads will be there when the AGS start value is reached, and will remain there while the generator is cranking.  I have never heard that using an AGS affects the depth of discharge (1 - SOC) versus charging with Shore Power.  

There are other considerations when switching to LiFePO4 batteries.  Will the inverter work with them.  Almost all inverters with updates built in the last 20+ years will work.  But you will need a DC-DC Charger if you want to charge from the alternator.  Some don't use one, but many have fried their alternators.  Even if you don't damage your alternator, you don't want 14.4 Volts applied to LiFePO4 batteries for 8 hours while driving down the road (I don't want that applied to my Lead Acid either, so I disabled alternator charging of my house batteries).  

There are many other factors, like freezing temps, that need to be considered when changing to LiFePO4 also.  But the OP really was asking about how to manage his current rig when boon-docking (BD).  I think wholesale replacement of the batteries, generator, and adding solar are outside the scope.  But things like switching to LED lights and choosing the location for a climate where A/C or Heat is not required for 24 hours a day are smart considerations.  

I guess the next step would be for the OP to relate why he wants to BD.  Is it to save money?  Is it because there are no other facilities where he wishes to go?  Getting a feel for how the OP wishes to travel would be more helpful than tossing out lots of suggestions that might not be appropriate to his wishes.

  -Rick N.

My alarms from my  Victron 700 series are quite accurate.  It isn't the bluetooth or alarms that makes a false reading, but the source of the alarm.  

  -Rick N.

As i said, we have a lot of smart folks on Lithium.  Good the price is coming down.   Your knowledge of how they work and such would be appreciated.  However, even with my out od date facts on costs, the successful Lithium users, if I can generalize have a much more technical and practical level of experience….and he states he is just learning.  In addition, the charging and proper care of the investment is, or at least what I gather, the major obstacle….so, if he converted, his Magnum would not be the charging device.   So, until he defines his needs and verifies the SOC of his AGM’s talk of replacement seems premature….but all the posts seem to be advocating a change.  Maybe a change is not necessary….that is fundamental….maybe got lost in the info blitz.
 

As stated, OP @Steve P is still in the perhaps, information overload state…..and needs to understand exactly how the basic charging system and how his banks work and such first.  Then determine his needs.  But fundamentally, he asked about “tips” and got bombarded.  My focus is basic understanding of his equipment and also what he needs…

Over the past 10 plus years, I have spent a LOT of time on the phone with Trojan and Magnum.  Not exaggerating, but probably 5 or more extended discussions on care and maintenance with Trojan.  Three or more…approaching 20 calls with Magnum.  So, here is the way that I understand it and why the “simplistic” set your AGS to 50% SOC or 12.0 VDC, to use your term, is 10 years out of date.  I’ll try a different approach to explain it.  At least 5 Magnum techs have agreed that this concept is the correct one for the Magnum system. THEN, you might ask….why not change the manual.  The resounding answer is….”Our average user would not be able to fully understand it”.  The consensus was that if the house bank was on the “fair” side, then there might not be enough House capacity to crank the Generator.

OK, point blank asked them….what if the Genny is cranked off the Chassis like most of the newer (as in 2006 or so) Dynasty and above are configured.  Half did not know that….and the comment was that most MH’s use the House Bank to crank the Genny.  Then they revert back to the “keep it SIMPLE” and not get into the real world…..and most of our folks here, that delve into the level that you do, should easily understand.

OK…..This is what Magnum and Trojan say and agree with my statement.

First….the Magnum remote is NOT a precise instrument and there is NO Calibration procedure.  Purchase a new remote….it may not display the same voltages..  +/-10% is the advertised tolerance.  Now, from helping many folks, off and online, I know the remote is more accurate.  But, the “Load” or “unloaded” comparison of the House Bank with a quality VOM and comparing that to the Remote USUALLY results in the remote reading lower…I ballpark that at 0.1 to 0.2 VDC.  So, in effect, your batteries are a bit better than the remote indicates.  The CAVEAT…an owner MUST do the comparison and have his own “real voltage” compensation number.  It sure would be intriguing if I could post a poll and get a lot of knowledgeable Magnum owners to do the load and no load VOM vs Remote readings….maybe I could try that??.

OK…let’s assume that the remote and the VOM ARE the same….

Now, lets look at what one is trying to accomplish….you want the Genny to start when the “RECOVERY” voltage is at a 50% SOC.  This is Trojan’s Mantra.  Run or discharge the batteries to a 50 SOC…which is NOT the LOAD Voltage.  Trojan recommends a “test” or discharge rate EDIT 5 to 10% or around 7.5%. END EDIT….of the total Amp Hour capacity.  I did the math in so many posts….but for a 4 battery bank, you need around 450 Watts of AC load.  Please run the numbers yourself and verify…I do it occasionally as a “did I do it right”. OK, you put on a Quartz Halogen work light in that range.  That, other than a carbon pile tester, which I was told won’t work, is the simplest.

Next up.  The intent is to set the AGS to the LOAD Voltage that will be expected so that the batteries are at a 50 SOC.  The definition of SOC is the RECOVERY voltage….NOT the LOAD voltage.  

NOW…how big a deal is this….depends on you.  If you don’t mind getting say 75% of the optimum life out of a bank….set it for the load.  But. If you understand that there is only a finite number of discharge and recharge cycles, like Trojan says, then, based on their testing and research and experience, to get the optimum life, you need to set the AGS to start recharging at the REAL or Recovery SOC.  

Thats the best I can do, approaching it from a different avenue,  YES….the Magnum does NOT trigger the AGS when a blip hits….but the AGS works off the DISPLAYED voltage….maybe the voltage has to drop 0.1 VDC for a minute or two.

SO, first you have to know how accurate the REMOTE is…compared to the actual bank voltage.  Second, you need to know, from the standard 10% drawdown or discharge rate, what the recovery voltage is…..but you also need to know what the LOAD voltage is…so, you do the test, as Trojan outlines…and set the LOAD voltage to the value….that achieves the 12.0 VDC Recovery voltage….and the laws of physics or EE show that a discharged battery, left alone….no load, will spring back.  How much…that is the purpose of the test,  I know mine.

That’s the long and short of it….

BTW, I assume your statement about your Victron 700 and the accuracy is based on a side vy side comparison.  Just how accurate are they?  But regardless of the meter vs VOM, the set point for the AGS has to be the “load voltage” to achieve a 50 SOC or around 12.0 V….

Thanks for the comments….and I will defer to you and others now that Lithium prices have come down….

12 hours ago, Steve P said:

Started to ask why the chassis wouldn't just stay fully charged... then started to wonder what besides the dash radio would drain the chassis batteries, and realized, I don't know -- more to learn!  More reading of the manual.  It's amazing how quickly I forget...

@Steve P
 

Steve, the chassis batteries only power the radio when ON.  The “standby” or memory for the clock and presets are PROBABLY….assuming that our lower ends are all the same, hooked up to the House.  Yes…look at your prints….or kill the house bank…disconnect the jumpers…..wait a while….the radio has in internal capacitor for blips……maybe an hour…..then reconnect….turn on the ignition.  Is the clock right?  

Next, yes, you DO have, based on what I know, a BIRD system.  But you stated there was a maintainer.  There are two types of maintainer.

One is the Lambert or the Ample Start.  These are DC THIEVES.  They STEAL power from the House to keep the chassis maintained.  It COULD have been that the previous owner did NOT have shore power in storage and added that.  Having that does NOT mean that the Big Boy BIRD Charging system does not work.  The downside of the theif….it will eventually KILL the house.

the OTHER type of maintainer, for folks WITHOUT a BIRD system, but have power in storage, is a 120 VAC 1.5 or slightky higher “box”….this is quite common.

You need to be specific in which type.

You are already inundated.  So, getting into “OK, HOW DO I TEST AND VERIFY” my BIRD system is another subject for another day after you grasp the basics.  Delving into that is not recommended now,

BUT, if you DO have power in storage and are concerned about your BIRD system working….the simple, temporary step…put a jumper cable between the POSITIVE terminals on the HOUSE and CHASSIS….thus…both banks stay charged.   Many of us do that for extended periods…..

Stay focused…..and read….

[waterskier_1]

14 hours ago, Steve P said:

 

Everyone's insights are tremendously helpful.  I'm just wanting the convenience of overnighting at a Cracker Barrel or similar.   Maybe Harvest Hosts if that goes well.  And after that, who knows, maybe NP / BLM...

GOOD tip Rick N on using the battery disconnects to see what the generator uses for starting !

Tom - I'm still digesting all your advice before I start any battery testing. 

As far as my BIRD, the previous owner said he just used the battery maintainer on the side of the battery compartment to charge the chassis batteries.  It wasn't until a couple months later the solenoid in the BIRD circuit must be bad... although I haven't tested it (too many other projects).

That solenoid is used both ways.  If it is bad charging the chassis batteries when on ShorePower, it is also bad charging the House batteries when running the main engine alternator. You can tell if it is engaged because it will be hot to the touch.  If engaged, you should not have more than 0.2 Volts difference between the two main lugs. 

  -Rick N 

[Tom Cherry]

On 10/23/2023 at 10:34 PM, Tom Cherry said:

Ah, yes.  But have you calibrated or compared or tested it?  The real test is to run the exercise test….3 cycles.  Then find the real SOC after you remove the surface charge.  Then let the batteries sit, disconnect off, jumpers removed….and sit for 30 minutes.  Then measure the SOC and VDC and compare to the Trojan chart.  The chart tells you the real SOC. Interpolate to the nearest whole number.  Then compare to what the instrument says.  That is the only real way….otherwise… the reading may be false.  OR correct!.  But yet, folks are purchasing BMK’s and Shunt systems and such and putting total trust into a device that may have not been tested or validated.

I really want to know if they work and how accurate they are….looking for real data.  They may be 100% or off by 10 or more %….but we don’t know.

All my reading and talking to Magnum and Trojan and testing shows that the recovery voltage or SG after being discharged, is the REAL discharged SOC.  THEREFORE, the load voltage, is usually 0.1 -0.2  VDC lower than the recovery.  But, each bank or brand may be different.  The only way is to measure the load voltage at say, 11.8 VDC and see if the recovery voltage or SOC is close to 12.0 or 50% SOC.

I hope you accept the challenge.  I would like to know how accurate they are.  Magnum says that their remote meters are only +/- 10%…so how do you trust them?

 

@jacwjames

Jim,

I had a long conversation with Frank on the Magnum BMK.  He also commented that there is a “slight” design issue and there may be better ones.  What he said is that, YES….you could run the test.  Whatever the SOC meter says….if you shut down at a given SOC, then quit the test, let the bank “recover” and then use either or the Voltage or Specific gravity, then interpolate the SOC from the chart….remember the AGM and Flooded voltages are different….look at the Trojan chart.

Bottom line, his Magnum BMK is like a recording or accumulating flow meter.  You got a tank.  You KNOW it holds 450 gallons (or Amp Hours).  The flow meter records the amps that have been pulled or drained out.  So, you know how much there is left.  The BMK in the Magnum, resets the clock or timer to full capacity or 450 gsllons or amp hours when the batteries is 100% charged.  What I didn’t ask….was, what if your batteries are only 90% SOC, due to age.  Then, logic would tell you that you need  to do a discharge test and find out what the REAL recharged capacity is….not a theoretical 225 X 2….  Since a bank may be older…it might NOT have full 100% rating.  Will run that by him later…

 

[Tom Cherry]

Steve @Steve P, there are so many posts…..one word of advice…or specifically for you.

Look at the Trojan Chart for AGM.  The 50% SOC, which is based on the actual Battery’s RECOVERY voltage is 12.24 VDC. Based on what we know….under a relatively constant drain…..like in the evening, you are going to not pull more than 10%….unless you tried to run a space heater.  Once you go to bed, that drain decreases.  Without you running the tests…..my advice.  Set your AGS to 12.0 or so.  That will NOT deplete a GOOD BANK more than 50%.

BUT, you need to exercise and run the recharge cycles….that will tell you if the batteries are capable of 100% SOC which is 12.84 VDC.  If they are not 100%, then your the Genny will come on quicker as they will hit 12.0 volts quicker….as they only recharged to say 12.7 VDC. 

BOTTOM LINE….learn HOW, read the Magnum file, to set up the AGS.  Also use 3 Hrs for the Genny run time….that gets you about 90-95% of FULL charge.  If you boon dock for a long period….let the genny run for maybe 5 -7 hours every week or so….

Also go through the SET UP and make sure the AGM’s are set up properly.  Use the AGM2 profile.  Use 450 Amp hours….plus read how to set up the REST of the 8 or so parameters.  It’s all in the chart….easy to read….

THEN…rock on.  But, to optimize your batteries and potentially save them, you DO need to do the drawdown exercise….3 times….like stretching your muscles prior to a strenuous work out or a long run.

This is as simple as it gets.

Read the post that touches on how to test the BIRD and the need for you to post or take a picture of the added on maintainer….

[96 EVO]

Steve stated in his opening post, he doesn't have AGS!