Confession, a place to start......

[woodylmiller]

After getting a flat tire while stopped for dinner we had to boondock on the side of the road for the night.  I have 4 Trojan 8D AGM's and 4 Lifeline 4D AGM's which are my chassis batteries and  the Trojans are house.  I turn on the inverter, Magnum, and my biggest load is the residential frig installed at the factory in 09.  Monitor shows the total load pulling 18-19 amps.  Voltage started at 12.4 and began to drop as I watched.  Turned the inverter off and ran the gen all night.

So, we are midway to our winter destination where we will be for 6 months at which time I will start to determine what is wrong with the charging/battery bank(s), inverter, Big Boy BIRD or ???   Those Trojan's 8D's are big batteries, 4 should easily go for hours before the voltage is dropping below 12 volts in the matter of a few minutes when the biggest current draw is a residential refer.  Add to that, the monitor is showing the charging is in a "float" state when I just drew the batteries down to just above 12 volts.  Don't mind spending the money to fix it right, just don't want to spend on something that isn't the problem.

Where would y'all start?  Thanks,

Woody Miller

09 Dynasty Regal IV

PS: those TPMS systems works, it was dark after stopping for dinner and did not see the flat on the tag, and I mean flat.  Bead broken and the wheel sitting on the ground.  Started up to go and the monitor went off.  Saved a ton on money on a new tire, wheel and the fiberglass damage had we driven off.

[FishAR]

That seems like a lot of juice to run a refrigerator. My Monaco is sitting in my driveway getting ready for florida and all I have up here is a 30 amp service. It shows I'm pulling 19 amps running one ac and the 1402 fridge on electric, along with a few lights and a tv on.

[dl_racing427]

20 minutes ago, FishAR said:

That seems like a lot of juice to run a refrigerator. My Monaco is sitting in my driveway getting ready for florida and all I have up here is a 30 amp service. It shows I'm pulling 19 amps running one ac and the 1402 fridge on electric, along with a few lights and a tv on.

You're referring to amps at 120v.  I think the OP was referring to amp draw from the batteries, which is at 12v.
1a at 120v is 120watts, while it takes 10 amps at 12v to equal the same power, not including losses in the inverter and wiring.

[Ivylog]

Starting at 12.4 (assuming the meter is accurate) is on the low side…I would check the voltage on either side of the BigBoy when hooked to shore power with it hot to the touch/engaged…voltage should be the same. Cleaning the BigBoy’s contacts isn’t that hard.

Unfortunately you cannot equalize AGMs…how old are the 8Ds? You should be able to go 24+ hours (before needing to recharge) with that many AH even with the AquaHot running.

The refer is using 10A and TVs and other electronics (even if off) can draw another 4-5A so 18 is unfortunately normal.

I had almost 1.0V difference between battery voltages and meter (meter is accurate) when drawing 100+ amps (0.4 V at 25amps). By tightening every connection I could find and cleaning the ones at the batteries I cut those reading in half. Changed my cut off voltage to 11.8 because it would jump up to 12.2 without the load.

Edited September 15, 2021 by Ivylog

[Nevada Rob]

On our 2008 Dynasty with the original Sharp TV is the big power user. Our refer draws 7 amps on the high side when active cooling. Add in just the TV and it jumps up to 28+/- amps. I 100% agree with the others about making sure your connection are all very clean and secure. LifeLine batteries has a great write up on equalizing your batteries including AGM batteries. Why they get sulfate and what to do ti try and recover your batteries.

[vito.a]

I'd start by checking and cleaning all battery cables and terminals.  Then check (or replace) the Intellitec Big Boy battery isolation solenoid (this is more than likely the issue).  

If that doesn't fix it then start checking each 8D battery individually.  

Just a note from my experience, I've never had good luck with 8D batteries of any kind including Lifelines.  

When you do replace them, I would go with two 6V deep cycles in place of each 8D.  Or take the leap to LiFePo4 batteries.  

[cbr046]

If money were no object I'd look at a lithium battery solution, but then, because they charge differently and can draw much more current charging you're looking at upgrading the charging system also, maybe even a new alternator (or limit the draw).  It's definitely a rabbit hole but the end results are long periods on battery power. 

Now, if you're just going from powered site to powered site, probably just go with making sure your batteries are up to snuff, connections tight, etc. 

That residential fridge is a power monster on batteries.

My 2c,

- bob

[waterskier_1]

I'm going to make some assumptions, and you can supply additional information if they are incorrect.  First, it appears you were traveling, i.e., driving the coach before you stopped for dinner.  If so,  the engine alternator should have been charging both the chassis and house batteries.  Your 12.4 Volts is 60% or so charge.  It should have been close to 12.9 after being charged, assuming you drove for a few hours.  This indicates that the house batteries are not being charged properly.  That can be due to a faulty alternator, but more likely the isolator circuit.  I think you have a BIRD system, and if so, I'd look to the Big Boy or equivalent relay (solenoid).  These are prone to getting high resistance on the contacts.  When the engine is running, check the voltage on both sides of the relay. They should be within 0.1 Volts.  Another possibility is bad batteries.  Your four 8D batteries have a rating of 230 A-Hr each of a total of 920 A-Hrs.  Drawing 20 Amps would take 46 hours to delete - really 23 hours since it is recommended to never run the batteries below 50% charge.  Even starting at 12.4 Volts,  you should have had over 13 hours before the batteries got to 50% discharged.  That fact that you say you could watch the voltage (assuming you were not watching for hours) go down suggests weak batteries. 

I would being by charging the house batteries fully, and running a load lest.  I think Trojan has a procedure for that on their website.  This will tell you how good the batteries are.  The second thing I would do is check the voltage on each side of the isolator relay with the engine running to see if that might be the cause of your house batteries not being fully charged.  There are many more tests and possibilities, but this is where I'd start, and using those results to direct further troubleshooting, if necessary. 

[Fonman]

Just 2 quick comments to add.

Voltage vs state of charge needs to be measured with no load.

Have you checked the actual voltage at the batteries with a good meter to verify what you are seeing inside the coach is accurate?

Edited September 16, 2021 by Fonman
Verbage

[oregondarrell]

I may be able to help. I have a Magnum 2812 in our 2004 Monterey with Samsung residential refrigerator.

Last weekend I pulled too much power while cooking dinner and heating RV. The circuit breaker on the side of the Magnum tripped and shut down power.

I reset the breaker button and Magnum went into High power charging mode. The Magnum was humming loudly and was drawing between 19-20 amps as noted on the Electrical readout on Alladin system.  This is the 3rd time this has happened, I pushed power button on the Magnum and held for 30 seconds. The Magnum cycled and restarted and charging went back to normal.

I contacted Magnum service center in WA on Monday and explained my issue. Apparently this is common and acceptable. The Tech walked me through a few changes to settings which would drop charge amps down if/when this happened again.

Call Magnum tech support, they will walk you through making the changes that at least drop the Amp draw when this happens. I am a little surprised that he did not consider this a problem.

Darrell Terry

[woodylmiller]

Thanks to all.  We have arrived at oThankur winter destination and I'll start the checking the system.  The Trojans are now about 4 years old and were run down to almost death thanks to the fine folks at Cummins that had the coach in for service and it sat for a month or so and they didn't turn the batteries off.  Trojan came and picked up the batteries and took them to their shop for recharging prior to needing to replace them under warranty.  Their industrial charger got them back to full charge and the batteries seem to have been fine.  And for the last couple of years the voltage shown on the Magnum display is over 13 volts which I would expect at full charge.  We never boondock and this is the first time we tried to  run on the house batteries instead of the gen since we were stuck for the night.  To see a start voltage at 12.4 to run the inverter seemed way too low.  Once inverting the voltage was dropping a tenth of a volt every couple of minutes.  So I went to the gen for power instead of running the Trojans down to nothing overnight.  We went with the Trojan 8D's, 4 of them, to be able to handle an emergency like we had when the tire went flat.  By the way, on this trip we had 3 of the stainless braided valve extensions go bad.  $300 in charges for mobile tire repairs to have the tires aired back up and one new Schrader valve.  The remaining 3 valve extensions will soon be going in the garbage. 

If got a good Fluke meter so I'm going to start by comparing the Magnum readings with the Fluke.  Then onto cleaning and connections and taking a close look at the Big Boy.  The latching relay for the salesman switch was "jumped" some time back, but I don't think that's the problem.  Magnum has great tech service so I'll be giving them a call as well.

Thanks, Woody Miller