Going HIGH TECH….2007 Dynasty. New Inverter Charger and Lithiums and such. Questions??” and Help Needed.

[Tom Cherry]

Again….my “simple” solution was that …

1… A 20 odd year old Magnum is on it’s last legs and the high dollar investment in Lithiums was NOT worth the risk of being improperly charged.

2…. The “charging profiles and parameters” of the older Magnums, like my 2009, do NOT support Lithium.  The AGM parameters are elementary and were an AFTERTHOUGHT.  So, I doubt my Magnum can be upgraded.  YES, the newer remotes, assuming the Inverter might work…

3…It was my understanding that using an older Magnum was a recipe for disaster.  Has Magnum added a function to “permanently” disable charging.  There is no “big diode” that will block the Magnum from charging a Lithium by mistake.  We have had scads of posts where even the simple “AGM” settings…failed and ruined them.

4. BTW….factoid.  If the Magnum Remote goes flaky and gets intermittent….IT WILL change the settings and it WILL reprogram the Inverter.  I had this. Magnum helped me troubleshoot it,  It was changing the bank size to 1000 AH and the various cutoff points and control parameters.  ONLY FIX….new remote.

Maybe the experts have figured out how to “FOOLPROOF” a Magnum…but from my experience and that covers maybe 50 members that I have helped and probably 25 cals to Magnum to test an idea or get information…. The Remote failing is a common thing and then Magnum says…”Don’t worry”….as in it will REVERT to the Factory Default.  The Factory Default is Bulk, Absorb, Float and the voltage will be well into 14 VDC. The Factory default for a bank is 450 AH.  So…based on what I know and have learned and such….a Magnum failure, underected…and some folks don’t understand or pay attention….WILL DESTROY or DAMAGE a Lithium bank.

NOW….that is my thiughts….so any comments on how to totally foolproof a Magnum, since you can’t reprogram the main board would be helpful…so chime in….but understand why the idiot proof or KISS, as I understand Magnums and Lithium….put in a new Inverter charger snd don’t be penny wise and mega pound foolish…

[Frank McElroy]

2 hours ago, wamcneil said:

It's been a couple years since I've shopped for an inverter, but at that time, magnum and xantrex were the only vendors that I could find with dual-in/dual-out.

I think Victron now makes a dual in dual out inverter charger.  Would need to study it a bit more but it looks like it would be a direct replacement for a Magnum on a Dynasty and above coach with an inverter sub panel.

Victron Energy MultiPlus-II 12/3000 Inverter/Charger - 2 X 120V Model

Rating:

0%

[Grey Goose]

1 hour ago, Tom Cherry said:

Again….my “simple” solution was that …

1… A 20 odd year old Magnum is on it’s last legs and the high dollar investment in Lithiums was NOT worth the risk of being improperly charged.

2…. The “charging profiles and parameters” of the older Magnums, like my 2009, do NOT support Lithium.  The AGM parameters are elementary and were an AFTERTHOUGHT.  So, I doubt my Magnum can be upgraded.  YES, the newer remotes, assuming the Inverter might work…

3…It was my understanding that using an older Magnum was a recipe for disaster.  Has Magnum added a function to “permanently” disable charging.  There is no “big diode” that will block the Magnum from charging a Lithium by mistake.  We have had scads of posts where even the simple “AGM” settings…failed and ruined them.

4. BTW….factoid.  If the Magnum Remote goes flaky and gets intermittent….IT WILL change the settings and it WILL reprogram the Inverter.  I had this. Magnum helped me troubleshoot it,  It was changing the bank size to 1000 AH and the various cutoff points and control parameters.  ONLY FIX….new remote.

Maybe the experts have figured out how to “FOOLPROOF” a Magnum…but from my experience and that covers maybe 50 members that I have helped and probably 25 cals to Magnum to test an idea or get information…. The Remote failing is a common thing and then Magnum says…”Don’t worry”….as in it will REVERT to the Factory Default.  The Factory Default is Bulk, Absorb, Float and the voltage will be well into 14 VDC. The Factory default for a bank is 450 AH.  So…based on what I know and have learned and such….a Magnum failure, underected…and some folks don’t understand or pay attention….WILL DESTROY or DAMAGE a Lithium bank.

NOW….that is my thiughts….so any comments on how to totally foolproof a Magnum, since you can’t reprogram the main board would be helpful…so chime in….but understand why the idiot proof or KISS, as I understand Magnums and Lithium….put in a new Inverter charger snd don’t be penny wise and mega pound foolish…

I did not realize that the Magnum products had such a bad reputation. 

I do know they make a remote that supports a lithium profile as well as custom settings to set up specific CC/CV to match your batteries.

Magnum also makes a BMK (monitoring kit) which is must if you want to get the most out of a lithium battery bank. Not a must if you are not a high demand user and spend most of your time with FHU.

As you already know I have a 2007 vintage Magnum inverter with a late release remote. 

As far as defaulting to 14V that should not bother my Lithium batteries as they are supposed to charge at 14+ and have a BMS that will stop over charging. As far as I know most Lithium batteries are similar is this regard.

I have considered getting a Magnum BMK kit but I am on the fence about spending more money on Magnum products because I know utlimately I will end up with Victron seeing how they have more control/monitoring and charging products available that seem to be more future proof than Magnum.  I am guessing all are made in China these days anyway. I do question Victrons factory support as I hear they push it all down to their retailers.

Do you still run your Magnum or did you upgrade/change to something else?

15 minutes ago, Frank McElroy said:

I think Victron now makes a dual in dual out inverter charger.  Would need to study it a bit more but it looks like it would be a direct replacement for a Magnum on a Dynasty and above coach with an inverter sub panel.

Victron Energy MultiPlus-II 12/3000 Inverter/Charger - 2 X 120V Model

Rating:

0%

Another feature that some of the late model Victron Inverters have is a hybrid mode (Power Assst) it basically allows the inverter to draw power from the battery bank if the shore power is not enough. So if you were plugged into 20 amp and needed a bit more it would make up the difference. I am sure there is a limit but if it worked well it would be good for short periods of time and hypothetically could provide a more stable 110 voltage in those situations that were pushing or exceeding 20 amps. Of course Magnum has a similar feature as well.

Edited February 23 by Grey Goose

[Rocketman3]

As a Victron user for over 5 years on my 2000 Dynasty- yes the Multiplus II 12/3000 2x120v would be a very nice direct replacement for the inverter that was in my rig.

i wired mine up with a regular Multiplus 12/3000 (because that unit was not out yet).

Additional stuff needed, you will need to change the AC input limits: (one of the following):

1. VE.Bus Smart Dongle (with this you change on your phone in an app)

2. Cerbo and Touch - awesome display for inside the rig that puts all info at your fingertips (and can also allow changes from internet w/VRM).

3. There is a DSU- but get one of the other ones instead.

There are some great features that the Multiplus has.

One that I used a lot this Winter RVing in Baja, the power was very poor in one park, so my Watchman kept dropping the power as voltage drop below 106v, I didn’t even notice the dropped power if I didn’t hear the click from the transfer switch. I just kept the AC power input at 7.5amps to not stress the parks grid, when power came back - the charger slowly recharged if needed. We used the microwave during that with no issues.

If you have any Victron questions- let me know.

[wamcneil]

2 hours ago, Grey Goose said:

I did not realize that the Magnum products had such a bad reputation. 

I do know they make a remote that supports a lithium profile as well as custom settings to set up specific CC/CV to match your batteries.

Magnum also makes a BMK (monitoring kit) which is must if you want to get the most out of a lithium battery bank. Not a must if you are not a high demand user and spend most of your time with FHU.

As you already know I have a 2007 vintage Magnum inverter with a late release remote. 

As far as defaulting to 14V that should not bother my Lithium batteries as they are supposed to charge at 14+ and have a BMS that will stop over charging. As far as I know most Lithium batteries are similar is this regard.

I have considered getting a Magnum BMK kit but I am on the fence about spending more money on Magnum products because I know utlimately I will end up with Victron seeing how they have more control/monitoring and charging products available that seem to be more future proof than Magnum.  I am guessing all are made in China these days anyway. I do question Victrons factory support as I hear they push it all down to their retailers.

Do you still run your Magnum or did you upgrade/change to something else?

Another feature that some of the late model Victron Inverters have is a hybrid mode (Power Assst) it basically allows the inverter to draw power from the battery bank if the shore power is not enough. So if you were plugged into 20 amp and needed a bit more it would make up the difference. I am sure there is a limit but if it worked well it would be good for short periods of time and hypothetically could provide a more stable 110 voltage in those situations that were pushing or exceeding 20 amps. Of course Magnum has a similar feature as well.

Magnum has a very good reputation. I think he means that if you had a really old Magnum, it would probably be better to upgrade the inverter.

As long as you have the capability to manually set all of the charging voltages, you don't need any charging profiles labeled "lithium". 

I replaced the original 2003 xantrex with magnum ms2012 3-4 years ago. This was very close to being a direct replacement for the xantrex, with just slight modification to the mounting and wiring. For me, that was the 80/20 solution. In terms of internet-connected features, Magnum is pretty archaic, but it gets the job done.

Sure, I would love to have a flagship victron hybrid system. It's undeniably cool, totally integrated and has lots and lots of features that magnum doesn't have. But I'm just not willing to go to the trouble and expense it takes to really benefit from all of those features. If I ever do make another big change to my system, it'll be 24v (or maybe even 36v/48v), that's for sure. It's just silly to try and deal with 3kw@12v.

Edited February 23 by wamcneil

[Tom Cherry]

MODERATOR ALERT - PLEASE READ for content and understanding....

Frank McElroy and myself have been monitoring this Topic and feel that there is some misinformation that needs to be corrected…which is the responsibility of the Moderating Staff. Frank has “hypothetically” reviewed a Lithium option if he ever decided to abandon his FLA Trojan T105’s and go “HIGH TECH”. He has a 2008, however all the information below will be pertinent for at least 2005 Imperial/Dynasty and above. I have a different configuration, but try to assist with inverter and charging issues and such.

There are two main issues to discuss first. FIRST…MANY comments about using older Magnum Inverters and such. So, I called Magnum Tech Support and asked specific questions. I had talked at least once or twice to the tech support lady and she has always been very knowledgeable and competent…so no sexist throughs about her NOT being capable of answering and understanding these “High Tech Thingies”. I asked very specific questions and gave very specific scenarios and also asked about issues of reliability and common problems.

Dual IN – Dual OUT. There are TWO 30 Amp breakers in the main panel (to feed the Magnum) and two 30 Amp breakers in the Sub Panel to distribute the power.

·         A Magnum MS2018 (2800 Watt) inverter has ONLY the capacity, via the internal ATS to deliver 2,800 watts. At 120 VAC that is about 23 AC Amps. So…that is the limiting factor.

·         There is a BRIEF (5 second) surge capability of 3,900 Watts or 33  Amps. If that load is greater or lasts for more than 5 seconds, it will trip a breaker.

·         The Dynasty (2005 and higher) have Dual IN – Dual OUT and there are TWO 30 Amp breakers that feed the subpanel.

·         The Dual IN – Dual OUT were designed for appliances requiring 240 VAC. You do NOT DOUBLE the wattage on the internal ATS switch …. thinking it is 30 AMPS per leg…  The rated capacity is based on the Inverter’s output wattage.

·         THUS…for the ease of installation, one needs a Dual IN – Dual OUT 30 Amp inverter. BTW…Victron DOES make this Inverter…it is fairly new. The model that will easily interchange is called:

o   Victron Energy MultiPlus-II 12/3000 Inverter/Charger – 2 X 120V Model

o   Amazon has them for $1,196…and THEY supposedly come from the VICTRON Store. Verify that if purchased, you get all warranties.

UNDER NO CIRCUMSTANCE should you use a Lithium House Bank on any Magnum Inverter in the 2004 range. They will DAMAGE the Lithium batteries. Circa 2014 there were some minor changes. However, that was in Version 5.5.  If you have a 5.4 or OLDER…. FORGET IT.

Misinformation has also been posted or is “out on the net” that you can just TURN DOWN the Charging Percentage to 0% and the Inverter will NOT charge is ERRONOUS. YES, maybe, but the majority of the time NO. So, Magnum says ONLY use Lithiums on 2014 (Version 5.5 or higher), but be aware…there are STILL Major issues and there are reported problems.

Version 5.5 to 5.9 MAY work OK…or NOT. You WILL need a NEW remote…but there are features in the remote that appear to work but do not. The ONE feature that seems to be “OK”, there is a parameter to disable the FINAL (FLOAT) stage. You have to set it to SILENT. BUT some inverters and some remotes will not do this reliably

Version 6.0 is the ONLY Inverter that does have a “good” system for Lithiums. You can select from the NEW Remote…a LITHIUM setting. That Lithium Parameter or Setting actually DOES tell the Inverter that it has…flat out…Lithiums.

OPPS…. if you buy the NEW remote…and it does have the Lithium…and you choose Lithium….and you have a 5.5 – 5.9 Version….NO JOY. The REMOTE does not control or change the Inverter…thus you are going to DAMAGE the Lithiums as they will FLOAT. SOME have tried a “CUSTOM” configuration…Magnum will assist…but there is NO GUARANTEE that it will be reliable.

OK…Common ISSUES. The Inverters are pretty bullet proof…NOT SO THE REMOTES. I and several others have found this out. A faulty or damaged Remote will take a “setup” …and then if you scroll back through….it is gone. A common problem. SO, you MUST have a NEW REMOTE…preferably with a Version 6.0 to have the MOST reliable system. For those that understand, it IS possible to do a SOFT or HARD Reset…and NOT have the Remote hooked up. The Magnum, since day ONE, will install or work off the DEFAULT settings. They are in the manual. BUT they are for 3 stages of charging and FLOODED cells…used to be 450 AmpHr…NOW 600 AmpHr. SO, if you were like me and needed to keep the batteries charged in storage and had a defective remote…you did the reset…without the meter…and then put it to bed…and later installed a NEW remote. This is MORE common that folks think…

FINALLY…  Magnum does NOT make a Charger/Inverter designed exclusively for Lithiums.

She closed, after our discussion, and said that NOW, at least 50% of the Tech Support calls were “How do I make it work?” She said that owners are NOT doing any homework nor reading nor calling first. They then get caught up in the Hype and buy Lithiums and then wonder…How do I make it work? She said that individuals calling like me for information and then posting it various places and dispelling the myths and misinformation would definitely make their jobs easier and also save customers a LOT of money.

In the end, she said that MOST of the phone calls ended up with the SAME ADVICE. Based on the age or version of your inverter/charger, you would be well advised to purchase a NEW Version 6.0 (maybe higher) and a NEW Remote. Otherwise, your investment in premium Lithiums will most likely be LOST and the Lithium batteries are NOT REPAIRABLE…

OK…. that is what I was told….and what we, the Moderators believe, is correct…based on our knowledge over the past 15 or so years or so…. This post is long….so the “BEST SOLUTION” discussion will be a NEW POST….

 

 

[bryan browne]

Got a lot of info from you guys again. This time Im less Warm and Fuzzy with changing my 2007 Dynasty to Lithium as I thought I was. I have learn I know a lot less than I though when gthering my materials for the swap.

I will keep reading and learning so thanks for your knowledge.

Edited February 23 by bryan browne

[Tom Cherry]

MODERATOR NOTE...Please READ for CONTENT and Understanding...

SECOND POST. This is a summary or discussion of the “simple fix” solution presented previously. Frank and I have been debating and discussing….so here goes.

HOUSE BANK. Lithium Batteries.

Per the previous post…if one has the older Magnums that the two main posters are discussing…. there is NO FIX….to use them.

NOW…an OFF THE WALL solution…totally a BRAIN GAS EXPULSION. One COULD purchase a 150 A Rectifier Diode. There ARE many listed…some are high voltage. I think it would be preferable to have on in the 12 – 24 VDC range… You NEED 150A as the Magnum will put out up to 100 or maybe a smidge higher. Then cable in the Diode so that the current will FLOW from the Lithiums to the Magnum Inverter. You would THEN need a specific Lithium charger…probably in the 100 Amp size. It should be a high quality and not a cheapie. THEN you charge the Lithium Bank from it. It SHOULD keep the bank fully charged…and then the Diode, IN THEORY, would prevent the Charger from passing current back. NOW…this was NOT a topic of discussion with Magnum. There is NO WAY to totally DISCONNECT or prevent the Charger section per Magnum Tech Support.

Will ALSO need a GOOD Quality Lithium Charger…probably in the 50 Amp range for “BULK” charging….

OR…. most LOGICAL…purchase the Victron Dual IN – Dual OUT listed in the previous post. That is the MOST reliable…and probably the CHEAPEST. That is all the MOST BULLET PROOF…Frank and I discussed and totally agree…get RID of the OLD Magnum…otherwise…Murphy will come in and cost you BIG TIME.

CHASSIS BANK. Two options….

CHEAP…. Recable the Magnum to the Chassis. Use the Block Heater outlet to power. That will provide GOOD and RELIABLE Charging. Options if you want MORE inverted power…Use the Block Heater Outlet….20 Amps will work just fine. BUT if you do NOT have room or space for TWO Chargers…then abandon the Magnum and do the following…

OPTION…more $$..  Purchase a THREE State high end Charger. YES, you only need 5 amps to maintain…but if you run down the Chassis or need to put a quick charge…you probably need a 50 Amp Model. Use it in lieu of the Magnum

BOOST…Two options...

The cheapest and easiest is the solution about using a SPDT (Center OFF would be best) selector switch to Power the Big Boy Coil. NOW, this assumes that the Big Boy is OK or marginally OK. If you have a GOOD coil, then clean the contacts. That is simple…and will work. You will NOT use this often. You DISCONNECT the 8 Pin from Board 6 and utilize the GROUND signal coming from the Front OEM BOOST SWITCH.

BUT if you want to spend a little or the Big Boy might not be OK…install the ML-ACR with the remote wiring required to the front and the full “CONTROL” system. NOW…you could purchase a NEW Big Boy for maybe half that and not have to run the new harness….

It just DEPENDS…BOTH, properly installed WILL WORK

We think that is the EASIEST to do and makes the most sense…NOW THAT ALL THE MYTHS about the Magnum and Lithiums have been addressed…

 

 

 

 

[John C]

On 2/22/2024 at 5:43 PM, wamcneil said:

Sure. You could use two dc-dc converters. That’s not much different from the two battery isolators originally on my dynasty. 
Might need to have a switch on them so only the one that you need is active 

The Victron DC to DC has a cut of voltage, if you set it both charge at right voltage they will be only one charger active at one time. One will be activated when engine is on and another will be on when engine is off

[PTTech]

22 hours ago, wamcneil said:

I replaced the original 2003 xantrex with magnum ms2012 3-4 years ago. 

Can I ask why you replaced the Xantrex? Do you know if

the same issues apply to charging lithium with the Xantrex as the Magnum?

[Ivan K]

7 minutes ago, PTTech said:

Can I ask why you replaced the Xantrex? Do you know if

the same issues apply to charging lithium with the Xantrex as the Magnum?

I was thinking the same when I compare Battleborn's recommendations to my old Xantrex's specs. What would the problem be here?

[wamcneil]

2 hours ago, PTTech said:

Can I ask why you replaced the Xantrex? Do you know if

the same issues apply to charging lithium with the Xantrex as the Magnum?

Something went haywire with the xantrex built in AGS. Every time I would start the generator, the AGS would shut it back down. That was the primary motivation. Thought that might be a sign of bigger failures in the future. Plus I wanted true sine. Did lithium and solar shortly after replacing the inverter. 
I never really looked into how customizable the xantrex charger is

Edited February 24 by wamcneil

[Tom Cherry]

2 hours ago, Ivan K said:

I was thinking the same when I compare Battleborn's recommendations to my old Xantrex's specs. What would the problem be here?

MAIN PROBLEM.  If one has a THREE stage charger, with a FLOAT….NOT GOOD.  The Lithium does NOT, per Magnum, work or stay charged when there is any FLOAT charging for an extended period.  That is why Magnum added to SILENT mode, as in DISABLING the FLOAT step.

Now, case in point….Local Tesla owner could not get or did not want to pay for a “Lithium” Low Voltage battery.  The main drive battery in an EV is higher voltage and the CHARGER is built in.  Tesla, and I am told, OTHER EV’s, have a supplemental or conventional 12 VDC Deep Cycle battery.  Tesla got FLACK for a cheap FLA/SLA battery….the owners wanted HIGH TECH…LITHIUM.

This supplemental battery runs conventional items like radio, door locks, etc…to keep the range UP.

A well intentioned and obviously HIGH TECH individual locally watched the YouTube and popped out the supplemental or low voltage.  He carried into his kitchen and put it on the granite countertop in the kitchen…then popped a NAPA or WallyWorld 12/6 V 8/4 A charger and left.  Then the Lithium shorted….exploded and caught fire.  Major damage to the $1.5 Million home and his neighbor who tried to extinguish it with a conventional fire extinguisher breathed a lot of toxic fumes.

Thus, the Xantrex, Magnum or Battle Born (which has a FLOAT) are totally unacceptable or not for Lithium…

See my post on the Q&A yesterday with Magnum….

[Ivan K]

Interesting, even my Victron solar charger has a float of 13.5V for LiFePo4 setting and Battle Born indicates that while not necessary, 13.6V and below is OK for float:

• bulk and absorption: 14.2-14.6 volts (aiming for a sweet spot of 14.4 is recommended) 
• float: 13.6

[Tom Cherry]

1 hour ago, Ivan K said:

Interesting, even my Victron solar charger has a float of 13.5V for LiFePo4 setting and Battle Born indicates that while not necessary, 13.6V and below is OK for float:

• bulk and absorption: 14.2-14.6 volts (aiming for a sweet spot of 14.4 is recommended) 
• float: 13.6

Is your Victron Solar rated for Lithium?  I know a little about Lithiums...learning MORE daily....  They do NOT like to be charged like Deep Cycle... as in having a "Float or constant low amperage current".. it upsets their insides and they have "gas pains"... 

Should I use float chargers or battery maintainers for my lithium battery?

No, LiFePO4 batteries should be disconnected from the charger when fully charged. Float charging, or maintainers are not good for lithium batteries. Keeping a constant float charge or topping off charge also can cause metal plating and will reduce the lifespan of lithium batteries. Dakota Lithium batteries also have a low self-discharge rate of <5% a month. This low self-discharge rate makes a battery maintainer for long term storage un-necessary (for more on battery storage see section below).

Right from the "Horses" Mouth...

https://community.victronenergy.com/questions/163662/float-lithium-manufacturer-says-no.html#:~:text=Float charging%2C or maintainers are,of <5% a month.

That is exactly what I learned from a Buddy that actually took apart a Mercedes Benz Hybrid Battery and he is really sharp and read a lot before he cut it open. If you read, I THINK, the specs on Lithium ONLY chargers, I would expect that they do NOT call out a FLOAT charge...remember the guy locally..

So if you Solar has a FLOAT, I would NOT think it would be advisable to use on a Lithium bank...call Victron and ask them...but the above is pretty straight forward...as well as coincides with what the Magnum Tech Support told (and hammered into me)...LOL.

[Ivan K]

I know that lithium are happiest with below top voltage when unused but yes, the Victron charger has a default setting for lithium to include float, of course it also has custom option to change it all to whatever else.

[wamcneil]

Tom: do you have a lithium battery??? Just wondering if you have skin in the game 

[Tom Cherry]

11 hours ago, wamcneil said:

Tom: do you have a lithium battery??? Just wondering if you have skin in the game 

No, and I don’t plan, unless there is a major failure of my Magnum to go that route. But if I do, I now have sufficient information to make an intelligent and cost effective decision.

Since 2009, I have learned a lot about the Monaco Charging systems and the differences in the various configurations from the early 2000’s up to the REV models,

What I have posted here is based on conversations with Trojan and Lifeline and Magnum and Blue Seas and friends who are scientifically and electronically well versed…as well as reading a lot,

I don’t need “skin” in the game.  We have a LOT of folks here that understand the basics, which I do, as well as the practical experiences.  Unfortunately many have learned what NOT to do, the hard way and asked for help..as is happening with Magnum. Some of our experts have avoided this thread as it was “difficult to grasp and too many comments, some incorrect, had been made”. That is a pity, but group dynamics rule.

When this topic started it was interesting.  The overall premise was that the Dynasty is one of the models that we have the least input or experience on.  That being said, we the moderating staff, have been following it and learning nuances and often see  comments that were incorrect.

So, my “SKIN” in the game, as well as others on the staff, is to provide factual information or ask pertinent and intelligent questions.  It is the charter of the site to allow vendor supplied information or member’s postings that are “First ..do no harm”. As this evolved, then conceptually, we developed a scenario that would be best suited for the Dynasty as their systems are unique

Likewise, if we learned something that would benefit all members, whic was discussed and reviewed as a group, then it was posted.

There may come a time…if prices drop…that I decide to convert. but every member should be as knowledgeable as we are and then carefully plan, design, test the circuits for “will it work” and then proceed to implement.

I hope this answers your question as well as an explanation.

If at anytime, something is misstated, then we need to correct and edit. We do that constantly so the a comment, “read somewhere on the net” which is totally incorrect will not appear here as fact….that covers every subject..just not only lithium’s,

[Grey Goose]

16 hours ago, Ivan K said:

Interesting, even my Victron solar charger has a float of 13.5V for LiFePo4 setting and Battle Born indicates that while not necessary, 13.6V and below is OK for float:

• bulk and absorption: 14.2-14.6 volts (aiming for a sweet spot of 14.4 is recommended) 
• float: 13.6

"Float" seems to be sort of a generic term depending on the manufacturer. I assume in your case a lower voltage (float) would prevent over charging the battery while still maintaining the SOC.

[Tom Cherry]

12 minutes ago, Grey Goose said:

"Float" seems to be sort of a generic term depending on the manufacturer. I assume in your case a lower voltage (float) would prevent over charging the battery while still maintaining the SOC.

Per MAGNUM, float is defined as “continuous” current AKA Voltage.  Float connotation is “LOW” current. Magnum said that in some cases, turning off or setting the charge rate to ZERO might work, but there were reported instances (Lithium batteries failed or were damaged) with just 3 or 4 amps.  Therefore, they say all their Inverters, up to a certain level should NOT be used with Lithiums.  Any voltage, sustained….as in”float” is not recommended.

See the Q&A post with Magnum’s tech support input.  This also mirrors Victron’s  FAQ.  Two stage is fine….preferably with a charger designed for Lithium….but not any float or maintenance cycle.

 

[wamcneil]

Float is a voltage set point. 
If float voltage is higher than the resting voltage of the battery, a current will be induced. This is the case with a lead acid battery. 
If float voltage is lower than the battery resting voltage there will be no current. That’s what happens with a lithium battery. 
The lithium chemistry doesn’t need to be float charged, and the battery lifespan will be shorter if continuously held at 100%. That’s why a lithium charge profile will end without holding a float voltage. 

Edited February 25 by wamcneil

[Grey Goose]

16 hours ago, Ivan K said:

I know that lithium are happiest with below top voltage when unused but yes, the Victron charger has a default setting for lithium to include float, of course it also has custom option to change it all to whatever else.

 

54 minutes ago, Tom Cherry said:

Per MAGNUM, float is defined as “continuous” current AKA Voltage.  Float connotation is “LOW” current. Magnum said that in some cases, turning off or setting the charge rate to ZERO might work, but there were reported instances (Lithium batteries failed or were damaged) with just 3 or 4 amps.  Therefore, they say all their Inverters, up to a certain level should NOT be used with Lithiums.  Any voltage, sustained….as in”float” is not recommended.

See the Q&A post with Magnum’s tech support input.  This also mirrors Victron’s  FAQ.  Two stage is fine….preferably with a charger designed for Lithium….but not any float or maintenance cycle.

 

My point is Victron uses the float term for its second stage of charging. 

It basically uses bulk to 80% charge (also known as constant current) and then it goes to "float" (second stage) which is constant voltage. Assumption is this second stage would maintain charge to offset a load on system and or time out and stop charging at a certain period of time if there is no load. But either scenario would prevent the battery from being overcharged.  Of course it depends on how the user sets the parameters  for the second stage/float voltages and will vary depending the manufacturer of the LifePO battery.

My main point is that "float" may be configurable based on the battery chemistry/charger and not necessarily taboo as far as LifePo is concerned. 

Edited February 25 by Grey Goose

[96 EVO]

16 hours ago, wamcneil said:

Tom: do you have a lithium battery??? Just wondering if you have skin in the game 

I have a couple of E-bikes! That count 😄?

I charge them to roughly 80% charge 3 or 4 times, then charge 100% to balance the cells on the 4th or 5th charge.

Even Musk agrees that will give your lithium's their longest life.

[wamcneil]

44 minutes ago, Grey Goose said:

…Assumption is this second stage would maintain charge to offset a load on system and or time out and stop charging at a certain period of time if there is no load. But either scenario would prevent the battery from being overcharged.  Of course it depends on how the user sets the parameters  for the second stage/float voltages and will vary depending the manufacturer of the LifePO battery.

My main point is that "float" may be configurable based on the battery chemistry/charger and not necessarily taboo as far as LifePo is concerned. 

When docked, I actually don’t use the magnum  “lithium” profile for this reason (mainly…). I have the float voltage set to maintain about 50% and once the battery voltage falls to that point, the charger supplies whatever the load is. 
Lifepo4 cells have a maximum voltage of something like 14.6v (3.65 x4). So if the voltage set point is lower than 14.6v, the battery won’t be overcharged. The battery will last longer if not held at a high voltage, but float voltage cannot drive current through the battery if the battery resting voltage is at or below float voltage. 
Something important that I forgot to mention earlier…. The battery temp compensation should be turned off, or if it can’t be turned off (ie- magnum charger), then unplug the temp sensor. Otherwise in cold temperatures it will crank up the voltage set points.

Edited February 25 by wamcneil

[Grey Goose]

 

7 minutes ago, wamcneil said:

When docked, I actually don’t use the magnum  “lithium” profile for this reason (mainly…). I have the float voltage set to maintain about 50% and once the battery voltage falls to that point, the charger supplies whatever the load is. 
Something important that I forgot to mention earlier…. The battery temp compensation should be turned off, or if it can’t be turned off (ie- magnum charger), then unplug the temp sensor. Otherwise in cold temperatures it will crank up the voltage set points.

By "crank up" do you mean exceed the settings or just go to max voltage setting? I assume you are using CC/CV or customer settings.

Edited February 25 by Grey Goose