Questions about AGM -> LFP

[booster]

Originally Posted by hbn7hj

SOK allows the battery to be opened. You could disable the Bluetooth if you wished. I choose not to order it

Did you locate the converter circuit breaker?

On the SOK is it a separate module you can cut out or how does that work? I assumed it was turned on by programming software.


The plastic case, "marine" SOK batteries are sealed, but the steel case ones are openable, and serviceable, it appears.

[hbn7hj]

Marine is sealed with a large O-ring. Allen head screws open it up. A little surgery on the BMS to kill the bluetooth which they will tell you how to do. Will Prowse has a disassembly video on the 206AH.

It will take me a week or two to see how well it charges.

[Urlauber]

Originally Posted by hbn7hj

Did you locate the converter circuit breaker?

Not yet. I believe to test this it would either have to be plugged in, or the generator running. Will report back when I have a chance. It could be the bottom one, but that could be a "spare" as well and not be connected. I think they would have labeled it. Maybe.

[JonMN]

I have also been considering changing to lithium, and also want to make sure I can start my Onan 2800. I was surprised at the differences in the battery specs for surge current.

From all the brands I looked at, Battleborn seemed to have the highest surge ratings. For example, their 100Ah 12V battery has a surge rating of 200 amps for 30s seconds. Chances are pretty good that this would start a generator.

[Urlauber]

Originally Posted by JonMN

I have also been considering changing to lithium, and also want to make sure I can start my Onan 2800. I was surprised at the differences in the battery specs for surge current.

From all the brands I looked at, Battleborn seemed to have the highest surge ratings. For example, their 100Ah 12V battery has a surge rating of 200 amps for 30s seconds. Chances are pretty good that this would start a generator.

Have you looked into the option to rewire some and use the chassis battery to start the generator?

[booster]

Originally Posted by Urlauber

Have you looked into the option to rewire some and use the chassis battery to start the generator?

No rewiring normally needed to do that. Most B's all you need to do is put in a switchable separator instead of an isolator or auto connect only separator.


Don't need to do anything is you start the van engine as they will connect all be themselves.

[booster]

Originally Posted by JonMN

I have also been considering changing to lithium, and also want to make sure I can start my Onan 2800. I was surprised at the differences in the battery specs for surge current.

From all the brands I looked at, Battleborn seemed to have the highest surge ratings. For example, their 100Ah 12V battery has a surge rating of 200 amps for 30s seconds. Chances are pretty good that this would start a generator.

Are you looking at only one 100ah battery?

[JonMN]

Originally Posted by booster

Are you looking at only one 100ah battery?

Hi! I thought the OP was looking at just one battery, so I checked on specs for the 100ah.

[My van has a single 330Ah AGM size 8D, so I have seen several 300Ah lithium in the same size/shape.]

[Urlauber]

Originally Posted by booster

Are you looking at only one 100ah battery?

Originally Posted by JonMN

Hi! I thought the OP was looking at just one battery, so I checked on specs for the 100ah.

[My van has a single 330Ah AGM size 8D, so I have seen several 300Ah lithium in the same size/shape.]

Correct, planning on a single 100Ah battery. Like I said in the initial post, my energy demands are rather low, and usually more than offset by the 190W Solar Panel. It sends about 10A to the battery, so depending on location and direction etc it will recharge the batteries by afternoon.

Biggest consumer is the fridge, it eats about 55W when compressing, no idea what percentage of the time it does that, depends on many things obviously.
The roof fan takes 14W on its low setting, 20 and 28 respectively on medium and tornado setting, which we usually don't use.

We don't use the inverter, lights are all LED, plus we have camping lanterns that light up things separately. Gas solenoid 10W, only used when cooking (or in Winter for the Truma). Water pump is negligible.

I mentioned before and in some other places that I have a 1220Wh power station which can run the car for 2-3 days. That is WITHOUT solar input which, I would say, I have available maybe 90% of the time. So I could take that along as well and double the Amps to 200. I can also charge that separately with a 100W folding panel I happen to have.

And, if necessary, I can run the generator for a little bit to recharge the battery. With the 55A converter it would take 2 hours in theory, not complicating it with absorption and stuff. Again, this should be the exception.

Most of our outings are (at the moment at least) long weekends with 2-3 nights. If that should change in 5 or 10 years when/if I retire then I can add a second battery or replace it with a 200A one.

Makes sense? Again, this is just thinking through the possibilities, with finding a electrician/mechanic and a potential home for two AGM batteries as a first step. I like learning new things, and surely make a lot of mistakes along the way. Thanks everyone who contributed so far, maybe one day I can pay some of it back.

[W9TR]

Originally Posted by Urlauber

Thank you for the replies, very helpful in thinking this through.



2) Understood, but I feel that most of the time I do NOT want to charge via the alternator. It would tend to always fully charge the batteries on my way back from my usually short trips, and LPF batteries are happier when NOT fully charged all the time while waiting for the next outing. I would make the Solar input (off-) switchable as well to be able to further control that and only charge it to 100% shortly before leaving.

4) It is a WFCO WF-8955PEC

5) Charge sources would only be Solar, and generator/hook-up via the converter.

Good point about the current needed to start up the Generator. I read that too, where someone was doing this switch, but with larger LFP batteries. With a single 100Ah battery it may be iffy. I don't see fuses for the Generator, so not sure. It's one of the quiet-ish Onan 2800i, fed by propane.

I was thinking about re-wiring it to the Chassis battery, that might work, although add a bit to the overall hassle with the additional connection.

The other thing I was wondering about is the switch which somehow connects the batteries to either start up the vehicle with the house batteries or start up the generator with the chassis battery. I assume something would go "boom" if I would do the described drop-in and the LFP battery would be lower in voltage than the chassis Lead Acid one. Maybe it could be re-purposed as the Generator startup button, lol. Being able to recharge a depleted chassis battery from the house battery sounds like a good thing too, although most of the regular cars do OK without it.

I'd definitely need to find someone who is very good and familiar with the electrical setup of these beasts.

I’ve measured the 2800 generator startup current with a DC clamp on ammeter and it is less than 100A @ 40F.

I have a Thor Tellaro 2020 20AT and it has a lot of the same components are your van.

Your van has a BIM 160 battery isolation manager. As-is it will charge your lithium batteries to about 80% off the engine alternator since the chassis battery charges at a lower voltage than the Lithium battery you intend to install. So you don’t really need to do anything here.


The WFCO 8955 PEC is also an AGM charger and will charge Lithiums to 80%. It may exceed this in bulk charge mode but you’ll need to try it out. You have full control of this anyway so not a big deal.

The Solar controller can be set to Lithium where it will fully charge a lithium battery. You can add a switch between its output and the battery if you really want to keep charge at 80%. I wouldn’t bother, see below.

The 80% rule isn’t really a huge factor for LiPO4 based batteries. I liken it to the ‘don’t discharge AGM’s below 50% rule’. There may be a slight life penalty but it is insignificant and way overblown by self-styled internet experts. So don’t sweat it.

I have researched the heck out of this as I have been a abusing my AGM batteries for 3 years now, routinely running them down to 10% SOC. I figured I’d have to replace them any day now. But after 3 years they are holding strong and I’m not replacing them until they are at reduced capacity.

[Urlauber]

Thank you for chiming back in, always good to hear from someone with similar model/thoughts.

Originally Posted by W9TR

I’ve measured the 2800 generator startup current with a DC clamp on ammeter and it is less than 100A @ 40F.

That is close to what a single LFP is capable of... something to keep in mind. I don't think I have a way to measure the amps, and my propane 2800i starts up almost instantly. Certainly don't want to trigger the BMS. Of course, if it can provide 300A for a few seconds it may be fine. Would need to inspect the battery spec sheet closely.

Originally Posted by W9TR

I have a Thor Tellaro 2020 20AT and it has a lot of the same components are your van.

Your van has a BIM 160 battery isolation manager. As-is it will charge your lithium batteries to about 80% off the engine alternator since the chassis battery charges at a lower voltage than the Lithium battery you intend to install. So you don’t really need to do anything here.

From what I have read, the problem is that an exhausted LFP battery will draw more amps from the alternator than what it is capable of. Not sure if the existing BIM prevents that, but I think not, that's why most folks upgrade to the 225 or equivalent.
However, like I said, I don't really want to continue charging via the alternator at all, so no BIM or any DC-DC charging as I plan on starting my trips with a full battery and use solar charging to keep thing from bottoming out.

Originally Posted by W9TR

The WFCO 8955 PEC is also an AGM charger and will charge Lithiums to 80%. It may exceed this in bulk charge mode but you’ll need to try it out. You have full control of this anyway so not a big deal.

Yes, I hope this is how it will work out. I don't quite understand the background of 'not charging to 100%' as the voltage to do that really only needs to be 13.6V or so, but maybe it will incorrectly think the battery is full since at that voltage it takes forever to trickle it full. In any case, charging it to 80% should be just fine. Just slightly skeptical of these statements as I understand it is difficult for chargers to determine the 80% point due to the flat charge curve of LFPs.

Originally Posted by W9TR

The Solar controller can be set to Lithium where it will fully charge a lithium battery. You can add a switch between its output and the battery if you really want to keep charge at 80%. I wouldn’t bother, see below.

The 80% rule isn’t really a huge factor for LiPO4 based batteries. I liken it to the ‘don’t discharge AGM’s below 50% rule’. There may be a slight life penalty but it is insignificant and way overblown by self-styled internet experts. So don’t sweat it.

Yeah, hoping the solar controller will fully charge the batteries and take care of any cell leveling etc. I don't think one would want to add a switch on the controller output, as that may fry the controller if I understand that correctly. I would add one before the controller, which also gives me a neat way to use the panels to recharge my power station as needed.

Originally Posted by W9TR

I have researched the heck out of this as I have been a abusing my AGM batteries for 3 years now, routinely running them down to 10% SOC. I figured I’d have to replace them any day now. But after 3 years they are holding strong and I’m not replacing them until they are at reduced capacity.

Good point. I am amazed that apparently a (plain no name) LFP battery can be cheaper (~300) than a single Group 31 AGM battery that is currently installed in my camper (Trojan Motive Overdrive). This will probably play a role when I decide where to put it and how to protect it (from heat and splashes, mostly).

[W9TR]

I’m a member of the Thor Tellaro and Sequence Owners and wannabes Facebook group. Several owners there have replaced their AGM batteries with LiPO4 batteries. All have replaced the converter in the WFCO to the lithium version. About $225. One us replaced the BIM 160 with a BIM 225. One added a DC/DC converter. All changed the solar charger to its Li setting. All are reporting great results.

For me, the juice is not worth the squeeze. The upgrade doesn’t really give me more capability. So I’ll continue to abuse my Trojan AGM batteries and cross the Lithium bridge only when I have to.

Good luck with your mod. Seems like a lot of effort and questions for a modest weight reduction.

[Urlauber]

Originally Posted by hbn7hj

Did you locate the converter circuit breaker?

You were correct! Going over wiring diagrams, it looks like the 5th breaker does the converter. Thank you - no need for another switch then.

[Urlauber]

So I took some wiring diagrams and played around with them, combining different things into one big, but simplified mess. Here is what came out of that:



Then, I greyed out the components that I want to remove or disable, and added the missing Solar Controller.



Of course, some things are absent. Like the "emergency switch" which allows starting the van using the house batteries. Anyone know how that is wired in, and if it could cause any issue (assuming full house battery and empty chassis battery). I think it might work (...sniffing around for burnt plastic... )

[Urlauber]

When it comes to placing the LFP batteries, is there anything fundamentally different from AGM APART FROM TEMP LIMITS?

Are they intrinsically more fragile and prone to explode when there's some splashing?

Stuffing them into the same carrier that holds the AGM underneath the camper makes some sense wrt cabling and such.

Again, I realize they can't be used/charged when frozen, and excessive heat cuts into their lifespan.

[@Michael]

Originally Posted by Urlauber

When it comes to placing the LFP batteries, is there anything fundamentally different from AGM APART FROM TEMP LIMITS

AFAIK the case material is much tougher on AGM & ordinary lead-acid batteries, so they tolerate cold better. And AFAIK sealed lead acids & AGM's are sealed against weather & hence more weather-resistant.

[Davydd]

I've had two different types of lithium ion batteries installed in my two vans both inside and outside going on 9 years with no problems with heat or cold in over 120,000 miles of driving and I live in the frozen north of Minnesota and have camped in -15 degrees F. in the UP of Michigan. Have you ever heard of house lithium batteries exploding or shorting out or whatever with splashing in a Class B? I'd never go back to AGMs.

I will say, unless you desire high battery capacity of more than 400ah or more (mine were 800ah an 576ah) you are wasting your time and money considering lithium ion. That's just my opinion. The weight advantage and the higher capacity in a smaller profile is the advantage other than a longer lifetime. I couldn't achieve that in either of my vans with AGMs. Now that I have had both, I do prefer them inside the van.

[Urlauber]

Thank you M!

Is this mainly because those older batteries contain corrosive acid and heavy metals? Or because LFP batteries are made to be used in other, gentler applications?

I guess further encasing it would be an option, with the downside of reduced ventilation.

[booster]

The underbody of the van is a very hot area and likely too hot for lithium batteries, that are more sensitive, it appears, than AGM are. If hung underneath you would likely need to encase and insulate them and add some fan forced ventilation like Avanti did on his new van. Our AGM are hung underneath with a bit of heat shielding/deflecting but we over see 120*F on them even when they are not being charged our used, if the weather is hot and sunny. It appears to me, based on a lot of the more recent recommendations are, that the upper end for high temps being listed in specs is really too high if it is more than a very, very rare happening that they get that hot. Lithium specs have gotten very much tightened to the conservative side in the last year or so, compared to very wide open ones they touted 5 years ago when all the lithium stuff started.

[Urlauber]

Very good points, thank you! I read Avanti's thread and solution. I think it is good, but harder to implement in an existing configuration. There's a place behind the fridge that has a hole in the chassis floor, which I could probably turn into a duct with a fan.

Have to think about this some more. There is room for a battery behind the driver's seat, but I'd rather use that for something else. Plus, the wiring is gonna be a PITA.

In our area Temps are generally mild, just as few weeks in late summer when they approach 100. However, we probably do a trip to the southwest every 2 or 3 years, where it may get mighty hot under there.