An ultimate lithium RV Battery?

Phil G. · 01-17-2021, 04:26 PM

(Below is a near copy of a post of mine from another RV forum that I thought might be of some interest here, too.)

We don't yet have lithium batteries in our Itasca 24V Class C motorhome, but I follow lithium battery technology to keep informed just in case.

In many Class C motorhomes storage is at a premium, so area for installing a "larger than normal" battery bank is hard to come by without giving up some other valuable built-in storage area needed and intended for other things.

Like many Class C motorhomes, our stock battery compartment is located under the entrance step. This area in our motorhome can nicely hold two Group 31 size 12V batteries connected in parallel, so for years I've had two Group 31 12V AGM batteries mounted there. My current two Group 31 AGM batteries under the step are rated at 115 AH each, for a total usable capacity before charging them, of around 115 AH (50% state of charge for the two in parallel).

However - since popular lithium 12V batteries currently being used in RVs can be discharged without damage down to way lower than 50% SOC - a couple of the popular 100 AH 12V lithiums mounted under my step would provide a total usable capacity of 160-180 AH ... a nice upgrade should I go for it.

HOWEVER and WOW -> I recently discovered these Group 31 size 12V lithium batteries: https://www.lithiumion-batteries.com...on-battery.php

These Group 31 size 12V lithium batteries have typical Group 31 dimensions, so two of them would still fit under my Itasca's step ... BUT THEY'RE CLAIMED TO HAVE A CAPACITY OF 200 AH EACH!! So two of them would provide DOUBLE the usable capacity (320-360 AH total) ... over what the common popular 12V Group 27/31 size 100AH lithiums would provide.

Are these batteries real - assuming I could live with their 60 lbs. each and $1999.99 each ... or am I misreading something?

Winterbagoal · 01-17-2021, 04:50 PM

The size and 2 X weight seems a little odd.
If they're GR31 sized, but weigh twice as much as many other 100Ah LiFePO4 batteries of the same dimensions, where is the extra 30 lbs coming from? Double density lithium iron or phosphate? Hmmm? They've found a way to pack twice the power into the same physical space?
The price seems about right for double the capacity.
They're located in Florida. You could call and ask. Or send them an email.
https://www.lithiumion-batteries.com/ContactUs

MicroMinnie · 01-17-2021, 07:16 PM

That's quite expensive or that capacity (imho) but guess their warranty is solid plus local.

But If you're technically inclined you can build 400AH very clean for << $2K ,
something that fits right in group31 x 2

Switching to lithium would also require a DC-DC charger in your case plus maybe some solar charges changes (if you have it)

Winterbagoal · 01-17-2021, 07:38 PM

The Chargex Battery (lithiumion-batteries.com) website says they're drop in replacements for the FLA batteries of the same size GR31. Why would you need a DC to DC charger? The battery manufacturer suggests on their website...
"This 12V 200AH Lithium Ion Battery is the perfect replacement from a group 31 AGM, GEL or Lead Acid Battery. Designed as a "drop in replacement" meaning all you have to do is take out your old group 31 battery and place the Lithium Battery in the same way."
They do suggest you might have to tweak your solar charger settings to lithium, but that if your converter/charger or inverter/charger has an AGM setting that will work. LiFePO4 and AGM FLA charge profiles are very similar.
The price/Ah, and weight/Ah are approximately right for a 200Ah lithium iron phosphate battery (I have 2 X 100Ah Relions), but I still don't get how they double the amp hours in the same sized package?

MicroMinnie · 01-17-2021, 07:46 PM

DC - DC will prevent the alternator from cooking
The lithium batteries will take more than the alternator can take. AGM or Flooded don’t have that problem as they don charge at that high rates.

Must be a new chemical trick. it’s interesting for sure my 100ah battery takes about 70% of the group 31 box.

Winterbagoal · 01-17-2021, 08:43 PM

Quote:

Originally Posted by MicroMinnie

DC - DC will prevent the alternator from cooking
The lithium batteries will take more than the alternator can take. AGM or Flooded don’t have that problem as they don charge at that high rates.

Must be a new chemical trick. it’s interesting for sure my 100ah battery takes about 70% of the group 31 box.

Do you know anyone that's cooked their alternator, or is that just the "recommendation" of some of the sites that sell DC to DC chargers, like Victron? Yes, they've managed to fail some alternators under their test conditions, on the test benches in Romania or or Amsterdam or wherever they're from, but I haven't read of anyone burning up their alternator after dropping in a couple of lithium batteries, plug and play, like I did. I have put over 4,000 miles on my Relions/MB 220A alternator combo, PD 9245 converter/charger with Charge Wizard Pendant, and a Zamp ZS-30A PWM solar charge controller, with no ill effects. That is real world anecdotal experience. Not just an opinion, or something I read somewhere. Not a generalization like "The lithium batteries will take more than the alternator can take."

Phil G. · 01-18-2021, 12:30 AM

Good points above on lack of real world experiences with alternators burning up trying to recharge thirsty RV batteries - lithium or otherwise.

Aren't modern alternators protected from burning themselves up ... anyway?

The little 130 amp Ford OEM alternator spun by our motorhome's V10 gas engine does just fine year after year keeping charged A) the large OEM engine battery I installed under the hood that's the battery model used in Ford diesel trucks, and B) the twin 115 AH deep cycle coach batteries (for a total of 230 amp hours) I installed in our motorhome.

I have a permanent ammeter installed in the cab that shows current into, and out of, our motorhome's two coach batteries. I sometimes idle the V10 to recharge these coach batteries and at times the ammeter has shown over 70 amps flowing into the coach batteries during this time. The V10 is only turning around 550-600 RPM when doing this, but of course the alternator is turning much faster due to it's over-driven pulling arrangement.

I don't know exactly what makes up this Ford alternator charging system, but it can delivery pretty good amps for awhile into the coach and engine batteries, in combination.

Winterbagoal · 01-18-2021, 06:35 AM

Modern alternators have built in technology to avoid over heating.
Low RPM charging, like at idle, are the situations where some suggest there may not be enough airflow to keep them cool, so they start reducing their own output accordingly, as I understand it.
For a battery to "demand" a lot of current, it would have to be really depleted, to start, and that's not a normal situation for me, I guess. My alternator is a 220A and my entire coach battery bank is 200Ah. Maybe my system isn't prone to having this problem.
Either way, I still haven't seen a lot of folks say their lithium drop in batteries have burned up their alternator, except under controlled conditions on a test bench. It is possible, but I don't think very likely in the real world.

Elkman · 01-18-2021, 03:56 PM

A battery is not going to burn up an alternator unless there is a bad cell which can greatly increase the resistance on the circuit. More likely the alternator was failing already and so not properly charging the lead acid batteries.

Lihium phosphate batteries can take more than 4 times the charge level of lead acid batteries and that translates into much shorter generator run times to get them to 100% SOC and also enables the solar panels to be more effecive during daylight hours.
Good idea to change the charger settings on the Xantrex and the Zamp chage controllers to lithium from flooded type batteries for faster charging.

I ordered my two Lithionics125AH batteries from J.R. at offthegridrvs.com and paid $2898 in total to have them shipped from the factory in Florida to my house in California.

misteracng · 01-18-2021, 07:59 PM

This 200AH battery doesn't make sense to me, but it would be amazing if it was true. All other Group 31 lithium batteries seem to be around 100AH each, and the lithionics being the highest I have seen at 125AH, also being more expensive, but with a nice built in bluetooth battery monitor. Looking at there pictures, it seems they are using 5AH cells, 3.2volts each. Would seem they wire 4 in series to get 12.8volts? and then there are 5 columns in parallel, giving 25AH. Then the picture shows 4 of those 20 battery sets which should give 100AH? I am not an electrician, does that seem right? I don't see how they get 200AH. If it were 2 group 31 at $2000 then it makes sense. Also the weight of 60lbs is pretty much what 2 group 31 lithiums weigh from most other manufacturers. I think something must be off here, because no other manufacturer I have seen offers this much capacity in a single GR31 battery.

Phil G. · 01-18-2021, 08:14 PM

Quote:

Originally Posted by misteracng

This 200AH battery doesn't make sense to me, but it would be amazing if it was true. All other Group 31 lithium batteries seem to be around 100AH each, and the lithionics being the highest I have seen at 125AH, also being more expensive, but with a nice built in bluetooth battery monitor. Looking at there pictures, it seems they are using 5AH cells, 3.2volts each. Would seem they wire 4 in series to get 12.8volts? and then there are 5 columns in parallel, giving 25AH. Then the picture shows 4 of those 20 battery sets which should give 100AH? I am not an electrician, does that seem right? I don't see how they get 200AH. If it were 2 group 31 at $2000 then it makes sense. Also the weight of 60lbs is pretty much what 2 group 31 lithiums weigh from most other manufacturers. I think something must be off here, because no other manufacturer I have seen offers this much capacity in a single GR31 battery.

You hit on exactly why I made the original post - along with the link to the 200 AH lithium battery website.

My whole point is how are they packing 100 AH more capacity into the same Group 31 case as other lithium battery providers are only able pack in around 100 AH of capacity? They may be using some technique or technology to do it that is difficult to pull off ... hence their very high price for each 200 AH Group 31 lithium battery.

However if price is no objective for one who wants the highest possible battery storage capacity in their available RV space ... then one or more of these ground breaking (if "real") lithium batteries is the way to go.

BobC · 01-19-2021, 05:42 AM

Quote:

Originally Posted by Winterbagoal

Modern alternators have built in technology to avoid over heating.

How old can a MH be to have a modern alternator?

AJMike · 01-21-2021, 02:39 PM

As I have said before, I am not an expert on the need or lack of need for a DC-DC charger when using Lithium batteries but, having said that, I am convinced of the need to use them not by the Victron or Renogy adds, but by the fact that Winnebago installs a BIM in their new RVs when ordering the Lithium option. That is the case in either a new order or an upgrade to an existing system and I suspect that Winnebago would not bother if there was no reason to do so.

I understand that some people are using Lithium batteries successfully without one, and I hope that they can continue to do so, but until a manufacturer like Ford or Winnebago (or Thor or Coachman, or ...) officially say that their alternator does not need that protection I guess I will continue to use the DC-DC charger. I assume it is easy insurance against having to replace an alternator.

Winterbagoal · 01-21-2021, 03:11 PM

Quote:

Originally Posted by BobC

How old can a MH be to have a modern alternator?

It depends.

Winterbagoal · 01-21-2021, 03:29 PM

Quote:

Originally Posted by AJMike

As I have said before, I am not an expert on the need or lack of need for a DC-DC charger when using Lithium batteries but, having said that, I am convinced of the need to use them not by the Victron or Renogy adds, but by the fact that Winnebago installs a BIM in their new RVs when ordering the Lithium option. That is the case in either a new order or an upgrade to an existing system and I suspect that Winnebago would not bother if there was no reason to do so.

I understand that some people are using Lithium batteries successfully without one, and I hope that they can continue to do so, but until a manufacturer like Ford or Winnebago (or Thor or Coachman, or ...) officially say that their alternator does not need that protection I guess I will continue to use the DC-DC charger. I assume it is easy insurance against having to replace an alternator.

I don't think it's the chassis manufacturers saying use a DC to DC charger to charge lithium batteries with their alternators, it's those who manufacture the DC to DC chargers saying it. Some battery manufacturers are recommending it too, since many are now distributors for these devices.
I only just found one person that said they damaged their 200A, almost new alternator, over on another forum. I had some follow up questions about how many amp hours he was trying to replenish with it, and state of depletion before charging, am waiting for a response. I still suspect that the size of my system may be partly the reason I've had no problems, 220A newer alternator, charging 200Ah of batteries.

To each his own, and good luck to us all.

UPDATE: More or less confirmed that "size matters", as in, alternator output and battery bank amp hour capacity. A "one size fits all" statement that using your alternator to charge your lithium batteries will burn it up, doesn't always apply, and it seems to depend on those size parameters.

ScopeDope · 01-21-2021, 03:34 PM

I would say, search and study, internet and Youtube. There are some posts out there of guys who take these batteries apart -- physically, destroying the battery, just to see what's in there. Some of the new Lithium batteries are junk...destined to fail, way over-rated, and not what the advertising claims. If you spend a lot of money on one, I'd be sure where it came from and how far I was risking my cash. They may be great, but I thik I would really do some serious research. There are some really good Lithium batteries.... but there is some real junk out there, too. Just sayin'''

misteracng · 01-21-2021, 05:07 PM

on my 2021 View 24D, it comes with a chargepoint pro 40 under the passenger seat. I called mastervolt to find out exactly what it does. It is essentially an isolation unit. It connects the chassis to coach batteries if the coach batteries reach a certain voltage and then excess amps can be used to charge the coach batteries up to 40 amps. When engine is off it cuts the connection so the chassis battery has no chance of being drained by the coach batteries. It is technically a charger, but it does not have multi-stage charging like a DC charger would have to accommodate lithiums. It just connects the circuit when conditions are right and allows flow to the coach batteries. It says its able to handle lithiums but in the specs it requires a multi-point contact accessory. Mastervolt tech said this is cable or something that will turn the chargepoint on and off, but it needs to be connected to some mastervolt main panel to be used, which the View does not have. I heard some concern that say in a very long drive, the coach lithiums would be charged up and then this chargepoint unit would not be capable of changing to a float charge, since it does not have that capability. If this is indeed an issue, you can also wire in a switch to manually turn of the chargepoint whenever you want, but it is not as capable as a 3 stage DC to DC charger.

Phil G. · 01-23-2021, 01:56 PM

Quote:

Originally Posted by ScopeDope

I would say, search and study, internet and Youtube. There are some posts out there of guys who take these batteries apart -- physically, destroying the battery, just to see what's in there. Some of the new Lithium batteries are junk...destined to fail, way over-rated, and not what the advertising claims. If you spend a lot of money on one, I'd be sure where it came from and how far I was risking my cash. They may be great, but I thik I would really do some serious research. There are some really good Lithium batteries.... but there is some real junk out there, too. Just sayin'''

BINGO!! I agree 1000%.

The cutaway photos I've seen of drop-in 12V lithium RV capable batteries don't make me feel comfortable at all. A whole bunch of tiny cells matrix'd together with a cluster of PC boards and solder joints can be an open circuit failure waiting to happen from eventual corrosion and/or mechanical vibration.

I wish an "expert" lithium battery designer would jump onto some of these blog sites to explain why, say, a 100AH Group 27 size 12V lithium vehicle battery can't be made up of 3-4 large cells similar to the cell counts inside lead-acid batteries. Is it about the basic electro-chemistry involved that makes use of larger volume cell sizes impractical and/or unsafe ... or has it to do with it being cheaper to produce commom size vehicle drop-in batteries when using a bunch of small cells?

AJMike · 01-23-2021, 02:06 PM

Quote:

Originally Posted by Winterbagoal

I don't think it's the chassis manufacturers saying use a DC to DC charger to charge lithium batteries with their alternators, it's those who manufacture the DC to DC chargers saying it. Some battery manufacturers are recommending it too, since many are now distributors for these devices.

In my case it was the folks at BB that recommended the DC-DC charger, although there did not seem to be any consistency in their recommendations. One tech told me to use a BIM and another told me to use a DC-DC charger and to stay away from BIMs, so who knows which, if either, is best. And, as it is, BB sells both the BIM and DC-DC charger and says if you are going to use a charger, then you should buy it from them.

I am reasonably happy with the Victron charger I am using, but I can see that much of the push for them may be for marketing. I just don't know, but believe that it is better to be safe than sorry. The charger cost me less than $200 and the wiring another $300 or so, but a new alternator would be considerably more and I am sure if I needed to replace the alternator Ford would tell me that they would not stand by their warranty because I was using non-standard equipment and stressing the system beyond recommendations.

Elkman · 01-23-2021, 02:55 PM

Battle Born sells their LI-BIM devices for use to protect the batteries from charging damage to the lithium batteries. From their website:"The LiFePO4 Battery Isolation Manager (BIM) monitors voltage and connects batteries when needed. Under normal charging conditions, the BIM will connect for 15 minutes every 35 minutes. That means that the BIM will connect for 15 minutes, disconnect for 20 minutes, and repeat this cycle until the coach battery is charged.

If the coach battery resting voltage exceeds 13.4 V then the BIM will disconnect. A resting voltage greater than 13.4 V indicates a fully charged battery. Note that “resting voltage” means that no current is flowing to the coach battery.
The BIM will disconnect if the alternator voltage exceeds 14.4 V. This protects the coach battery from over charging. The LiFePO4 Battery Isolation Manager will disconnect if the voltage difference between the alternator and the coach battery is less than 0.1 V. If the voltage difference is too low, then there is a negligible charging current, and no need to connect to the coach battery. The BIM will disconnect if the alternator voltage drops below 13.3 V. If the alternator voltage is too low, then it cannot adequately charge the coach battery, so there is no reason to connect."

With the DC only fridge in my Navion lithium phosphate batteries are a must have if one wants to dry camp with the RV. The question is whether to get 100AH or 125AH and what connectivity is desired to the BIM. If my RV had a 3-way fridge I would have stayed with the factory flooded 105AH batteries but Winnebago stopped installing this type of fridge after 2019. If I had realized it was a DC only fridge I would not have bought the 2021 Navion.