Community Forums

2004Horizon · 06-09-2023, 08:39 PM

I want to get rid of my 4-6V-6C2 batteries (420AH) and install 400AH of LiFeP04 in the coach's slideout battery tray, but I don't seem to enough width in the tray for 2-100A-12V-LiFeP04 batteries.

My current slide out tray dimensions measures on inside: 14-1/4"W X 23-1/4"L x 11" high.

Therefor, and I have just enough height and width for 4-GC2-FLA-Batteries or 3-12V Deep Cycle (Group #???) but if I get 2-100AH-LiFeP04 batteries that are 7-1/2" wide, these will not fit.

Does anyone know what LiFEP04 manufacture offers narrower LiFeP04 batteries so I do not need to modify my slide out battery tray?

If utilizing this battery location is not possible, where are you Winnebago RV owners storing your new Lithiums when you do an upgrade to 400AH-LiFeP04 batteries?

Below is a picture of one owners 4-6V-GC2 battery setup, in the slideout battery tray, which I would like to utilize for my lithiums, unless this is a no-no, because all these batteries are exposed to the "open air" and outside temperatures.

Note: I do have a slideout cargo shelf in my basement that would work, but then I would be wasting this FLA battery space if I yank them from the coach.

Has anyone build an enclosed storage area where these batteries sit, if I do indeed put the 400AH of LiFeP04 in the basement?

Paul_D · 06-09-2023, 09:30 PM

When I replaced my FLA battery, the 100Ah LFP was smaller than the FLA.
My LFP is on a unprotected/unheated battery rack. I make sure the chargers are off when 32F or below. Many, but not all, LFP battery management systems will prevent charging in cold temps.
I have never been in -4 F so I don't worry about discharging when they are cold.

Biljol · 06-10-2023, 08:46 AM

Not sure what brand of lithium your looking at but I have a 400 ah single battery that would fit there no problem.

Look on Amazon and maybe get 2 200 ah you don’t need to stay with 4.

Lifepo4 100ah 200ah 300ah 400ah 12V Lithium ion Battery for Solar System/Motor Home/Boat/Golf Carts car battery (12V 400ah ×1pcs)

https://a.co/d/58FYr6s

This is what I got I am not saying it’s the item you should get because it may not meet your needs but is an example of different options.

2004Horizon · 06-10-2023, 12:32 PM

Biljol: Thanks for your info. I liked the metal battery box and amps display, but I'm guessing that there is really no advantage to the metal box over plastic. Is there? I.e., can you open the metal box and insert a heating blanket?

...Or when you have an open-air battery tray, is this when it is better to buy a Lithium battery with internal heating (for more money of course)?

=== Chins Seems To Have Better Reviews ===

Since I may upgrade my inverter, and add 800W (more) of solar to my existing 400W of solar I now have, I searched on Amazon and compared different Lithium voltages vs. physical dimensions, and there was no space savings/advantage. (See pictures below.)

So, if I am stuck with utilizing my battery tray a new lithium battery, it looks like the maximum I can install is 5120W, and I can go with either 12V or 48V and get the same foot print.

I also presume I can get 80% utilization out of these new 400AH-Lithiums which is 320AH usable vs. only 210AH I now get from my 4-6V-GC2 FLA house battery with a capacity of 420AH or 50% utilization if I want these FLAs to last.

Ergo, this $1,600 LiFeP04 upgrade is giving me ~110AH more capacity, which does not sound that much. However, it also represents 50% more capacity over my current FLA house batteries, which sounds better. (Marking 101.)

Note: My residential refrigerator consumes about 60AH/day; so this is why I really think I need to bite the bullet and get 2-400HA-LiFeP04 batteries if I add 800W more solar. (Giving me 1200W total.)

Sitll, $3200 just for 800AH of LiFeP04 sounds pretty expensive. Of course, anything over $1000 sounds expensive to me.

However, when I think I will save about saving ~60 hours of generator time per week, because of this upgrade, which saves me ~50 gallons of diesel or ~$200/week if diesel is $4/gallon -- plus a savings of less wear-and-tear on my genset -- then I figure -- after about 3 months of camping (per year or more) the savings starts to add up year after year. (ROI=2 years under these conditions.) Hummm??? Now I'm thinking??? ...I think it is worth it. ...Never mind the noise of running a generator, which I really don't concern myself with that much as I usually am not camping with neighbors close by.

Question: If I install a 12V-400AH-LiFeP04 battery with 5120W capacity, can I use my existing 12V inverter battery cables (as-is) and keep my 300A fuse or do I need to change these?

Biljol · 06-10-2023, 09:03 PM

If your moving to 48v and replacing your inverter to a 48v your wire size will be fine higher voltages lower amps your fuse may need to be replaced if it is only a 12v fuse but I think they don’t think it cares it’s all about amps.

Think about your solar also when converting to 48v.

Now if you switch to 48 v you will need a 48 to 12 to run all your 12 v stuff.

I think more rv’s will convert to 24 or 48 at time goes by and more people want all electric coaches.

This conversion is on my list but no $ at the time.

Biljol · 06-10-2023, 09:04 PM

In regards to heating I never worry about it. That’s what the big round things on the bottom of the coach is for.

Biljol · 06-10-2023, 09:08 PM

Also most 48v units need 240v input so don’t plan on any 120v shore power connections.

2004Horizon · 06-10-2023, 09:11 PM

Good point. Are you saying the Solar Controller will not step-up the output voltage?

I have 4-100W-12V solar panels. Currently they are connected in series and parallel and the Tracer Solar Control put out 0-36V at 0-20A. So this is short of 48V if I decide to go that way.

In this case, would I have to wire all 4 solar panels in series so I have 48V coming into the solar controller? ...Or will the solar controller step-up the voltage so the 48V LiFep04 battery bank will see 56V+ in order to charge it?

Biljol · 06-10-2023, 09:14 PM

You would need to look at the spec on the controller to know. I think that why most go with 24v but more amp hours the size should be the same on the battery box.

Most off grid systems are 48v so the price on those have come down faster than 24v

2004Horizon · 06-10-2023, 09:29 PM

NEW CONCERN:

When you install LiFeP04 batteries in place of your house batteries, what happens when you join them with the "Battery Boost" Switch on the dash. Can the Trombetta Boost Solenoid handle the current in-rush? ...Same goes for the starter relays on top of the starter!

Biljol · 06-11-2023, 08:06 AM

You would not use the battery boost with a 24 or 48 v system. If you did you would use the power for the 12 converter so you would need to connect to charge the starter batteries not start form the converter.

It is not recommended to start from lithium’s at any time.

With your dc to dc connector (if you plan on using the alternator to charge the lithium) that would allow you to charge the starter battery’s but not “boost” them.

2004Horizon · 06-11-2023, 12:09 PM

Biljol: Thank you! This point seems to have escaped every LiFeP04 upgrade post I have read.

Not that I am that concerned. I never liked the boost function anyway, but that is also because I carry a large jump pack that will start my diesel engine I would use that if necessary and not the boost switch on my dash to start a weak engine battery.

Biljol · 06-11-2023, 03:00 PM

BTW when you leave MT don’t forget to turn of the light.

Captain8 · 06-11-2023, 06:29 PM

Typically with any lithium setup you disable the battery boost as it'll join the batteries to the alternator when charging which causes all kinds of issues.

A battery charger with booster is a great addition. If your starter batteries die we have genny or shore power we can use to charge it. Might take a few hours but it'll work. I have this setup

There are tons of 48v inverters that are 120v my victron quattro is 120v and I can use 2 for split phase 240v if I want or just double 120V.

You need about 6V higher voltage of solar to power the 48v batteries so 54v or so. Check the open voltage on the panels to get max voltages. You can just wire them together depending on your charge controller.

48v makes much more sense. How wide is your actual hole? If 17.5" you can get rack mount which is ideal then maybe take the slide out and get 14" height to fit 2 of them. I got the SOK 48v 100AH and they're great. Also got the EG4 12V 400ah and have a bunch of problems.

Both are metal cased and you can put a tank heater on the bottom (or between 2) and it'll warm the whole battery case.