Good Sam Club Open Roads Forum: RV Batteries - Lithium as Option
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obiwancanoli

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Posted: 08/12/20 07:15pm Link  |  Quote  |  Print  |  Notify Moderator

I've read enough to develop questions I can't seem to find the answers to, so I'm here once more to soak it in.

I've had some concerns that the current and original batteries on my Class A might need replacement, even though they're about 3 years old, in part due to my lack of experience in depleting voltage to a point that running off the batteries inevitably runs out of power in the wee hours, with the meters showing me LOW VOLTAGE somewhere in the 11's, so, I'm considering Lithium.

I also have 480 watts of Zamp solar, maxxed out at 26.1 Amps, along with a separate portable 120 watt panel, and a Zamp Solar 30A Controller. Am considering adding another panel or two -if I can find a place to mount them, and realize I'd need a new Controller, maybe 45-60 Amps, MPPT, and should be more than sufficient.

Having recently retired, I now have time for some extended travel, and boondocking will almost certainly be a part of that. I'm looking forward to getting off grid periodically, so power resources are key.

I'm aware of the cost, and believe that this is the most economical long-term approach to my power systems. So I'm willing to consider Lithium, and need some answers to fill in a few holes...

My rig came with 4-12V batteries, each 115 min at 75 Amps, 220 [email protected] 20Hr.

If I connect Lithium in parallel, do I double available amps?

Are Lithium's all 12V, and if so, would I need only two to replace what I currently have?

What changes, if any, must I make to existing systems in order to accommodate Lithium batteries?

* This post was edited 08/17/20 11:07am by obiwancanoli *

naturist

Lynchburg, VA

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Posted: 08/12/20 07:27pm Link  |  Quote  |  Print  |  Notify Moderator

If I read correctly you have 220 AH capacity, of which you should only use 110 AH for battery health, but you have frequently over used them.

If you parallel lithiums, yes you will be able to double the draw, as it will come from two batteries.

200 AH of lithium batteries would work just about right with 480 watts of solar panels.

And lithium batteries come in voltages other than 12. They also come in sizes other than 100 AH.

Finally, changes needed include different charging parameters. May I suggest having a look at mobile-solar power.com for answers and suggestions for suppliers.





obiwancanoli

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Posted: 08/12/20 08:10pm Link  |  Quote  |  Print  |  Notify Moderator

Thank you, naturist... appreciate the tip

free radical

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Posted: 08/12/20 08:13pm Link  |  Quote  |  Print  |  Notify Moderator

Theres also ,,DIY solar power with Will Prowse,, chanel on YT
Highly recomend checking that

StirCrazy

Kamloops, BC, Canada

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Posted: 08/12/20 10:49pm Link  |  Quote  |  Print  |  Notify Moderator

naturist wrote:

If I read correctly you have 220 AH capacity, of which you should only use 110 AH for battery health, but you have frequently over used them.



actualy he has 440AH, 220 usable. he has 4 batteries. I have 4, 235ah 6v batteries and with my 480 watt solar set up we do just fine. dont run the ac at all though...

Idealy i would lover to upgrade it to 24V panels and a MPPT controler.

Steve


2014 F350 6.7 Platinum
2016 Cougar 330RBK

valhalla360

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Posted: 08/13/20 05:03am Link  |  Quote  |  Print  |  Notify Moderator

Lithium charging/control is very different, so it needs to be an independent battery bank from the lead acid batteries. Doubly so if the old batteries are in poor shape.


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wa8yxm

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Posted: 08/13/20 05:17am Link  |  Quote  |  Print  |  Notify Moderator

obiwancanoli wrote:


My rig came with 4-6V batteries, each 115 min at 75 Amps, 220 [email protected] 20Hr.

If I connect Lithium in parallel, do I double available amps?

Are Lithium's all 12V, and if so, would I need only two to replace what I currently have?

What changes, if any, must I make to existing systems in order to accommodate Lithium batteries?


Ok so you currently have 440 amp hours 220 usable. Close to what I have.
Note that that 50% usable is for DEEP CYCLE and other types might not be so forgiving of a "DEEP discharge" (Some batteries only 15-20% of the power is usable (Starting) about 25 for MARINE/deep cycle)

Lithium. Some types are good for close to 100% of contained power

Next. WIll I need 2: I can not answer that it all depends on that amp hour. YOu need more usable amp hours. Just to "example" you currentlyu have 4 GC-2. Well you could use two 4D and geet about the same powere.. and a hernia (joking on that) as they are 2x as heavy as the GC-2. (My Deka G-20's I can not install by myself.. the Interstate's they replaced I could 10 amp hours more in the Deka was just enough to cross the line)

How to figure amp hours for a multi-battery system

If you wire them in series like this

-{6v}+==-{6v}+== 12 volt to house. You do not add the VOLTS together (See how I got to 12 volts) not the amp hours and I might add this is where the Belief that all batteries need to be identical comes from. IN the pair. they do need to be identical

But when you wire them this way

-{12V}+
-{12V}+

(That is parallel) Then you add amp hours, not voltage.

DO you need two.. Again that depends on the battereries. Lithium types are lighter so you can put one BIGGER battery in or two smaller ones or even 4 or 6 depending on the size of the battery and the battery box.. The more amp hours the better. I will give you the caution over just counting batteries later.

Do I need to do anything different charging.
Depends on who you buy from Top end Lithium battery firms build assemblies. not just batteries but batteries with built in charge controllers and for the most part you can treat these normally. You may need to change your converter to one designed for LIthium however. (I would recommend it)


Why just saying I have 1-2-3-4-5-6 12 volt batteries is NOT enough info.

Where as with GC-2 6 Volt Golf car we can say 220 Amp hours give or take 10 and that's close enough for most use.... We can not do that with 12's here is why

Group 24 is about 70-75 AH
Groups 27 and 29 100 more or less
Group 31 120-130
4D and 8D about 220

All different sizes.

I have some as low as 5 amp hours here Still 12 volt (jump starters are often in the 7-25 amp hour range)

So the only IMPORTANT numbers when designing are
Maximum level of discharge (50% for GC-2 Flooded wet)
20 hr Amp Hour rating (220 for the above)

Size and shape of the space to stick 'em in.

You want to maximize the amp hours and not exceed the space


Home is where I park it.
Kenwood TS-2000 housed in a 2005 Damon Intruder 377


folivier

Southeast Louisiana

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Posted: 08/13/20 07:05am Link  |  Quote  |  Print  |  Notify Moderator

Buy a SOC (state of charge) meter, Victron BMV 7** series work nicely, the BMV 712 has bluetooth.
Then you can tell just how many amphours you use overnight and in 24 hours. Then you will know how many amphours of batteries you actually need. Once you know that then you'll know how many watts of solar you'll need to replace what you use.

ReneeG

Meridian, Idaho

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Posted: 08/13/20 07:19am Link  |  Quote  |  Print  |  Notify Moderator

We would really love to have the lithium for the increased capacity as well as their much lower weight compared to conventional batteries, but the price! We'll have to wait.


2011 Bighorn 3055RL
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theoldwizard1

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Posted: 08/13/20 10:24am Link  |  Quote  |  Print  |  Notify Moderator

DIY LiFePO4 banks, made with 200+ Ah cells are getting to be cost effective. You can build a 280 Ah bank with a charge controller for under $500 !

Besides higher energy storage per pound AND per cubic foot, the other big benefit is you can run them down to a very low SOC without damage. They have a very slow "self discharge" rate. Like any other battery they should be stored at 100% SOC, but do NOT require any trickle charging, even when stored for months.

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