Do these batteries look appropriate? Great deal.

[OldSmokey]

Might boil a tub of water with a 1kw heater now and then, so that will be my max power usage I think (1kw). Cooking, heat, all gas + wood.

better off heating that with propane..

[Sunking]

I get your points with FLA, but the more than double energy density of Li-Ion is very attractive. Money is not a terrible issue here, but I don't plan to pay more than hopefully $4k for 10kwh.

Double the density is pushing it for LFP, and energy density is not likely important in a solar system, EV yes, but not so much for RE storage. Besides no EV manufacture other than Chi-Coms would use LFP because the energy density it too low.

As for price you have to look at long term cost. Not only is initial cost higher with LFP, you have service cycle life to deal with. Lithium claims are greatly exaggerated, and the Chi-Coms are the biggest liars on the planet. I dabble in DIT EV's and racing golf carts. in 2008 or so all we had was the Chi-Coms with CALB being the best of the bunch. I started with CALB and took me 6 months to realize the mistake. Yeah CALB and Winston claim 2000 to 5000 cycles but come far from it. The real truth is in the 1 year warranty, and try making a claim. The Chi-Coms are the lowest quality of the LFP's. A123 Systems are the best of the bunch but cost some 5 to 7 times more if you could buy them, and they only claim 1200 cycles.

A CALB will run you roughly $450/Kwh and you might get a couple of years of service out of them and you can pretty much forget about a warranty taking your chances. Pb FLA's run a gauntlet too. You can get a 1-year Pb FLA for as low as $75/Kwh or a top of the line Trojan Industrial line with 10 year warranty for $220/Kwh. The Trojan warranty is 3/10 meaning the first 3 year is 100% free replacement, and Trojan stands behind their product with with warranty centers across the USA . The Chi-Coms have 1 year as worthless as the paper the warranty is written on. So when it comes to cost and operation, there is no comparison yet.

PB's are tough as nails and can take all kinds of abuse. Make a mistake with LFP and you have a brick. Added up, you make up your own mind. But if you go with LFP or any lithium, you had better be an expert, This guy here will not use them for Solar, only an EV or racing golf cart where the expense and risk can be justified.

[nebster]

K, will consider FLA. Essentially it is for an RV that I'll be travelling in a while. Only real power-hungry stuff I do is listen to music on a decent set of speakers! Might boil a tub of water with a 1kw heater now and then, so that will be my max power usage I think (1kw). Cooking, heat, all gas + wood. Eventually I think I will be stationary and will expand on the system... Do people mix FLA and Li-Ion? Suppose it could be useful to have both, as backups and such, but need totally independent systems I'm assuming. Might consider a more invested Li-Ion system when the technologies improve, perhaps.

Sorry, I somehow missed the application.

Listening to music is pretty low power consumption, especially if you have an efficient amp. You might want to try to get a handle on your real consumption first, because lighting and pumps and other things can add up. It's hard to reason about a design without a good energy budget. I'm surprised you are interested in a 10kWh system (very large in RV terms) when you feel you have such a small demand.

You can't really mix LA and lithium in the same pack (well, you could, but it would be very exciting). In RVs that use lithium packs, there is oftentimes a mix in the sense that people will retain a lead acid engine starter battery. These two generally are totally independent as you suggest. What do you have on board already? What kind of RV is it? Do you have space for a couple large LA batteries to form a house bank? How do you power stuff today?

You may want to check in on some RV forums where power needs and designs are discussed frequently.

[rw3iss]

Thanks guys! FLA is definitely feeling more attractive, especially considering I don't really have tons of time to get the LiIon science down. $220/kwh is NOT a bad price. Can you guys chime in on the actual available usage of a 10Kwh FLA system? Like, would I only be able to use 5kwh or something, realistically, before I'd need to recharge the whole thing, or can it charge->discharge->charge 100%-0%-100% or something close to that?

As far as my RV and it's usage, it's a custom build, no electronics in it yet. I will have a small water pump, some lights, my laptop (I work from home as a programmer), and the speakers (but I do have decent speakers, am a music aficionado if I can say so, JBL desktop monitors + a ~400W subwoofer that only sees about 20% of it's capacity mostly). So with that in mind, 10kwh seems reasonable as I need to make sure my laptop and such can stay powered for work even in shady days (I'll have a backup gas generator in case). I did do the full energy calculation a while back, but lost the note somehow, but remember I needed around 10kwh to last a day or two safely, was aiming for 15kwh ideally, but will expand later if I need to.

Also OldSmokey, yeah, probably should heat the tub with wood or propane, lol. Only reason I mentioned otherwise is because I already have a 1kw 12v heater element, figured it could come in handy, but yeah, wood or propane makes a lot more sense. Got any suggestions on good propane water heaters? Otherwise I might design a copper-pipe-around-wood-stove kinda thing with a hot water circulation pump. I like simple physics...

Still need to source solar panels too (~2kw). Was looking for tier 1 @ 20%+ efficiency from the Chi-Coms, but maybe that's not so smart as I'm hearing, heh. For a different thread maybe...

[nebster]

Plan on 50% DOD for FLA.

The gold standard for large RV LA systems are Lifeline GPL-8DLs. My rig has the largest assemblage of them you'll see on a typical large motorhome, 6 in parallel for 12v * 255Ah * 6 = 18360Wh. With 50% DOD that's about a 10kWh system, and that pack was designed to be able to sustain an air conditioner underway for a bit as well as run a much larger set of loads (cooktop, microwave, etc.).

To be honest, the 255Ah is under ideal (1/20 C) conditions, and LA will deliver less under higher loads. Practically, with fresh cells, that system is probably good for about 8kWh. There'll be 10%-12% losses to wire and inverter in a 12V system as well.

And that is probably the largest system you can find, anywhere, on an RV. Most people either use a much smaller LA pack, or you'll see a few brave renegades using a lithium system. Even the lithium folks are typically in the 5-6kWh pack size.

So, color me suspicious: you're either overestimating your consumption, or you're truly crazy like just a few of us are!

[Mike90250]

.....Still need to source solar panels too (~2kw). Was looking for tier 1 @ 20%+ efficiency from the Chi-Coms, but maybe that's not so smart as I'm hearing, heh. For a different thread maybe...

I can print a flyer that states 25% eff, but ...... physical laws still apply even in china

[OldSmokey]

Also OldSmokey, yeah, probably should heat the tub with wood or propane, lol. Only reason I mentioned otherwise is because I already have a 1kw 12v heater element, figured it could come in handy, but yeah, wood or propane makes a lot more sense. Got any suggestions on good propane water heaters? Otherwise I might design a copper-pipe-around-wood-stove kinda thing with a hot water circulation pump. I like simple physics... ...

these work quite well for a budget heater..
https://www.amazon.com/dp/B01CJPU7ZQ..._t2_B01CJPU6JI

[OldSmokey]

Plan on 50% DOD for FLA.

The gold standard for large RV LA systems are Lifeline GPL-8DLs. My rig has the largest assemblage of them you'll see on a typical large motorhome, 6 in parallel

seriously ?

[rw3iss]

these work quite well for a budget heater..
https://www.amazon.com/dp/B01CJPU7ZQ..._t2_B01CJPU6JI

Looks perfect, thank you!

[nebster]

seriously ?

Yes... ?

[Sunking]

So, color me suspicious: you're either overestimating your consumption, or you're truly crazy like just a few of us are!

Well if you have 6 parallel batteries tells us you do not know what you are doing.

[littleharbor]

Well if you have 6 parallel batteries tells us you do not know what you are doing.

Who's "Gold Standard" is it to have 6 parallel batteries? If you have the room for, and weight carrying capacity for this much battery Then you can get a single string of 6, 2 volt , 1100 Ah. batteries.in the same vehicle.

[nebster]

This place is so caustic.

Well if you have 6 parallel batteries tells us you do not know what you are doing.

That's the manufacturer-supplied configuration in many of the largest, high-end diesel pusher RVs. Some of them use 6V in 3p2s. Lately they've started moving toward LFP.

Just because it's the standard doesn't mean they know what they're doing, but it also doesn't mean I don't know what I'm doing.

(As it happens, my LFP array is 16s6p, which by coincidence is six parallel batteries. And I know exactly what I'm doing, Sunking.)

[nebster]

Who's "Gold Standard" is it to have 6 parallel batteries? If you have the room for, and weight carrying capacity for this much battery Then you can get a single string of 6, 2 volt , 1100 Ah. batteries.in the same vehicle.

6p or 2s3p, or the equivalents for 8 cells, is the standard across the industry. A very few bus converters use a dual 24v/12v architecture. I've never seen an RV with 2v cells.

[J.P.M.]

This place is so caustic.

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