Lifepo4 battery choice

[Riverbug]

SOK 206AH. First one purchased last June, plan to purchase another this year and install a 3000 watt inverter/charger/converter, and a DC to DC charger once the new truck shows up.

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SOK 206AH. First one purchased last June, plan to purchase another this year and install a 3000 watt inverter/charger/converter, and a DC to DC charger once the new truck shows up.

Just curious if you have a specific need for the 3K inverter? The reason I'm asking is two fold. First, those batteries have a maximum continuous discharge rate of 130 amps. Paralleled, that would be 260 amps. If the inverter is loaded up to max, you would be pulling right at 230 amps from the batteries to supply the inverter. That would likely get you maybe an hour and a half of inverter time. Just something to think about..

[DaveMatthewsBand]

We've been using four Battle Borns for four years but planning on going with Chins or Ampere Time (same product) on my next build. Four years ago BB didn't really have any competition but things are much different now.

Since we're full-timers we don't need low-temp cutoffs which is the Achilles heel on most of the "off-brand" batteries. That being said, I'll be able to pickup 900 amp hours of lithium storage for what my 400ah BB's cost me four years ago and I'll be doing it with less wiring since the batteries are 300ah each.

As far as dedicating a year to learn how to build your own lithium goes, I think most of us could do it in a month or less. I just have no desire to DIY anymore.
I'm retired and I can afford to pay other people to do stuff for me.
I want to save some money, so I'll skip the BB's but I'll still pay someone else to install them.

[Riverbug]

Just curious if you have a specific need for the 3K inverter? The reason I'm asking is two fold. First, those batteries have a maximum continuous discharge rate of 130 amps. Paralleled, that would be 260 amps. If the inverter is loaded up to max, you would be pulling right at 230 amps from the batteries to supply the inverter. That would likely get you maybe an hour and a half of inverter time. Just something to think about..

Thanks for giving me something to think about. We wouldn't be running max. The thought was really just to avoid buying something smaller and upgrade as we go. Will likely add solar down the road, but also considering a future 5th wheel too so who knows. For now, while in transit for days and not staying at campgrounds we just want to be able to warm something in the microwave, my wife wants to use the blow dryer, etc., (not necessarily at the same time) without having to set up a generator to run something for a few minutes at a time. While in transit I would like to run the fridge off electric. So, We could go smaller but I'd rather spend once and be done.

[Butcher]

I have this idea that if you need 2k to run everything, why not get a 3k and know that your inverter is not running at full throttle to deliver the goods?

If you elect to get a 3k, then you need to be able to deliver that many electrons. Why get the very minimum capacity, when you could get a few more batteries to insure none of the batteries are overloaded?

There are a lot of things like that. Axles, fuel tanks, water tanks, waste tanks, etc. I remember when I was a kid how long the campers were. They were tiny back then. We can blame it all on Tim Allen.

[MoonShadow_1911]

I have this idea that if you need 2k to run everything, why not get a 3k and know that your inverter is not running at full throttle to deliver the goods?

If you elect to get a 3k, then you need to be able to deliver that many electrons. Why get the very minimum capacity, when you could get a few more batteries to insure none of the batteries are overloaded?

There are a lot of things like that. Axles, fuel tanks, water tanks, waste tanks, etc. I remember when I was a kid how long the campers were. They were tiny back then. We can blame it all on Tim Allen.

Well, with LiFePO4 batteries, "overloading" them is not bad like it is with AGM or FLA batteries, however, it was pointed out, earlier in the thread that a 3k watt inverter can burn through approximately 250 Ah of battery storage. This is fine, if you have a system that replenishes the batteries at a rate faster than the discharge rate (like solar or a generator or a DC-to-DC charger from the tow vehicle).

If not, you could very well run your battery bank "dry" in an hour or two.

For us, it's not "what can we run on batteries and solar", it's "what is necessary for us to survive a day". We game planned two different scenarios. 110°F New Mexico heat and -32°F Colorado cold.

The refer is a Dometic propane/AC POS that I hope to retrofit the JC Refrigeration AC compressor refit kit with, but I digress.

For the heat, we would want the availability of one AC unit, note that is the availability of one AC unit. We figure, on solar/batteries, we can deal with temperatures into the high 80's and low 90's before we would turn on the AC unit. With the EasyStart, we should be able to run the AC on and off most of the day if we were boondocking, with the direct New Mexico sun, the solar should keep up nicely.

For the cold, we have figured blankets and longjohns, and the heater would be running most of the time to try to keep the heat at around 60°F. With usually overcast skies, during winter storms (and winter in general in Colorado), we figure we could go 24 hours before we would have to break out the generator.


So, all I'm trying to say, with this long winded post, is, if you want to "go big or go home", that is really up to you, and more power to you! We chose to go with what would be acceptable to both of us. (Acceptable means that I went from over 2000 watts of solar to 1400 watts, and from 600 Ah LiFePO4 batteries to 200-400 Ah. I'm still pushing for 400 Ah, but, I probably won't get that, unless I find 100-200 Ah battery kits for around $100.00... (Not yet, but it's getting closer!)

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[Scott'n'Wendy]

Just curious if you have a specific need for the 3K inverter? The reason I'm asking is two fold. First, those batteries have a maximum continuous discharge rate of 130 amps. Paralleled, that would be 260 amps. If the inverter is loaded up to max, you would be pulling right at 230 amps from the batteries to supply the inverter.

And no matter how well you build it, high amperage wiring/connections/lugs/breakers have a short lifespan.
Powering 120vac devices with 12vdc storage, with it's required high dc amperages to accommodate even moderate a/c loads, is to me, a complete misapplication.

But, to each their own...just my opinion and you know what they say about opinions..lol

[Conner58]

Sok 206ah x6 here also . Working great !

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And no matter how well you build it, high amperage wiring/connections/lugs/breakers have a short lifespan.
Powering 120vac devices with 12vdc storage, with it's required high dc amperages to accommodate even moderate a/c loads, is to me, a complete misapplication.

But, to each their own...just my opinion and you know what they say about opinions..lol

I disagree about the short lifespan part of it, without adding "if not not done correctly" to that phrase. High amperage circuits will last just as long as any other circuit, if done correctly and the proper sized components are used and they are of a good quality. When I worked in a steel mill as a Journeyman Electrician, some of our overhead travel cranes were 250VDC operated. The main hoist on those cranes, which were capable of lifting 400 TONS (800,000 lbs) obviously had DC power and everything in those circuits were substantial enough to allow very high current when the crane was lifting those heavy loads. I've personally seen the amp meters in the 2500-2600 amps at 250VDC while the motor was lifting the loads. That is..volts times amp = watts, so in that case....625,000 watts of power being consumed. And my point is, lots of that equipment lasted for years and years and years without failure, so it can be done, you just need to have the correct stuff for higher amperage usage. Lots of folks are driven by cost, and chose to buy the cheapest thing they can find on Amazon or ??? and they throw on cheap components that are not only low quality, but also undersized from an amperage perspective.

[Scott'n'Wendy]

@xrated
I respect your opinion, we have similar backgrounds, I've worked on similar equipment for the same amount of time. You know as well as I that there is nobody using in their RV the kind of components you saw on those cranes. But I will agree with you that it 'could' be built to last, but nobody would pony up the $$ for those kind of quality components. So the stuff you see in an RV...will not last.
But my real point was why use 12vdc to power a device designed for 120? Spend your $$ on a 12v fridge rather than on a large battery bank to have the storage capacity to invert 12vdc to 120vac. Which...I think...you would agree with as well.