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400AH lithium cells? Best price per AH? $0.85/ AH?

15450 Views 216 Replies 12 Participants Last post by  sportcoupe
I'm looking to make a storage battery for a camper. Lithium is a better value for the money than lead IMO.

I want a 12v 400AH lithium pack as simple as can be. Fewer cells is better, isn't it? So, that's four 400AH cells I need plus a BMS.

I've heard prices are as low as $0.85/ AH if not in a hurry. Is that correct? Suggestion or comments?

Thanks!
-John
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3 pairs of those Deka GCs should do it.

But the battery bank is the least challenging, and certainly the least expensive aspect here.

Getting properly recharged each cycle should be the real focus.

Make sure you have a good SoC meter, and ammeter + AH counter.

If you really do run those IMO crazy inverter loads, count on a big genset running 3-4 hours a day every day, and with lead you will still need as much solar watts as will fit up top

Going to LFP would maybe shorten runtime a bit, and let you forego the solar.
 

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I did not notice anyone stating otherwise?

AH per cycle is the concern, not amps.

For example, 30min per day for the microwave?

Aircon's already been discussed.

Since you need to run the genny for hours anyway, just run the aircon and do your waving while the genny's going, ideally doing some charging then too.

If they're really needed in the first place.
 

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Discussion Starter · #166 ·
What good is the house battery if you never want to use it running genny all the time? :)

I can substitute running genny for days that I'm driving 5-6 hours.

I may have over estimated micowave use slightly. :D

Aircon is required. I can't sleep when it's hot and humid.

It's much easier to plan the entire electrical and systems before build conversion starts then to wait and redesign for something that just doesn't work during or after conversion. Camper van on paper is easy to change.

Budget for conversion is $15,000.
 

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OK, so:

With lead, getting properly recharged each cycle will be the real challenge. You will still need as much solar watts as will fit up top.

Going to LFP would maybe shorten ICE charging time a bit, and let you forego the solar completely.

In either case, make sure you have a good SoC meter, and ammeter + AH counter.
 

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With lead, you're referring to the absorption portion of the charge cycle correct? Does that apply equally to AGM as FLA?
All batteries even lithium go through what you are calling is Absorption phase all that means is the Constant Voltage Stage where current tapers to zero. A better term and more accurate is SATURATE. Think of a dry sponge. Dunk it in the water, and even though submerged takes a while to fully saturate slowly.

Both lead acid and lithium have charge speed limits and they work the exact same way. The faster you charge, the longer you will spend in Absorb mode. When a battery manufacture recommends a specific charge rate, they are telling you the fastest most efficient rate. It is the point of Diminishing Returns. When you charge at say C/10 most manufactures of lead acid batteries recommend, you will arrive at Absorption at roughly 90% SOC, and should take another 2 hours to fully saturate. Charge at say C/4 and you arrive at Absord voltage at 70% SOC and now spend the next 5 hours until you saturate down to 2% of C. So take note you can charge at higher or lower rates. Once you get up to around C/8 on FLA, you hit the brick wall where you cannot charge any faster in time, it wil take 10 hours at C/8 or 1C. Tip here, you can speed up FLA charging time by eliminating Adsorb phase, or at least most of it. Real easy to do, we change the Voltage setting to higher voltage. Say from 14.8 volts for a Trojan FLA product up to 15.0 volts. That forces the MPPT Controller to stay in Constant Current longer. Do not attempt with AGM or any Lithium. FLA no problem.

Same for Lithium, but the penalty i snot quite so bad. Example most manufactures recommend C/2. Like Pb you hit Absorb voltage at 9o-% SOC and fully saturate within an hour.

Big difference is with PB you need the ability to be able to fully recharge without time constraints solar puts on you. But do not knock yourself out and get in the mindset they have to be fully recharged every day. A good full charge once a week keeps the doctor away.

As for meters and such IMHO are a waste of money and not capable of telling you anything. Last thing they will tell you is the SOC. Coulomb Counting Pb is a guessometer and would require calibration every cycle. You have to guess at what the charge efficiency which changes with temps and humidity. Lastly there is no algorithm to account for Peukert effect. They can be useful with FLA, but just a hole in your wallet on Pb batteries.

As for SOC, common sense will tell you it is useless on a in service Pb battery where it is either discharging or charging. SOC is only useful on an Open Circuit Battery that has rested for 24 hours and comes to 75 degrees F. That is not how the world turns. The real world of an operating system is it is either charging, discharging, or sometimes Floating.

Check the ole memory vault inside that piece of meat stuck between your ears. Remember being concerned about voltage sag? A SOC meter would tell you the battery is at 0 SOC when you know it is fully charged. I can take a fully charge battery brand new battery and make it read 10.5 volts or even 7.2 volts (CCA voltage) despite being fully charged and in brand new health.

I can take the same new battery, discharge it down to 0% SOC @ 10.5 volts, and make it read 14.4 volts in under a minute indicating full charge when in fact it is FLAT.

Not saying a Volt Meter is not useful, but is no indication of the battery SOC. There is only one way to accurately determine a Pb battery SOC and that is with a temperature corrected battery hydrometer. AGM and you are SOL.

What a meter will tell you is if your system is working. When th esun comes up the voltage should climb to say 14.8 volts, hold 14.8 for a couple of hours, then drop to 13.5 until dark and the voltage will bleed off to 12.6 volts and lower by morning.

Again I caution you to use watt hours.
 

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Seems like 500Ah FLA and 500W solar would satisfy my power requirements?
Battery is a little light because that is only a 2-day reserve meaning you will use 50% daily. You could make it work, but not with solar. You are asking for a huge amount of power at 2.8 Kwh daily.


To generate 2.8 Kwh of usable power with solar with 500 watts of solar panels is impossible even under ideal conditions. With a 500 watt panel under ideal conditions would require a 8 Sun Hour Day. There is no place on earth that has that kind of Solar Insulation any day of the year. 5 to 6 Sun Hours is as good as it gets in summer in Tuscon AZ, and if in Gloomy Doomy Seattle and Portland 4 hours is top on June 21, and by Xmas is less than 1 Sun Hour.

Point here is if you want solar, OK, but it will only be a supplement and show-n-tell material. With a battery only sized with 2 day capacity means you will have to charge with something else because solar is not going to work with you power requirements. No need spending a a lot of money on solar, because no matter how much money you throw at it will not work. A 10 watt panel would be as useful as a 500 watt panel because you will be using either a generator, driving, or shore power to recharge.



The AC is killing you.
 

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With lead, you're referring to the absorption portion of the charge cycle correct? Does that apply equally to AGM as FLA?
Well it isn't so much Absorb vs Bulk but total charge time to get to 100% as per endAmps, how it's divided depends on current level.

And yes all deep cycle lead will take 5-7 hours to get there even at high current available, high CAR AGM as I said might save 30-60 minutes over FLA.

And LFP does never **require** any Absorb hold time, since it has no need to ever get to Full, and in fact when not actively cycling, lower SoC helps longevity.

I do use a little AHT, 3.45Vpc / 13.8 until current tapers to .04C, but **only** when precise calibration of 100% Full is required for SoC meters.

This is actually within 2% SoC of the vendor definitions of Full at destructively higher levels.

In normal cycling, I charge **to** that voltage and just stop, no Absorb at all, sacrificing at most another 1-2% capacity, but gaining a lot of longevity, and eliminating any balancing issues.
 

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500W solar would satisfy my power requirements?
On days with great insolation conditions - summer or near the equator - you will put maybe 140-180AH into your bank.

Have you checked to see how much will fit on your roof?

Note if your bank is lead, even if your solar is under 20% of your daily AH input, you still need it for the long tail, to have any chance of decent bank longevity off grid.

Running a big genny for hours and hours of very low acceptance make zero sense.
 

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As stated, no Absorb is required for LFP except to calibrate the AH-counting SoC meter. Once every 5-10 cycles is plenty for decent accuracy. I like Victron BMV-712. Peukert coefficient for LFP is so close to 1.0 can largely be ignored.

Yes, voltage is largely useless for estimating SoC.

Absorb for LFP should be very short, at low rates a matter of minutes - stop at .04C or hurting longevity, pushing into the shoulder.

LFP can accept very high C rate charging, no less efficient but temps need watching - .5C is a reasonable limit for longevity.

Quality AGM makers recommend over .2C for longevity, Lifeline's minimum is .4C.

Hitting 100% SoC once a week is still PSOC abuse and will drastically shorten lifespan. Every cycle is ideal, most cycles is good, a few times a week is OK.
 

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Discussion Starter · #175 ·
Roof length is between 12–14 feet in length, almost 80” wide. Just one fan is planned so the rest could be solar.

Saying 500w solar panels are the same as a 10w panel because neither will supply 100% of plannned demand is kind of silly. Sure it’s supplemental but 500w seems substantial to me. Might even work most days because the van will be moving hence charging. I’d almost never leave it parked for two days and not drive it.
 

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They are not found in EV's you moron spammer. Now get lost.
Sunking, you need to chill-out and learn some manners. How old are you, 15? Yes they are found in EV's, they are also used for backups or high energy storage.

LiPos are not Lithium Ion. That's like saying NiCD are the same as NiMH batteries. Their are pros and cons to all different types of battery chemistry. Some have higher internal resistances than others. However, if you have a large enough bank, then it doesn't matter as you would be able to pull in all solar energy as it would be distributed over your entire bank. Kind of like pouring water into an ice cube tray really fast.

Stop spamming me Sunking and offer information, not animosity.
 

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They cannot and is of no concern for scum bag spammer. LiPo is the last thing you want for a house battery or any application requiring long life as LiPo only have roughly 100 cycles in them. LiPo's are used in RC aircraft where C-Rates run 20C or greater continuous. Extremely dangerous lithium batteries notorious for catching fire.



They do have a application in EV used as Drag Racers where you can put a very small battery in, just enough for 1 or 2 runs. Some of the new ones claim 100C-Rate for 10 seconds which is all you need for a drag race. A 20 pound battery vs a 1000 pound battery.
(1) Lithium batteries have been used heavily in all EV's, not just drag racers.
And please by all means Sunking, tell me what deep-cycle or AGM battery can put out the equivalent of a Lithium pack and weigh less? However, I don't think weight is much of a concern in the case posted here anyway. So I'm not sure why you are making a case for it. And while Lithium Ion batteries are more unstable, I don't have Lithium Ion, they are Lithium Polymer, which are used heavily on electric bike conversions as well. Don't hear about a lot of fires with them....or are you just talking smack?

(2) You get different voltages from configurations that are higher, such as a 4S configuration that would have a nominal voltage of 14.6V using things like DC converters and voltage regulators.

I've built battery banks using these before. Mostly for my personal computer, but have also used it in conjunction with a couple solar panels on top of my camper, and other projects. The only real limitation I'd say they have would be their terminal voltage being around 3-3.2V and requires a monitoring device and charger that can prevent over-discharge and over-charging.
 

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Brian

I couldn't find the the actual post you made within the length of this thread. Here's a link to all the information I have gathered on these cells.

https://drive.google.com/file/d/1Wlxp7owKb3vn9fsp4GlT_JU9S07ufezu/view?usp=sharing
In the Classified thread (to which you're probably responding), I linked directly to my post...
... To avoid misunderstandings, what are the EIG cells which you are selling, GreenGyver? Are they the T020 pouch cells? If so, they are LTO cells...
But anyway, thanks for the information. There's not much specifically about the cells in the module specification document, but by comparison of voltage specifications, these are not the T020 cells - the nominal voltage is too high for that.

Nothing in that module document indicates either the chemistry (although not LTO or LFP) or the construction (polymer electrolyte?) of these EIG cells.
 

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LiPos are not Lithium Ion.
Saying that LiPo is not lithium-ion is like saying that sedans are not cars; yes, a sedan is a specific style of car, but it's still a car.

Their are pros and cons to all different types of battery chemistry..
True, but "LiPo" does not describe the battery chemistry, just one aspect of the cell design. What chemistry are the cells that you are selling, and what chemistry do you think that common RC cells use?
 
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