Which battery chemistry for extreme climates?

LockH said:

^^ "but good luck to cool anything with a Nichrome wire"... :lol: Again, pretty sure this thread is about "too cold" ambient temps. :wink:

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I know, don't worry
I just thought I could share an other method which would work in both situations, could be useful to other people than the OP reading this thread
Anyway sorry if this was off topic.

LockH said:

Re Aerogel... supplier:
http://www.cabotcorp.com/solutions/products-plus/aerogel

Yeah, maybe "pricey"... but one nice thing about "small EVs"... the parts/components are also small.

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I know aerogel, it is indeed some fine piece of insulating material. But the one you're pointing me at wouldn't work at all, reason being it is way too brittle. Aerogel is nice for static loads, it can support hundreds if not thousands of times its own weight, but it would be crushed in no time with a 10-20 kilos battery moving around with all the vibrations of a moving vehicle, it doesn't hold very well if the load is dynamic.

But since you insisted on this matter, I made a bit more research and it turns out that they are now making some aerogel sheets, very similar with the fiberglass whool you can find in home insulation.
This stuff is not as expensive as I would have expected, at least here in China, about 25 bucks for 1 square meter:
https://detail.tmall.com/item.htm?spm=a230r.1.14.22.5d04310fO9JEu8&id=542263140467&ns=1&abbucket=8

It should work better than the polyurethane I expected to use so I might give it a try, thanks for the idea!

Thanks for insisting on this matter! :lol:

A while back I was helping a team that was building a lunar lander (yes, to be flown to the moon). Their research indicated the A123 cells would have the best performance at extreme cold temperatures.

fechter said:

A while back I was helping a team that was building a lunar lander (yes, to be flown to the moon). Their research indicated the A123 cells would have the best performance at extreme cold temperatures.

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cylindrical or pouch?

skeetab5780 said:

cylindrical or pouch?

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Cylindrical.

Couldn't you use the batteries as a passive radiator resistance loop by passing a current through them, i.e 12v 40A through all the caps, as if they were a nickel-chrome radiator wire? They warm up more uniformly through the caps than the sides of the cylinder. Perhaps you can warm the batteries in 30 seconds hyper efficiently.
There isn't a lot of choice other than Li-ion for price/performance, and it's usable in -30 over another radiator resistance loop. An insulation layer under the radiator and battery and a different battery or capacitor to run below a certain temperature. They last longer when they run at room temperature compared to cold. Tesla's are sealed in dry air to ward off condensation with a meltable plug which can provide venting if necessary.

I don't know about the cylindrical A123 cells, but I can attest that the A123 pouch cells don't really like the cold.
Anything under 20 degreeC and the voltage sag starts to get noticeable.
But they work wonderfully when the weather is hot.

I made the first tests of my battery air conditioner system:


It uses two Peltier modules. One side is air cooled, the other water cooled. The air cooled side will go inside the battery box and include two little fans as well as some kind of system to collect and evacuate condensation. The water cooled side will remain outside of the box, probably with a little computer radiator.

The thing is controlled by an Arduino nano who drives two relays, which allows to reverse the current to get both cooling and warming. It currently has two temperature sensors (one for outside temp, one for battery temp). I'll add a detection system in order to know when the charger is plugged, and maybe a screen or some kind of visual indication of the battery temperature state.

Currently the whole system is drawing around 5.5 Amps @ 12V, including the water pump, the fans, the 2 modules and the arduino psu.

My first tests show that the thing is pretty powerful, it cooled or warmed the little box down 10 degree C in less than 2 minutes. Sure the box is small and it will take much longer to cool/warm the whole battery, but it is encouraging since it managed to do that without the little fans.
Next step will be to build a temporary battery case with cardboard just for testing purpose, and then if it works I'll build the final version.

Hello

I have been testing a 30ah set of lto cells 6s starting a 8 liter diesel tractor with out a block heater. We have had a few -5F degree
days so far and had starting on the first try. I am using a QNBBM 6S Active Battery Equalizer Balancer on the set and no bms.
The set was tested to 1000 CCA at 14.4v at a local parts store.

The russian was using pouch cells and those need compression to get the max out of them, where the round cells do not.

Your 4 cylinder car doesn't need anywhere that much CCA, I try to limit the number of parts to limit possible part failing .

I have tested this set from 0v to 18v and still have 100% capacity

I like what the capacitors can do with very little watts, but when the cap board fails, it would be like a m-80 unexpectedly going off
behind you

JimJr.

The only realistic way at -40°C ist to keep the batteries warm when usng them and especially when charging them

LTO can handle 0°C quite well and this is because the usual limit for cahrging at low temperatures is the graphit anode

Using other methods will quickly destroy your battery when charging or using regen. You can even produce internal cell shortages which can cause battery fires. This is even more dangerous than an extrenal short or overcharging a cell

LTO batteries are the safest chemistry of the lithium series of batteries . I have squish them using a 12 ton press, overcharged to 5+
volts . shot them , arc welded with them(1/4 rod). The nastiest result was a pouch cell that looked like it was pregnant at @160 F
at 5+ volts
LTO doe not contain graphite.


A 30ah 6s at 14.4v cell setup should have @ 600CCA at -40F , had better have "0" weight synthetic oil in that motor or rip the crank seals right out of it.

Any suggestions on a source for LTO cells?

I use these people for some of my buys , Be prepared for the air freight sticker shock..

https://osn.en.alibaba.com/product/60742956247-805843374/OSN_POWER_30000_times_cycle_life_lithium_titanate_battery_2_4v40Ah_45Ah.html?spm=a2700.icbuShop.prewdfa4cf.23.44dc336erKQToe

Jim

Ecky said:

Any suggestions on a source for LTO cells?

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Are you in the USA? PM me...I may know where a bunch of 11,000mah pouch LTO's are in the USA. They are brand new.