[scubadoo]

[https://www.youtube.com/watch?v=jgoIocPgOug

I have been following Jono on YouTube for a long time.
1. The alternator is bench mounted. Our truck alternator is usually force air cooled.
2. The smoke appears at a relatively low 1500RPM. My alternator typically spins between 4000-6000RPM. Much better cooling.
3. My 100A rated alternator is current limited by me to c70A or c90A into our 300Ah LiFePO4 battery. No smoke after 5 years of fulltime travel.

[scubadoo]

another expert ?? also commented on the ability of this battery to stay cool enough if this type of energy [eg 80 amps]is imputed for long periods. Most manufactures recommend charging in 2 stages . maybe this is to do with internal heat and this 270 A/h having no cooling system fitted which can be seen.

With all respect to the "expert". Typical LiFePO4 cells have extremely low internal resistance and charging at say 0.5C - 150A for our 300Ah battery requires no cooling. I doubt many here would be interested or even capable of testing temperature rises at even higher currents.
I have yet either by feel or the external battery temperature sensor to detect any level above ambient. Warmer has never occurred or more correctly been observed.
I can't easily check for example 150A for 2 hours. The battery pack would be well and truly be full long before the test ever concluded.

The internal BMS circuitry temperatures at high currents may be another matter but would hopefully be minimal.

[divxmaster]

@Johnny,
Have you tried pulling large amps from our 270ah batteries via an inverter? I dont have that capability yet.
150 amps or similar?


edit: @all: the seller says he could only source 80 more of these and is having trouble sourcing them.
so far ive put 45.5AH back into the battery, pretty slow going at 3A.

Cheers,
Mike

[divxmaster]

CHARGING COMPLETE!

It took 65AH.. so within the margin of expected error.

I guesstimated I drew 77AH from it, but that is an extremely rough guess based on two amp draw meters on two buck converters, but they were jumping all over the place somewhat.

Still pretty happy, battery seems ok from my limited testing.
I did notice my charger and the batteries inbuilt meter pretty much showed the same voltage.. I stopped charging at 14.17v
The inbuilt battery meter is only one decimal place, but when the charger went to 14.10, the battery went to 14.1 almost at the same time.

What is interesting is my multimeter shows 0.1v below this. If my multimeter is wrong, then 0.1v less draw from the battery than I thought, this can be a huge amount. it showed 13.19v at the end of discharge. If that is a real 13.29v, then the battery was a higher soc than 67% initially estimated.

Anyway, so ends my testing.

edit: I checked the cell balance, and took the lid off, and after putting in a bit more charge it went into balancing mode. It kept balancing even after I turned off the charger. The two leds in the photo are 6.4 and 9.6v and they both are showing higher cell voltage, so it is working.


Cheers,
Mike.

[DarrenM]

Even at the now more expensive price on trademe, they work out to a cell price better than I can get on aliexpress. So I have ordered a couple...

[DarrenM]

So I got them, and pulled one apart. As we know there are 12 cells, 3p4s, looking closely at those cells they are labelled ATL-VOD5NO, and maybe a serial number that is hard to read. But more interesting, it says 3.2V-256Wh.
Watts being volts times amps, that just 80 Ah right? 3 in parallel would give 240Ah, not 270 as advertised right?
The cells look well packed but actually only have a thin strip of packing at the top leaving a 5mm air gap between them rather than being held under compression and are quite swollen.
Balance out of the box ranges from 3.327 to 3.368 volts, quite a spread
Perhaps still reasonable value, Im going to strip the other one, balance all of the cells, reconfigure them and see what they can do

[divxmaster]

Well 240ah at 12.8v.

Thats why I hate AH as a measurement, its meaningless because it depends on the voltage!
These are advertised as 270AH at 12v, and they are in fact 256AH at 12v.

Watt hours is a much more meaningful measurement and these batteries are 3072wh, advertised as up to 3000wh/3kw, so by that measurement they good.

Glad you took one apart, I wasnt brave enough, with that big copper plate and complicated BMS, didnt want to short anything.

Anyway, I'm happy, close enough to stated capacity for me. In line with my tests showing a bit under 270ah.
My second one should arrive on Friday, 6kw is a good amount of power to have.

Edit: found them here:
https://www.aliexpress.com/item/32702168154.html

If this info is correct they are CATL V0D5N0 prismatic 80AH.

Cheers,
Mike.

[Nut17]

The second hand ex AA Solar "A Batt" 150 AH batteries I have installed were extensively tested by my son who has good skills and the equipment to do this. He was only able to do the discharge - charge sequence on two cells at a time, but having the internal resistance info enabled the reassembly of the packs to be better balanced. The individual cells were top end balanced prior to assembly and are now protected using HA02 automatic cell balancers. The chart in the photo below shows that all cells exceed the nominal 150 AH capacity.
I suspect that the cells in these new 270 AH packs are capable of receiving and delivering a high current - up to 200 amps, but are limited by the connectivity and management systems built in.