DIY Lifepo4 Car battery starter capacity test after 2 years of use

[@ericklein5097]

In my experience (like capacity testing my M1B cells yesterday) you'll get a max of 2 more Ah from 3.0 to 2.5 assuming your cells stay relatively balanced and by the time the lowest one trips the BMS the other 3 are all below 2.60 or close to it. The length of time spend from 3.0 to 2.5 was about 1/4 to 1/8 of the time spent during the flat part of the discharge.I can take better notes next time to tell you exactly what % of the capacity you avoiding (for good reason, if you don't need every mAh out of your pack just cut if off at 3.0) The major concern is the internal resistance. The EOL 80% figure is used because that's when we begin seeing a noticeable increase in the IR of the cells. Prior to that it rise but at an almost unnoticeable rate. Once you double the IR you've significantly reduced your discharge current (unless you're ok with your cells getting nuked at 100 degrees Celsius). I don't want to say a 2X increase in IR will equal a 0.5X change in discharge but I'd imagine its something in that neighborhood. This is why I avoid the A123 packs that test near 80% and will seek out ones that test as close to 100% as possible. Recently found some that test right at 98% in the Wh and 101% Ah but I am doing a rather slow discharge for these power cells. I'm going to try to do a 10A discharge for a 0.5C discharge rate. If I can find a way to do a 1C I will definitely give that a shot. Might hook up some resistors for a 2C discharge that I'll just have to do some math on.

[@hajjiturbanos6186]

May i know the link of the bms you use?thank you

[@charlschuck6]

How many amps discharge max is that bms I have had bad luck maybe cause we try to cheap out and they all sucks saying some rating and cutting off or not giving out those amps and fry to quick in my case . I noticed some bms cost more than a well on sale lithium pro made battery 😀😅 and also the opposite where they put some cheap cells but make the enclosure look like huge and insane labels on throes batteries .

[@diylithiumguy]

You have any details on that capacity tester?

[@trongminh2804]

After 4 years of use, how is the battery condition? Can you make another video?

[@vsl5917]

friend, in aliexpress they sell empty boxes for batteries, it would have been easier for you to buy a box so you would not have to disassemble the battery

[@EVCustoms]

Hi.. yes i know that, for sure is more easy to do with ready case.. but 45+shippings + waiting is not for everyone.. ;)

[@carsandtools]

I am building a Lifepo4 pack for my campervan and while I did order that empty case, it was so expensive ($80 for the size I needed) I seriously considered doing the same. The cheapest Pb batteries of that size are actually even cheaper than the empty case. :D

[@EVCustoms]

😅😂😄

[@curits8260]

what size is the wire sir?

[@ericklein5097]

Forgot to mention this in my original comment but ditch that balancer. You should only be balancing at either the very top or bottom of LiFePO4 otherwise you are unbalancing the battery

[@EVCustoms]

Balancing must be done only at max voltages of the battery (ALWAYS) in this case the battery almost every time is at full charge so no worries..

[@markveenstra702]

I,m looking for a good load/capacity tester wich brand is this and were can i buy it ??

[@EVCustoms]

Hi... specs of voltage and currents? this one in video is DIY..

[@markveenstra702]

@@EVCustoms i have several lithium 48/60 volt battery,s most of them are 35/40 Ah and 4x with a maximum 100 Ah and trying to find something that can measure the real capaciteit.

[@curits8260]

Do you have video diy on that battery? planning to make one for my car.

[@EVCustoms]

Hi friend... here is the link (old video) >> kzbin.info/www/bejne/fnbHZnmhfNOfoLM

[@curits8260]

@@EVCustoms thank you sir, is the new bms and the old bms safe? will not cutoff the power once fullycharged the battery?

[@EVCustoms]

@curits8260 you mean the active balancer?

[@curits8260]

@@EVCustoms i mean the bms. i wonder what if the battery are fully charged, and what happen to alternator?

[@josephamaral419]

​Altenator can spike up in voltage while running and ruin your whole car curcuitry/ECM. This is mostly on some newer cars though. The "proper" way would be to have lead + lithium combined with isolators or managers designed for this use. Also, there are lithium batteries sold specifically for starting vehicles that have components designed to never cut off power from the battery to your car to prevent alternator/car damage. Not saying his way won't work, it does, just at the risk of the lifespan of his alternator.@@curits8260

[@paveljelinek772]

😂😂😂 it cuts on 2.5V but WHILE DISCHARGING!!! You expect it to be 2.5V on 10A and be the same voltage on opencircuit??? 🧐 You're not sane if you do

[@Mavstang73]

If you dont already have one its time to get a 3d printer. Print up a nice custom enclosure for that battery.

[@EVCustoms]

I have two 3D printers... but time is to expensive, also tis video is for every one, some people didn't have chance to buy 3D printers, so here you have a cheap option idea.. ;)

[@h8GW]

You sure exposure to all that sulfuric-acid-covered lead didn't affect you? You connected the negative terminal _first._ Sus af 🤨

[@igorkvachun3572]

Yes👍🔋⚡💡 🇺🇦✌☀