SOH Meter for Battery Pack When You Purchase Them

[Tachopis]

Wanted to start a discussion here. I'm planning to buy a battery pack and here in Poland, there are many options. Although my main goal is to go for ID3 or ID4 batteries from VW, I could consider others. The problem comes when trying to know the SOH state of the pack. When you are buying them, the vendor is not very reliable about their state, even if they tell you the kilometres it has. Do you know any reliable portable meter? Ideally, you should be able to charge them to the max and discharge them to test, but obviously, when you're going to buy such a pack, you have a few minutes to make a decision. Any ideas? Is it a matter of luck or intuition?

[johu]

The BMS that is sufficiently hacked and provides reliable SoH is the Nissan Leaf BMS. It's just a matter of briefly waking it up and it will spit out CAN messages where one contains SoH.

CarScanner can probably extract the info from other packs but for some cars I don't trust it. E.g. the 28 kWh Ioniq still reported 100% after 160 kkm (some CarManiac video). I don't think that is likely.

If you have a good voltage/SoC curve you "only" need to extract like 5-10% of charge to get a rough SoH estimate. But even that is daunting on those large car packs!

Just my 2 euro-cents

[Tachopis]

Nice Johu!!!, I will check the Nissan leaf BMS option that sounds like a short-term solution for me. Thanks, I will keep updating this post. EDITING:
I'm checking and I have a few questions I will have to search for. First, if the BMS from Leaf will sniff SOH data from other battery packs, not Nissan Leaf, if yes, that will work only with CAN L/H, power cabling.

[Marat]

BMS is hacked and provides unreliable SoH, - Nissan Leaf BMS

B,293A0-5NR4C,To:293A0-5NR4C,5NR4C_150Ah_50KW.kwp,RNDS_SC003.ini,LBC_150Ah_50kw
B,293A0-3NK2A,To:293A0-5NR4C,5NR4C_92Ah_35KW.kwp,RNDS_SC003.ini,LBC_92Ah_35kw
B,293A0-4NP4C,To:293A0-5NR4C,5NR4C_118Ah_40KW.kwp,RNDS_SC003.ini,LBC_118Ah_40kw
B,293A0-5NR4C,To:293A0-5NR4C,5NR4C_125Ah_45KW.kwp,RNDS_SC003.ini,LBC_125Ah_45kw

This is an example of BMS firmware, and any indicator is adjusted.

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[johu]

First, if the BMS from Leaf will sniff SOH data from other battery packs

No, you can't just connect a BMS to a battery and expect it to magically determine SoH. The LBC only provides for the battery it has been connected to because it observes the behaviour over long time.

[Tachopis]

No, you can't just connect a BMS to a battery and expect it to magically determine SoH. The LBC only provides for the battery it has been connected to because it observes the behaviour over a long time.

Yep, well this is what I thought. And actually, will be great to create some device capable of connecting to the HV and performing a fast check. Of course, there are some low-voltage 12V, and 48V devices like this that never saw in HV battery packs. A device like that will help this EV Retrofit market buy second-hand batteries.