Tag: battery discharge

Leoch DJW12-5.0(F2 12V5.0Ah) Maintenance-free Sealed Lead-acid Battery cohort testing and refilling (WHL #79)

Batteries. Plain old lead-acid batteries for today.

Before I left to Scotland, IT dropped a bunch of UPS batteries in my office. And since I wasn’t present, they asked my colleague to get them tested, you know, just sort out the bad ones. Sure thing.

It’s 119 of them, plus two dozen more of a larger size (9Ah) that are more common in those desktop APC units that I also use at home. All in all over 200kg of lead. Well, thanks a lot…

Thing is: I don’t have time for that. And it’s not my job. And with the limited equipment I have at hand (at work…), it took me well over a month to get them all tested alongside regular work. […]

9th October 2022 5th March 2023 By Bzzz In No Comment

CITYSAX 160Ah LiFeYPO4 battery discharge and teardown (WHL #51)

Speaking of electric cars: A colleague recently bought a used electric car and (obviously!) contacted me in order to diagnose/troubleshoot it. Sadly he was able to sell it for a profit before we got it fully fixed, so no live data recordings, no power/torque graphs, no nothing to show here. But he left me a dead cell for which he got a replacement from the seller right away, as the traction battery had voltage dips under load that indicated (at least) one damaged cell.

If servicing individual battery cells sounds a bit strange for a modern electric car, that’s because we’re talking about a CITYSAX from a company that is conveniently named the same. […]

8th September 2019 8th September 2019 By Bzzz In No Comment

O’CELL 26650 LiFePO4 8S 3.3Ah battery pack with BMS (WHL #28)

Same thing again – but different manufacturer. That’s what you get when you clean up your new lab… ;)

I know, might be boring to see another battery pack with almost identical specs (3.3Ah instead of 3.2Ah), but trust me, this is like night and day – or like quality China and Wan Hung Lo.

Of course these two batteries were purchased at the same time for the same thing, and they cost around the same as well. But (spoiler!): These two units work fine.

Top view:

Nice shrink wrap, proper label (shout out to O’CELL and their caring but not nagging sales people). […]

24th September 2017 3rd October 2017 By Bzzz In 2 Comments

26650 LiFePO4 8S battery pack with BMS (WHL #27)

This weeks article is another by-product of the ADC testing (WHL #26) from last week. Could’ve packed in there, but I wanted to share some remarks on Chinese battery technology…

So first of all, this isn’t a piece of kit that I bought myself. After testing two 12V/2.2Ah lead batteries from work that were sitting unused on a shelf for five years, I needed another victim. Those quality Panasonic cells were flat as Kansas – the LC-R122R2PG datasheets recommends 8.6V cutoff voltage at 3C = 6.6A or 9.7V at 1C. Fully charged, they delivered 1C at 7V or 1.5C at 2.5V at full charge – slow 10.5V discharging to 0.1C cutoff and recharging didn’t help much. […]

10th September 2017 10th September 2017 By Bzzz In No Comment

A beefy electronic load (#P4F2)

Hello again!

I’ve been asked: What do you do with this electronic load thing? Well, I‘ve been using it as a battery torture device, what else could you do with a variable resistance device…

For a crude first step in actually testing my unit and also classifying a newly harvested set of deeply discharged 18650 cells, I slapped together some minimalistic Arduino program and hooked the thing up in parallel to the battery under test. The electronic load was set to 2 Amps with another battery, which was monitored by the Uni-T 203A current clamp. […]

27th August 2017 3rd September 2017 By Bzzz In No Comment