DIY Charger for Panasonic 26V Flyer, Gazele etc.

[Ruskapralka11]

Hi
I have two batteries for Panasonic system Panasonic 26V 25,9V w.e.
For batteries NKY259B02, NKY265B02

My original charger burned, PCB is just one big mess.

I would like to make a charger from laptop charger + step up module



Problem is, that if I connect 29.4V to + and - of input connector no current flow, BMS dosnt want to accept this voltage.

Does any1 can help how to charge this battery? Do I need to apply some other voltage on other pins, or maybe some resistance?
I have basic knowledge of BMS, electronics, and I am not afraid of soldering

What are those terminals? Why they are needed, and how to charge this battery using included BMS?

Please help me...



There are some replacements, but those are extremely expensive, or inaccessible

 

[amberwolf]

Relative to battery negative, what voltage do you read on the S and T pins?

It is possible that the T pin is a thermal sensor in the battery itself, that the charger reads to see if it should keep charging or not. (but it could be a thermal sensor in the charger taht the BMS reads...or something completely different).

The S pin could be a serial data pin that is used to talk between charger and battery. If so, it's possible the battery wont' start charging until the charger gives it the right command...or the BMS may be telling the charger to start and then waits for the right response from the charger before it opens the gates to charge. If it is a data line there won't likely be a constant voltage on it, but porbably toggling from 0 to 5v, so it might read about 2.5v as an average of those.


Either pin could be for something else entirely. Or not actually used in cahrging, and only used to talk to the bike's controller.


Unrelated, but when making your own charger, you will not only need to keep the right final voltage, but you also have to have "constant current" or "current limiting" (CC) in a way that simply drops the voltage to limit current. Most power supplies and voltage converters (up or down) simply turn off if current exceeds their limits. (so they don't work as battery chargers).

LED PSUs (like Meanwell HLG and ELG) work well enough as battery chargers. But the average voltage converter or DC power supply don't.

If you're not sure if the converter you have uses CC/CV output, then it probably doesn't, and probably wont' work well (or at all) as a charger.

 

[Ruskapralka11]

Yea, its smth like 2v difference.

And I use CC/CV converter connected to PSU. Will do some more pictures and let ya know.
So if its data, I probably wont be able to spoof it....

 

[amberwolf]

Might not be applicable, but:
https://endless-sphere.com/forums/viewtopic.php?f=14&t=114108