30S Charger

Jul 6, 2022

I am rebuilding a Pack for a friends Mower right now.

The owner got two original 30S1P (nominal 120v) batteries for it (but the mower just takes one at a time), both packs died just after a couple times of using them (no wonder with Samsung 29E cells (10A)... and its a huge Mower lol). I can not reuse the original BMS(es?) because the owner already killed them with some solder adventures. Just ripped one pack apart and tested each individual cell and all seem good (capacity and low voltage drop over 4 weeks). Might salvage the second battery too and give it a try and build a 30S2P w/o BMS.

My question is: does anybody have a clue how to get this nice 550w charger working/activated? One pin just gives me 5v, that's it. Obviously I can't just see 126v here (because Germany, regulations and working with voltages >120v this is not directly exposed). Am I thinking too complicated and it will just start charging when a suitable sized battery (I mean within voltage range, >90v or something like that) is connected?

Larger pictures (+ pics of original batteries): https://imgur.com/a/c8lvyXj

Other route would be to split-charge it with 3 (isolated) 36v-chargers.


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I think the charger needs the battery to close those relays. Have a similar charger (with just -&+) that won't output anything unless a battery with at least 60v is connected.