Toro 48V 4Ah Battery & Charger

[ayedurand]

So I have a bunch of 88509 batteries for Toro line trimmers. I'm planning on using them for ebikes for my nephews. I'm planning on running three of them in parallel (maybe four). They're 12s2p packs made up of Sanyo ur18650rx cells (attached). The battery pack has what appears to be a sophisticated BMS built into it (more pictures). I'd like to leave them as is and take advantage of someone else's engineering work.

I don't exactly know how LiPo batteries are managed. Meaning what is the key parameter that is monitored to ensure the batteries are not over charged. NiMH batteries had a voltage plateau and associated temperature rise that indicated full. So here's the trick there's a microcontroller on it that I "think" communicates with the charger. The chip that I "think" it talks to is a TS1102A that shows up in other battery packs for handheld tools but no one can find any data on. My fear is that this communication channel is going to get confused if I try to charge the three or four battery packs in parallel. Is this something I ought to worry about? Most tool battery packs have four lines connected to the charger or tool. I just don't understand why.

So, before I go and do a bunch of testing that others already know the answer to I thought I'd ask.

 

[cal3thousand]

With lithium batteries, voltage is of utmost importance. Generally, they have a top voltage of 4.2V per serial cell. Those boards will monitor voltage and attempt to keep them in balance.

As for charging them in parallel, the charger will have no clue that the pack is 3 to 4 times as large as before and will not care. It's the same principal that allows them to have larger/smaller capacity packs and only have 1 charger design. The charger will just keep putting in energy until the pack voltage tells it that it is full. (Of course how much it puts in at what voltage/current at any one time depends on where the pack is in it's voltage curve).

But, having a charger for each pack will certainly get you back on the road quicker. Sounds like your nephews will have a fun summer thanks to a cool uncle.