Ebike query

[David C]

Good morning all. I have been looking for knowledgeable people out there to talk about ebike batteries and I have found you. Hope you may be able to help me with a query.
I’ll go straight into my question.
I have two 36v folding ebikes. Essentially they are the same but use slightly different seat tube batteries. One bike uses a battery with two pick up terminals at the bottom one positive and one negative and the other has four pick up terminals. Two + and two- I guess.
My query is…. can I use the two terminal battery onto the four pins on the other b

 

[matthewslack]

Good morning all. I have been looking for knowledgeable people out there to talk about ebike batteries and I have found you. Hope you may be able to help me with a query.
I’ll go straight into my question.
I have two 36v folding ebikes. Essentially they are the same but use slightly different seat tube batteries. One bike uses a battery with two pick up terminals at the bottom one positive and one negative and the other has four pick up terminals. Two + and two- I guess.
My query is…. can I use the two terminal battery onto the four pins on the other b

A few ifs, and rather important ones. It is the physical fit and polarity that you need to be sure about.

Two pins means simple + and - connection, no extra pins so no communications link.

Four pins on a generic system likely also is no comms - virtually certainly - so either two pins are + and two - or two may be not connected. If you have a multimeter, check. Often symbols will be moulded in, so look for those too.

First, before trying a physical fit, you need to check that + will sit on +, - sit on - , in all combinations you want to use. If not, then of course it will NOT be OK, and components will fail through reverse polarity connection.

'Fit' means pins in the same place and of the same type. Reasonably high currents are carried by these connections, so need to be good enough.

If polarity is correct, then should be fine if it physically fits, as any multiple + and - pins are typically linked in the battery mount. Any generic 36V battery is OK with a generic 36V bike from an electrical point of view.

I would make a diagram of each mount and each battery end and label them with + and - symbols, as a desktop sense check.

Just be aware of the consequences of getting it wrong, and check very carefully first!

 

[Nealh]

If the polarity is the same then yes, the two extra polarity pins will either not be used or if wired are for on bike charging where the original charge point may not be very accessible on the battery.

However some pics of the bases first would be a good idea so we can see.

 

[David C]

If the polarity is the same then yes, the two extra polarity pins will either not be used or if wired are for on bike charging where the original charge point may not be very accessible on the battery.

However some pics of the bases first would be a good idea so we can see.

Thanks for your help. Had a close look and although the fit would be good the polarity is opposite. It’s a pity but now I know.
Another query I had was should I switch off the charger as soon as the green light comes on or leave it on for a while.?
David

 

[guerney]

Thanks for your help. Had a close look and although the fit would be good the polarity is opposite. It’s a pity but now I know.
Another query I had was should I switch off the charger as soon as the green light comes on or leave it on for a while.?
David

The Ingrish instructions which arrived with my kit says to leave the charger on for "Awhile" after the green light has appeared "For to balancing of the cells"... which makes me wonder what triggers the green light, if not a balanced battery pack? I leave my battery charging via a mechanical timer set for however many hours I think it'll take to charge (thanks @Andy-Mat), plus a short "Awhile". It hasn't burst into flames yet.

 

[Nealh]

One can leave it for about an hour to balance if the balance is out, but never over night or allow charging when asleep.

With regards to polarity, one should be able to remove the battery base and rotate the discharge pin block and then swap the base connection as well on the receiver so both batteries can be used and both bikes have polarity arranged the same.