Electric Cargo Bike Owner

[decotopian]

Hi thanks for having me as a member, I own an electric cargo trike (the ones with the kids seats up the front) which I imported from China. I am very pleased with it ans so is my family. One of my friends also wants one so I have ordered one for him, but I am shippign it air freight rather than having to wait 12 weeks to get it by sea. The issue with air freight is that they wont ship a lithium battery over a certain size without 'hazmat' cert. Of course the chinese wont spend any money on certifcation if they dont have to so mine naturally has no certification.

So I am going to have to give him my battery to go with his batteryless bike when it arrives.

My question then is in general how do these lithiums work compared to a conventional lead acid battery bank? My particular unit has a 36V 10Ah Lithium battery which has 4 spade like sockets built into its slide in frame. It then has a charger connector like an old RF TV antenna connector. Why 4 pins not 2 for +Ve and -Ve? what role does a BMS have and is this typically part of the battery or part of the docking frame on the bike?

If I were to purchase locally a 36V 10Ah lithium battery what should I be considering before purchase?

Lots of questions I know for an introduction so please feel free to move this post to the relevant tech forum or advise which?

I work for Ampair a DC wind turbine manufacturer so I am failry cluey with lead acid charge /discharge/ regulation and SOC etc but am fairly clueless with these Lithium units and how the whole setup works, any advice much appreciated!

Thanks

Jeremy

 

[Deleted member 4366]

Most bikes have standard Chines batteries in them. You can inter-change them between different suppliers. Normally, only the outer two pins of the battery are connected. The charger connector sounds like a RCA jack also known as phono. They just use them for convenience. There's nothing special about them. It's just a two wire connector.

The BMS sits inside the battery case between the cells and the output socket. It makes the battery simple. You just charge it and use it leaving the BMS to manage balancing and protection functions.

If you showed a photo of the bike/battery, we could recommend a replacement. Batteries are just a voltage source, so you can use any one that you can physically fit to the bike. Rack-batteries are the easiest to substitute, but if you've got one that slides in behind the seat-post, ideally you need one the same shape, although you can still fit a rack-battery like this one, where the seat-post case is empty:

 

[decotopian]

Hi Here are some more photos which show the battery size and the terminals. Its slider is rail is 68mm wide and the ID of the receiving rail on the battery is 70mm - the length of the unit is 335mm long

Any idea what brand the control unit is?