Where do 24v battery packs come from?

As a long-time user of of the 24v 250 watts 8Fun motor electric bike kit, I know that dealers (from where I bought my battery packs) purchase these from suppliers in China. I am not entirely sure if these dealers are merely resellers or if they design the packs and have them manufactured in China.

Comparing the pictures from Alibaba.com and my pack, one can see similarities.

My 24v 10.4 Ah pack

The one on Alibaba ad

If you search google for "24v 10.4 Ah battery pack" you will get the following search results here and here.

The price offered on Alibaba.com for each of these 24v 10.4 Ah packs are USD 99 and USD 101 but you have to buy them in bulk.

I also checked for "24v 5.2 Ah battery pack" and I got the following search results here and here.




My 24v 5.2 Ah pack looks similar to the ones on Alibaba.com. For example:

The price offered on Alibaba.com for each of these 24v 5.2 Ah packs are USD 70 and USD 85. But again, you have to buy them in bulk to get that price.

How about the battery management system (BMS) module inside the packs?

The BMS inside the 30K battery packs from LEED looks like this:

Back side of BMS board inside LEED 30K pack

Front view of BMS board inside LEED 30K pack

As you can see from the markings, the BMS is made by fcybattery.com. If you check their company website (FCY Technology) you will see that the 24v battery packs they sell look the same as the ones sold by LEED so maybe FCY is the supplier. FCY also has Alibaba ads on their site and the picture of the battery pack looks exactly like the picture of the pack on the Alibaba ad mentioned earlier.

The FCY website does not quote their price for the 24v battery packs but if these are the same as the ones on the Alibaba ad then the retail price must be the same or lower if you are buying in bulk.

LEED packs contain 2600 mAH Samsung cells but the pack themselves contained in a hard plastic box which offer good protection from accidental collision with other objects. Bothe the 30K pack and the 10K are contained in plastic boxes. The plastic boxes probably costs about 8 USD.

The 10K Sprinter pack sold by Clean Republic does not come with plastic box, only heat shrink wrap and some kind of insulation cover. The BMS board, however, show that Clean Republic may have designed it and only had it manufactured in China. The reason I say this is because the board has a different model number (LT-P721 v1.1, 2012.06.19 ROHS) unlike most BMS boards that include the website of the manufacturer. Clean Republic Sprinter BMS board also uses a prototyping circuit board and white JST female plugs for the balancing wire connections.

Clean Republic Sprinter BMS LT-P721 v1.1

If you have one of these 24v battery packs yourself, you can take them out of their nylon bag and compare if they look the same as the ones pictured above.

If you have old packs that are dead and are beyond the warranty period, you can also try opening the pack itself by removing the cells from the heat shrink wrap and/or the plastic box. CAUTION: be careful in opening these packs. They contain lithium ion cells that are prone to catching fire when shorted. I cover the exposed nickel plates with insulating tape whenever I open them for testing and fixing.

My next project it to add battery holders to my 10K 7s2p Sprinter pack from Clean Republic so that it will be possible to replace single failing cells instead of throwing away all 14 cells. According to batteryuniversity.com, doing so is possible. It is unlikely that all the 14 cells will fail at the same time so having battery holders instead of spot welding the 18650 cells will allow removal and testing of individual cells for replacement with new similar cells. If this can be done safely, it is better for the pocket and for the environment. Amazon sells Samsung 2900 mAH cells for 12.50 USD each (175 USD for 14 cells). Clean Republic sells new Sprinter packs for 269 USD. Amazon sells Samsung 2600 mAH cells for 5 USD each (70 USD for 14 cells). LEED sells new 10K packs for 199 USD.

NOTE: More posts on e-bike conversion projects are available here.