Where to find cheap e-bike batteries

[Adrian Parkinson]

Okay, what I'm currently leaning towards is getting three of these and connecting them in series. Does this sound like a good idea?

https://www.takealot.com/universal-hoverboard-battery/PLID71780271

[MORNE]

16 hours ago, Adrian Parkinson said:

Okay, what I'm currently leaning towards is getting three of these and connecting them in series. Does this sound like a good idea?

https://www.takealot.com/universal-hoverboard-battery/PLID71780271

Not gonna work. But lets humor the idea for a second.

In series you’ll still only end up with 4.4ah of capacity but 108V (36x3). Theres your first problem….. about a third of the capacity of an avarage ebike. Probably enough juice for like 10km. 

Ignoring the too high Voltage for a second and just looking at capacity and C rating, Realistically you'd need 9 of those to bodge it in a 3 x 3 setup. Three clusters (of 3 x series) connected in parallel to get you the capacity you are after.

But again…you'll still be at a 108V then. If you took 3 and wired them in parralel you'd have the capacity (range) but you'll only be on 36V. What does your setup need to operate at 100%? most ebikes are 48V or 52V ish i think. So 36V is gonna feel like a flat battery and they will overheat becasue they will be working too hard. Another option is to bodge some sort of high voltage regulator to get the 108 down to what you need. 

also, you’d need to wire them in a way that would make it possible to balance charge each pack/cell individually . That means balance ports, and a proper charger that would put you back a few grand more.  So theres another hickup.
You could of course charge them all wired up but with the nature of these things re internal resistance and inconsistencies between packs, you’d end up with a dodge/dud/ dead cell sooner or later.

to conclude, at R500 a pack x 9 and the effort involved to get it user friendly, i wouldn't do it imo. Even if it were 48 or 52V instead of 108V

 

edit:

what i’ll ad though is this:

those are 10 cell packs (10s2p). a single cell is about 3.6V ish and gou g by that..those are 4400maH cells most probably. R500 is cheap when you consider that. If i REALLY had to, id buy the packs, take them apart and rebuild them in the configuration that would give you the numbers you need.

series= increases voltage. Parallel increases capacity. 
so 2 x 3.6v(4400mah) cells in series would yield a 7.2V 4400mah pack.

2 x 3.6V (4400mah) in parallel will yield a 3.6V 8800mah pack.

 

Edited September 8, 2022 by MORNE

[ChrisF]

.

 

EDIT - Morne answered already

Edited September 8, 2022 by ChrisF

[Jackie Thamsanqa Maholwana]

On 9/5/2022 at 6:22 PM, Adrian Parkinson said:

The battery it had been using was actually 3 12v lead acid batteries wired together. That was completely dead and even if it wasn't, it would be ridiculously heavy to ride with.

I would much rather avoid Aliexpress, but sadly we are in an electrically primitive country where batteries are scarce and expensive so I'm not sure what alternatives there are.

If anyone knows of any local suppliers (preferably in KZN) I'd love to hear about it.

Contact E-Bikes Adventures Neil Kemp (ebikeadventuressa@gmail.com. 

[Adrian Parkinson]

7 hours ago, MORNE said:

Not gonna work. But lets humor the idea for a second.

In series you’ll still only end up with 4.4ah of capacity but 108V (36x3). Theres your first problem….. about a third of the capacity of an avarage ebike. Probably enough juice for like 10km. 

Ignoring the too high Voltage for a second and just looking at capacity and C rating, Realistically you'd need 9 of those to bodge it in a 3 x 3 setup. Three clusters (of 3 x series) connected in parallel to get you the capacity you are after.

But again…you'll still be at a 108V then. If you took 3 and wired them in parralel you'd have the capacity (range) but you'll only be on 36V. What does your setup need to operate at 100%? most ebikes are 48V or 52V ish i think. So 36V is gonna feel like a flat battery and they will overheat becasue they will be working too hard. Another option is to bodge some sort of high voltage regulator to get the 108 down to what you need. 

also, you’d need to wire them in a way that would make it possible to balance charge each pack/cell individually . That means balance ports, and a proper charger that would put you back a few grand more.  So theres another hickup.
You could of course charge them all wired up but with the nature of these things re internal resistance and inconsistencies between packs, you’d end up with a dodge/dud/ dead cell sooner or later.

to conclude, at R500 a pack x 9 and the effort involved to get it user friendly, i wouldn't do it imo. Even if it were 48 or 52V instead of 108V

 

edit:

what i’ll ad though is this:

those are 10 cell packs (10s2p). a single cell is about 3.6V ish and gou g by that..those are 4400maH cells most probably. R500 is cheap when you consider that. If i REALLY had to, id buy the packs, take them apart and rebuild them in the configuration that would give you the numbers you need.

series= increases voltage. Parallel increases capacity. 
so 2 x 3.6v(4400mah) cells in series would yield a 7.2V 4400mah pack.

2 x 3.6V (4400mah) in parallel will yield a 3.6V 8800mah pack.

 

A mistake on my part, it would be in parallel, not series.