# for the experts 48v battery 36v bike



## billym0404 (16 Feb 2018)

ive found this product and wonder if i fit it, will i be able to use a 48v battery on a 36v system 

http://www.ebay.co.uk/itm/DPS5020-S...720980?hash=item3d4ec7c8d4:g:CYMAAOSwmudaBqBO

it says from 50v and upto 20a

do you think it will work


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## raleighnut (16 Feb 2018)

billym0404 said:


> ive found this product and wonder if i fit it, will i be able to use a 48v battery on a 36v system
> 
> http://www.ebay.co.uk/itm/DPS5020-S...720980?hash=item3d4ec7c8d4:g:CYMAAOSwmudaBqBO
> 
> ...


Depends on the motor, you could easily burn some of them out.


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## billym0404 (16 Feb 2018)

bafang


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## raleighnut (16 Feb 2018)

billym0404 said:


> bafang


Some are capable if they're the 250/500w rear wheel versions.


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## billym0404 (16 Feb 2018)

so does that device i showed not adjust the vault age and ampage


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## Tim Hall (17 Feb 2018)

billym0404 said:


> so does that device i showed not adjust the vault age and ampage


Reading the blurb on your link, yes it does. 


> Its adjustable output voltage range is 0-50.00V, step by 0.01V. Its adjustable output current range is 0-20.00A, step by 0.01A.


Whether that will do what you want is another matter. It's a question for @mickle or @kimble I think.


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## cheys03 (17 Feb 2018)

Whilst this should work in theory I think you'll find that in practice the DC-DC device is not up to the task and burns out shortly after trying it. Especially if you're not adding heatsinks and airflow to cool it.
What happens then ...? If the DC-DC shorts it will blow the fuse on your battery. If it bypasses it will put 48v in to your 36v eBike controller and might be game over for e part of the eBike. Best case it just blows without consequences but leaving you having to arrange return shipping etc.
In short you'd be better trying to source a 36v battery within your budget or modify/replace the controller to accept 48v.


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## billym0404 (17 Feb 2018)

cheys03 said:


> Whilst this should work in theory I think you'll find that in practice the DC-DC device is not up to the task and burns out shortly after trying it. Especially if you're not adding heatsinks and airflow to cool it.
> What happens then ...? If the DC-DC shorts it will blow the fuse on your battery. If it bypasses it will put 48v in to your 36v eBike controller and might be game over for e part of the eBike. Best case it just blows without consequences but leaving you having to arrange return shipping etc.
> In short you'd be better trying to source a 36v battery within your budget or modify/replace the controller to accept 48v.


 thanks for that. so bad idea then. i was just wanting to use the same battery on different motors. there must be some way of cutting 48v output down to 36v.


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## billym0404 (17 Feb 2018)

so, and this may be a stupid question. "replace the controller to accept 48v" so on a bafang BBS01 is the controller in the screen (as my screen has a vault-age setting) or is it in the motor case, which is where i think it is.

i do have a plan b but out of practice and not sure if im up to it, and dont have the right solding iron. i have a neally new 48v 13a battery would guess at 65 cells. i could turn it into 36v 15a using 60 cells and a new BMS. or plan c as the battery is barley used just sell it and buy a new 36v. though that defetes the orginal plan of trying to use the same 48v battery on two different motors lol


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## midlife (17 Feb 2018)

Way back in the 70's doing A level physics I'm sure we messed around with voltages using Zener diodes and split circuits with resistors....


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## billym0404 (17 Feb 2018)

someone has suggested diodes but running 48v through 36v diodes they would just blow.


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