Author Topic: Lithium Battery Chargin Ebay Board Mod ??  (Read 1024 times)

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Offline locoo

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Lithium Battery Chargin Ebay Board Mod ??
« on: September 03, 2016, 09:58:38 pm »
  Hi

 I dont know if it is possible or cost effective , correct me if not.

 I have an old Cordless drill NIMH 14.4 v and want to replace the battery with liion.

 But i would like to make my on BMS .

 Was thinking buying eBay auction: #http://www.ebay.com/itm/10PCS-5V-Micro-USB-1A-18650-Lithium-Battery-Charging-Board-Charger-Module-/201414932553?hash=item2ee543f849:g:oEEAAOSwrklVO5q7

 But it has Max 2A Fet for overdiscarge protection and i need more my Liion can give out 15A burst .

 So what i want is to pull out the existing mosfet and replace it with a big TO220 some .
 
 I dont , i cant see will that work or what new fet to pick out , will the small DW01 be capable to run a big mosfet.



 
 
 

Online amyk

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Re: Lithium Battery Chargin Ebay Board Mod ??
« Reply #1 on: September 04, 2016, 10:52:44 am »
A 4S pack might be a bit too much voltage (16.8V fully charged) but 3S is probably not enough (12.6V fully charged). If the motor and control circuitry isn't designed for the extra voltage they could be damaged.

Also your cells are probably not sufficient if their burst current rating is only 15A. You should use low capacity high current cells, something like these (30A continuous discharge):

http://lygte-info.dk/review/batteries2012/Keeppower%20IMR18650%201600mAh%20(Black)%202014%20UK.html
 

Offline locoo

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Re: Lithium Battery Chargin Ebay Board Mod ??
« Reply #2 on: September 04, 2016, 07:51:43 pm »
But but 14.4v is a nominal voltage  14.4v÷1.2v =12 cells 
Full
12cells×1.45v = 17.4v
1.45 v is cca fully charged Nimh cell
So 17.4v is almost prefect 4s
 
The cells I will use are
https://batterybro.com/products/samsung-15q-inr1865015q-1500mah-18a

And 15A burst I said is what I think the drill will pull Maaax probably much less.


But my question was not obout the cells but can convert this cheap bms from eBay to run more than 2 amps ading an external Fet.

Thanks
 


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