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Charging NiMH battery pack - Page 4

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Posted by Snag on June 21, 2021, 1:03 pm
 
On 6/17/2021 6:52 AM, Jim Wilkins wrote:

   I bought 2 aftermarket NiMH batteries for my 18V DeWalt , the 9118  
charger worked fine . Until a couple of weeks ago when I let the magic  
smoke out of it . Probably moisture in/on the PCB . The new aftermarket  
unit will only charge batteries that have the 3rd contact on the center  
fin , so 3 of my batteries are now useless .
Snag
Race only matters to racists ...

Posted by Jim Wilkins on June 21, 2021, 9:15 pm
 

   I bought 2 aftermarket NiMH batteries for my 18V DeWalt , the 9118
charger worked fine . Until a couple of weeks ago when I let the magic
smoke out of it . Probably moisture in/on the PCB . The new aftermarket
unit will only charge batteries that have the 3rd contact on the center
fin , so 3 of my batteries are now useless .
Snag

----------------------

The DW9118's no-load output is 45V. On Amazon it's described as being only  
for 7.2V to 14.4V NiCds. I'm still investigating how to fully charge a NiMH  
by measuring the voltage rise at zero charge current, which the DW9118  
appears to do briefly once a minute. I've seen hints that the DW9118 and  
similar fast chargers use the curve of voltage rise to determine the battery  
voltage and state of charge, but I haven't found many specifics.

https://lygte-info.dk/info/batteryChargingNiMH%20UK.html  

My homebrew LM350 solar-powered variable linear regulator charges the NiMH  
pack to 17V pretty well. 18V at zero current is within the suggested safe  
range.




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