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Old Oct 24, 2001, 09:00 PM
Registered User
Burns Lake B.C canada
Joined Jan 2001
7 Posts
charging 8 cells from a 7 cell charger?

i have an mrc brain charger which is meant for 6-7 cells and i want to put an 8 cell pack in place of the 7 cells that i currently use. Is there a simple way of charging 8 cells from a 6/7 cell peak detection charger and keep the peak detection working or is it a lost cause?
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Old Oct 24, 2001, 09:38 PM
Andy W's Avatar
Marietta, GA
Joined Jun 1999
43,312 Posts
If you use a 13.8V power supply and it stays at that level until the pack peaks, there's a chance the pack will be charged. Not very reliable, however. You're better off buying a new charger.
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Old Oct 25, 2001, 06:42 AM
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plinse's Avatar
Baden Baden, Germany
Joined Feb 2001
1,059 Posts
The chargers which are limited on something like 7 cells can not increase the input voltage and 7 is the number of cells which can be charged even from a quite empty car baterie. Such chargers just control the current and if you want to charge more cells you just have to make sure, that the input voltage is high enough, 8 cells is usually no problem. But the input voltage should not exceed the highest voltage the charger can handle (usually 15V but check that out before trying )

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Old Oct 26, 2001, 12:58 AM
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tekochip's Avatar
West Dundee, IL, USA
Joined Jul 2001
845 Posts
A higher input voltage may not work. The current pump in switching regulators usualy has a maximum voltage setting, and your charger may have this clamped at a 7 cell level. Also a peak charger is looking for a decrease in voltage somewhere around 1.6mV per cell (I've seen 1.2mV to 2mV), and with more cells you may get false peaks at high charge rates.

The best thing to do is measure it, and then give it a try.
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