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Old Oct 27, 2009, 09:45 PM
GravityGun is offline
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Flight n00b
Stamford, CT
Joined Oct 2009
11 Posts
I made a bad assumption here, so I wanted to correct it so others don't fall into the same trap:

Originally Posted by GravityGun
For my first charge, it's been plugged in now for about 18 hours and reading 8.24V (It's a 7.7V battery), so it looks like it's working splendidly for me.
There's no way of knowing how full a metal hydride battery is by the voltage alone (unlike lithium batteries). In fact,
a new NiMH battery has false peaks early in the charge cycle, and so the charger will terminate too soon.
This is consistent with my observations, as my battery will peak at about 8.3V and come back down to about 7.8V while charging fully.
I recommend the following site if you're interested in learning about metal-hydride batteries.

To pay for my sins, I threw together a quick spreadsheet to act as a guide for how long a fully discharged battery should stay plugged in given a certain amount of red-light charge time. For instance, my first charge gave me only half an hour of red-light charging. Therefore, going across the table, I should have kept it plugged in for 71.25 hours. Now, I wish I had done that because it is taking me forever to cycle my battery again after keeping it plugged in for only 24 hours.

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