View Full Version : NiMH charging oddity

03-28-2010, 10:33 PM
I've noticed an odd thing with the NiMH battery in my hexapod, and I wondered whether this is normal. It certainly seems strange.

When I charge the battery, there is a period after I disconnect the charger when it doesn't seem to work properly. The hexapod fails in various mysterious ways - servos just give up, and I noticed also that the servo mux chips were getting hot. I can't see any explanation for all this.

If I leave the battery for a hour or so, everything is fine.

Is this normal?


03-29-2010, 02:08 AM
Did you try measuring the voltage across the battery? After charging, the NIMH voltage should be quite a bit higher than usual, as high as 1.5V/cell. Could you be overvolting your components?

Within a few minutes of drawing current, the battery will be down in its usual voltage range of 1.2V/cell.

07-05-2010, 07:51 PM
Could you describe your setup in a little more detail? I'd say Nammo is probably correct about voltage being the problem. Many cheap servos can't handle even 7.2v. What is your batteries rated voltage and what is its after full charge voltage? What kind of regulator are you using on your logic circuit? Basically the more info you can give the more likely someone can help you.