High Battery Voltage

The actual answer to this is the same as right after it came off the charger, because within far less than 24 hours, we’ve used it and put it back on the charger.

I am doing a test “rest voltage” today. I’ve been going about 6 hours so far, and it seems to have settled for the most part at about a half volt down. I’ll try to remember to add a few more points over the next day or so.

Volts  Time
13.42  10sec
13.08  0.7hr
13.03  1.4hr
13.00  2.0hr
12.98  3.0hr
12.98  3.5hr
12.96  4.2hr
12.95  5.5hr
12.91 19.9hr
12.90 27.8hr

This is a battery which is two years old, went through a dozen or so cycles in its first month as part of Pereichi’s electric bicycle project, and has been used for rather light duty since. All measurements made with the same voltmeter - another one I have shows about 0.03V higher.

Edit: This Power Patrol battery and the AM one bank charger.


made in China.jpg

If you don’t already have one, pick up a Battery Beak and check the internal resistance (at the bottom of the display), if your batteries have an unusually high resistance it might be time to replace them. Our batteries generally have an internal resistance of around 0.017ohms-0.024ohms, and get a floating charge between 13.8v-14.2v right off the charger (I actually even saw one as high as 15v once, but that might have just been a fluke).

Also keep in mind that SLA batteries loose roughly 10% of their maximum storage capacity every 6 months when stored at room temperature (even more if they’re stored without a full charge). As a general rule, we try to replace our batteries every 1-2 years (though some older batteries can be kept for demos, practice bots, and as “pit batteries”).

The picture looks like the one I have, which is not what the current Power Patrol batteries look like; I had to search five or six before I found one with markings that look like mine. I suspect the picture is out of date. (That doesn’t mean I trust Amazon’s text 100%.)

Edit: Yes, mine says Made in Vietnam.

Hey Gus, do you have an automotive parking light laying around (like a .6A 3157) ? Hook it up to the battery for 5 minutes (0.05 Ah) and see what the voltage does.

*Hey Gus, any update on this ??