Battery voltage -- Multimeter 2.5 v higher than LCD

[rjbutler]

I have a CrossCurrent S that's about 2 months old (standard 48V battery) . I've been a little disappointed in the range but I assumed it was due to cold weather.

Yesterday I rode 20 miles on a full charge and the display showed 46.2. When tested with a multimeter, it showed 48.4. I charged it last night until the charger showed green and then unplugged, it sat for about 20 hours, then I tested it with the multimeter -- 55.8. On the bike, 53.3.

I can understand a slight difference, but 2.5v is about 20% of the battery.

Is the motor cutoff based on the faulty bike reading? If so, I'm losing about 20% of the range which is about what it's felt like when I've been riding.

Is there a way to calibrate the voltage? I did send an email to support yesterday, but haven't received a response.

 

[harryS]

Check the battery in your multimeter first. That causes bad readings if they are low.

A 48V bike battery's max voltage is 54.6V, and that's also what the max voltage of the charger should be. You would need two failures (charger too high and battery control circuit bad) to see 55.8V, and if that happened, it's really hazardous.

 

[rjbutler]

I went for a ride so the battery isn't full right now, but I replaced the battery and still see a 2.2V difference between the bike and the multimeter. I suppose the multimeter could be defective but spot checking other (lower) known voltages it seems spot on.

 

[rjbutler]

I came across a couple of sites that described "Surface Charge". Since I'm testing immediately after I pull it off the charger, is it possible that's what I'm seeing? Once it charges fully again, I'll test it, put it on the bike and run the motor for a bit, then test it again.

 

[devhead]

I always let the battery rebound/rest after riding before testing the voltage. Same goes for charging, take it off the charger, let it sit for 15 minutes, then check voltage.

I too have a CCS 48V. I was told, or read somewhere on this forum, that the charger that came with our bikes will only charge to 95% full. My personal observation concurs with this info, twice I've accidentally left the charger on over night and each time the battery voltage was 53.7. I could see it losing a bit of charge after 20 hours. So...your 53.3 noted in your original post doesn't seem to far off to me.

 

[KLee]

The battery voltage on my CCX LCD display shows about one volt less that the voltage taken from the battery directly from my multi meter. The ticks on the bar graph also shows lower than actual battery capacity.

 

[Bruce Arnold]

I too have a CCS 48V. I was told, or read somewhere on this forum, that the charger that came with our bikes will only charge to 95% full. My personal observation concurs with this info

Tora Harris mentioned this in a post about a year ago. It conforms with my experience, too.

55.8 is really high for a 48 V battery. I'd be worried about that. Let us know what you hear from the support techs please.

 

[rjbutler]

I finally got my hands on another multimeter and the voltage was 54.6. I'm relieved there is no issue with my battery.