Checking a batteries charge

[wehey]

hiya all
Sorry if this is a bit of a noob question....
So I have a 48V 10.5 amp hour battery on my Ezee conversion. After I've been for a ride is there any way of checking the battery to roughly figure out how much charge it has left??

Also, if I know the charge rate in Volts and Amps of the charger, can I roughly calculate how long it would take to charge to full??

 

[Deleted member 4366]

Best would be to fit a wattmeter, then you'll know everything. The GT knockoffs don't always work at 48v even though they're supposed to handle 60v. The blue box ones are OK. You need to think about how/where to install them because they're not waterproof. Find them on Ebay - about £7 to £12.

 

[wehey]

Best would be to fit a wattmeter, then you'll know everything. The GT knockoffs don't always work at 48v even though they're supposed to handle 60v. The blue box ones are OK. You need to think about how/where to install them because they're not waterproof. Find them on Ebay - about £7 to £12.

Ahhh....ok so would I be right in saying that I have a 504 watt hour battery and a watt meter would show in watts, the current capacity?

Also my charger is 6v 2A, so what are the maths involved in calculating the charge time?
Thanks

 

[cyclebuddy]

Also my charger is 6v 2A, so what are the maths involved in calculating the charge time?
Thanks

That doesn't compute. A 48 volt battery needs a charger of 54 volts.

A watt-meter tells you how many watts of your 504 watts you've used.

Watts = Volts x Amps.

So if you'd used 200 watts, you'd calculate 200 watts / 54 volts = 3.7 amps needed to fill it back up. Using a charger rated at 2 Amps, that's 3.7/2 = 1.85 hours.

Except it will take longer in reality because the charging process isn't linear - charging slows down as the battery nears full capacity, and the cells start to balance.

So you can add another 1/2 to 1 hour on that, and expect maybe 2 1/2 hours to replenish the 200 watts used.

 

[wehey]

That doesn't compute. A 48 volt battery needs a charger of 54 volts.

A watt-meter tells you how many watts of your 504 watts you've used.

Watts = Volts x Amps.

So if you'd used 200 watts, you'd calculate 200 watts / 54 volts = 3.7 amps needed to fill it back up. Using a charger rated at 2 Amps, that's 3.7/2 = 1.85 hours.

Except it will take longer in reality because the charging process isn't linear - charging slows down as the battery nears full capacity, and the cells start to balance.

So you can add another 1/2 to 1 hour on that, and expect maybe 2 1/2 hours to replenish the 200 watts used.

Thanks buddy. That's makes sense.
I have just had a look at the charger and I think I have misread it....oops