Battery charging times

[sshrinivasan]

Hi all

I'm just trying to figure out how long to charge my battery to reach 80%. Its a 48V 19.2 Ah battery. The current readout is 47.1V. I got totally lost in another thread discussing the chemistry behind all the batteries. can someone do a simple explainer on what numbers do I use from my LCD readout, and how to compute the charging time using the stock 2 Ah charger?

 

[sshrinivasan]

My current plan is as follows.

1. From the graph, find the current depletion percentage. 47.1V is around 50%
2. 50% of 19.2 ah is 9.6Ah
3. I need to get to 80% of 19.2 Ah, i.e 15.4ah
4. (15.4 - 9.6) / 2 = 2.9 hours

Is this right?

 

[Bruce Arnold]

You might try the empirical method.

1. Get a multi-meter (they come cheap so no sweat.)
2. Check the voltage prior to plugging it in.
3. Let it charge for a while. 3, 4, 5 hours.
4. Check the voltage again.
5. Subtract starting voltage from ending voltage and divide by hours. Now you have a fair idea of volts per hour.
6. In the future, decide how many volts you want to add and put it on the charger for X number of hours.
7. It's not as precise as a Satiator charger but costs about 2 percent of the price.

 

[sshrinivasan]

In the future, decide how many volts you want to add and put it on the charger for X number of hours.

Thats one thing I'm not sure about. Does the graph above seem accurate, i.e 80% is 51.5V for a 48V battery? Also is charging uniform, i.e is that battery charged the same amount each hour?

 

[Justin Fischer]

https://electricbikereview.com/forums/threads/charging-to-80-without-a-satiator.24763/

Charging is uniform until the battery reaches a high level of charge, and the charger then switches to "trickle charge". This rate is 2 amps of current. The trick then comes in converting volts to Ah (charge %, because the volts aren't linear to pack charge), and dividing by 2 to get the number of hours necessary to charge that many Ah into the pack.

This specific post in that thread might help, because 11 pages is a lot https://electricbikereview.com/forums/threads/charging-to-80-without-a-satiator.24763/post-200279

I wouldn't, and didn't, use any premade charts though. See the first post there. I'd recommend using the ebike calculator, which is where the Satiator gets it's profiles, to make your own chart. You'll have to find out what Juiced advertises their 48v pack as in Wh, cells per series/groups of parallel, find a battery that gets very close, with that config, and put in voltages until you have a good breakdown like the one in that thread's OP. That'll be different from your chart, which is different from Juiced's own chart, but I definitely trust the calculator more.