Advanced designed Charger upgrade for Enginer kit

[hybriddriveguy]

I am working on building an upgraded charger for my Enginer 4kw kit to help keep the cells healthy.
My goal with this charger will be to have something that will fit in the space allowed for the current charger, but slightly higher. It will charge all cells individually to 3.65 and maintain them there. It will also feature a timer that can be set to charge from 2 hours to 12 hours or continuously. The chargers will be user adjustable if someone wishes to play with the maximum charge settings

The big question is: what would any of you be willing to pay for this charger?
I need to decide on whether to buy my parts in larger quantities or just build for the units I install at my shop. I will post the results of my tests in this thread once I have the prototype installed and working.

[bwilson4web]

Do the LiON cells have a similar dV/dt signature of max charge?

When they start to show a temperature rise, is it 'game over'?

Can temperature increase be safely used to detect fully charged?

Bob Wilson

[hybriddriveguy]

Although it may be, I have not found this to be the case with the LiON chemistry I have worked with.
It has been like learning a new language compared to the Lead Acid and NIMH.

[smokeyj]

Li ion cells are usually charged with a CC (constant current) CV (constant voltage) followed by float (disconnect from power source) technique.

Charge current can be as high as the amp-hours of the pack, voltage limit is usually 4.1 or 4.2V (for laptop cells) and needs to be quite precise. There is no temperature correction for this. Once the cells have reached constant voltage the charge current decreases. You can either disconnect at C/10 (about 95% charged) or run a timer for an hour or two.

You don't want to keep the cells attached to the charge voltage once they have reached 100% charge.

[SVOboy]

Would this charger work for other packs or just the Enginer kit?

[hybriddriveguy]

This is exactly how our design will work except we will not be going for a 100% charge on the top end. We have found these cells too finicky on the upper range limits.

Originally Posted by smokeyj

Li ion cells are usually charged with a CC (constant current) CV (constant voltage) followed by float (disconnect from power source) technique.

Charge current can be as high as the amp-hours of the pack, voltage limit is usually 4.1 or 4.2V (for laptop cells) and needs to be quite precise. There is no temperature correction for this. Once the cells have reached constant voltage the charge current decreases. You can either disconnect at C/10 (about 95% charged) or run a timer for an hour or two.

You don't want to keep the cells attached to the charge voltage once they have reached 100% charge.

[hybriddriveguy]

This is being built specifically for the Enginer kit, but would work with other 48 volt packs.

Originally Posted by SVOboy

Would this charger work for other packs or just the Enginer kit?

[hymer544]

Definately interested, no idea as to cost, but relative to the cost of batteries I would like a more efficient charger.