Honda Insight battery trickle charge/discharge cycle control.

[MannyJG]

Hi, I'm new to this forum. This question might have been answered? I have built a Honda Insight Nimh battery trickle charger. It charges at approx. 100ma until the battery reaches about 175 volts.
I would like to automatically switch it into discharge mode and discharge to approx. 110 volts. then repeat the cycle. Can you help with with a circuit that will do this? Can a comparator with hysteresis work or are the voltages too high? Oh, counting the number of cycles and complete shutdown after x number of cycles would be nice also but not necessary. thanks in advance.

 

[Frankchie]

I see this post is a little old and I probably cannot help much, but with shelter-in-place I have some time to offer some comments.
I think Insights have something like a 1kwh battery. Charging that at 100 ma seems pretty miniscule even for a trickle charger. Still more problematic is significantly discharging a 1kwh battery creates a lot of heat that has to be dissipated, although I suppose if it's over a long time period it's doable. However, cycling a battery tends to shorten its life.

Probably the biggest question is why do you want to do this? Am I missing something?

P.S. The high voltage concern that you ask, can be handled by a simple resistor voltage divider circuit.

 

[MannyJG]

Thanks for the reply. From what I have read on the insight websites, Doing one or two slow charges and discharges over a long time will equalize and possibly rejuvenate all the cells in the battery. Don't know if this premise is accurate but I thought I would try it any way. Any circuit that would switch from charge to discharge at preset voltage values and recycle a set number of times would be greatly appreciated. the battery i have has 120 nimh in series at 6 or 7 ah.
thanks,
Manny

 

[Frankchie]

To do this right probably requires a microcomputer like an Arduino and a significant effort. However a workable simple solution might be possible. Here are some thoughts.

1. Charging your battery at 100ma after a significant discharge is probably too slow unless you have a lot of time. Especially for multiple cycles.

2. Turning on and off at predetermined voltages might be possible using high voltage zener diodes (100v - 200v) and relays.

3. Instead of turning the charger on/off, just leaving it on during discharge might be acceptable and simplifies things.

4. An adequate and cheap load for discharge can be provided by a couple of incandescent light bulbs in series.

5. Final shutdown after several cycles is a little complicated. There may be some event counter modules that can do that.

Frank

 

[MannyJG]

Thanks Frank, That is the plan. Slow, long period charge and discharge through incandescent bulbs for two or three cycles. I am close to testing the charge circuit at full voltage soon. Hope it works.
Manny

 

[WHONOES]

I expect you do could do as you require with some relatively simple hardware. A couple of comparators to determine peak voltage and discharge status plus a simple counter using a 4017 to end the cycle of charge and discharge.

 

[MannyJG]

Thanks WHONOES, I'll try to find a circuit that would do the job. Can you direct me to such a circuit?
thanks,
manny

 

[WHONOES]

I'm not aware of any published circuits that would satisfy your requirements.
I expect there is enough knowledge within this forum to help with design.
What sort have equipment do you have to help with your design?

 

[Frankchie]

I'm not sure of your electronics skill level, but maybe this helps?

Output Q1 active on the first pulse, Q2 on the second pulse, etc... Probably needs a clean input pulse (must debounce if input is mechanical i.e., switch or relay).

The output can drive a relay instead of an led or whatever you need, perhaps with a driver circuit.
http://www.next.gr/circuits/4040B-LED-Counter-l37526.html

Data sheet:https: //www.ti.com/lit/ds/symlink/cd4024b.pdf

Frank

 

[MannyJG]

Thanks everybody. I think I found a "power line voltage alarm" by Mr. Johnson that i can adapt to my circuit. It lights an led at a present high and low voltage which i can use to actuate a relay. I am not a circuit designer but know how to make my own boards using Eagle. Thanks again.

 

[WHONOES]

If you get stuck, come back and we will see what we can do to help.

 

[MannyJG]

Thank you very much!