Battery self discharge/imbalance during long periods of standing idle
Hi All,
A newbie here.
Please can I call on some experienced views, regarding the fact my car has now not run for over a week, and I still have no date for a windscreen replacement.
So I am wanting to ensure my battery pack, which is all good, and last left with 4-5 bars charge 9 days back, is going to be ok with my car laying out of use with broken windscreen. Wondering if colder weather can influence things too, although I think we have only had one or two frosts in the last 9 days.
I have no special charger - and I dont have the money for it atm.
Should I run the car at all? Charge by running engine when warm at 4000 or so rpm?
I cannot drive the car due to screen breakage in my line of sight.
I'd start the car and let it idle a minute to get a little bit warm and then run it at 3300 RPM or so and you should see the charge bars light up, you don't need to run it as high as 4000RPM, just enough to where 4 regen bars are visible. Let it run until the charge bars either go away, or until the engine has warmed up to 6 bars for a minute. I suggest letting the engine get up to temperature so that the oil has a chance to burn off the fuel loading that is introduced from the cold start. At either of those points, you should have added plenty of charge to the battery to where you should be fine. No need to charge the battery until its full. If you do this now you should be fine for 2 weeks as long as the battery is showing a mostly full state of charge on the gauge since yours is low I'd do it right now and then come back in 2 weeks. Once you get your windscreen replaced, I'd run the pack down to empty and back to full to give it some exercise.
Cold temperature is actually better because there is less self-discharge to the pack.
I have no special charger - and I dont have the money for it atm.
Should I run the car at all? Charge by running engine when warm at 4000 or so rpm?
I cannot drive the car due to screen breakage in my line of sight.
Tim
Yes, I would highly encourage you to charge the battery. Since you don't have anything to gather any data on the battery, you don't know how low the weakest cells might be. You need to keep the battery well charged until you can drive it again.
I'd start the car and let it idle a minute to get a little bit warm and then run it at 3300 RPM or so and you should see the charge bars light up, you don't need to run it as high as 4000RPM, just enough to where 4 regen bars are visible. Let it run until the charge bars either go away, or until the engine has warmed up to 6 bars for a minute. I suggest letting the engine get up to temperature so that the oil has a chance to burn off the fuel loading that is introduced from the cold start. At either of those points, you should have added plenty of charge to the battery to where you should be fine. No need to charge the battery until its full. If you do this now you should be fine for 2 weeks as long as the battery is showing a mostly full state of charge on the gauge since yours is low I'd do it right now and then come back in 2 weeks. Once you get your windscreen replaced, I'd run the pack down to empty and back to full to give it some exercise.
Cold temperature is actually better because there is less self-discharge to the pack.
My 2 cents
HTH!
I like his approach even better than mine. Do it his way
I would only add that I'd do it once per week since you don't actually know anything in basic terms about your battery. I would also bump start the car if I had an opportunity. You can bump start in both second or reverse at fairly low speeds if you are parked on a slight hill. Otherwise, it is difficult. Bump starting would avoid a high load on a unknown battery condition
Charged up to 2/3s or thereabouts.
I did let revs drop and then it would not kick in again, and I do wonder if I hadnt it would have charged a bit more.
Just curious as to the control parameters that cut charge in and out.
Charged up to 2/3s or thereabouts.
I did let revs drop and then it would not kick in again, and I do wonder if I hadnt it would have charged a bit more.
Just curious as to the control parameters that cut charge in and out.
Cheers
Tim
Hi Tim,
JimIsbell used to turn on the headlights to force a background charge. Do a search for this from several years ago.
I have a grid charge tap on the pack and MIMA, which is all I need to keep the pack going strong.
You can check the link below for how I added a trickle charge cable.
Charged up to 2/3s or thereabouts.
I did let revs drop and then it would not kick in again, and I do wonder if I hadnt it would have charged a bit more.
Just curious as to the control parameters that cut charge in and out.
Cheers
Tim
It uses voltage on the 10 taps as queues. I've also seen the behavior you note just with regular driving.
A few things..
It would be best, in this case, to pull the negative cable and reset the systems. The battery will be losing charge as it sits, but the computer won't be. It needs to be reset to have any chance of "fully" charging the battery.
When you reset the systems, the charge is automatic - there is no need to rev the engine. If you want to charge more quickly, you can go ahead and rev - but remember the idea here is to input as much as you can. Higher charge current causes the pack voltage to spike and will cause the positive recal to occur more quickly.
I am beginning to believe that internal resistance is the primary cause of the IMA light these days. High internal resistance is perceived by the car as low capacity.
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Im still waiting to have my windscreen replaced. Long story... but im getting more concerned about battery imbalance and damage now.
I have been running the car weekly until fully warm and the battery is indicating near full charge, but today it had to start on the starter motor again, as it did about two weeks ago too. When it did this two weeks ago, the charge went down from 2/3 (which was the charge obtained via running at >3000 rpm) to only two bars very quickly, and then the charging commenced up to near full very quickly. Wondering if this was a reset occuring?
So Im wondering if I need to disconnect the battery negative as suggested to reset things. If so, do I do this with the engine running?
Any advice greatly appreciated. Hoping to get new screen next week, so battery can have a proper excercise.
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Battery self discharge/imbalance during long periods of standing idle
