IMA batteries lose charge while sitting?

[2001Insight]

Do the IMA batteries lose charge while sitting there?
I parked my car last night in my driveway with a full charge.


Today I got back about 20 hours later and noticed it lost a bar or two.



Is this normal or a sign of unbalanced/failing batteries?

I'll let her sit there one more night and check it out again tomorrow.

[aisbell]

Yes, your IMA battery will self-discharge when not being used. However, the IMA battery charge level gauge is unaware of self-discharge, so it would not register the lower charge level due to self-discharge. As further self-discharge periods occur, the accuracy of the IMA charge level gauge will decrease until the IMA battery's voltage drops so low that the IMA logic recognizes that the charge level gauge needs recalibrating. At this point, the IMA charge level gauge will drop about 1 bar/second toward 0 bars. The gauge will probably never quite reach 0 bars before starting to increase because of forced charging.

I don't know how to explain what you've observed. A partially-shorted or discharged 12 v. battery would suck some charge out of the IMA battery after the car is started, but that wouldn't happen instantly, and I don't know whether it would suck 2 bars of charge out.

[2001Insight]

Thanks Aisbell,
Your explanation helped many. So I guess just waiting longer will be the only way to truly tell, updates tomorrow!
I did start her up for about 1 minute and turn the radio all the way up, trying to blow the speakers before I replace them. That's about it.
Then shut her off and noticed the 2 bar drop.
Guess will wait till tomorrow and check again.

[Eli]

I've never seen what you've observed either. No offense or anything, but I'll have to chalk it to simply not remembering what the charge was at before.

I don't think it's even possible. Ten seconds after the ignition is turned off, the BCM powers down. The state of charge level is saved in volatile memory, which is kept alive by the 12V battery. That's how the BCM remembers your state of charge next time you turn the car on, and why disconnecting the 12V battery resets it. It has no awareness of anything happening with the car when off.

[2001Insight]

Hey Eli,
I remember, I have such good photographic memory I projected the photos of it before and after the 20hr sit, you will notice in my first post. the mileage is the same also if you take a look. lol

[Willie Williford]

Mine does the same thing. Especially after entering autostop and sitting for a while (5 min).
The 12V shows being charged by the IMA battery through the DC-DC converter at 14.2 volts during that time.
I don't know what the amperage drain off the IMA battery as it starts the engine. At idle there is a minimal charge from the IMA system, (Unless you are in a RECAL mode) especially with a high wattage drain from the radio at full blast.
To me there is a small drain of the IMA battery at the time. Usually about 2 miles of spirited driving brings the indicator bars back to full. (I do have a deterioated battery pack)
HTH
Willie

[Eli]

Hmm.. I really have no idea? I've never seen it. Insight #1 has been sitting for a couple of weeks, the SoC hasn't moved... Which would result in a recal if I drove it(but I won't until it's grid charged).

Not that I'm trying to doubt you, but it's easily explained by other things. I could take a picture with the battery completely full and then completely empty without having moved an inch. The DC-DC converter draws about 0.6A from the battery with no other accessories on. So you didn't sit with the ignition on or anything at any point?

I have seen the SoC go down in auto stop and with the ignition on, things like that, but never while the car is off. I can't see how it's possible, just based on how the systems work. Then again, they're pretty voodoo devices, so who knows.. Maybe it's a CVT thing?

Willie, the IMA motor draws about 30A peak with a hot start. This is just for a fraction of a second though. I'll have to look at a cold start, bet it's more.

[2001Insight]

I did start her up for about 1 minute and blasted the music. that might be it.
I did also turn the ignition key to the on position without starting a few times also to roll the windows up and down, I keep the windows open during the day to keep the interior cool while using a windshield shade.
That could be it, so the 1G Insight uses the IMA batteries to start the car and the battery up front is just for accessories now it seems, am I correct?
Also if the batteries are fully charged while warm/driving and when it cools down can the temp drop cause a charge drop? Sorry I have no schooling on batteries what so ever except the experience when I was young, someone dared me to rub AA battery acid on my cheek and putting 9 volt bats on my tongue! lol

That does sound about right Willie and Eli. Thanks
So the Bat in front does get a charge from the IMA bat in the rear.
That's so COOL!
I love this car more every day and drive!

[TopFuelTim]

After a couple of months, and the addition of a Calpod switch, I have been able to get my SOC up to 20 bars. I try to time it where it quits charging as I am coasting down the hill to my house, but sometimes get it fully charged just before I get to my subdivision.

Almost every morning I notice it is at 19 bars after I start it up. I guess it's not a big deal. My IMA battery is 21 months old, so it is still in pretty good condition. I'm looking forward to getting Mike's grid charger soon, and hope the once every two or three month grid charge will keep the battery happy.

Tim

[Hybrid-Battery-Repair]

Originally Posted by TopFuelTim

After a couple of months, and the addition of a Calpod switch, I have been able to get my SOC up to 20 bars.

For anyone who cares, BetterBattery modules will reach 20 bars easily just by driving gently (50 mph on level ground) with no issue. MPG then goes up a little bit, probably due to the car not doing any opportunistic regen. The slightest use of assist will pull it down to 19 or less.

This may be what's happening here. The power surge to start the car may have caused the drop.