Impact of Turning Off the IMA Battery Switch

jimepting · #1 10-19-2011, 06:17 AM

I'm wondering about the full impact of turning off the IMA battery switch so that one drives without assist/regen. Obviously one loses assist and regeneration, the 12 v battery does not charge, and autostop may not function. Are there other impacts?

It would seem like a very good AND cheap way to be rid of the assist/regen negatives, but unfortunately the positives. Certainly night time driving would be severely limited.

Please don't tell me about MIMA. I don't think I want to go there.

Thanks all

Right Lane Cruiser · #2 10-19-2011, 07:41 AM

Hi, Jim -- you may not lose DC-DC capability. I haven't tried it personally but I know that Larry did and his battery seemed to be charged just the same.

The car will only start from the conventional starter if you do this.

The biggest risk you run is letting your pack self discharge to a too low voltage or to an unbalanced state. Neither of these is fatal to the pack, but only as long as you don't try to use it. If your pack got to that level and then you wanted to use it you'd have to externally charge and balance to be sure you wouldn't damage the cells upon first use in the car.

jimepting · #3 10-19-2011, 08:39 AM

Thanks Sean. I see what you mean about the IMA battery being put at risk. I just wanted to do some testing, so I might give it a brief try, with the SOC full.

Harold · #4 10-19-2011, 10:25 AM

Keep us posted on the results and how the car does with the switch of. H

Mendel Leisk · #5 10-19-2011, 02:16 PM

I'm thinking the 12 volt would continue to charge, but not sure. If it didn't you would be in doodoo pretty quick.

lxmike · #6 10-19-2011, 08:11 PM

Jim: you can do the same and keep you 12v charged. you have to take the cover off the get to the bcm and there are 3 plug you have to disconnect and that will take the ima battery out of the loop but still enable you to keep you 12v charged. I have been like this for quite a while now. Not sure how it's affecting my numbers cause when i did have my ima battery working i was still learning the car. I'll take a look tomorrow and let you know what plug to disconnect if you want. You loose autostop, and have to watch your 12v battery, It helps to have a scanguage or something to keep an eye on 12v status as your driving.

jimepting · #7 10-19-2011, 08:18 PM

Quote:

Originally Posted by Mendel Leisk

I'm thinking the 12 volt would continue to charge, but not sure. If it didn't you would be in doodoo pretty quick.

I can read the voltage on the 12v battery with my Scangauge, so this one is pretty easy to watch

jimepting · #8 10-19-2011, 08:25 PM

Quote:

Originally Posted by lxmike

Jim: you can do the same and keep you 12v charged. you have to take the cover off the get to the bcm and there are 3 plug you have to disconnect and that will take the ima battery out of the loop but still enable you to keep you 12v charged. I have been like this for quite a while now. Not sure how it's affecting my numbers cause when i did have my ima battery working i was still learning the car. I'll take a look tomorrow and let you know what plug to disconnect if you want. You loose autostop, and have to watch your 12v battery, It helps to have a scanguage or something to keep an eye on 12v status as your driving.

So you are indicating that the DC-DC converter will not work and the 12v battery will not charge unless these steps are taken? Right?

I do have a Scangauge.

Thanks

Right Lane Cruiser · #9 10-20-2011, 12:18 AM

Jim, the disconnected BCM plug is a way to completely bypass the normal DC-DC converter control. It is a useful procedure for people with failed IMA batteries that cause a disabled DC-DC functionality. The reason it works is that the control line for the converter is in that plug and it is a simple high/low signal logic. It is set up so that the converter is turned on when the line is low… which is exactly what happens when you break the circuit by unplugging the BCM.

IIRC when Larry flipped off the IMA switch the way you propose to configure your own car the DC-DC converter remained active and kept the battery charged. Try it and see what your ScanGauge reports.

jimepting · #10 10-20-2011, 06:07 AM

Quote:

Originally Posted by Right Lane Cruiser

IIRC when Larry flipped off the IMA switch the way you propose to configure your own car the DC-DC converter remained active and kept the battery charged. Try it and see what your ScanGauge reports.

I'll do'er next week. Got a busy weekend already under way