How can I drain my IMA battery deeply?

elcerritotom · 11-15-2011, 05:13 PM

I've got a deteriorated IMA battery. While I'm waiting for my Better Battery replacement, I am trying to improve/rehab the bad battery with a grid charger. I've been told that I should go through 3 to 4 deep discharge/full grid charge cycles to improve battery performance (again, the performance of the old pack). How can I drop my SOC charge level way down? I tried going up some very steep hills a mile or more long, but can't drop the SOC indicator below about 75% now. (Before I installed the grid charger, and did an overnight charge, I was getting no bars showing on the SOC indicator, as well as no assist/regen indicated on the dash.) any advice for me?

Eli · 11-15-2011, 05:24 PM

A lightbulb will work, but you'll have to watch the pack voltage very closely.

This risks cell reversal and permanent damage if you aren't careful.

It shouldn't be hard to drain a deteriorated pack. Shift early and keep it floored, clutch in when you need to slow down to avoid regen.. rinse, repeat.

**AClewell** · 11-15-2011, 05:30 PM

Wow! If you can't get your SOC below 75% going up a mile long hill your pack must not be to bad. I thought I had a good pack and I have to work to keep mine above 75%.

Eli · 11-15-2011, 05:31 PM

Quote:

Originally Posted by AClewell

Wow! If you can't get your SOC below 75% going up a mile long hill your pack must not be to bad. I thought I had a good pack and I have to work to keep mine above 75%.

I was kinda thinking the same thing.. lol

elcerritotom · 11-15-2011, 05:50 PM

thanks much for the thoughts, guys. It's a CVT, so I've tried hard acceleration up the hill, but I definitely fill the battery mostly up via regen on the way down. Is there some way to avoid regen with a CVT? I've also tried putting it in the "Sport" mode (with button on steering wheel) but that didn't help much either. If I can get another 10K or more miles on the old pack, I'd definitely be psyched, and would hold off on battery replacement. Sorry for my ignorance!

Eli · 11-15-2011, 05:58 PM

Oh, I see.. CVT, that makes sense. I'm not sure of a way to disable regen on a CVT.

Technically, it would be best to discharge the pack below what the car would discharge it to anyway(~20%).. But the reason for your weak pack is imbalance, so discharging the whole pack through something like a lightbulb is dangerous because the weakest sticks/cells will become empty first, and it will be hard to tell this is happening. Very easy to reverse cells and cause damage this way.

I'm not sure there's much you can do without removing the pack.

Mikeyy · 11-15-2011, 08:22 PM

Why are you trying to improve it?? Have you ordered a better battery yet??

Mcfly · 11-17-2011, 03:18 PM

Quote:

Originally Posted by elcerritotom

thanks much for the thoughts, guys. It's a CVT, so I've tried hard acceleration up the hill, but I definitely fill the battery mostly up via regen on the way down. Is there some way to avoid regen with a CVT?

To avoid regen you have to put the car in neutral before hitting the brakes. Also works when coasting downhill.

kennysmith · 11-18-2011, 12:57 PM

My CVT HCH will charge even going up hill when the SOC gets low. BTW, it is an amazing piece of engineering. I always marvel how it decides to use assist or vary the gear ratio when climbing, all dependent on SOC & a million other factors. After flying across the country to get my Insight I was shocked & worried to see the SOC at 3 bars. Now I'm shocked at the consistently high SOC on the rare occasion I drive my wife's HCH.

elcerritotom · 11-21-2011, 02:39 PM

Sorry not to have not checked your helpful responses in awhile. I've been trying to improve the pack by grid charging because I figure if the current/deteriorated pack ends up fine for my use, then I wouldn't have to get the new pack for some time, so it would end up lasting longer. I did order a BB by putting down half the purchase price, but believe I can put that order on hold if the older battery is rehabilitated through grid charging. Great suggestion for putting the car in neutral on the downhill; this should let me tonight drain the battery fully down prior to overnight charging.

Interestingly, the existing pack was consistently throwing the IMA light, with a battery module deterioration code prior to grid charging. If I disconnected the negative battery terminal, the IMA light would come on quite quickly, within perhaps 5 miles. Since the last grid charge though, I have driven about 500 miles, and still no IMA light. (I charged the pack so far a total of 3 times.) The assist/regen are working well, and the pack SOC indicator is showing consistently high SOC, with me having a very hard time dropping it below perhaps 60%. Not sure how long this will hold up, but hey, grid charging this pack initially seems to have been very beneficial.