Steve,
You mentioned in another thread that you are on your 3rd battery on both of your HCHs. Does that mean there is no long-term benefit to quarterly charge-discharge? If the packs only last ~60k miles with your quarterly schedule then I might give up on doing it at all and just replace the packs when the time comes?

Thanks for all the information by the way.

 

I am a pathological tinkerer with two cars, 4 packs and a spare pack's worth of sticks. I am refining a diagnostic process to identify ailing/failing sub-packs. All five packs have a mix of good and bad sticks.

HCH2 #2 had a deep cycled pack that lasted 8 months before ever throwing another recal, and it already had 110k miles on it from a car in NH that threw an IMA light, so I'm confident recommending that as a preventative measure.

With spare packs, I can have one ready to install and do a swap in 20 minutes, so I don't mess with in-car charge/discharge.

AZ is also about as bad as it gets for NiMH cells. They can hit 140°F just sitting in the sun, so my rate of degradation is faster than most. We are over 100°F an average of 92 times per year.

If you prefer to drop around $2K on a new pack for convenience, go for it. Bumblebee and Hybrid ReVolt both offer great products with as much as a 3 year warranty.

 

So what I gather is that the benefit to deep cycling is real, but has varied results. Since I do not have nor want to spend $2000, grid charging and discharging is the way to go for now and drive it like a insight not a civic si.

I can also get obsessed with fixing things, my comfort level with a car in general is up to changing timing belts. So I could dive in but I am trying so hard to avoid it. I spent waaaay too many hours under my outback and I would rather spend the time building furniture. Although, all that time tinkering with my Subaru has given me quite the education. I used to not know the difference between a timing belt and a v belt.

 

DIY can get it done on the cheap. You can build a charger/discharger for about $75, but it requires pack removal OR leaving the ignition on with a 12V charger on the 12V battery (so the car will run the fan. IMA cooling fan requires a PWM signal to make it operate... can't just turn it on with 12V.

If you want a professional clean solution, check out hybridautomotive.com

 

I get down to 2 bars maybe once every 3-4 weeks, sometimes when I do a second or third acceleration, but I NEVER lose power when trying to get on the highway or pass someone. Those days are long gone. I live in Cleveland so my packs never get really hot temps. The car feels as nice to drive as the first day I got it. I am confident that I don't have to mess with the battery for a long time but we'll see.

I take my battery out and hook it up in the basement with a small fan blowing across it. Basement is nice and cool anyways.

 

Thanks. Actually bought a discharge ready charger from HA last night.

 

Do you mean that is how you charged it last time? I'm planning to charge it in the car using the Hybrid Automotive harness with fan controller.

 

Yes, since I do this so infrequently, I just remove the entire battery pack (60 lbs or so) and carry it to a place with my charger and discharge lamps.

Honestly, I think people started hooking up the charging wires in their car to make it easy to do, because people were doing the frequent grid charges.

But once people started trying the discharges which fixed the issue, its not a big problem to remove the pack once every year or two

 

So this is weird.

I drove 200+ miles today, averaged 48mpg (according to the dash) where half the drive was suburbia 45mph stop-go driving and the other half the drive was 65~75mph on country backroad highway driving up and down hilly terrain. I was getting 53mpg until I got on the highway and pushed to 75mph. No recals.

At the end of the 200 miles, I drove that same exact hill that gave me recals. Twice to be sure. Both times the car used assist and regen without any SOC jumps. The ASSIST slowly drained the SOC bars but never went below 4 bars, so the last 1 mile was a slow 3000rpm climb with the car refusing to give any more assist. But maybe that's normal. The REGEN slowly charged the SOC bars unto all 8, but no jumps and it was all gradual. My average on the two hill climb/decent shows as 57MPG according to the dash.

I am still going to do balance charge and discharge, but it seems like the recals have stopped for now?

 

While it never shows on the gauge, there is a "trickle" charge function where the car puts a ~300mA current into the pack during extended cruise phases. It won't charge over the ~80% true SoC mark, but it can help bring ailing cells up into the functional range.

Without intervention, recals only get more frequent.

Another quickie technique is the 12V reset/forced regen method. Should have mentioned it sooner. You can pull the negative terminal from the 12V (make sure you have your navigation or radio code), reconnect and start the car. It will charge at idle for at least a few minutes until the car concludes the battery is at max SoC.