Grid charging and balancing the I2

[Cobb]

After reading about the wonders grid charging and balancing the pack can do on the other forums I decided to give it a try. My I2 was having a lot of regens and useless in many cases. I decided to give it a try. I found someone to build one and bought it. Doing this will likely void you warranty and can be dangerous.

To access the hybrid battery you need to remove the rear flap, tire, foam insert, spare tire holder, then metal shield. The spare tire holder ie held in with 12 mm bolts. You will need to fold down the back seat and kock off the plastic cover to access them. Lift that point upwards, then lift out.

The metal shield uses a few torex screws and 10 mm bolts. There is one inside the lid area where the master switch is and move it forward to turn it off for good. Then remove the 2 plugs in the bottom.

Removed junk.



Hybrid battery. Thats just the case, the actual battery is smaller. This included some controllers and some other things than just the sticks that make up the battery.



Connections.

Those 4 bolts next to the switch are hot when the switch and key are on. The front ones are positive, rear negative.



Lay out.

So, when charging I use a 12 volt battery charger to keep the 12 volt side good and use a voltage meter to measure progress. Yes, I have a second battery in the trunk for the 12 volt side for the amp and subs.

[Cobb]

part 2

To turn on the back push the red button and move the switch backwards. Then route the wire and secure it so it wont get pinched or rub against anything.

Plug in the chargers and power them up before turning on the key. I used a beach key so the car can not be driven. I used the rear key to lock the doors. Make sure to crack a window to allow ventlation. With the key on you have the cooling system of the pack working to prevent any over heating.

I find the pack sits at around 112-114 volts. This is about 50-90% full. I find 117 voltrs to be full. It takes just a few hours to fully charge the pack. To balance it takes at least 24 hours. It seems to settle at 120 volts when balanced. You may see it reach up to 126 at its highest. The more out of balance the wilder the flucations. When balanced I see it go to 122 then back to 120. It shouldnt fall in voltage unless it has gotten colder out. It the voltage does fall it means you got more balancing to do and give a few more hours.

Once done I find when I refire the car I get an IMA error or the generic chassie ground c65556 type of error. Turn the key off and on again and it goes away. This only occurs after the balancing operation and not normal grid charging. I am guessing the abnormally high voltage causes that.

Since the charge will be 100% vs 80% you will get a negative recal a few miles down the road, supreme fuel economy and tons of assist. Then it resets to the new battery capacity. The supreme fuel economy is short lived. Themore you drive the lower it becomes.

Since this procedure I find the car changes in some ways, but others remain the same. For one the fuel economy seems to stay the same although filling up the pack helps to skew it.

Main change is in performance. When the going gets tough it will just return to zero or no assist no regen vs several bars of regen. When I crest a hill or back off on the throttle assist returns with no dip into regen.

When coasting to a stop I can achieve 100% on the soc screen vs 60% or so. The assist lasts longer and when riding the brakes it seems to recharge faster.