Grid Charger questions????

[Gatorade]

OK. I have an I2 for about a month now. I have been reading the forums and have seen a lot of discusson on making and installing grid chargers. However I haven't seen any posts on why you would need one? Maybe a grid charger is more of an I1 thing than an I2 thing but when I check my battery I want to say that most of the time it is above 80% charged. Why would I want to top it off using a grid charger instead of letting the motor do it? I would think that the only time you would need a grid charger would be if you were using the battery a lot and the charge was getting low. However on my I2 the charge never drops low. Maybe I am missing something that would give me better MPG but I don't know how to use the battery assist any more than it is using it already. I would love to use more battery power and cut some of the fuel usage but I don't know how to kick the battery usage up higher.

[MN Driver]

The grid charger is mostly being used for people with the MIMA modification which has only been developed for the 1st Gen vehicle. MIMA lets you control the assist and regen directly which provided a huge benefit for the manual tranmission car that has lean-burn, it allows us to climb hills or accelerate without dropping out of lean-burn and also to charge while going down hills without slowing down or dropping out of lean-burn to charge. It gave us better gas mileage by staying in lean-burn and allowing us a purpose for the battery. After the grid charger was developed those who needed to balance their battery pack could do so and those who wanted to use MIMA to provide assist and then charge when they were back home are now able to.

There is less use for it with the 2nd Gen Insight because the car weighs more, has 70% the battery capacity, and since there is no lean-burn it won't help too much for the MPG. It would provide enough energy to drive a little more spirited by using full assist more often and be able to charge it from home rather than having it regen as you drive and dragging down your MPGs. I'm not really seeing much benefit with having a grid charger on the 2nd gen, at least not with your battery under warranty (8 years/80k miles) because if there was an issue and the dealer sees you've installed something that defeats how the car normally operates you could encounter a bit of a battle if they claim it caused your battery to fail.

[Gatorade]

Thanks for the reply I figured it was pretty much an I1 thing but just wanted to make sure I wasn't missing out. It would have had to have been a pretty substantial gain for me to modify and possibly run into warranty issues but no need to worry about that for now.

You mentioned changing the assist. Is there any way to change the assist on the I2? I don't think I have seen that needle go above 20% into the assist range. I am thinking this version of the Insight relies less on the electircal assist than previous versions.

[MN Driver]

The CVT version of the 1st generation is the same way, the manual transmission allows someone to force the assist more my putting the car in a higher gear and pushing the gas peddle well beyond the point where it would produce maximum power.

So with a CVT the engine spins up faster instead of providing more assist. This actually helps gas mileage because if the car would otherwise begin background charging rather than charge using regenerative braking you actually lose gas mileage getting that energy that was used with the extra assist back into the battery. Of course modest acceleration and coasting more to a stop will give you better gas mileage than flooring it around town and waiting for the last second and using lots of regen and friction brakes to stop.

[RahTX]

Originally Posted by Gatorade

I don't think I have seen that needle go above 20% into the assist range.

Under normal conditions, I'd say that figure is about right - however, assuming the battery is sufficiently charged, it should provide more assist under heavy acceleration.

I'm sure there are some other factors (temperature of the pack?), but if you floor it, it should give you all it's got and peg the assist needle. Well, I'm not sure if it will truly "peg", but it should easily hit 90%.

There is no way to really control that, though, other than throttle position. Which is unfortunate, because I know there are plenty of times where I need a sudden burst of acceleration, but have a long coast or known regen opportunity (small hill, etc.) ahead, and would rather use more assist by itself, instead of just giving it more gas.

On the same note, a way to prevent or stop a forced regen would be most welcome. There's nothing quite like trying to merge into 75MPH traffic only to find out you're not just limited by the small 1.3L engine, but also fighting a forced regen. I'm sure the guys in really hilly or mountainous areas see that a lot more than I, though...

[Cobb]

Well, it does 2 things.

1, it allows you to charge the hybrid battery to 100% vs 80 in normal operation.

2, it charges all the cells which are hooked in series so they do not get over charged or under charged. The i2 for example has 84 C cells hooked in series for 100 volts nominal.

With use or lack their of the cells become unbalance or different states of charges. Just like how a battery in a multicell flashlight will go dead and cause the light not to work, this can happen in your car.

Anyway, I have one and have achieved 84mpg with careful driving. The effects are short lived since our pack only holds .5kilowatts. That extra 20% you squeeze in it isnt as much as for the i1 owners.

[E27006]

Honda packs are not as dependable as Toyota packs, the 2006 -09 Civic HCH forums are alive with reports of problems with their batteries, can we expect the same with I2 cars in 2012/13?

The grid charger delivers a fraction of an amp over several hours, the IMA charge delivers tens of amps over a fraction of an hour.

I view the grid charge as a high quality conditioning of the pack, the cells balance, self-discharge and memory effects are overcome, at least that is my opinion.

I have used a grid charger for the last 15 months, I hook up the charger at two week intervals, my pack performs like new.

[MN Driver]

Originally Posted by Cobb

2, it charges all the cells which are hooked in series so they do not get over charged or under charged. The i2 for example has 84 C cells hooked in series for 100 volts nominal.

The NiMh cells are D size, not C size. 84 is correct for 100.8v nominal, although it will almost always be higher than that voltage at rest.

[Cobb]

My bad. Cant speak for the panasonic they use, but typically most c and d cell recharagable batteries are the same guts and capacity just the d cell is in a larger case.

Ive see 112-117 volts myself. 120 is balanced. Ive seen upwards to 122 during the process.

[Hybrid-Battery-Repair]

Originally Posted by Cobb

My bad. Cant speak for the panasonic they use, but typically most c and d cell recharagable batteries are the same guts and capacity just the d cell is in a larger case.

Only in consumer grade cells. The 6.5Ah cells that are used (Panasonic and Sanyo) are only D cell. In a standard current battery, the same guts will get you 10,000 to 12,000 Mah.

BTW, D is the largest size allowed by the holders of the NiMH patent (Chevron). Toyota got in big trouble for the 95Ah cells they created for the Rav4 EV.