I have read where people have said a plug in future for Honda's IMA system is not really practicable due to the electric motor size, but have a question.

Shouldn't it be possible to use a larger battery with plugin capabilities with more aggressive assist programmed in. Even if the car is not capable of fully recharging the battery under normal circumstances you could just have the amount of assist reduced.

Ex: Assume vehicle is capable of recharging the battery to 50%. As long as the battery is over 50% assist is set to aggressive once it falls below 50% assist is set back to normal.

I'm not an expert in battery technology by any means so feel free to correct my assumptions.

 

It can't be done because of the size of the electric motor, all the battery power in the world will not cause a 20 hp motor to power the car from standstill.
20 hp is for assist, it adds a nice bottom line to the tourque, it can help the car glide where little power is needed but if you have read the complaints of poor acceleration with a low battery using the gas engine, well, if 90 isn't enough, what would 20 do?
An example, is watch your instant mileage, start from stop, 3-5 bars, once you reach speed, it goes to the 3/4 mark, while not directly, the need for fuel is about oppisite of your gas mileage, more power, lower mpg, less power higher mpg...I hope this makes sense coming from my non tech. brain.

 

Sorry if I did not make myself clear. I was not talking about powering the car solely on battery and I understand that FE drops when the battery is depleted. I was thinking more along the lines of extending the assist capabilities of the existing motor before regen was needed.

I guess even if it was possible the additional weight would negate any benefit.

 

I have been looking myself for something like this for the Civic, but have not been able to find anything.

I think most people look at it as not being useful due to the design of the civic, however when I drive around town (most of my driving) I find that I am in forced regen mode far to often, which would be fixed if I could plug the thing in.

In my situation with mostly city driving I can keep a 42 to 45 mpg average when I start with a fully charged battery, but when I start out with a half charged battery it drops to 36 to 38 mpg while it does it's off and on forced regens.

When I drive on the highway it's similar, the first 10 to 15 miles are spent charging my batteries (due to all the city driving), once charged I get over 50 mpg easy, so I can see how it could make a dramatic difference being able to plug in the car and always have a full charge.

Actually I think I would get far better mileage if I could reprogram the computer to get rid of the assist and forced regens and use the auto stop feature only, I would lose some power but I really think my average mileage would be better.

 

You are dead wrong. I converted an Eagle Talon to full-electric and I used a 10 HP motor as the only propulsion in the entire vehicle. Not only does it power the car from a standstill, but will get it up to 55 mph. In fact, accelleration from a standstill is when it does best. The accelleration really starts to level out and take forever above 30 mph.

There is no doubt that a larger battery pack which is charged from the grid would increase fuel-economy. But, because of the IMA design you probably wouldn't be able to ever drive around in EV mode. Even if the computer were modified to allow that type of thing, the drag from the engine would make it very inefficient. (yes, even with the valves closed)