I'm new here.

I purchased a used 2006 HAH a couple of months ago and am totally thrilled with the vehicle. I'm really getting the hang of maximizing the IMA and see regens and assists all the time. The assists don't last very long which leads me to my question. I've been contemplating getting a Honda Insight (version 1) and on the forums over at insightcentral.net they have a few brave folks adding 2 or even 3 battery packs in parallel with the stock pack. These packs are charged at home and this then gives the driver several more minutes of assist time which leads to incredible MPGs.

So I was wondering what would happen if I did the same thing to my Honda (after the warranty expires on the battery pack).

My thought was to get some used Civic packs or whatever I could find for cheep that had the same voltage as the stock HAH pack but maybe slightly higher voltage. Then going through a blocking diode essentially paralleling the packs. Maybe even a relay that would engage when the SOC of the stock pack got low so the recharge came from the secondary pack rather than the IMA motor.

I guess what I'm trying to do is build a weak plug in hybrid with the goal of 40 mpg on a regular basis for my 80 mile commute. I get 32mpg now. And yes I know these modifications will not pay for itself. I used to install car stereos for a living and am pretty handy when it comes to ripping cars apart and putting them back together.

Any thoughts? Anybody do something like this or direct me to someone that has?

Thanks

 

TimDH

I have an 05 HAH and my take on the assist is that the HAH is so powerful that assist is not called on as often as a smaller engine would. That being my hunch, a battery many times larger in capacity still would not activate the assist any more than it currently is. IF it 'does' come on more, it would have to be because of the extra weight the additional batteries present to the car.

Best of luck with your HAH

 

You are right, the 6 cylinder engine is pretty powerful, however this is what I've come to learn from the IMA behavior. (and my conclusions)

The scenario:

Accelerate from 0mph to 65mpg in 45 seconds

If battery meter is at 3 bars - no IMA assist.

If battery at 4 bars - from 5 seconds to 10 seconds of assist

If battery at 5 bars - from 10 to 15 seconds of assist but mostly when engine RPM is low.

If battery at 6 bars - from 15 to 25 seconds of IMA assist and again mostly when the engine is at low RPM and under 60mph.

In order to get the battery level up to 6 bars I had to manually shift and keeping the engine RPMs high and never go into D but rather keep it in D3 and then slow down. This would prevent the IMA from assisting. I did that about 5 times and it brought the battery from 4 bars to the top at 6 bars. Even at 6 bars I did it one more time to really get the charge on the battery.

Once at 6 bars I put it in D and did my test of slowly going from 0mph to 65mph on a flat road. The amount of assist was incredible under 60mph!

Since this experience I've been able to keep the battery at 4 bars most of the time and I can predict when the IMA will assist just by listening to the engine and strategically using the throttle. When the assist occurs I lift up on the throttle slightly and this prolongs the amount of assist.

You all might be scratching your head because your HAH might not act like this. I don't blame you. I test drove a 2005 with the possibility of having 2 of these great cars. The regen, assist and battery levels acted completely different. And by the way, my 06 Accord never charges the battery when accelerating. It only charges from coasting or braking. I never let it go below 3 bars.

So in conclusion: The higher the state of charge on the hybrid battery the more assist you will get.

So this is what I want to do since I drive long distances at 65 on slightly hilly roads without stops and without traffic. When accelerating to 65 will bring down the hybrid pack to 3 or 4 bars. While I'm driving I would like to flick a switch that dumped current back into the hybrid pack from secondary pack that was charged from the grid. This secondary pack would have a much larger overall capacity than the stock pack thus being able to do this up to 20 times in a 80 mile trip.

So whenever I'm climbing slight hills the IMA will assist more often because the state of charge is up. If I know I will have to slow down in a mile or two, I would not charge the pack from the auxiliary but rather let the regen do that.

I know, too much hassle, but driving this car is just incredible. It is even more fun when you can predict the assist and tailor your driving habits around that. Add a secondary pack and make it even more fun!

Perhaps if no one has done anything like this I will have to be the first to try?

This should also apply to civic owners if the IMA system behaves like mine.