Combining aftermarket hybrid system modifications

[KarenRei]

So, the Insight we bought has two noteworthy aftermarket modifications to the hybrid system: a toggle that enables/disables the hybrid system (say, to prevent assist when hill climbing), and a button that, when held down, changes the regen when the gas pedal is lifted to max regen instead of the default pittiance.

We greatly enjoy these two features, but find them both very inconvenient to use. We're wanting to combine them into a single three-way steering wheel hand-control switch:

0: Hybrid system off
1: Hybrid system on
2: Hybrid system on with max regen

The problem is, I know nothing about these systems. If I could safely wire one pole from each current button together, I could use a standard three pole switch. But I don't know that I can safely wire them together because I know nothing about the circuits they're attached to, and the last thing I want to do is fry the hybrid system.

Does anyone know about these particular mods, or do I have to contact the owner (who used to post on this board as "RyanA").

[red1dr]

Probably better not to think of hybrid system "ON" of "OFF" because features of the hybrid system remain operative even if assist is prevented or regen is maxed.

Also, max regen probably isn't most productive. Feeding in 20A or so of regen is probably preferable to maxing regen at say 50A from POV of (a) battery's ability to absorb the current, (b) not heating the battery to the point that the MCM does not allow further charging, and (c) (possibly) battery life.

The MIMA system, developed by forum members, combines the ability to modulate regen, block assist/regen, and FAS safely. It's described here:
Is it too late? I think not if we act now - MIMA Honda Insight Modified Integrated Motor Assist

[KarenRei]

Thanks. To be more specific, the "off" toggle disables regen and assist. So if other elements of the system are running, I wouldn't know; from my perspective, it appears off.

Max regen is most productive if you need to slow down that fast. The goal of the button is to stay off the brakes

So I take it these aren't some sort of common mod, and there's no way to know exactly how they're wired and thus whether it's safe to link one pole of each together other than to contact Ryan?

[02insight]

These are actually very common mods for Manual Insight owners. The "Clutch Switch" and "Brake Switch" mod

The "Clutch Switch" mod simply imitates the clutch being pushed in. In one position there is no assist/regen, and in the other position it works as normal

The other mod is the "Brake Switch", which does the same thing as tapping on the brakes very lightly, as to just enable max regen, but not use the physical brake pads.

Another user used a switch and mounted it on the steering column plastic, and attached a lever. This is probably alot more convenient to use sort of like the other levers for turn-signal/wipers.

See here:
Brake and clutch switch mod walkthru.
(Scroll down to post# 19 for pics)

[KarenRei]

Thanks -- that's perfect! And that's really clever how those switches work; I just assumed it was a lot more involved than that.

[red1dr]

Originally Posted by KarenRei

To be more specific, the "off" toggle disables regen and assist. So if other elements of the system are running, I wouldn't know; from my perspective, it appears off.

With assist/regen off, things that still work include:
- Autostop/restart
- EPS
- electronic engine balancing
- DC : DC conversion from the 144v IMA to supply 12v for the other electrical functions (there is no alternator)

Among other things, these slowly drain the IMA battery and require some regen. So with Assist/regen off, the IMA battery isn't just sitting there isolated.

Originally Posted by KarenRei

Max regen is most productive if you need to slow down that fast. The goal of the button is to stay off the brakes.

Well, yes, BUT:
(a) To drive really efficiently, one big goal is to minimize the amount of slowing down you need to do, which means that the number of times one can get regen from "braking" is reduced (eliminated would be preferable, but stopping for red lights and stop signs is necessary!!).
(b) With a few exceptions such as moderate regen on long freeway offramps, most braking events do not add much charge to the battery. Because the actual braking times are usually short, because batteries capture power more efficiently at moderate amperages than at 50A, and because capture (and release) of energy into the battery is not 100% efficient.
(c) One more effective way to get the necessary regen is to feed in moderate regen (with MIMA) while driving down a downgrade too gradual to coast. Yes this increases fuel consumption, but at least it moves the IMA from a less efficient slight throttle opening to a more efficient larger opening, hopefully still in lean burn. Another way is to coast steep downhills in gear with foot off the gas. This will invoke fuel cutoff (as long as you are above ca 1100rpm) so no gas is burned, but you will get regen (as long as the regen/assist cutoff switch is off). And engine braking will help keep your speed down. If the SOC is low and you want regen really badly, you can drive down a moderate downhill while feeding in regen rather than simply coasting down it ICE-off, which would burn less gas.

Personally, when I must stop I often don't bother with trying to capture extra regen by avoiding friction braking. Frequently, I just brake and let the stock system apportion braking between regen and friction brakes.

[KarenRei]

Thanks for the info about which systems remain on.

Concerning regen:

a) That's just the issue, though -- cars ahead of you brake. Lights change. Offramps have limited length and approach time. Believe you me, I know about hypermiling. But needing to slow down faster than the default regen will take you is inevitable in pretty much every cross-town trip.

b) I'm well aware that energy capture isn't 100% efficient and that higher charge rates are less efficient than lower charge rates. But that's all irrelevant given (a). It's just a fact of life -- when you need to slow down, you need to slow down. And I'd much rather put it into the pack than into the brakes, even if it's less efficient than slow charging -- because slow charging isn't an option.

c) I don't have MIMA, and engine braking is as much of an enemy as pedal braking. :P Any conversion of kinetic energy to heat is waste. In my Saturn, on the highway, I used to switch to neutral and shut off the engine to avoid it whenever I could. Also, I'm not talking about downhills; I'm talking city driving and the normal cycles of accel and decel that happen therein (although there are slopes as well, they're not as big of an issue)

But that does raise an issue I've been wondering about: does anybody have a brake-specific fuel consumption graph for the engine (assist-off)? It'd be really useful in planning when to use assist, to shift, etc to minimize fuel consumption. I.e., I frequently have to make decisions about whether to go with higher RPMs and no assist, or a higher gear with lower RPMs but use some assist. Also, any good efficiency numbers for round-trip pack efficiency and motor efficiency? That's the other aspect needed

[02insight]

an alternative to the brake switch mod is to adjust the brake switch so that the slightest touch of the brake pedal will activate it and full regen as well. I have mine set like that, and I its usually activated even if I just move the pedal a couple of cm, and I dont think the physical brakes start working with only a few centimeters of brake pedal press. I am almost hovering my foot on the brake.

[KarenRei]

Ooh, found a BSFC graph



Too bad there's no torque gauge in the vehicle. Oh well, though; I can get close enough. Looks like 2k RPM is optimal, there's almost no difference between 1k and 3.5k, but then there's a big drop off starting at around 4k. Now I just need to know the electrical system efficiency numbers.

[red1dr]

Worth reading the Insight Encyclopedia system here. Lots of info about which systems do what and how they interrelate.

Originally Posted by KarenRei

That's just the issue, though -- cars ahead of you brake. Lights change. Offramps have limited length and approach time. Believe you me, I know about hypermiling.

Then you must know about maintaining a cushion ahead of you to minimize the need to slow when cars in front of you slow down. And about timing lights. Pretty standard hypermiling stuff.

Originally Posted by KarenRei

I'm well aware that energy capture isn't 100% efficient and that higher charge rates are less efficient than lower charge rates. But that's all irrelevant given (a). It's just a fact of life -- when you need to slow down, you need to slow down.

And back to (a), minimizing slowdowns is key, especially in traffic.

Originally Posted by KarenRei

engine braking is as much of an enemy as pedal braking. :P Any conversion of kinetic energy to heat is waste.

That tactic would be used only on downhills that where some sort of braking is necessary to keep from going too fast for safety, whether in the city or on the highway. I suppose crashing the car would convert kinetic energy to heat, which would be a waste too, no? And how about pumping up the tires to avoid converting kinetic energy into heat of tire flexing??

Along the same lines, unnecessary frictional or pumping energy is a waste too, no? So some method for turning the ICE off safely while coasting saves fuel. IOW, rather than focusing narrowly on capturing kinetic energy, avoid generating excess kinetic energy in the first place.

But hey, this is only advice from others that has worked amazingly well for me. I just wish I had started using it right away when I got the car rather than messing around and getting poorer mpg than I get now.

P.S. It doesn't look like that BSFC chart factors in lean burn??