[Corey872]

Been reading the "CVT 10-15MPG" thread and some opinions on replacing / using "the small battery" aka the 12 volt battery under the hood. This has me curious about a couple of things...as I understand it, the 12V bat. is simply a redundancy for the 12volt starter incase of IMA battery failure but supplies no real power to the car or on-board systems? And definitely supplies no power back to the IMA system?

If that is the case, has anyone actually had to resort to this for "emergency" starting?

If you were going for ultimate MPG what would be the effect of disconnecting / removing the 12V bat and starter? A couple dozen pounds of weight and less electrical drag?

If both batteries were somehow dead or nearly dead would it still be possible to push-start a 5 speed like a normal car?

Just letting the mind wander a bit

 

[Willie Williford]

For being a R&D engineer, You have everything wrong. The IMA supplies voltage to the 12V battery, which runs darn near everything in the car. There is no alternator, the IMA motor is the alternator. When the IMA battery is near zero, or overheated, the 12V is used to start the car. By removing the battery and starter, you are not gaining anything. Yes you can "bump start" a stick shift Insight. ...........PERIOD.

 

[Tim Maddux]

Re: "The Small Battery" and Push-Starting the Insi

what would be the effect of disconnecting / removing the 12V bat and starter?

Well, for starters (bahahaha! hoo ha! hee! whew... ok) a dead 12V battery will render your Insight inoperational and unable to start, because the 12V is required to throw a solenoid to connect the IMA and start the car. What's more, Insight drivers have found that the 12V battery is vulnerable to failure because it is always given a positive float and rarely discharged (see Yahoo groups discussions from a year or more ago).

A disconnected or removed 12V battery would have the same effect.

 

[Corey872]

I never said I was an R&D engineer for Honda or on the Insight. Believe it or not, there are other fields of research besides gas / electric hybrid cars, too. I'm just trying to digest as much info as possible on the gizmos because I think it's neat technology. But, thanks for the additional info on the workings of the IMA and 12 volt systems, deputy.

 

[Willie Williford]

Oops, might have stepped on someones toes. Sorry about that. For a complete and logical understanding of the Insight suggest you check out the KOWLEDGE BASE on this Forum. It has a ton of information, compiled in various threads and easy to read..........."RETIRED" Deputy if you don't mind................... :lol:

 

[b1shmu63]

Corey, certain automotive engineers have proposed a one battery 48 volt system. Running radios, lights etc on 48 volts creates all kinds of compatability problems. Going higher than 48 volts gives the car an electrically lethal side. Having a split system gives the potential of solar charging the 12 volt battery, thus potentially increasing overal efficiency. Someday I want to try that but am tied up 24/7 with product developement right now.

The 12 volt battery is also used to start the car in extreeme cold

 

[No. 166]

You should NEVER bump-start a vehicle fitted with a catalytic-converter.
With excessive unburned fuel getting into it, you'd burn it's interiors quicker than you can say the "f" word.
Take this advice from an experienced mechanic :wink:

 

[b1shmu63]

#166, in my restless dreams I see myself as a teenager pouring a can of carbout into the carburator of my LTD while a 2X4 kept the revs up. :shock: Young and fuelish.

 

[Rick]

Wouldn't no 12 volt to turn on the IMA to turn on the DC/DC mean no spark anyways? Or in theory could the engine actually start but have no power comming or going to the IMA so you'd have no 12 volt accessories anyways? Nah, I guess the computer would have to be on for that to happen.

Really all the 12 volt does is turn on computers and close a few relays. Maybe a whole 2% of it's charge would be needed. After that the load moves to the DC/DC. Under some circumstances the backup starter motor is used, but rarely. This is one reason why a few of us have gone to much smaller 12 volt batteries. Though, the Hawker Willie and I are using does have more than adequate power to turn the car over on the starter anyways.

 

[james]

Believe me, the Insight won't start if the 12-volt battery goes dead, and it can go dead even if the IMA battery has nearly full charge. If that happens, you can NOT push start it. I found that out the hard way (pant, pant), by getting stuck in a several-hour traffic jam at night, and forgetting to turn off the lights.

 

[Corey872]

Oops, might have stepped on someones toes. Sorry about that.

Willie, no problem. Sorry if my post came off as a gripe. I just wanted to be clear that even though us engineers do know 99.99% of everything, it's that .01% about the Insight I'm after. :wink:

I also guess my confusion comes from the fact that I read the car has a DC-DC converter to keep the 12V battery charged. I further suspected (we could even use the "assumed" word) that would mean the DC-DC converter is appropriately sized to keep the battery charged with a full (reasonable) electric load (lights, windshield wipers, AC blowing, radio, etc. Putting the two together seemed logical that if the IMA battery could supply all the cars 12V needs unless it was dead, overheated, etc it made the 12V bat just a redundency.

Since everyone says it's not, I will be making more effort to assure it's proper maintenance.