charging the 12V battery with no IMA

[Mike Dabrowski 2000]

Many people have asked if the Insight or Civic can be run without the IMA.
The answer is yes, but the 12V battery is not being charged, since the IMA must be operational to charge the IMA battery, so it can power the DC/DC converter, to maintain the 12 volt system .
Ways around it?
Use a large deep cycle 12V battery instead of the tiny one. This would give 6-10 hours of driving, with the lights on, and could be recharged each nite. A plug in hybrid for a different reason

Mount an alternator on the car?
Difficult, not much room. The AC area would be easy, but I like AC. A major mechanical project.

We know from our hybrid training classes that the IMA motor is always generating ac voltage, and can output 50 or more Amps at up to 250V at high rpm. This is with the IMA out of the car, totally disconnected.

A simple 220V 60hz transformer with a 24V secondary, connected across any two legs of the motor terminals, would give isolated 0-35V output to power a 12V charging system with voltage regulator. That would allow the complete removal of the IMA electronics and HV batteries, with only a lb or two of charger weight added back.
Should work. Anyone with a dead battery that wants to try it, let me know.

[retepsnikrep]

Nice simple idea/solution Mike I like it.

I wonder how many warning lights/codes you get though with the IMA battery and controller etc removed completely?

Dash lit up like a Christmas tree?

What hit on mpg?

Peter

[Mike Dabrowski 2000]

There were some dash lights on, and codes set, but the car drove quite well. We were not looking at MPG, so I can't say what the MPG hit would have been, but many hypermilers say that they feel the IMA is not necessary?
For me, I love that electric turbo, so I want more electric rather than less.
The next time we try it, I will look more closely at the codes.

[b1shmu63]

Mike, a standard 60 Hz transformer is designed so that its rated power is delivered at 60 Hz. Below that frequency its imedance lowers allowing more current to pass through it. The transformer could burn out if the car wa idling too long, and depending on the frequency and voltage produced at idle speed. At higher frequencies the impedance goes up so the transformer delivers decreasing output power. I suspect that a switch mode power supply with a wide input voltage range would be a better choice and would acomplish the task in a single step. Then again, that is exactly what happens in the IMA system. The difference being that in the IMA system the IMA battery acts as a storage element allowing the 12 volt battery to be charged even if the engine is not turning.

[Mike Dabrowski 2000]

I believe that the drive frequency at idle was in the 30-40 HZ range. I will have to take a measurement to make sure.
While you are correct about the lack of efficiency at higher frequencies, and increased current draw at lower frequencies, we need to remember that the voltage increases with higher frequency, so the net effect should allow the 220Hz 25V transformer to work over a fairly wide rpm range.
Of course one could rectify the output voltage of the motor, and then do a DC/DC conversion. That would be more complex than a simple transformer, but would be more efficient.
It may be possible to just rectify the ac, and charge a large capacitor, and to run the existing DC/DC as the charger, since it is designed to operate from 120VDC to 180VDC ?Lots of possibilities.

[b1shmu63]

"It may be possible to just rectify the ac, and charge a large capacitor, and to run the existing DC/DC as the charger"

I see no reason that wouldn't work, and I would be comfortable with that technique. You would definately reduce weight, simplify the electronics, gain space, and perhaps even gain a couple of MPGs on a really long road trip. You would also castrate perfomance and trash the city MPGs.

Personally I'd rather see a really big IMA pack, perhaps using one of the emerging "safe" lithium technologies. In a few more years such packs may be available from scrapped Prii, which by then might be selling a million a yearl!

[Mike Dabrowski 2000]

The only downside of that technique may be the voltage getting too high at high rpm, and damaging the DC/DC. The pack never gets to much over 180V, but I have seen the IMA motor on the civic hit >220V when reved. We blew up a set of shop lights when the engine was reved. Some sort of top end regulation would likely be necessary.

I continue to find uses for the Prius NIMH subpacks that I have. The latest is to use two in series as a 12V starting pack for my John Deer backhoe, as well as the spare Dodge Caravan that my sister gave me. The little pack cranks like a standard size 12V battery, but only weighs 4.8 lbs.
http://www.99mpg.com/mikestips/

[joecvt]

Wouldn't a simpler method be to add a modified circuit of MIMA that would disable normal charge and assit by keeping the duty cycle at 50% at all times...This would still allow background charging to the 144V battery (when needed) and keep the 12V charged as well. AutoStop and engine idle control would still work and no check engine codes (unless the 144V pack is too far gone)....This would prolong the life of a weak battery pack with the limited usage. No additional weight (besides the circuit board ) would be added. It may also be a benefit for those who usually try to keep the battery use to a minimum.

For anyone that has not heard of MIMA, please review it here:

http://www.insightcentral.net/forum/...pic.php?t=3357

and here: http://www.99mpg.com/mima/ for current status and discussion.

JoeCVT - Just your average CVT owner

[Mike Dabrowski 2000]

What you are suggesting would be good if the pack was useable. I guess I was responding to the many people that have asked about totally removing the IMA, battery, inverter, and converting to a gas only car. The 150 or so lbs that would be removed would make the car lighter.

The key connection here is that the IMA motor/generator is generating voltage whenever the motor is turning, with no loading of the ICE until current is drawn. A built in alternator.
The rest of the IMA electronics are not needed, if you wanted to convert to gas only.
There are numerous ways to use the generated power to keep the 12V system charged. Just have to step it down and control voltage so the 12 v system is not over charged.

[Mitch]

This sounds like a product worth marketing. Many of us will have battery packs failing outside of our extended warranty in just 3 years. Many of us may not have the perhaps $2,500+ or so to spend on the new IMA parts, or perhaps it won't seem justifiable to spend such money on a car that's worth barely more than the repair cost by then. This can be a permanent solution or just a temporary one until one comes up with the $ for the new IMA parts.
The only real drawback to permanent usage is not knowing if a new check engine light code has arisen, give that the light would be on all the time.