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I was wondering if it would be possible to replace the 12V battery in my car with a bunch of 1 Farad capacitors. Since the car mostly starts on the hybrid battery and doesn't use the 12V much for regular driving, would it be possible?

1 Farad equals 12 amp seconds at 12V. Get the amp hours of your battery and calculate how many Farads it would take to replace it. It will be a bunch, since a AA battery contains the equivalent of 10,080 Farads.

and doesn't use the 12V much for regular driving

I haven't really kept up with your rides additions, but don't you have some stereo equip onboard? What do the amps run off of?

Randall

Some time ago, I suggested doing away with the 12-volt battery and power everything with the hybrid battery pack. The objections I got was the applicances would need a 12-volt inverter or designed to run at a different voltage, and that the 12-volt battery is a backup system. Would still like to see the 12-volt battery eliminated eventually, esp. since we have trollers soooo concerned about toxic batteries. :p

The Amps run off the 12V system and consume about 120Amps.

Hi Tom:

___Although not a SuperCap, the Valance Technology - Ucharge Li-Ion 12V looks like a winner. I tried to contact these guys about a year ago and did not receive anything back. A few rumors were talking over a Grand each w/ the Monitor and that is just plain stupid pricing for a 12V :(

Valance Technology U-Charge Power System (http://www.valence.com/ucharge.asp)

___Good Luck

___Wayne

Lets see the amps draw 120A peak, and the DC-DC puts out about 75A, so you better leave a nice 12V battery in there.
When comparing caps to batteries, you need to look at the discarge curves, the caps voltage just drops and keeps on dropping when loaded, the 12V drops, then the voltage flattens out as the chemical reaction continues to produce current. Under heavy loading the caps would drop voltage till the DC-DC was doing all the work.
Prius subpacks make a nice 12V replacement for the Insight.
I had my 12V battery die while we were doing scan tool test at UDHEV(original 6 year old). At 10V the dash lights went out, and the car would not start. I happened to have two Prius subpacks handy, and was able to jump start the thing with them.
The last time I checked, the Valence U charge U1's were about $800 each, very pricy.

For a typical Prius (not one with massive audio), I have suggested elsewhere that one of the NiMH modules from an HV battery assembly might substitute for the '12 volt' battery. Or possibly 2 in parallel? Having them looking at only 13.8 v all day long might remove the need for thermal management or a rigid case, but I am not an expert on that.

At least I can say that for a fuel economy run where modifications are allowed, you could substitute a 7 amp-hour gel cell and remove 20 lbs of weight or so.

DAS

I have been using two Prius subpacks in series on my lawn tractor for the last two seasons. 14.4V nominal. They seem to hold up quite well, and start the thing better than the lawn tractor 12V battery that came with it. I figure that the 13.6 V point is just about the 70-80% SOC,point so no thermal management or venting is needed. In the spring, I will replace my Insight pack with two prius subpacks and see how that holds up. The problem with doing it now, is that when it gets cold enough for the Insight to start on the 12V system, (now)the Prius subpacks will be too cold to help, so it would only be a warm weather mod. Kind of nice having nearly 100 of the subpacks in my spare parts bin so I can play with them. A 720V 100A battery pack.:eek:
By the way, the gen1 subpacks will not stack properly with gen 2 subpacks, as the ball and sockets on the subpack sides are different.