Capacitor battery
 

Alright guys a few months ago i was posting looking for ideas for battery replacements and one of you fine individuals pointed me to this video


Being the nerd i am i thought hell yeah, that would be perfect to replace my big ass crappy looking battery, so i got on digikey and ordered up a bunch of these guys
and built myself one, of coarse they were back ordered and by the time they were in stock my 7 had killed itself, however it is now going back together and i have been waiting on parts so i decided to go ahead and build one wile i waited, after much pain and suffering (mostly from burns and the frustration of figuring out how to get solder to stick to these things) without further ado i give you the home made supercap battery:

(pardon the honda, its my winter beater, and yeayea i know about the filter, but if i put the cold air pipe on it, it actually can get hydro'd in puddles, which can happen where i live)

I built the case out of 2 inch square teflon stock and milled out grouves that i was originally just going to put plates between the cells, however that failed so i carved grouves and soldered ring terminals with pig tails between the cells (after trying 4 other things and ending up with about a dozen burns from molten solder trying to get it to stick to whatever shitty material these things are)
I used 10 gauge wire between the cells and the pig tails on either end and they never seem to get to warm to touch, after the initial charge they barely get noticeably warmer than ambiant in the engine bay.
This still requires some further testing, i have added a 12v LiFePO4 18650 Battery: 12.8V 4500 mAh ( 57.6Wh, 7A rate ) w. PCB battery to the side of it to keep my clocks alive without draining the cap's however still on cold days it is hit or miss weather it starts, which could be just due to the cold oil, the fact that the prelude has "high compression pistons", or the draw off my car alarm (even though i havnt been arming it with this installed)
Testing with a multimeter shows that even 36 hours after shut down the capacitors still maintain 13.5 volts even when cold, so i am also thinking that i may have just fried a couple of them with all the soldering i tried to do to them which may have reduced the actual capacity without affecting the voltage, so i may try swapping a couple of suspect ones out at some point here to see if it will become more reliable
If i were to start again i may go with some slightly bigger as this cell is only about 10"X2"X4" and i could possibly go a bit bigger capacitance, maybe a 450 or 500 farad to possibly improve reliability, however i am interested to see if the RX7 will be easier to start with the lower compressions (prelude is getting 190-200 per)
will update or post a new thread once i have the 7 running with this in it

Interesting use for that technology, for years I used an Odyssey PC680 AGM battery that weighed 14.5 lbs. I thought it was a significant weight savings over the 35lb stock lead acid battery. It worked pretty well except during long term (over a month) storage it would run down. I'm currently using a SSTX14AHQ-FP Scorpion Stinger battery. It's a 2lb Lithium Iron Phosphate battery with approximately 360 CCA. The best part is if it ever does discharge, it can be recharged in a matter of minutes with a LiFePO4 charger.

dude, awesome!!!

let us know bout the updates!

yeah, i actually put it in about 2 weeks ago now and just got to makeing the post last night, it does some really weird things that i dont like such as after driveing for like a half hour, parking and turning it off for 2 minutes it wont have quite enough juice when i try to restart it (doesnt happen every time just intermittently), yet then i can drive it and turn it off and come back the next morning and it will start fine like 6 times in a row without letting it idle for more than 2 seconds each time, so i am trying to think why that is happening and am haveing trouble figureing it out
i tested my alternator and its putting out 14~ volts unless its intermittently failing idk why it would do this, unless there's like corrosion on a essential wire somewhere that increases resistance when it is hot or something

Edit: ill take some pictures tommorow and post of what it actually looks like and how i have it mounted

forgot to take the pictures, but to update definitely does not like being hot or cold, going to try and relocate it to the trunk and use my subwoofer cables to get power up front and see if that helps with the hot starting issues, which should let me know if its system resistance or the capacitors not performing at high temp

Interesting project. Keep us updated.