Replace your car battery with capacitors!

[hayden55]

Originally Posted by jray3

Thx Werefree- I should've mentioned that I do have a large number of the 3000F Maxwell ultracaps complete with 6-pack interlocking frames. They were used in hybrid bus research by Azure Dynamics. I'm not actively marketing them, but PM if you're interested. The six I'm using have been propping up dead lead for four years now. I haven't gotten around to building any balancing boards to use this large lot.

I know you said you weren't messing with them, but whats your charge time? Thats equivalent to almost a 69Ah deep cycle battery.

[werefree]

OK I just spent 1/2 of a normal battery on two sets (12) of 500F capacitors, some 1N4935 rectifier/diodes to help balance the pack under alternator load, and 1 30A, 4s balancer for lithium batteries. In the garage I have like 90 Lithium cells from some recycled laptop batteries. So I put together a pack that is 5 in parallel and 4 series. I will then bridge the lithium pack using some resistors in parallel with the capacitor bank. When the F250 starts, the capacitors will come down in voltage, then the lithium's will bring them right back. Or so I think right about this moment. when my parts get here in Feb 5 or so, then that might be a different story. So off I go to make a preliminary cad model of the wood box I will need to house this stuff neatly. When the caps get here, all I need to do is change the size, update the model and print the drawings and go to the garage to start cuttin. In another forum, someone sarcastically mentioned that their car was blue, thus making this stuff work better. Hey It just so happens that my truck is blue! Hurray for unscientificity! I'll be taking my precautions with this thing, no worries. I know first hand what a hydrogen torch looks like coming out of a lithium battery. I should say finger. A flash type non rechargeable lithium battery puts out a nice flame for about 2 seconds. A laptop cell will probably do 5 to 10 seconds, and there are 20 of those plus 12 supercaps. So incident-wise, we are looking at minimum a large hole in the hood of a vehicle parked in the freeway neatly between lane 2 and 3. At worst, a larger hole and some missing personal parts. In three weeks when the parts get here, I might not even remember what I bought them for, ah we'll see.

[oldtamiyaphile]

Originally Posted by werefree

When the F250 starts, the capacitors will come down in voltage, then the lithium's will bring them right back. Or so I think right about this moment.

Will your caps not draw too much power for the lithiums to handle? I wouldn't consider using one of the flammable chemistries under the hood of a car when alternatives are available.

[redpoint5]

Originally Posted by oldtamiyaphile

Will your caps not draw too much power for the lithiums to handle?

The resistors in parallel with the capacitors will limit the rate of charge/discharge from the battery.

Normally LiFePO4 chemistry is used for auto battery replacement, so I'll be interested to see how using Li-ion batteries from a laptop works out.

[werefree]

not too long ago I made a battery pack with exactly the same configuration for a 2 pack 24V system for an ebike. I didn't have a good way to charge it back then so I just sold it off. But I did try it and it did start the truck. I think the capacitors will just make sure I have the amps and also protect the battery. I got an idea of how to make sure there is no thermal run away. I got two wireless nodes "acorn digistump". I'm going to have one in the battery monitoring temps all around the battery/cap. If the derivative goes too high compared to some sample initial derivative or preset, then I will stop and disconnect. I was thinking that maybe the alternator would charge them too high, but then I realized that the alternator will only get to ~14 volts while these things have to be charged at ~16 to get 1 to 2 amps in. Unless maybe the alternator goes to a different higher voltage based on a higher battery voltage? probably not, but I'll take a look.

[redpoint5]

The reason LiFePO4 is used is because the voltage for a 4s battery is just about perfect for the typical 14.4v output from an alternator. I'm unsure what will happen by using a Li-ion battery and undercharging it, but I'm very interested to see the results.

I would think it could accept a relatively high charging rate since it won't even approach a full charge. Maintaining the charge level somewhere in the middle should be ideal for longevity. It will be necessary to remove the battery for when the truck sits for long periods unless it has an extremely low (or zero) parasitic load. My truck has a 5 mA parasitic load to maintain the radio presets and time

The alternator should not output anything above about 14.6v regardless of what battery is connected.

[ChewChewTrain]

Originally Posted by Old Mechanic

God help him if those capacitors are made in China.

regards
Mech

They likely ARE made in China and, because of that, no amount of praying will help.

[werefree]

So I tried my lipo yesterday (4s,5P) and all I heard was clicking. but one of the clicks reminded me that my old bike was 24V, errr, 2 packs in parallel. I think this time I will just grow the 5p to 10p. Last time with 2 packs it got annoying to have to remove one from the charger to charge the next. The old charger that came with the bike didn't have the voltage required and was not a good source for my turnigy charger. So I've been using a computer PSU since. I got my balancing diodes yesterday...useful. Now I just have to wait for a very long time to get the CHINA ucaps.

U know china is not a bad bunch of people. The gov of china is what is wrong. Otherwise, they would have taken over the planet already. Wife's philipino, close enough. But Ok, there can be something wrong with the caps. My bro-inlaw's water heater in the philipines consists of a 220V cable attached to a resistance coil. You drop this in to a bucket of water... no groud and humidity 100%. And he is not the only one doing this, I saw this "model" in a hardware store, it is something they sell. so either the caps I get work, or I might find that they are empty shells with liquid or solids inside that don't do much. But I did find someone not in china using the same exact set up.
in youtube "watch?v=7NJXGsGIr4I", So I will cross my fingers on this to work. Its very scientific.

[werefree]

https://www.youtube.com/watch?v=BCfy3v4GKqM

in the video he says that it will not start his van. So I think double the caps and double the batteries will do good.

[werefree]

He is using 4 diodes across the caps so that the extra voltage passes thru after the caps are completely charged. I tried the circuit in a simulator just for fun and sure enough it works. When the current stops completely and diverts into the diodes, it drops to less than 1 amp... probably better MPG. as soon as the caps get used, the current drops to micro amps on the diodes and increases to something large in the capacitor side.

https://www.youtube.com/watch?v=n8mzi0u-rd8