Replace your car battery with capacitors!

[werefree]

I forgot to say that I measured the voltage this morning and it was 0.99V.... from last night's 2.7V. So it is very significant and the use of a small battery to maintain charge is necessary. Things we all, already knew, I know, I know.

[werefree]

I put together a pack. One dead open capacitor was found and replaced. When connected to the the F250 all I heard was a lot a clicking. Thus I will try connecting both the battery and the capacitor. I feel like there is enough pics so I will only post a video when the truck successfully starts from my ultracrapacitor. So far and am really impressed at the weight of the little things almost cranking the truck.

[werefree]

Another dead capacitor was found on the second pack. OK let's make a note about these particular caps. I remember Maxwell had the same doa issues. Most failed open. I'm going to get another two sets so I can have some extras.

[redpoint5]

Worthless anecdotal evidence... but I have had zero defective Maxwell caps out of 11, and zero defective Eaton caps out of 6.

[ChewChewTrain]

Originally Posted by redpoint5

Worthless anecdotal evidence... but I have had zero defective Maxwell caps out of 11, and zero defective Eaton caps out of 6.

You likely spent ALL your good luck on the flawless caps. Next time, spend your good luck on the PowerBall.

[werefree]

We used to buy them as a continuous supply probably in the thousands to meet our needs. The ESR was checked and strings of 3 with similar values were paired (tried?, thirded, threesomed) together. Every now and then a dead ultracap showed up either there before assembly or inside a the assembly...with like a 100 screws to remove and many things to disconnect. Not a fun event for anyone. Specially not for the poor guy having to disconnect a 600V live pack. Incidentally, there was one incident of instant cable vaporization. The guy was OK an lived to tell the tale, but his hand took a few months to recover. The part of his shirt that was facing the wire was never found. A dead cell can be a big deal. But I don't care too much at 12V or for the 17 bucks I paid for a set of 6 (4 really...). I'm going to open it to see if it is a fake one like in the videos I've seen.

[werefree]

Stayed home to help the wife while at the doc. So I finished putting together more lithiums together. I tried starting the truck and nothing. Except now it clearly was engaging the starter. Then I charged the cap bank and paralleled it. This time the truck made a few gear movents. So its getting closer now. Next I will add two more ucap packs. Probably by next week whenever the caps get here

[werefree]

ok I have not given up, however I must report the happenings. I now have 3 sets of 6 chinese 500F capacitors 6S. I also have two battery packs from old laptop batteries. each 10P,4S. The voltage is 15.3 or so. Well last night I got all the packs together in parallel. I got into my truck and gave it a go. It actually cranks by like 5 gear teeth or so... Then I plugged in the old dead battery and the voltage went to like 14.5. It gave a few more teeth. So then I added a 75A starter/charger, and it did it. barely, but it got there. The pack is able to start my mini cooper no problem at all, but on the truck I need peak 700A. So The long term next phase is to buy a battery and get my smog check so I can keep using my pile of rubble to get stuff from home depot... total failure I know for this goal at least... Next phase is to give up on these commercial crapola and get my self some home made super capacitors ala Robert Murray Smith. Actually yesterday he posted two videos detailing the quickest way to make a super capacitor. I am going to use activated carbon and salt water for the electrolyte. The dissadvantage is that this will make a 1.2V capacitor rather than 1.7 and you know CV^2... but OK who cares, I am just playing with junk in the garage and playing is the goal.

[Enki]

Sounds like you've not sized your bank properly. I'd estimate you need a bank of 6 3k farad caps to push a reliable 700 amps through that truck long enough to get it started; from 15v down to 10v would be 2500 amps and should be enough for just under 4 seconds of cranking (at 700 amps per second draw).

[teoman]

Originally Posted by redpoint5

I just purchased 6x 350F capacitors ($77 shipped ) to test out in various applications, both with a LiFePo battery and without. I don't have the battery yet, but I do have an ATV with a dead lead acid battery. My first test will be with the ATV, to see how long it can sit and still start with just the capacitors.

The nice thing about having it in the ATV is that if it fails to start, there is a pull cord as a backup.

Next, my truck has 2 very weak batteries that will barely start the Cummins motor after 3 days of sitting. I'm wondering if throwing the capacitors in parallel with the batteries will give it the extra cranking oomph it needs.

Unfortunately, I don't think I can cheaply replace the lead acid batteries with a boost pack because the grid heaters suck down serious amps. Since the speedo on my truck doesn't work, the grid heaters continue cycling even though I exceed the cutoff speed.

Another vehicle I'd like to replace the battery with a boost pack is the TSX. I've already measured the parasitic load at 0.041 Ah, so sizing a LiFePo battery for my needs should be simple.

Last, I have a CBR600 motorcycle that I'm curious if it could loose the lead altogether and just run capacitors. The problem is that it charges using a generator instead of an alternator, and that means it doesn't charge below about 1,500 RPM. In other words, I'm draining the capacitors anytime I'm stuck idling. Even worse, if I idle too much the engine temps rise enough that the E-fans kick on. Fortunately, bump starting a motorcycle is easy enough.

I'll start a new thread when I begin experimenting and report back my findings, but it will be a few weeks to a month before I have anything to share.



Any update?



I just measured my TSX draw at 41mAh today. With 12.4v on the battery, that is just barely more than half a watt drain.

As I've just learned, capacitors don't behave the same way as batteries when placed in series. 6x 3000F capacitors in series has only 500F capacity at ~14V.

The formula (Vmin + Vmax)/2 * F / 3600 = Ah is used to convert F to usable Ah.

I'll assume my car is happy with voltages down to about 10V (correct me if you think it might be different).

(10 + 14) / 2 * 500 / 3600 = 0.83 Ah

If my calculations are right, 6x 3000F capacitors in series and charged to 14v would give me 0.83 Ah and with a drain of 0.041Ah, my car would go for 20hrs before the voltage dropped below 10v and the computer dies.

Someone please analyze my assumptions, formulas, and arithmetic.

Here is a series/parallel capacitor calculator -> Electronics 2000 | Series / Parallel Capacitor Calculator

I wonder why supercapacitors only exist in the 2.5-2.7v range? If someone could just come out with a 15v rated supercapacitor, there would be no need for a series configuration and the resulting loss in capacity. Wiring in parallel to boost capacity would come at zero penalty.

That is really a minuscule amount of energy. You could have a single 18650 battery on a keychain that you insert in to your car to fill up the capacitors and then get it to start.