What is this and how do I make one...
 

So it is clear I have not had much luck with batteries lately! Anyway, when the Mazda MX-5 battery died, I had nothing useful, no jump starting cables etc etc. So I got the AA to give me a boost.

When he arrived we started talking motorbikes and how I had recently created a video around jump starting a bike from a car. He dug around in his van and pulled out this capacitor- he explained they use that on motorbikes they get called out to.

Now this looks pretty small to me, like, could stash it under the seat small, so I figured maybe it would be a good idea to make one up. I can see there is a capacitor, a fuse and some cables. That is all the info I have, can any of you out there share any more info, like how to charge it? Or any reasons why this might not be a good idea?

http://i1260.photobucket.com/albums/...o/IMG_1056.jpg

Re: What is this and how do I make one...
 

Curious. All I can think is that it charges up from a nearly-dead battery and discharges quickly enough to turn the starter, which might be enough to fire it up. It's a big one alright!

Re: What is this and how do I make one...
 

If I understand electronics correctly, the capacitor will charge when connected to the battery terminals, but only to the voltage of the source.

It can then dump it's charge quick enough that the starter motor can turn. That one looks very crudely made, but it must do the job


http://uk.rs-online.com/web/p/alumin...itors/5436628/

Re: What is this and how do I make one...
 

You're mixing your units.
http://hyperphysics.phy-astr.gsu.edu...ic/capeng.html
68000uF at 12V gives 5J of energy stored. Power is time-dependent so 5J in 1 second is 5W which isn't much, 5J in 1/1000th second is 5KW. Say it needs 20 amps=240W then you'd get all of 0.02 seconds at that power, if you could fit it all through those little wires. Might be onto something re. the ECU though.

Re: What is this and how do I make one...
 

the capacitor is only used as a buffer to safeguard the electrics of the bike. there is no way you can jump anything with a capacitor. yes big capacitors will give you a nasty shock but thats about it.

Re: What is this and how do I make one...
 

Look on YouTube
There's guy's in the USA who run cars on these in banks
https://youtu.be/gzaLF5tFf88

Re: What is this and how do I make one...
 

just because you can does not mean you should ;)

large caps like those are expensive then add in the circuit board etc.etc and its not cheep but does make for interesting bragging rites :rolleyes:

a small cap like Tamsen has shown has about as much luck starting a bike as finding rocking horse poo.

Re: What is this and how do I make one...
 

Looking forward to solid state battery s ..

Re: What is this and how do I make one...
 

I bet you used to charge up a condenser and chuck them to do unsuspecting persons lol....

Re: What is this and how do I make one...
 

Thank you to all for the replies, I think this makes the most sense, if you are out and about/ roadside, it would be unlikely you would have a completely flat battery, and this could dump enough power to get it started maybe?

The AA guy stated he had used it on motorbikes on call outs.

I have looked on youtube and all the videos on there seem to be looking to replace the battery with capacitors, rather than using one to jump start the bike... Maybe I should just build one and see what happens....