Replace your car battery with capacitors!

[redpoint5]

The price has dropped on the BCAP3400 supercapacitors! They were originally $80, but are down to $71 each. If purchased in a quantity of 10 or more, the cost is $67 each.

These caps have a higher voltage rating than any other supercap on the market at 2.85v. Most others are rated at 2.5-2.7v

They have a peak voltage tolerance of 3v, which means it is likely possible to get away with running only 5 in series instead of 6. At 3400 farads, they have the largest capacity for the money.

Anyone want to buy 5 with me to get the quantity discount?

Originally Posted by PaulB2

...Also I needed to turn up the idle a bit as at low rpm generators don't put much out and the headlight has to be on.

Anyway a couple of things worry me about this supercap business. Having your capacitance cut down to 1/6 or 1/5 by using caps in series seems a huge waste. And I worry about the voltage spikes in the system.

My CBR maintains 12v at 1000 RPM idle. Once I swap the 55w headlight out with a 35w HID, I will do another test to see if the voltage is held higher.

The voltage doesn't spike any more than using a battery, peaking at the output voltage of the generator/alternator.

[PaulB2]

I thought starter motors injected spikes into the 12v bus?

I was wondering if the series connection of capacitors could be avoided by finding a dc to dc converter design (stepping from 2.5v to 12v) that would handle the large current, but it would have to be able to go both ways and all I found was quite expensive and only went one way (sigh).

[Enki]

I agree that it's better to run as few as possible in series but also to not charge them up to peak, and that capacitors are normally used to filter out voltage spikes, which could also be dumped using schottky diodes.

I'd love to buy 5 but I don't have anything to use them in at the moment, so it would be a bit of a waste.

[PaulB2]

Now that I think of it some more, any voltage spikes are likely to be swallowed by the large capacitance. In fact that is why people use capacitors as filters, to get rid of voltage variations.

[Enki]

I've been talking to an alternator company and a lack of em noise filtering was mentioned...I've been doing some research (it's mostly car audio related) but I'm still going over information.

[elhigh]

I don't know why it's taken me 'til now to have this idea, but now I'm wondering about replacing the battery on my Farmall with some supercaps.

The battery on the tractor is dead. Deader than an Allosaurus. I don't use the tractor enough to keep a charge on it and it spends its time in the weather. Adding a solar maintainer didn't really help.

Now I'm thinking that a bank of supercaps and a few bicycle dynamos wired in series to generate 12v might be a sufficient substitute. The tractor starts up well enough on the crank, but some days it's just a bear on my elbows and hands to yank that handle one. more. time. Some dynamos all run together by a single chain or gear, cranked by a single handle (one with a spinner, please), crank at a comfortable pace for a couple of minutes instead of giving mighty, elbow-snapping yanks might be the way forward. Stomp the starter and off she goes.

Anybody want to weigh in? This sounds like the first idea I've had that would be a crosspost to MyTractorForum.com

[redpoint5]

Originally Posted by elhigh

I don't know why it's taken me 'til now to have this idea, but now I'm wondering about replacing the battery on my Farmall with some supercaps.

The battery on the tractor is dead. Deader than an Allosaurus. I don't use the tractor enough to keep a charge on it and it spends its time in the weather. Adding a solar maintainer didn't really help.

Now I'm thinking that a bank of supercaps and a few bicycle dynamos wired in series to generate 12v might be a sufficient substitute. The tractor starts up well enough on the crank, but some days it's just a bear on my elbows and hands to yank that handle one. more. time. Some dynamos all run together by a single chain or gear, cranked by a single handle (one with a spinner, please), crank at a comfortable pace for a couple of minutes instead of giving mighty, elbow-snapping yanks might be the way forward. Stomp the starter and off she goes.

Anybody want to weigh in? This sounds like the first idea I've had that would be a crosspost to MyTractorForum.com

I'm not following. Does your tractor have both an electric starter and a hand crank?

A solar maintainer should be sufficient to keep batteries topped up as long as the tractor lives outside instead of under cover. I found that one of my solar maintainers has an LED that stays on constantly, even when it's dark outside. The 10 mA constant drain was more than the solar charger could make up for during a cloudy day.

I removed the LED from the charger, and now it keeps my truck topped up.

We have an old Alice Chalmers One Ninety that has a huge battery that is often dead due to sitting too long. I'm curious if an ultracap would help it start, but a little doubtful since it often takes 10 seconds or so to get her fired up on a cold day.

[elhigh]

Crank and electric starter, yup. '45 Farmall A, starter was optional.

It's entirely likely the battery is well and truly dead. I haven't bothered to stick a meter on it yet, it starts well enough on the crank to not be fussed about.

[sreeve212]

So I've read through most of this thread and have wondered myself about getting into this.

I'm due for a new car battery but, instead, does anyone think a kit of 6 350-F Maxwell capacitors with a balancing board all assembled would work? Search "ultracapacitor module battery eliminator" on ebay and it is the one that is assembled.

I want to be able to start my 2.0 liter engine with only this (58 Farads) while also having a 20 watt solar panel connected to maintain a full charge. Does anyone think this would be possible? My concern is whether the constant current could burn out the balancing circuit... I don't know nearly enough about these things, however.

Is it also more cost effective considering it doesn't need assembling or extra tools? I could go with bigger capacitors individually but I would have to connect them which would be more work.

Thanks everyone!

[Enki]

You shouldn't really need a balancing board, and the effectiveness depends entirely on how much current your vehicle draws upon start.

One way to find out for sure, though.