Supercapacitor/Ultracapacitor starting bank

BlindAmbition

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I've just finished up making a supercap starting bank for my truck. It's charging now, I'll post results in a couple hours on how it works.

Here is a thread with some info - https://www.ford-trucks.com/forums/1475925-diy-experiment-ultra-capacitor-bank.html

I ordered some 3000 farad capacitors from Electronics Goldmine to do this.

https://www.goldmine-elec-products.com/products.asp?dept=1028

Hard part was connecting them in series since I did not opt to buy new units with bolt on terminals because they are almost $90/ea after shipping and taxes. I used some silver epoxy to do the deed since I cannot weld aluminum.

The basic idea is the supercap can discharge massive amounts of current in an extremely short period of time, such as starting a diesel. It prevents shock loading the battery which helps extend battery life.

I will wire mine in parallel to a frame mounted battery. I'll have a second battery for all my accessories, glow plugs, and an amp if I ever add one to the truck.

This thread is for info mainly, just something I've wanted to mess around with. I'm sure there are better ways to do what I'm doing.

Since our trucks need glow plugs I could not figure out a way to isolate the caps for just starting.

Also, I'll have Lincoln Mark VIII fan that has an inrush current of 70A or so. I've read of electrical systems having issues with such a hard draw; a supercap negates all effects of that.
 

BlindAmbition

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Eaton XL60 Super Caps. 3000F apiece, 2.7v. Total bank will be 16.2v, 500F (Big F, farad, not microfarad)

IMG_20210319_153445340.jpg


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$5 Walmart lunchbox that had a tray that fit perfectly

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Rough fitting

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BlindAmbition

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Used welding wire with the insulation cut off to make small jumpers to go from isolated terminals to aluminum strips

IMG_20210415_231401804.jpg

Used silver epoxy and aluminum bar with the same dimensions as the factory terminals to make buss bars to wire in series

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A few days ago I'd done some testing with charging them up a bit by using an LED bulb as a current limiter. It worked alright, enough to throw the whole assembly on a trickle charger so it isn't completely dead and seen as a dead short.

IMG_20210416_162348917.jpg

Essentially final product, fit the whole thing into an ammo box. Will fill with spray foam or some such insulation to prevent movement once I ensure it works as it should. It'll go in the passenger battery spot
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CDX825

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I was actually pondering this recently on how well this would work on a diesel with two batteries with one replaced by a capacitor bank.
 

BlindAmbition

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If the diesel doesn't require glow plugs it works awesome. If it does need glow plugs then it is more difficult because as soon as you hit the glow plugs it'll pull from the supercap first and leave nothing for starting, unless you had a large enough bank I suppose.

It could be possible to just run a supercap for starting as long as you figure out a way to charge it while also keeping it isolated from the glow plug circuit.

I haven't figured out a way yet, so I just ran a second battery since I'd originally purchased two batteries when I started working on my truck restoration.
 

wthompson01

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BlindAmbition

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Test one didn't work out, silver epoxy does not flow enough current to work. I'm looking at purchasing caps with threaded ends so I can correctly connect them. Attempting to start from the capacitor alone triggered the starter, just not enough to crank. The epoxy itself was getting hot so I am back to the drawing board. This could have been easily bypassed by having the correct units, this was a learning and money saving attempt.


They cant be spot welded with a spot welder that is designed to spot weld battery packs together? I have a spot welder that is designed for things like this.

As far as welding, I am unsure. I have a quote of $150 to weld them from a local shop, which seems pretty expensive to me. The terminals are aluminum so I am unsure how spot welding works in that case. 1/8" thick aluminum bars if that matters. I'm game to try/make something to do some spot welding.

If I buy a new set of caps then I'll be able to create a different configuration which lets me mount the second battery in the passenger location and free up the driver side battery area for a front mount turbo in the future.

I have more silver epoxy, thinking of wrapping each terminal in copper then epoxying it in place. This is all for sketchy homebrew science and fun, will do it correctly as funds allow. Worst case I'm sure it'll be fine for a much smaller starter like on my car.
 

wthompson01

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Test one didn't work out, silver epoxy does not flow enough current to work. I'm looking at purchasing caps with threaded ends so I can correctly connect them. Attempting to start from the capacitor alone triggered the starter, just not enough to crank. The epoxy itself was getting hot so I am back to the drawing board. This could have been easily bypassed by having the correct units, this was a learning and money saving attempt.




As far as welding, I am unsure. I have a quote of $150 to weld them from a local shop, which seems pretty expensive to me. The terminals are aluminum so I am unsure how spot welding works in that case. 1/8" thick aluminum bars if that matters. I'm game to try/make something to do some spot welding.

If I buy a new set of caps then I'll be able to create a different configuration which lets me mount the second battery in the passenger location and free up the driver side battery area for a front mount turbo in the future.

I have more silver epoxy, thinking of wrapping each terminal in copper then epoxying it in place. This is all for sketchy homebrew science and fun, will do it correctly as funds allow. Worst case I'm sure it'll be fine for a much smaller starter like on my car.

The studded caps would be a better option in my opinion. 1/8" thickness is too thick to spot weld. And I'm not too sure that aluminum would spot weld properly even if the connecting strap is thin enough.
 

BlindAmbition

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Silver epoxy worked well enough to start my Scion XB directly from the capacitor bank without a battery

It didn't like trying to start my truck

So instead I have been checking various sources for supercaps and came across this pack on Ebay. $320, I thought it had 12 caps, turns out it has 18.

16.2V 1500F capacitor bank, already connected together.

Once I figure out how to charge it safely I'll report back with how well it works.

s-l1600.jpg
 

BlindAmbition

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Supercap works awesome, it fires up immediately. I did try it just by itself and it almost fired, though I had air in the lines and fuel delivery issues at the time so it isn't a fair test. I think it'll fire the truck just fine by itself. Given that I'd already purchased two batteries for this project I went ahead and mounted one on the frame. The cap and frame battery are wired in parallel and on an isolator relay so they do not connect to the rest of the electrical system until 10 seconds after turning the key to on. This lets me use my second battery for the glow plugs without depleting the supercap. I'm sure this can be made more efficient but I'm happy with the experiment.
 

renjaminfrankln

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I'm wondering how this will work when you run out of fuel and need to crank for 45 seconds (in bursts) to re-prime the system.

Or how bout your alternator fails on a road trip and you need to keep going for three hours to get home.

Or you leave the headlights on for 30 mins while you go in the grocery store.

None of these scenarios are a problem for me with two brand new $95 walmart 800 cca batteries in my truck. Just playing devil's advocate.
 

BlindAmbition

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I still have two batteries, one in parallel with the supercap, one that is isolated. As far as cranking for 45 seconds, I haven't had that experience since I'm running a electric fuel pump.

The idea is that the supercap supplies the rather large surge load of the starter, but the battery keeps it going. Battery longevity should be improved by several years, the supercap itself will be good for the next 30 years or longer. The added benefit as well will be running an electric fan with a ~70A surge load. Usually a controller is required in order to not harm the electrical system from large sudden loads being applied; it is no longer an issue in this case because discharge comes from the supercap.

I see your point, and it is the main reason I am not running the supercap by itself. I will test starting the vehicle off just the cap to see if it works for backyard science. It is also possible to run a much smaller battery, such as a UPS or fire alarm battery, in parallel to keep the supercap charged. Lots of different ways to go about running one, it'll be interesting to see what comes about.
 
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