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Playing with Supercapacitors - Truck Battery Replacement

dalmatiangirl61

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Last Subscription Date
07/10/2019
The 1000F cap bank is finished and ready for testing, slightly smaller than an 8D battery at 17.25" long x 8" wide x 8.25" tall (not including terminals), and instead of 130 lbs, its only 20 lbs. Terminal strips are 3/4" copper tubing hammered flat and doubled up, anti-oxident/dielectric grease applied between copper strips and at copper/aluminum interface. 1" insulation board was used to wrap it, not for temp insulation, but more for shock, and to get terminals where they would not contact surfaces. Wrap is gorilla tape, whole roll. The squeaky ball in pics is courtesy of satan's little helper, aka crazy dog:D
 

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cornbinder89

Registered
Please let us know how it works!
When I was younger and dumber that I am even now, I would stack two 8D's and carry them on a Bus. I think I might be able to manage you Cap's today!
 

dalmatiangirl61

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Last Subscription Date
07/10/2019
Got around to pulling batteries out of Dmax today, started it yesterday with a jump from Toyota, pulled it down by door and hooked it to batt charger overnight, this morning would not start (cranking too slow). With topped up batteries, even on a cold day (0F or above), it will start in 1-2 seconds so long as it spins fast enough. These are side mount terminals, looking at face of these terminals, they could definitely use a cleaning. Both batts read 13.5v when removed from truck at about 30 degrees F, when connected to charger both pull 3 amps (6amp charger) for a few seconds then it quickly tapers down to 1 amp. Both are in kitchen now warming, not sure if that will change charge rate, may have to drag both to town for a load test.

Ideally I would like to leave side mount battery connectors on truck, not that I like them, but if cap bank dies, sell truck etc, a battery can go back in that spot easily/quickly. I was hoping to use the original stud mounts on the cap bank, but that might not work. I'm trying to figure out some way to make a terminal on flat stock that the side mount connectors can attach to. Any ideas? I can do 2 flat terminals sticking out top like the last bank, but with both terminals at same end of the bank.

DKamp
You might have been right about cables, but I'm still going to play with the caps:p.
 
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Vanman

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Last Subscription Date
07/10/2019
However you decide to connect it, I’d bet she cranks right up with the cap and one of those weak batteries.
 

dalmatiangirl61

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Last Subscription Date
07/10/2019
Borrowed neighbors "smart" charger, it says both batts are at 100%, but one is 13v, other 12.5v , I don't trust these. Since smart charger senses batt is full, it won't even try to charge. I will alternate chargers tonight then run them to napa for a load test tomorrow.
 

Warwagon

Registered
Interesting experiment.

Some top post to GM side post battery adapters at a local parts house may allow you to wire in your cap box quickly...

As others have noted: The green cables are making one battery work harder starting the truck and then preventing the other battery (or both) from charging properly. The low charge battery then discharges the other battery when the engines is off killing both batteries by sulfation. No matter what you do the green cables need to be replaced. They will screw with your cap experiment as well. GM puts you behind the 8 ball and assumes the cables are good with their lower voltage S L O W charging system of ~13.5V. Other OEM's use a temp compensated system that will hit the batteries with 15V - but bad cables will overcharge fry the batteries on that system.

Looks like you have one weak battery already. Before you go crazy trying to save $300-600 in new batteries... Do you have AAA or other ways to get your truck towed cheaply if it doesn't start? It may not start for many reasons and having the option to get a tow may save you from burning out a starter on "hope it will start" when it simply won't without repair(s).

GM side connectors are horrible. Even GM is getting away from them. Use top post connectors that have better contact and let you see the corrosion on them "need service indicator". Build your own cables or truckstop / CAT dealer may have the tools to crimp what you need on cables. GM skimps on cable thickness to save a penny so thicker cables to the starter also help cranking speed. AGM batteries are better for battery cable life as they don't constantly puke acid everywhere when charging. In hot weather AGM life isn't much better esp. with diesel starting depth of discharge. Cool weather they last very well.

FWIW: The Dmax design, depending on model year, for battery placement up near the firewall actually overheats the passenger side battery from hot air coming off the engine fan and it nearly always fails first. More or less heat damage (esp. from summer operation in high/extreme heat areas like Texas) to the battery showing up as bad battery in winter when that battery is it's weakest and "cold" cranking needs are the largest. The bad passenger side battery then drags down the driver side battery. In the heat of AZ it's a known known you are pushing your luck on any battery over 2 years old: extreme heat sucks the life out of batteries.

Most people throw away the acid soaked battery insulator blankets and never replace them. It helps keep the batteries both cool from extreme underhood engine heat and warm in cold weather. They are like $7 each from a dealer and available online including as a generic battery blanket. They can help battery life esp. if you add a battery warmer instead of just a blanket (and engine oil pan heater).

You might get a couple of battery disconnects to keep parasitic draw from draining the batteries during the week long sitting times. An alternative is a single solar panel 20W or larger with a charge controller.

Are you using fresh 5W-40 synthetic oil for winter starting? (Oil run all summer is soot thickened.) Are you short tripping in town on the diesel where it can't charge the batteries back up from glow plug and starter drain? (If so drop a charger on it frequentaly.) Can you drag an extension cord out for the block heater 2 hours before going somewhere? In fact can you charge the batteries 2x weekly when sitting?
 
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Vanman

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07/10/2019
This is all good stuff, and I agree that the cables and connections should all be ultimately brought up to snuff. But for the sake of a controlled experiment, I’m really curious how the cap will do in place of one battery, with everything else the same. I’d bet that the improvement is substantial.

Keith
 

dalmatiangirl61

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Last Subscription Date
07/10/2019
Yes thinking of just replacing cables, but need to get to warmer temps to do that job, just pulling the batts yesterday had my fingers numb. Currently warming up a bottle of coke to dip connectors into, with all the plastic on them I cannot think of a better way, short of cutting the plastic off. I do not think there is enough clearance to hood for top post batteries, unless shorter ones were used. Yes last few months truck has only run to town and back, might be part of problem. Watched a few mechanic vids on YT last night dealing with parasitic loads on GM trucks, apparently its a common problem and most likely cause is instrument cluster, need to do some testing to figure out if that is part of my problem.

Cornbinder
Any chance you had the opportunity to see what is going on with second positive terminal on your Maxwell cap bank? Wondering if its just a diode so cap can accept power from main batteries, yet not feed back into that part of system. If so it would be easy enough to add a diode when re-doing battery cables so cap bank only feeds starter.
 
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cornbinder89

Registered
Maxwell inside.jpgNo, that is the feed from the trucks battery to the charging board, all power to the cap's goes thru the board, which charges each cap individually, uses a invertor to raise the voltage, so even if the battery voltage is only 12.6 the cap's will charge to 14-15 volts. This is pic of the guts I ripped from the .net, the charging board sits down the recess and you can see the individual wires to the caps were cut off. I can't tell if they charge in groups of two or 4, if 4 it is two in parrelle and those two in series with another two.
 
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cornbinder89

Registered
Here is a pic of it in the truck, Yeah, I know it needs a good cleaning! The light 4ga wires to the battery and the 8 ga to Maxwell ESM are the charging wires. The Truck batteries never see more than a 75 amp load, so that is why I can get away with 4 ga.
000 and 00 ga are the starter cables, disregard the red ground, it was what was on the truck, has black + and red - go figure!
 

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dalmatiangirl61

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07/10/2019
Looks like what I started with, including the wires that had been cut. Did not see anything in data sheet for voltage to the balancing board on these, stuck the complete one back on shelf for another day.

According to some of the YT videos I watched these cap banks are becoming fairly common and are used in many hybrid cars, and even some of the non-hybrids that for fuel saving kill engine when car is stopped, that is how they can stop/start so often without killing the battery. Couple years ago I pulled a battery from a Prius (have not played with it yet), in getting to the main battery I found a small battery in right rear quarter panel, I remember pulling it, but did not keep it. If I remember correctly, after pulling it I was surprised it weighed so little, it was well beyond expiration date, thinking it was just a plain battery I left it. So if you have access to a modern junk yard, watch for the light batteries;)

Edit: From the Maxwell site https://www.maxwell.com/solutions/transportation/auto/start-stop-micro-hybrid
 
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dkamp

eMail NOT Working
I rescued a hybrid Prius last year, it'd been parked in the garage of the mother of a close friend. His mother was stricken rather hard with Alzheimer's, they had to yank her license, and move her into memory care... so the Prius sat for well over a year, and yes, ALL the batteries were dead, dead, dead. I got the job of figuring out how to get it charged up and started, which involved getting INTO the car, then opening up the truck, and charging the small battery. That little one is used for holding up the computer AND... is just enough, with a little booster, to crank the engine.... which is exactly what I had to do to bring it into the world of the living. The console indication was that the main battery was totally flat, and apparently there was a third battery in the vehicle somewhere, but I never went looking for it... I got it started, drove it around the block twenty times, then out on the interstate, fueled it (with the engine running), then my buddy drove it 180 miles to his place to clean it up and put it up for sale. At first, it seemed like the batteries all survived, but the big battery apparently didn't bode well with the full discharge, as it failed after about a month in the proud-new-owner's hands, replacement cost exceeded the value of the car, so it got bought back, and sold for scrap. (sigh). So much for being 'environmentally friendly'...
 

dalmatiangirl61

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Last Subscription Date
07/10/2019
Second cap bank is ready, I was a bit disappointed it came out with posts 1/4" taller than a regular battery, then it occurred to me that I could just flip it on its side, duh!

Left both batteries on charger for 24 hours, then used a resistive load tester, under load both were right on line between good and bad, but that was at 70 degrees F.
 

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cornbinder89

Registered
Dal,
I've been thinking about your set-up and see a potential problem. You are using 1/2 the cap's I am and on an engine that has glow plugs, I worry that the glow plug load will draw the charge down to far for the cap to crank the engine. On my set-up it would be no problem because the board isolates the cap's from the other loads, only using the caps to crank. You may or may not be able to crank with the cap's alone, but I worry the glow plugs will be too much of a draw.
You can't use a diode to isolate the cap's because when they are discharged it is almost a dead short and will burn any diode, and you also have a voltage drop across them, I would suggest if it is a problem, using a NC contactor to separate the battery from the caps, use a relay to control the contactor and have it open the connection whenever the glow plugs are activated. In other words, it would be parralled to the battery with the key off or the engine running, but the connection would be opened when the glowplugs are energized. That way the battery alone will carry the glow plug load.
It may not be an issue, but it may. Something to think about.
 

dalmatiangirl61

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Last Subscription Date
07/10/2019
First problem with using sidepost cables on anything other than a sidepost battery is the bolts are too short, razor blade fixed that, note the corrosion. The second problem is the recessed section of the cable, dug thru the electronics teardown bucket and found a short piece of buss bar with a 3/8" hole drilled in each end, cut the ends off, stacked and turned in lathe to make thick washers to fit recess.

Did some trial fitting yesterday, I'm not happy with it, cap bank needs to be reduced by 1" in length, it is maybe 1/2" longer than the battery. Second issue is cables, both are stiff as a dead cat, and no matter how I try to route them, they want to rub against an engine part. Between those factors and my concerns about frying ECU or burning out glow plugs, I think I'm going to hold off on installing the cap bank till warmer weather when I can rewire it direct to starter.

Cleaned cable connectors, including bolts, re-installed both batteries, have to admit, starter has not spun that well in awhile, Dave gets a Gold Star:)

I see Cornbinder89 has posted since I started typing.

So I'm trying to figure out how to wire this, I want supercap bank to just feed starter, but it has to charge from battery, and ideally not be able to flow power back to battery. I was thinking diodes, but maybe that won't work (see post above). In researching supercaps it seems you are not supposed to charge these too fast (too many amps), they can take it to a point, but its not good for them. For an initial charge from 0v one mfr (xs energy) supplies a light bulb with leads, I do not know wattage. Instructions are to use a plain (not smart) battery charger, connect negative lead from charger to neg terminal, connect positive lead from charger to one end of light bulb lead, other light bulb lead goes to positive terminal. This charges cap bank at about 2 amps. The light bulb burns until capbank is charged, it acts as a buffer/resistor?, when cap bank is fully charged bulb goes out as there is no more electron flow. So would a resistor work and do the same thing?
 

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cornbinder89

Registered
MY Maxwell ESM charges between 5-15 amps, which sounds like what they are trying to do with the lightbulb. I run Delco 25SI alternators and they use the side terminal type connection but it has a 7/16 bolt! so either you have to find the correct alternator connector or drill (ream) out a normal side terminal to accept a 7/16 bolt. Not one of GM's better ideas. IMHO.
If you connect only the cap's to the starter solenoid "batt" terminal, you can have them do the cranking, but most vehicles use that stud to make a whole bunch of connections, so they would have to be moved elsewhere. Use the battery to "pull in" the solenoid but only the caps connected to the motor.
 

Vanman

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Last Subscription Date
07/10/2019
You guys are over complicating this.

Caps only supply current while their voltage is decreasing. But are very efficient at supplying short term, high demand loads. Like cranking an engine.

Batteries only (practically speaking) deliver current after their voltage has reduced some (due to load). They’re most efficient at supplying smaller load for longer periods. Like glow plugs.

Cap simply in parallel with the battery and you instantly have the best of both in one circuit. No controls of any kind are necessary. Battery supplies glow plugs, because that load doesn’t drop the voltage much. Cap mostly supplies the starter, and the battery helps as the cap (and thus battery) voltage decreases.

When the engine starts, both are recharged. Automotive AC generators are inherently current limited, so there can be no dangerous current while the cap charges. After several seconds, the cap and battery will be back up to normal charging voltage.

But you DO NEED a means of preventing the caps from going too far out of balance with each other. And LED of the correct voltage across each one should be sufficient.

Keith
 
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