Supercapacitor Battery Replacement

[Shepherd777]

Not as cool as the DIY setups, but my new big truck has the Maxwell ESM unit for starting the big 15L Cummins diesel.

[teoman]

That looks impressive!

[Nautilus]

The ideal setup should have 3 x LiFePO4 batteries for power storage and 1 x supercap starter pack for engine start. This way, the weight of the truck's battery pack drops from half-ton to about the weight of a luxury car battery and saved weight means more payload.

But not even a company like Maxwell can yet make a lithium battery immune to low temperatures.

[gumby79]

Originally Posted by Shepherd777

Not as cool as the DIY setups, but my new big truck has the Maxwell ESM unit for starting the big 15L Cummins diesel.

What battery configuration are you running ?1,2,3,battery+1, 2 maxwells? Or just the maxwell?
At 21lbs for the ESM ULTRA 31/1800cca and 16lbs for the ESM ULTRA 31/900cca its a big weight savings over 50+lbs for a standerd groop 31.
I called (left a masage)maxwell to find out if theas are suitable as a stand alone for my environment/ old tech vehicle or what size supplemental AGM would be needed to support sub 0f starting. The sub 0f temps make Lixxxx batteries unuseable for me . I'm trying to avoid dual groop31's , or stepping up to a d4 Cat battery the next size up

[Shepherd777]

Originally Posted by gumby79

What battery configuration are you running ?1,2,3,battery+1, 2 maxwells? Or just the maxwell?

At 21lbs for the ESM ULTRA 31/1800cca

Maxwell is a partner/sponsor of my company and our current project. We have the new Maxwell ESM Ultra at only 19 lbs. We use it only for starting the Cummins diesel. It is on an isolated circuit.

Odyssey Battery is also a partner/sponsor on the current project and the previous project. We have four 12 volt 200 amp hour Odyssey AGM batteries wired in series for a 48 volt battery bank.

Delco Remy is also a partner of the current project and the previous project. We charge the Odyssey's from the world's first 48 volt Delco Remy alternator and our 5000 watt solar farm on the roof of the 53' trailer. There is a second electrical umbilical from the trailer to the tractor so the solar farm can charge the Odyssey tractor-mounted batteries.

The 48 volt battery bank powers the dual 48 volt A/C compressors with their native voltage. We have two separate and independent all-electric A/C systems. It also powers our 48 volt to 120 volt 6000 watt inverter for hotel loads and appliances inside of the cab. And finally, we have a very high quality 250 amp, 48 volt to 12 volt DC to DC converter for all 12 volt truck loads.

I had initially bought four very expensive ($8000) 24 volt Li-Ion batteries, but charging them from our sources proved to be an overwhelming challenge. So they are being returned this week.

[gumby79]

Nice. 48v is a much more efficient form factor. Are you going to do a refer variant off the 5k as well? So that the refer would recharge the battery pack, when the cells are under preforming due to shadows or inclement weather. The refer would only have to start maby hafe as often or less as the rest of the time would be running off battery/ solar

How well would one of theas handle 200A grid intake heater on the 12v side and start on the 16v start side, or a groop 31 + there group 31 cap? How small of a battery FLA AGM LiFe PO4 with a temperature sensitive BMS (only charge when the battery is upto temp)?

[Nautilus]

PS Had the starter motor professionally overhauled: new brush set, cleaning, lubrication. Plus brass fasteners on the electric connections, to prevent oxidation and get better conductivity (3x that of carbon steel).

Amp draw decreased and is now 100% reliable.

Also got an overhaul of the front axle, and eccentric bushings fit for better caster, about +0.5 degrees. More positive caster increases front axle stability at the cost of heavier steering. This brings back the slightly heavy steering the car had from factory (at slow speeds) as the steering rack had been designed to give the easiest steering at motorway speeds. Had the wheel tracking done as well, to bring the toe-in to factory setting (nearly parallel).

Starter motor has a planetary-type reductor gear inside, to allow good starting torque in a small package. This way it can be made very small, the motor itself is close in size to the solenoid and the full assembly weighs 7 lbs, yet reliable.

[redpoint5]

Originally Posted by gumby79

How well would one of theas handle 200A grid intake heater on the 12v side and start on the 16v start side, or a groop 31 + there group 31 cap? How small of a battery FLA AGM LiFe PO4 with a temperature sensitive BMS (only charge when the battery is upto temp)?

I don't have specific answers to your questions, but from my experience, Supercaps are super bad at handling both the grid heating, and immediately after, starting my 5.9L Cummins engine.

It all depends on how long the grid heaters have to run, how many farads of capacity you have, and how much of that capacity is needed to start the engine.

That said, an undersized lead-acid battery in parallel with supercaps should work in many applications. I'd let the supercap charge up for a few seconds after the grid heaters turn off, which should then provide enough oomph to start the engine.

On my truck, 5-series 3400 farad capacitors alone are able to start the engine, provided I don't run the grid heaters at all, and haven't let cabin lights, or other electrical draws run them down too much.

[Nautilus]

Conclusion after 9 months: some cold water poured over the initial enthusiasm. The AGM battery did not withstand the test of time.

Supercaps did always fire the needed amps to start the engine in cold weather. But the AGM battery slowly lost the ability to hold a charge, and usually did not replenish them on time in hot weather. It lacked enough reserve capacity for this. 12Ah were not enough.

The alternator could give 120 amps instantly when needed. Alternators can give 70% of their rated amps in continuous use, that is 84 amps. At 2000 rpm, where alternators are most efficient.

Fuel pump drew 3-4A, ignition coils up to 30A at maximum rpm, radiator fans 15-17A on first speed and up to 35A on maximum speed, dash fan maybe 10A. That means a continuous draw over 60A when crawling in traffic and up to 79A with fans on maximum speed and dash fan running. Too little remained to replenish the battery and supercaps. So the battery slowly degraded in performance, day by day, and in the end it barely held any charge at all.

If the same supercaps were lashed to a bigger battery, in the 40-44Ah range, they worked just fine. But the 44Ah battery was enough to start the engine and hold a current reserve without any caps at all. So I've left the 44Ah battery alone. It still saves weight (10 kgs instead of the 16-18 kgs of the 60Ah factory battery).

For the supercap-battery combo to give satisfactory service over months or years, it needs either a stronger lead-acid battery, in the 30-40Ah range -to keep a current reserve- or a small LiFePO4 battery - to keep a current reserve by the fact it can use all its rated capacity, unlike lead.

I still have to try the same combo on my VW Bug, where there is no parasitic draw (no electronics) and the only electric consumers during normal running are a single ignition coil, an aftermarket electronic ignition and a radio. There is may give satisfactory performance and still save over 10 kgs.

[ME_Andy]

Thanks for trying it out for the rest of us