Lithium-ion 12v Battery Replacement

[redpoint5]

When I saw the Saran plastic on the supercaps, I was going to comment that they need better protection because a short would be spectacular. That pink foamular board is what I've made into a capacitor box.

Perhaps smaller gauge wire serves the purpose of acting as a fuse since it disintegrates rather than continue to weld parts together. I accidentally shorted an aluminum bus bar and it melted a chunk out of it instantly.

[teoman]

My friend in iowa has received the caps.

I should get them in a week or teo.

[IamIan]

Originally Posted by Stubby79

Any reasonable option(s) to keep the li-ion warm

Originally Posted by Ecky

So, for 4+ months of the year I'd need either a battery heater, or to disable the alternator until the battery has warmed up.

I've been playing some with the Panasonic's U-Vacua Vacuum Insulated Panels (VIPs).
R45 insulation in only 15mm thick.
R66 Insulation in only 24mm thick.

DigiKey is a distributor for Panasonic so you can get them from them.
Not all that expensive for the amount of insulation R value they offer.

With that much thermal insulation effect .. you could vastly reduce the amount of energy needed to keep them warm .. even in 0F outside temps.

Originally Posted by Ecky

Any recommendations on a 12v warmer with a thermostat? So far the only systems I've found are 120v.

What about PTC based heating element.
They self regulate around the temperature point.
Can design resistance around whatever voltage you want.

[TexasCotton]

Okay
I have been considering using the battery space LifeMnP04 prismatic 12.8V 20ah 256wh 10c rate in my 08 Gen 2 Prius.
Winter time use could be problematic even though limited colder days in north Texas

[teoman]

Over heating may also be a concern.

[Ecky]

Update on my old ~66F (400/6) cap pack:




Left it sitting in a cabinet for some weeks. After throwing it on a charger, the lowest cap was at 2.10v and the highest was at 2.60v. They definitely have problems with drifting, and probably need a more aggressive balancing circuit.

[teoman]

How is the balancing on the 3000f pack from china?

[redpoint5]

Yeah, the need for balancing sounds like problems caused by cheap junk caps that aren't spec'd well.

[RedDevil]

I think half a Volt drop in some weeks isn't too bad actually. Lead acid batteries don't fare much better when stored for long. But they do need some kind of balancing.

[Ecky]

Originally Posted by redpoint5

Yeah, the need for balancing sounds like problems caused by cheap junk caps that aren't spec'd well.

Well we can either rule out AVX caps then, or we'll need to buy more than we need and test them all.

Originally Posted by RedDevil

I think half a Volt drop in some weeks isn't too bad actually. Lead acid batteries don't fare much better when stored for long. But they do need some kind of balancing.

The issue with the caps is that if they get out of balance enough to overcharge one, it fails catastrophically, turning into a short. The other cells will then overcharge too and fail in a cascade, and if there isn't a fuse or a breaker you'll have a fire.

I'm coming around to the idea of LTO cells being the easiest/safest option. I really like my capacitors but I can't say I'd recommend caps to someone who isn't prepared for some risk.