How To: Alternator delete

[Daox]

Haha, nice catch.

[redpoint5]

I'm contemplating 4 of these. $200 only buys 40Ah of LiFePO4, but at least I can go to 80% depth of discharge safely.

What depth of discharge would you be willing to go to on your deep cycle battery?

[Daox]

I'm leaning toward just getting the 80Ah group 24 battery. It'll give me my ~1hr of run time without abuse which is still more than I need for nearly all my driving. Mostly I want that because it'll drop right in, and I have a nice 5A onboard charger for it already.

The other options are all superior function wise, but cost a fair amount more and will require additional modification.

I'd be willing to go with over 50% dod with lead, but not often at all.

[oil pan 4]

Do not use a LiFePO4 battery up north unless you plan on removing it from the vehicle when its cold out.
I have LiFePO4 cold issues and I am in new mexico.

[Daox]

Issues being what?

We have a bunch of guys running around in LiFePo4 EVs here, no issues.

[oil pan 4]

I have cold cranking power loss anytime they get much below freezing and the fact that charging them when the battery its self is at temperatures of 5'F and below can permanent damage to them in the form of lost capacity.
If you are talking about using a LiFePO4 battery of at least 80 amp hours to start a 3 cylinder engine then it might not ever be a problem. I don't believe I have read anything saying cold discharging permanently hurts them.
When it gets much below freezing my 67 amp hour LiFePO4 battery has difficulty starting my diesel, but that's 395 cubic inch, 22:1 compression V8 with a gear reduction starter.
But the way power output from these batteries drops off when cold I wouldn't be surprised if it could get cold enough in WI to where an 80 amp hour battery couldn't start a metro.

Do these electric vehicles have temperature regulated batteries?

[Daox]

I doubt they do. But I could be wrong. I also don't know if the owners baby them, or they're kept in a warm garage, etc.

One more reason to stick with lead.

[oil pan 4]

Oh, I thought I had read that the leaf used actively pumped liquid to cool the batteries during summer. Then figured it was reasonable that the pump coolant could also be warmed for winter time use.
But I have learned, just because that is how I would do it does not mean the OEMs will do it.

[redpoint5]

I have read that LiFEpo4 is safe to discharge down to about 0 F, but should not be charged at any significant rate if below 32 F.

The way I see it, LiFePO4 will work in my alt delete because I garage my car, where it would be safe to charge. Also, on a longer trip where I need to turn the alternator on to charge the battery, heat from the engine would keep temps above freezing.

[Xist]

Originally Posted by oil pan 4

But I have learned, just because that is how I would do it does not mean the OEMs will do it.

Aerodynamic cars, properly-geared manual transmissions, smooth wheels, smooth bellies, auto-stop, what else would we do differently?