[krisr]

Originally Posted by Half-Inch Stud

If i could modify the old GM Alternator's internal Voltage Regulator to match the Li-Ion Battery, i would:

Buy the Li-Ion, and keep the Lead-acid on a trickle-charge, with a power select switch for use in Winter temps.

What do you mean match the Lithium battery? Like in a newer model car?

[dataway]

Typically the LiFePO4 batteries take the same charge voltage as lead acid. I put one in my 22 year old motorcycle and the charging voltage is right in line with what the Li battery manufacturers want. Plus the onboard battery management would handle any over-charge situation.

As for low temps, not really an issue for most people. If you live somewhere where average temps are lower than maybe 20 degrees, and you park outside ... you might have to turn the headlights on for a minute or so before starting to warm up the battery.

In my case I bought one with no output current limiter, technically made for snowmobiles .. but I wanted no output limiter because the bike is such a beast to start.

[Half-Inch Stud]

Originally Posted by krisr

What do you mean match the Lithium battery? Like in a newer model car?

Lead-acid gets 14.4 V for maximum charge voltage at room temp, and scales vs wild temperature.

Li-Ipn is locked in multiples of 3.7V for proper charge rate (a tight scale exist from 3.9 to 3.65v if you know what you are doingk).

4 Li-ion Cells in series x 3.7 = 14.8 V for Proper charge voltage. Imagine only 4 series cells, so a few in parallel for reliable current draw. I believe Li-ion celles need a very narrow temperature range to be reliable. Too cold and they play dead or are dead. Too hot and any dirty chemistry activates.

Lithium tech has variations, so i could be wrongk, yet i doubt it until spcifics are shown.

[krisr]

I think you should talk with a manufacturer of a LiFEPO4 battery before anything.

[track73]

Thanks for the replies. I went back to the Autozone 800 CCA like I had before.

[ZeGermanHam]

For the sake of discussion, a number of race cars at the shop where I store and work on my GTO have lithium ion car batteries. The shop staff really dislike dealing with them because they are easier to permanently kill if there is a power draw that fully depletes the battery, and they cost a boat load to replace. They accidentally killed one in a highly modified Porsche and had to buy the owner a replacement to the tune of over a thousand bucks. No thanks. For a street car, I'll find other ways to save weight.

[dataway]

Any decent LiFePo battery has discharge protection in the battery manager, so basically impossible to discharge them enough to damage the battery. There are a lot of them out there now, not all of them are protected, lots of Chinese garbage too.

The brand I bought has LiFePo batteries that are FAA approved for aircraft, I'm guessing the requirements are pretty tough.

While the cold weather behavior is exaggerated a bit ... I don't think I'd put one in my truck in my climate where we can see below zero temps.

Charging range for LiFePo batteries is typically 13.8 - 14.6, they don't like more, they don't like less ... most vehicles before 1986 don't control voltage tight enough, so they would have to be updated to use one.