Adding batteries for longer EOC

[Daox]

Originally Posted by NiHaoMike

Have you thought about making a charger with a wall wart power supply?

I guess I'm just missing why that would be of benefit to me?

[NiHaoMike]

Originally Posted by Daox

I guess I'm just missing why that would be of benefit to me?

So you can just plug it in to top off the batteries before every trip.

[Daox]

I suppose I could look into that. I know I got an extra one or two laying around. I'll have to check their output voltages.

[blueflame]

The extra battery weight will lower FE.

If the car caught fire insurance may not pay, even unrelated events or if someone hit you first.

I think during starting the cables will really warm as large starting current will come from across all batts (if they are in parallel)

I used to be a sparky but that was a long time ago.

Lower battery voltage during EOC isn't really a biggy.

In fact, mild discharging can benefit some older batteries....

I have some near 4 minute EOC's and my old battery has been okay.

As long as when you park for the night or day at work that the batts have been fully charged from the EOC, battery longevity should be fine.

[bwilson4web]

Originally Posted by blueflame

. . .
If the car caught fire insurance may not pay, even unrelated events or if someone hit you first. . . .

I once had to deal with an electrical short in an old car and the wire literally looked like a 'fuse.' A battery arc driven fire is not something you want to have without provisions to open the circuit quickly.

I would recommend putting a fuse in to protect the battery wire. It is easier to deal with a blown fuse than a runaway short.

Bob Wilson

[Daox]

Yes, a fuse would be a great idea should this be more permanent. The wires do not get warm at all when cranking, I checked to make sure. The three batteries share the load, so the amperage is divided by three. The wire, which is only 14 gauge is more than enough according to charts I've seen online that say 14 gauge is good for 32A. That means I can easily pump out 100A, and I'm sure more for shorter durations. The alternator can only supply 60A, so I'm more than safe there.

Blueflame, you are right about the voltage. I did some digging on battery voltages and found out that you can in fact go much lower than I had expected. ~10.5V seems to be the recommended lowest you should go with a battery under load. I've not even touched 11.0, so I will probably end up removing the extra batteries sooner than later. I'll be a bit more aggressive with my EOC next time I drive the car and see what happens.