What's your volt meter reading when cruising around town? Options

[raynekat]

Just curious what the typical volt meter reading is:

1) when you're sitting at the stoplight

2) cruising down the boulevard at 3-4000 rpm

Trying to see if I'm seeing typical or low readings
Thanks

I just recently noted a low charging issue that I believe came down to an alternator/voltage regulator mismatch.
I was using a Bosch VR with my Motorola alternator.
Now I've switched to a Marchal VR and the charging voltages look better.
About 13.75 volts while cruising.

[raynekat]

Superhawk....I think you were dead on about that Lithium Ion battery not being "big" enough.
It just doesn't have the reserve to keep up with the electrical usage on the car.
This is what I measured on one of the big cables coming off the positive terminal on the battery.
The values you see listed below is the total reading I read off the clamp meter....not what each additional component added to the total (i.e. engine running with running lights on was 6.6A....the running lights alone were something close to 3A).

At idle (baseline): 3.6A

Add running lights: 6.6A (only about 3A added, Spoke's LEDs in rear, normal in front, with LED side marker bulbs)

Add headlights: 9.2A (guess the 914Rubber LED headlights are fairly energy efficient...added 2.6A)

Add front fog light: 16.1A (these are normal bulbs...about 7A)

Add rear fog light: 18.2A (again a normal bulb.....only about 2A added)

Add wipers on low: ~25A (the meter was really jumping around with the wipers)

At idle with wipers only: 8-10A (about 6A added)

So the 30 Amp-hr rating on the Lithium-Ion battery is not enough to keep up with all these loads turned on at the same time. I didn't even try adding the defroster fan or higher wiper speeds as the car (or built-in circuitry of the battery) turned itself off pretty quickly after I added the wipers and got the load up in the 25A range.

Luckily the battery always keeps a reserve allowing a couple of restarts after it shuts itself off. So the battery operated as advertised it seems.

Takeaway..... This battery is OK for race cars (autocrossing) and driving around town during the day in nice weather. Which is what I will likely only be doing. Any nighttime or distance driving and I'd want a different battery. I'll definitely be thinking about moving up to a 50-70 Amp-hr battery this Spring at any rate.