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]

My car still has normal light bulbs in all the gauges including the generator light. The generator light appears to act normally. Turn the key, and the generator lamp lights up until you start the car. When I first start it up, I get a small glow until I blip the throttle and get the revs up, and the light disappears. After a few minutes warming up on the hand throttle, upon release of the hand throttle and idling at about 700-800 rpm, you don't see the generator light.

The engine is your standard MFI with the CDI box arrangement.

When I had my issue, I had the headlights on, brakes on and wipers on plus the engine of course.

I'll pick up one of the current clamps that you mentioned here in the next day or so, and report back on what I find. Is it easy to measure DC current? Or are we measuring AC current? Thought most everything on the car was DC.

[Superhawk996]

My car still has normal light bulbs in all the gauges including the generator light. The generator light appears to act normally. Turn the key, and the generator lamp lights up until you start the car. When I first start it up, I get a small glow until I blip the throttle and get the revs up, and the light disappears. After a few minutes warming up on the hand throttle, upon release of the hand throttle and idling at about 700-800 rpm, you don't see the generator light.

The engine is your standard MFI with the CDI box arrangement.

When I had my issue, I had the headlights on, brakes on and wipers on plus the engine of course.

I'll pick up one of the current clamps that you mentioned here in the next day or so, and report back on what I find. Is it easy to measure DC current? Or are we measuring AC current? Thought most everything on the car was DC.

Glad to hear the Generator bulb is still incandescent. That takes one variable out of the loop. Seems to be working properly.

Don't underestimate a CDI current draw. Quick info I can find seems on Summit Racing site for a Mallory CDI indicate about 0.7 to 0.9A/1000 rev's. So at a 3000 RPM cruise, that is 2.7A just from that device alone.

We are measuring DC current.

With a current clamp it is super easy non invasive measurement.

Just place the clamp around the red wire that leads from the alternator to the B+ source (actually starter motor terminal IIRC) to see what the alternator is doing on its own (is it sourcing current to the battery, how much current, etc).

Likewise, if you want to see the net inflow/outflow of the battery, you can put the clamp around the large (like 4AWG gauge) red battery wire. This is where you would be able to see what your actual electrical loads are that the battery is sourcing current to.

There are hall effect AC/DC current clamps that can read both AC and DC current. The super cheap ones (like $30) usually are AC only - you don't want one of those. However, I think last I looked, you could find one that measure AC & DC for about $80.

Just be sure that it has something on the order of a 0-6A or 0-10A low range for DC current. Be sure to look at specs on low end units. Sometimes the range is 0-60A; depneding on the accuracy, something on the order of 6A load might very well be +/- a couple of amps which might make it difficult to see what is going on. Could definately tell current direction (charging or not charging) but it might be hard to see if the Li-ion BMS is throttling current by a couple amps.