I used one of these (from Autozone) for a while. Couple observations: The plug-in volt meter was not accurate, especially when hot (e.g. parked in sun) when it would read almost one volt high. Second, the voltage at the lighter will be low because of the IR drop through the fuses, wires, and ignition switch. The fact that the headlights don't greatly effect tour reading indicates you are seeing IR drop, mostly.
So it's a slick, EZ to use tool that worked OK when cool and with minimal load on the circuits. If you are concerned, recommend you run some temp wires from a voltmeter inside the cabin direct to the battery. Then check it under various conditions. The recommendation to get a new brush-regulator is a good one. The new ones put out a bit more voltage for the new batteries. Even better (and more costly) bet a Bosch reman from Rusty. They are as good as new. Scott Ritchey 82 300SD 70 300TD -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Levi Smith Sent: Thursday, June 21, 2007 11:51 To: Mercedes Discussion List Subject: [MBZ] Voltage Just curious if anyone else has taken much look at their voltages. I picked up a cigarette lighter voltage meter at Wal-mart for like $15 that I'm intending to use in some solar tinkering, but I decided to leave it in my 83' 300D while it's not doing anything else. This has proved interesting. Now, first off I don't know what's suppose to be in the car. The dual-belt alternator that was in the car when I got it died a few weeks ago, but the car came with a working (wasn't sure till I got it on the car) used alternator that I believe said 55amp Bosch on it, but it was a single pulley until I figured out the right combination of spacers and nuts and the pulley from the other one to get it to use that dual pulley. I also checked it's readings compared to a volt meter on the battery and it seems to average around .2V less than the battery is seeing. But what I've seen is that basically with nothing on (except a fuel pump) I think it might make it to 14v given enough time. It stays near that level with the radio on (though I can definitely see it kick on and I should note that it has some crappy amp the PO left in there drawing power). The gauge reads to hundredths of a volt so I can see it when I turn the fuel pump or basically anything on. Turning headlights on is usually ok an keeps it above 13.2V usually. (and I'm basing most of these while running, not at idle) The big sucker is the blower and worse yet with AC on. Basically, it just can't keep up. If I have max AC on and I'm cruising the highway I can probably hold around 12.8V. If it actually gets things to a semi-cool state and the fan slows a bit I can clear 13V. Now, with headlights and AC on? That's like 12V. Now, come to idle with those on? You're dropping into the 11V range for sure. So, I guess my question is, is this normal for an old alternator on an old car? To my knowledge, your voltage is *supposed* to be at least 13.2V. I'm wondering if that actually occurs with a new/rebuilt alternator, or if these old beasts just don't quite keep up no matter what... Levi _______________________________________ http://www.okiebenz.com For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com _______________________________________ http://www.okiebenz.com For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
