Alternator Wiring gauges...

[Clague]

Is there any obvious problem with running an 8 gauge wire where there used to be a 10 ga. wire to/from my alternator to my solenoid?

[Ol'fogasaurus]

While I doubt it; how long is the run (http://www.nooutage.com/vdrop.htm)? VW didn't put protection in some places, if this is a hand wire job you might think about some additional protection.

Some additional info: http://www.the12volt.com/

Lee

[Clague]

the run is about five feet at most, from solenoid to 55 amp alternator on '78 transporter.

[Marc]

Alternator to solenoid should only be a few feet or so, but it's never electrically a problem to upsize the wire. A heavier wire will be less flexible but there should be no relative motion between those two points so again it's not an issue. A heavier wire is going to take more current to melt away, but there's normally not any protection provided for this leg anyway - and the fire isn't likely to be any worse if you smoke an 8GA than a 10GA

Just observe the usual precautions and make sure that there's good insulation protection wherever the wire passes through or is secured to any metal along the way.

[Ol'fogasaurus]

Thanks Marc, I was being overly cautious as at the time as I didn't know what he was wiring or if he was wiring from scratch. If he, like some do, and use a amp gauge (I am one of those as I know how to read and depend on one) then I recommend some protection for the long run up to or down from the gauge to the solenoid (personal preference here) the same as from the solenoid to the ignition switch or fuse box; VW was lacking in protection here as I remember. Some say a bussed volt gauge will do the same thing as an AMP gauge but so far I have not seen one at work.

Lee

[Marc]

Series ammeters are really passé anymore on rear-engine cars, just not worth the current drop and added liability of a potential major short. A voltmeter gives enough information for most folks and is trivial to connect - just one wire, which can be hooked up nearly anywhere.

If you simply must know the amps you can use a shunt-style ammeter (actually the gauge is a millivoltmeter, but displays in amps because they're proportional to the voltage drop across the low, calibrated resistance of the shunt); the best place for the shunt is in the B+ wire coming off of the positive battery post, that sees all the current in or out except for the starter motor's - then it just takes some light wires between shunt and gauge.
The digital kind are cheap; if you want analog you're looking at a larger expense - it takes a special kind of "zero-center" meter that'll deflect in either direction depending upon the polarity of the voltage drop on the shunt (to show both charge and discharge amps).

http://www.ebay.com/itm/DC-0-100A-Blue- ... 27b4ad616e
http://www.bluesea.com/products/8252/DC ... with_Shunt

[Ol'fogasaurus]

Thanks Marc but not wanting to take Clague's question in a different direction I will concede to a point and that is the rear charging and the front distribution... unprotected.

Lee

[Marc]

I agree totally, it's downright foolhardy to run massive B+ wires all the way up to the dash and back to install a series ammeter - if you did do something this ill-advised, some kind of fuse (better yet, circuit-breaker) should be inserted in the circuit close to the battery/alternator. A fusible link would offer protection too, but since they're basically nothing more than a length of too-small wire it'd be rather self-defeating to insert one in the circuit if you're concerned about designing an efficient charging system.

I think the original question was only concerned with wire gauge (size) not actual instrumentation, but now there's enough info here to cover any future search on either subject.

[fusername]

I thihnk they call them "remote shunt" current sensors, if you feel the need for one. you have a small shunt which goes in the big fat wire you want to measure the current of , then two small sensor wires go from the shunt to the guage to read the current in the wire, without actually passing all that current.

otherwise just put a current guage in the engine bay for diagnostic work, you don't really need it while driving IMHO. Also as far as wire goes, I always say on high current stuff use the biggest wire you can afford and have a good crimper for. 4guage wire is useless if your crimper will only do a good job on 8 guage.

[Ol'fogasaurus]

Buggy wise, the AMP gauge has come in handy during off-roading in the past. The showing of a full short or an intermittent short in the original wiring that came with my buggy got me back to camp in time to not burn the car to the ground (actually part of the problem was the ground ). When I have working gauges I am usually well aware of them... especially after a hard hit suspension wise. On my old cars when I was a kid they also came in handy and also my friends cars when trying to find problems with them. Amp gauges used to be in (almost) all cars prior to ~ '56.