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I upgraded my alternator to a 100 amp from PI Motorsports. If my connections are all good am I still able to run my factory amp gauge or do I need to upgrade? I already know that when the wires are not secured properly they can be fire hazards, but if done properly can the stock gauge handle an upgraded alt?

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let me just make a comment...
the amp gauge only shows the current in and out of the battery (excluding starter current).
So if you are running 100 amps worth of lights, radio etc that does not go through the gauge (IF the altenator is working)

I have been thinking similair, but more towards a "smaller" span gauge since battery charging is normally less than 20 amps. (and Limiting current draw prior to running)


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Last edited by jfb05177
Basically the Amp Meter is a useless Instrument that only tells you how much the Alternator is loaded. Wether it is charging your Battery only or supplying current to other stuff also makes no difference. The Amp Meter is blind and can not see where the current is going, but it will show the full load. Apart from that it is compromising your safety by being a potential risk of causing a fire!

I always recommend to get a Volt Meter which is a much more useful Instrument. It tells you the condition of your electrical system. Just join the 2 connectors from the Amp Meter by attaching both of them to the + on a Volt Meter.

As suggested if you use a Shunt as a Jumper between the 2 connectors the only thing that will happen is that your Amp Meter becomes even more useless as it now stops showing the load on the Alternator too.

Btw to answer your question the OE Amp Meter will probably be able to handle your upgraded Alternator on a normal day. Just be aware that because of your upgrade the Alternator has the ability of a much higher output and it can potentially send 100 Amp through the Amp Meter under certain circumstances i.e. if you Battery was completely drained and you switch a lot of stuff on. That could become an issue!
Otis, if you really ARE using 100 full amps of current from an upgraded alternator, it may be that you will need a dual-belt drive to handle the load without slippage. On some Panteras, dual-sheave vee-belt pulleys may cause clearance rubbing on the steel access door, as might a gilmer-belt or serpentine conversion drive. And on such aftermarket pulleys, be careful. Some are machined from cheap cast aluminum rather than much stronger 6061-t6. Cast conversion pulleys are known to have broken in half on the highway, leaving the driver stranded. This is for both Panteras and Mangustas.
I shouldn't ever be using the full 100 amps. I don't have a large stereo and my A/C would rarely ever be on when I have my upgraded quad headlights on. I simply upgraded the alt when mine was not working and I found the upgraded PI one that is in a stock case with a stock pulley. I just thought I would check if the stock AMP gauge could handle it since I have found another one (I did have one burn up before). I am currently using a 100amp internally shunted Stewart Warner, but would like to go back to a stock looking one. I do have an old Veglia volt gauge but it doesn't match well enough for my taste. I have thought of either buying the stock appearing Volt gauge from Hall or have my stock AMP gauge upgraded internally from a gauge company.
Originally posted by goodroc:
hmmmm, now I had to rewind my memory back 3 Years and yes I did in fact I did combine the 2 Connectors but I took the Source for the Volt Meter from a Switched + on the Harness..... Sorry about this confusion (mine)

I too installed a volt meter that was a close match to the Veglia gauges. The two connectors were joined on a small bolt with nut and jam nut. Be sure to insulate well the nuts and bolt. You do not want a piece of electrical tape to fall off from the heat and expose the connection. Grab a switched 12 volt wire and splice to the volt meter. DO NOT use the connections from the AMP meter.

JB05177- Thank you so much for the simplified ampmeter electrical drawing posted above. I am in the middle of the last of extensive rewiring upgrades to 6997 and have had a few commissioning isolation gremlins - I think this simplified diagram has pointed me in the right direction to sort one of them out. Most appreciated.

Note to self - don't take a fully disassembled wiring harness , perform every upgrade known to man or beast and expect it to work first time .....!

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