Need help with charging

[andrewb_80]

I just finished switching my 94 v6 auto to a carb 302 5 speed. My new alternator is a 100 amp one wire chrome alternator from tuff stuff and it has an BBk underdrive pulley. When I did my swap I relocated the battery to the trunk. I was told that the one wire alternators really dont starting untill 2000 rpm, which seems to be the case. The battery also tested fine. I am having problems starting the car and when the car is at an idle, i am at very low volts around 8 i think. How do I go about fixing this? Thanks guys

 

[HISSIN50]

One wire alternators do require the higher RPM to get excited. So once you reach this threshold, your volts still are low, or they are low before you excite the alternator (blip the throttle)?

I dont think you could see 8 volts at any time. A car wont crank with less than about 9 (while cranking).

You can always have it bench tested but it should be simple to figure out without doing so.
Good luck.

 

[andrewb_80]

Yeah, its fine when above 1500 or 2000 but either below that or from a start i get nothing.

 

[HISSIN50]

So even after the car is started and has been driven some, if you let it idle, the charging output sucks? If you are reading these numbers off the alternator itself, I would have it bench tested.

Good luck.

 

[andrewb_80]

Yeswell the numbers come from my stock gauges? And what exactly is bench testing? My dad has some thing that tests the battery and alt, is that what it is? Thanks

 

[iapexl8r]

. under drive pulleys on alternators free up horse power but also @ lower RPMS do cause charging issues. it has to do with the fact the alt is now spinning at a slower than recomended speed. chris

 

[HISSIN50]

Grab your dad's DMM (multimeter or voltmeter) and put it across the battery terminals. Now see what the voltmeter in the car shows vs what you are seeing with your dad's meter. I bet the battery might read higher. If so, it can be mainly due to a voltage drop to the interior or due to a miscalibrated gauge. I have a voltage drop to the interior of my 94.
You can also put your dad's meter on the pins to the stock voltmeter to compare both readings AT the same location. THis is a pain IMHO. I would get a real gauge instead.

Good luck with the testing - perhaps your dad can help you if you are unsure of what to do (it will take about 5 mins of testing or less to see what gives).

If he helps, have him check voltage drop from the alternator to the battery.

Good luck.

 

[andrewb_80]

well i know there is voltage drop because all of my lights dim severly and my tach shift light flashes on and off like it is being turned on and off.

 

[andrewb_80]

Well, I changed from my underdrive pulley to my stock pulley, it worked for a couple starts, and now nothing. I will probably try to mess with my grounds....any more pointers will help!

 

[HISSIN50]

The only pointers I could give would be to do the above-listed testing, especially when things are not up to par. That is the only way to narrow it down.

FWIW, bench testing is when you take the alternator out of the car and have a parts store or a shop put it in a load tester. They can check that it is exciting, what its output is, that the diode packs are alright, etc.

Good luck.

 

[andrewb_80]

ok thanks man