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| Vr https://slantsix.org/forum/viewtopic.php?t=53123 |
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| Author: | valiant effort [ Thu Aug 22, 2013 8:40 am ] |
| Post subject: | Vr |
Hello everyone. I seem to be overcharging pretty severly. Even on a fresh battery the alternator is putting out about 15.5 volts. I replaced the voltage regulator and still have the same problem. I suppose the VR could be bad as well but it seems unlikely. Just to be sure I ran a seperate ground wire directly from the VR to the negative on the battery to elimate any grounding issues. Still have the same issue. Seems to me that when alternators go bad you have the opposite problem and there is little or no charging. Next step though is to pull the alternator and have it tested unless you guys have a better idea. Thanks for any input, Mark |
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| Author: | wjajr [ Thu Aug 22, 2013 9:56 am ] |
| Post subject: | |
Somewhere in the positive side of the regulator circuit there is a voltage drop, in other words the regulator is sensing or seeing low voltage, and adjusting alternator’s out-put higher so that regulator see 13.8 to 14.3 v or so. If your harness has a one volt lower reading difference between blur wire at VR, than VR will bump up alternator one volt to make up difference so battery will see 14.8 to 15. Put black volt meter lead on negative battery terminal, and using a simplified sketch of charging circuit record all voltages at each connection on it. If there is a total of 0.3v you have a bad voltage drop problem. Places to look for corrosion that introduces resistance to circuit are battery terminals, ground strap to block connection, bulkhead connector, ignition switch, and poor condition conductors. You were correct to check ground side of charging circuit, as VR has to have a good drop free ground. You will discover that as each connection is tested, small voltage drops will be seen at most of them. These resistances or voltage reading drops add up to one big drop. So your mission is to eliminate or reduce as much drop as possible by cleaning or replacing bad connections, and switches. To test voltage drop under dash, make an extension of black meter lead long enough to reach back to battery, this method will allow good readings independent of any of the normal ground path through body and battery connections. This MADD article will give you a look at charging system to make it simpler to test. |
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| Author: | valiant effort [ Fri Aug 30, 2013 11:04 am ] |
| Post subject: | Vr |
Thanks Wjar, I will do a bit more testing. I will add that I had already rewired the entire circuit when I did the HEI upgrade. The firewall connecters were all eliminated and everything is pretty much direct wired with new wire, new battery and batteyr terminals, and new body grounding. I did use the original wires from the VR to the Alternator so I will check those connections as well as the Ignition switch. When I first made the conversion all seemed to work well but has since made the aforementioned problems. Again thanks, I will let you know what I find when I get around to doing all of the testing...Mark |
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| Author: | wjajr [ Fri Aug 30, 2013 7:03 pm ] |
| Post subject: | |
You are getting close. Check the remaining old conductors & connectors in charging circuit, but be diligent cleaning battery connections and their conductors, ground to block, and head ground conductor to fire wall connections. If you use a battery cutoff switch be sure to clean its connections as well. One time I was chasing about a one volt drop and found it in the green knob battery cutoff switch connections; they looked good, but were found to be badly corroded once disassembled. That is one volt in about two inches of ground circuit… |
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| Author: | WagonsRcool [ Fri Aug 30, 2013 7:23 pm ] |
| Post subject: | |
I'd check what your voltage readings are at the blue (ign) wire at the VR & its case ground- then compare that to readings at the battery terminals as well as the alternator output stud & case. One thing to watch, I've seen aftermarket VR that were "bad"- they wan't 14.8V at the VR itself, so I ended up with well over 15V at the battery by the time "normal" voltage drop in the ign switch & circuits was factored in. |
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| Author: | zorg [ Fri Aug 30, 2013 10:42 pm ] |
| Post subject: | Re: Vr |
Quote: I suppose the VR could be bad as well but it seems unlikely.
There have been lots of reports of them bad right out of the box in recent years. I had 3 myself... Hate to say it but you shouldn't rule it out.
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| Author: | valiant effort [ Wed Sep 04, 2013 6:13 am ] |
| Post subject: | Vr |
Any recommedations on a good aftermarket VR?. I see they range in price from 12 bucks up to around 45, Delco being the most expensive. |
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| Author: | crater [ Wed Sep 04, 2013 8:57 am ] |
| Post subject: | Re: Vr |
Quote: Any recommedations on a good aftermarket VR?. I see they range in price from 12 bucks up to around 45, Delco being the most expensive.
I recently put in an Echlin from Napa. Was 36 dollars. Seems to be doing its job.
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| Author: | WagonsRcool [ Thu Sep 05, 2013 12:40 pm ] |
| Post subject: | |
The last few bad VR's I got were SMP (Standard) & Napa/Echlin- both were the exact same units in different boxes - both made in china- both were useless as they overcharged. |
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