scooter Posted July 3, 2016 Report Share Posted July 3, 2016 Does anyone know of a surge protection device that can be put inline on the bat+ wire comming off an alternator? Last year something happened to the gm alternator i was using and it voltage spiked and fried everything electronic in my car. I pretty much have it all fixed now, but it cooked thousands of dollars worth of stuff. -the alternator itself - msd 6al - start and step retard (for nitrous) - tach adapter - intermittent wiper control box - my amp - my wideband - blew up all my brake light bulbs - popped many fuses - melted the fusable link That alternator was thrown in the garbage and a new gm one is installed now along with all this shit. So i really really want to put in some kind of surge protection so this doesnt happen again to me. This was the first one that ive seen do this and my research tells me that if the voltage regulator fails you can have 80+ volt spikes. I know of aviation style ones that will kick the alternator off if this happens, but $$$$$$. Any ideas? 1 Quote Link to comment
datzenmike Posted July 3, 2016 Report Share Posted July 3, 2016 The alternator senses the system voltage and adjusts output to keep the charge rate at what ever it's designed for. Generally the battery load limits this and why you should never run with the battery removed from the circuit. Idling might be an exception as the output is lowest here. This is a very rare event and I don't know of anyone that has experienced this other than you. Unlikely to be repeated. Was this an actual GM alternator from a GM or a new replacement from an auto supply store? I did have a '79 Cutlass that once had the headlamps go extremely bright on me and the charge went off the scale, but it reverted back to normal, no harm done. Don't know if this was the same thing and it didn't repeat it again. 1 Quote Link to comment
scooter Posted July 3, 2016 Author Report Share Posted July 3, 2016 It was an older 12si style oe alternator that has been on the car for a few years since the old datsun alternator died. Had a new battery in it at the time and the wiring in the car is in decent shape. It wasn't idling but it wasn't screaming either. It has a power pulley on the crank so it's also a little underdriven. It has an ac Delco new-not remanned plastic fan 12si on it now. The voltage is rock solid, I'm just a little paranoid. I shouldof had the old alternator tested to see if it was still doing that. I'm sure someone would of been interested to see a voltage regulator fail like that. 1 Quote Link to comment
datzenmike Posted July 3, 2016 Report Share Posted July 3, 2016 OE isn't the same as a stock GM alternator. It only has to meet their specs. I don't have much faith in the over the counter stuff these days. 1 Quote Link to comment
scooter Posted July 3, 2016 Author Report Share Posted July 3, 2016 It was old.. I think it came off the parts chevelle my step bro had.. Worked. Dont know if it was an original gm one or not, definitley wasnt a piece of shit bosch alternator 1 Quote Link to comment
Lockleaf Posted July 3, 2016 Report Share Posted July 3, 2016 Shouldn't fuses have protected against this? Fuses actually blow when too many watts run through them. By 80 volts a 15 amp fuse rated for 14 volts would only run 2.6 amps before blowing. Or do I have a competely wrong understanding of this? 1 Quote Link to comment
banzai510(hainz) Posted July 3, 2016 Report Share Posted July 3, 2016 voltage is electromotive force. Fuses is a more a current limit. you can have 5000volts but if only 1/4 amp it shouldn't do anything to the fuse but the electronic chips inside a circuit might be sensitive. the wire from the starter lug should have melted. fuseable link. later GM alts are self exicting if I rememeber right 1 Quote Link to comment
scooter Posted July 4, 2016 Author Report Share Posted July 4, 2016 It melted the fusable link, but not fast enough. The alternator I have now kicks on the first time it hits 1800 or so. Everything turns on with the acc and on circuits except the msd has hard wires direct to the battery and so did the amp. 1 Quote Link to comment
kelowg Posted July 4, 2016 Report Share Posted July 4, 2016 Could likely make up something like cir breaker,but for overvoltage. Relay switched by voltage sensor. Nothing commercially made,tho might b ablemod a volt reg to switch the relay? Had same thing happen yrs ago,blew out headlights. Made dash lights super bright too. 1 Quote Link to comment
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