berg Posted April 22, 2017 Share Posted April 22, 2017 Installed a pair of SRD twin fans a few weeks ago Having a few issues with voltage drop every time the fans come on Can see in this video below how the voltage drops every time i trigger the fan relays Everything is wired correctly and other than the voltage dropping it all works fine The battery is in the boot, the battery cable goes to a circuit breaker, then distribution block, then to the starter motor, then another cable from the starter to the alternator (factory alternator wires not used now) All cabling is heavy 50mm2 cable (equivelent of 0AWG) rated to 345amps and ive also fitted a Mechman 170A alternator and its still the same Anyone have any ideas? https://youtu.be/riWl4wqAE_k Quote Link to comment Share on other sites More sharing options...
curious Posted April 22, 2017 Share Posted April 22, 2017 Installed a pair of SRD twin fans a few weeks ago Having a few issues with voltage drop every time the fans come on Can see in this video below how the voltage drops every time i trigger the fan relays Everything is wired correctly and other than the voltage dropping it all works fine The battery is in the boot, the battery cable goes to a circuit breaker, then distribution block, then to the starter motor, then another cable from the starter to the alternator (factory alternator wires not used now) All cabling is heavy 50mm2 cable (equivelent of 0AWG) rated to 345amps and ive also fitted a Mechman 170A alternator and its still the same Anyone have any ideas? https://youtu.be/riWl4wqAE_k[/url] Dude, Check the earth's returns to the battery. Carry out a vollt drop test and that should locate the point where you are loosing the current due to the higher electrical resistance. Quote Link to comment Share on other sites More sharing options...
np89 Posted April 22, 2017 Share Posted April 22, 2017 Thats the problem with electric fans the amp draw is huge and they dont really move that much air in comparison to the stock viscous Quote Link to comment Share on other sites More sharing options...
berg Posted April 22, 2017 Author Share Posted April 22, 2017 I know they will effect voltage a bit thats normal, just wasnt sure how much by, be good if other members with these could check the video and see if theirs do anything similar To be fair most aftermarket fans are junk yer, but these srd fans are tried and tested and easily keep the temps exactly where they should be, absolutely no issues with thier cooling abilities Quote Link to comment Share on other sites More sharing options...
Sheefa Posted April 22, 2017 Share Posted April 22, 2017 Erm, what's actually the issue mate? Voltage drops as they activate and then normalises? If so I'm confused as to what the problem is. Quote Link to comment Share on other sites More sharing options...
berg Posted April 23, 2017 Author Share Posted April 23, 2017 Erm, what's actually the issue mate? Voltage drops as they activate and then normalises? If so I'm confused as to what the problem is. /QUOTE] Not nessesarily an issue, Basically im asking if its normal lol, its a 2v drop and is effecting idle thats all If its normal then thats fine Quote Link to comment Share on other sites More sharing options...
and1c Posted April 23, 2017 Share Posted April 23, 2017 If this is all at idle then alternator armatures are not putting out their max rated output at idle. Meaning that it may only be putting out say half of its rated output at idle rather than the full amount. Have you done this test with the engine at say 5k rpm? Quote Link to comment Share on other sites More sharing options...
Sheefa Posted April 23, 2017 Share Posted April 23, 2017 I'll test my voltage later mate when my twin fans come on to see if it does the same. Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted April 23, 2017 Share Posted April 23, 2017 Absolutely normal, most fans will draw around 30-40 amps on start up, i would be more worried if it didn't, once running its fine its just the initial load, if they are drawing say 30 amps each then that's 1/2 to 2/3 of the battery's capacity, have you ever looked at a volt meter when you start the car? the alternator will take more time to catch up with the load, therefor you wont see it. Quote Link to comment Share on other sites More sharing options...
Guest Budz86 Posted April 23, 2017 Share Posted April 23, 2017 Perfectly normal mate, my twin fans do this and I have the same kit and setup as you. As Ricky said, initial draw is high but stabilises quickly. Have you got them staged? I've done that on mine so normally only runs one fan. Second doesn't kick in till 98c I think Quote Link to comment Share on other sites More sharing options...
mark newman Posted April 24, 2017 Share Posted April 24, 2017 You need to install a bigger alternator 190 amp or bigger , no more problems. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted April 25, 2017 Share Posted April 25, 2017 Perfectly normal. Brushed and induction motors have a very high start up current. Electric fans are NOT free power, they just move the load from the water pump pulley to the alternator pulley Quote Link to comment Share on other sites More sharing options...
SupraP-Z Posted April 26, 2017 Share Posted April 26, 2017 As above dude, just initial drain of power. I have a 300amp alternator that puts out 150amp at idle and 300amp on full pelt (used to use it when i was into sub woofer builds and the like) same used to happen when volume was increased to a higher than normal level, car's idle was affected. Always had to rev the engine if i was going to turn it up. Still got the little beast laying around here somehwere Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.