Thread: Fans drawing too much power

I have two (2) 12 inch aftermarket slim fans hooked up to my car. One pushes, the other pulls. The fans kick in when triggered by temp sensor on the radiator. It uses a relay to have the fans directly connected to the battery source.

When both fans turn on, it draws so much power that it drains about 0.5v to 0.7v of the battery and causes the car to drop idle as well alter my afr's.

Any ways to troubleshoot this? Voltage regulator? Higher amperage alternator? Or run with one fan instead of two.

Any ideas on how to troubleshoot this would be awesome. Thanks guys!

First thing, larger wiring to the fans from the battery. Verify you have a strong ground for them as well. There is no reason you can't run two aftermarket fans. Also, each fan should have its own wiring and its own relay/fuse.

Whats the amperage on the relay? B14s use just one relay for both fans, so I don't see that being an issue, I would check the relay amperage you need at least 30 amps for the fans, different polarity at the same time could probably be an issue also. And like coach said make sure it has a solid ground. I would try to get an ammeter or amp probe and check the amperage those are taking, it could be that they're going bad or one going bad. And I know they're probably new, but electrical components don't like heat or vibrations. I also have slim fans but with ac they're worth a damn, I replaced the relay for more amperage output and it worked a bit but still, I would start with those things first.

using 40 amp relays. it definitely is the reverse polarity that drains more power. i disconnected both fans to let the car warm up hot. then plugged on in at a time. the pull fan drained .1v while the push fan (reverse polarity) drained .5v.

i'll try to set up separate relays for the fans tomorrow if the weather is good enough. thanks for the responses