Vehicle Battery Draining After Installation of Derale Dual High-Output Radiator Fan # D16927
Updated 06/04/2020 | Published 11/12/2013
Question:
I installed Derale 16927 dual fan set up which draws 50 amps 25 amps each fan. After one week my battery went dead. Should I replace my alternator? The one that I have now its an 85 amp alternator. Should I go with an 140 amp alternator? Thanks.
asked by: Joe
Expert Reply:
The 85-amp alternator in your vehicle will deliver its full current output only at highway speeds when RPMs are high. In typical around-town driving it will deliver only a fraction of its rated current and only about 40 amps at idle.
If you have other current-hungry electronics in your vehicle, for example a powerful audio amplifier and/or a CB radio system, then the combination of power draw from these items together with the Derale fan may be taxing your alternator. You certainly can switch to a higher output 140-amp alternator and this would probably correct the battery discharge problem, but you may be able to install a smaller pulley on your existing alternator (possibly along with a new shorter belt) to increase its rotation speed and so its current output.
If your vehicle battery happens to be near the end of its normal lifespan then this also may be a potential cause for the problem.
Product Page this Question was Asked From
Derale 26" Dual High-Output, Electric Radiator Fan-and-Shroud Assembly - 4,000 CFM
- Radiator Fans
- Electric Fans
- High-Output Fan
- 26 Inch Diameter
- 4000 CFM
- Derale
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Carl C.
6/4/2020
I have a derale dual fan with PWM controller i just installed on my 70 Chevelle with 454 engine. The system works as expected and keeps the engine cool except that the fans keep running for as long as 30 minutes after the engine is turned off. The battery runs down especially after a couple of short runs with 15-20 minutes between. This can't be right but Derale only says there must be another heat source keeping the fans running so long after shutdown,but the sensor is right where the instructions say to put it.