As I see mentioned in a few posts above, if you are using or thinking of using a solenoid for connecting the alternator, do
NOT use a ford style starter solenoid as it is not for continuous use. There are "continuous" duty relays available for under $35 which will work MUCH better. Here is an article I found better explaining the difference between standard starter solenoids and continuous solenoids.
Quote:
Starter Solenoids and Continuous Duty Solenoids
Posted on April 04, 2011 in Featured, Technical
Check out this information on starter solenoid testing from Joe Glassford’s new book on vehicle testing procedures. This article gives you some much needed real world information on stater solenoid functionality that will help you better understand how to troubleshoot and diagnose problems later.
Starter Solenoid
Starter solenoid like the kind you see mounted on the fender well, or starter motor housing of some vehicles is used to bring current to a starter motor when the key is in the start position. This type is designed to pass as much as 400 amps.
The length of time this high current passes through a solenoid like this is limited. The limited time is the key to their usefulness. These solenoids use a coil with only 3 to 4 ohms of resistance. If this type solenoid was turned on and left on continuously, it would destroy itself from heat due to the amount of current passing through the coil winding. These solenoid windings pass close to 6 amps when operating.
Continuous duty solenoid
Continuous duty solenoid windings will draw less than 1 amp when operating. These solenoids will have approximately 30 ohms of resistance across the coil winding. This allows the coil to run much cooler allowing it to pass well over 100amps continuously without failure.
Never replace a continuous duty solenoid with a regular starter solenoid. The starter solenoid will burn out in a very short period of time if used for “continuous duty.”
Here is one I googled for under $20
Relay
There are also disconnect swithes available which have a second set of contacts for disconnecting power to an alternator relay.
Scott
