isolators
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For multiple battery installs at my shop we build battery isolation circuits using 200amp relays. The main reason is to allow the alternator to charge all batteries in the system while the engine is running but seperate the front "main" battery from the systems battery(s). This way, if the customer plays the system at a show with the car off and drains the rear battery(s), he can still switch to the front battery and start his car.
Additionally, a battery isolator has a .7 volt drop at each isolator (standard voltage drop for a diode), so we use relays to avoid the voltage drop.
Additionally, a battery isolator has a .7 volt drop at each isolator (standard voltage drop for a diode), so we use relays to avoid the voltage drop.
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Really? I would think most people would run them from a secondary battery, and it doesn't lighten the load on other factory installed devices at all. It actually adds to the load presented to the alternator.
Isolators are good - provided you use solenoid based ones (the article actually did a decent job explaining this). Standard voltage drop across a silicon diode is 0.6V - not a tremendous amount when you consider the alt should ideally be charging at 14.4V. Batteries are 13.8V, and there you have a difference of 0.6V. Since most alternators charge up a bit higher than that, though, their potential is still higher than the battery, therefore current will flow.
Let's be clear, though - batteries are only good for additional engine off time for accessories. If you are trying to feed more amplifiers or other equipment but exceed the capabilities of the alternator, you're not going to see a benefit until you add an alternator that keeps up.
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