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sprinkles08, ASE Certified Technician
Category: Car
Satisfied Customers: 22655
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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WK2 limited: looking for an iginition source

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looking for an ignition source for a redarc1220bc-dc ign battery charger for the 2012 jeep grand cherokee diesel to run an auxillary battery. My electrician is having problems locating a power source that does not run off the auxillary switch/system. Redarc could not help and Jeep are also struggling.

Hello and welcome to JustAnswer!

I see your question has been up for an extended time without a response. Do you still need help?

Customer: replied 4 years ago.

Yes, as I have not advanced any further

You need the power source to be live only when the ignition is on, correct?

Does it need to be under the hood or in the interior?

How many amps does the device need?

Customer: replied 4 years ago.

Yes I need the power source to live when the ignition is on. The supply needs to be 12 volt but the current would only be 100 milli-amps as it is only a signal for the charger to start charging. The supply can come from under the hood or the interior. The second battery will be located in the rear of the vehicle directly behind the rear seats

The easiest place for you to go would be the cigarette lighter then. The dark blue/pink wire at the cigarette lighter connector is powered only when the ignition is on and would be a perfect circuit to connect to the signal wire for your charger.
Customer: replied 4 years ago.

This supply also comes on when the accessories are on. My electrician says that I need to connect to a supply that only comes on when the engine is running otherwise the battery will charge while accessories are on. The charger is a 20amp/hr battery charger. I also have my uhf radio connected to this point.

Since you have a diesel engine there really aren't any circuits that are powered only when the engine is running rather than when the key is on. If you had a gas engine there would be the ASD circuit that powers the injectors and coils, but the diesel engine doesn't have anything that's powered only when the engine is turning. The only circuits that are switched power are going to be of the ignition accessory circuits.
If you have a need to have the ignition on but not run the engine you could just install an inline switch in the charger signal wire. If you needed to have the ignition on without the engine running you could just turn the switch off to break the signal circuit, when the engine is running again then you could flip the switch back to on, complete the signal circuit and have the charger running again.
Customer: replied 4 years ago.

As the engine has injectors etc I would have thought that it would have a similar set up the gas injection system. Is this not the case.

No, that's not the case. Gas engine injectors get a constant battery voltage on one wire any time the engine is running, supplied by a high side driver from the TIPM. The piezoelectric injectors on a diesel aren't controlled nearly the same as on a gas engine and they don't get any sort of constant voltage source like a gas engine.
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