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Alternator Fun


ajh
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I had thought I was exceeding the stock alternator on my 1991 but looks like it has simply been having issues and output dropped to 12.4v today so it can no longer keep up with drain.

The stock one has a multi-plug and I am guessing that it is the 45a one. I also have a 90 being rebuilt and that has a post-connector and is a Magneti Marelli type A127-65 which I gather is the 65a one.

If I simply swap them do I need to upgrade the charging wire right away or can I get away with just cutting the connector off and fitting ring terminal ends? (I drive 8h north on Monday).

The A127-65 has two square units on the back, only one is plugged into anything the other connector is loose and I assume it goes on the vacant post with the tab screwed onto it. Oddly it seemed to work fine as is.

Anything else to look at?

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The square units are radio interference suppressors.

What size wiring do you currently have fitted? What is the vehicle?

Both the 45A and the 65A were factory fitted on defenders, but I don't know if they changed the wiring, or went from a single to a double run etc.

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My guess is that it's 10 or 8 gauge, which I gather should handle 65A at least from time to time as it'll likely run lower at least until I fit the winches. Mostly before I pull the failing one out I want to make sure there aren't any actual wiring differences to worry about.

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One last question, any problem removing the current feed wires to the starter and running a 2ga from the alternator directly to the batteries? I'm trying to setup to fully isolate the starter and accessory batteries and my gut feeling is that it would be better to do it this way and let the starter pull using the already present heavy cable.

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You can take the alternator cable straight back to the battery if you wish.

2 gauge (AWG? rather than SWG?) cable seems to be 33.6 mm², which is overkill for a 65 alternator. 35mm² is good for 200A or so.

16mm² is a common size here, and would be plenty man enough (rated around 100A) - AWG 5?

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We use 4awg for that range and that is what I did. Put pigtails on the rings and for now I am wiring up the stock connections to that and will get more 4 to run to the battery. Thanks for the help, should be back on the road in an hour or two.

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