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Alternator upgrade


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I already have a Lucas alternator on my 2a. I think its a 15 acr, although not sure. I have a voltmeter in the system which shows 14.5 volts when the engine is running, the batteries are charged, and no extra loads.

There are a few modifications to know about, like 4 x 55w Lightforce spots on the roof, a 2.5 a fridge, and a few other electrics in the cab. The vehicle has an extra leisure battery wired in parallel with the vehicle battery, via a heavy duty switch to disconnect if required. All the additional lights and electrics take their feeds from the auxilliary circuit. I normally leave the disconnect switch connected, unless I run lights or fridge and phone/laptop chargers with the engine off, in which case I isolate the aux battery. I have used a standard battery master switch for this, I did not use a HD auto split charge system, mainly for cost reasons.

As I said, when things are charged and the accesories are off, there is no problem and the batteries keep their charge. However, when I use the vehicle lights, and the fridge etc, the volts drop to less than 12. To my mind this means that the demands of the vehicle are exceeding the alternator capacity. The Alternator also whistles quite loudly at higher revs when all this load is on.

If I discharge the auxilliary battery (keep the fridge going overnight for example), then the system volts remain at about 13 for a considerable time until its charge is replenished. If I have to use lights during this charging, the volts are again back at around 12.

I have replaced most of the charge circuit wiring over the years, so there should not be any bad connections.

The question is, what is the most powerful alternator that will fit the standard mounts. I have a series 3 alternator mount fitted to the left of the engine.

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Why do you specify the standard mounts - it's not exactly major work to drill a hole, crimp a new terminal on or change a couple of nuts/bolts which is all that's required to make a number of alternators fit.

There are many posts on fitting different alternators, the default answer is trawl the scrapyard for one that mounts the same side as yours but is on a car that has more electrical systems. Family Fords (EG mondeo/granada) are good as they're popular and cheap, most modern alts are 70-90A. You may want to fit a fatter battery cable to the unit when you swap over, just to be safe.

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