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Alternator Buyer's Guide

Bruce Smith August 1, 2012

 MAX AMPS: High-Output Alternators

Choosing the right high-output alternator for your harder working pickups


by Jim Allen (photos by the author or courtesy of the manufacturers)

Snowplows, winches, inverters, accessory lights, air suspensions, on-board compressors, fuel/lube dispensing equipment, multiple batteries and high-output communications/sound systems are all common upgrades found in today’s working pickups.

If pickups in your fleet already have – or you are planning on adding – such work necessaries down the road, seriously consider including a high-output alternator into the upgrade budget.

The extra expense of upgrading to a high-output alternator could be trouble-averting money well spent.

A few of you may have already experienced that magic moment when, after long hours operating with a lot of upgrades that draw electrical power, the truck battery is nearly dead and you are stuck on the jobsite waiting for help to arrive.

The problem could be either the stock alternator doesn’t have the output to keep up with the demand – or it has failed due to duty-cycle problems related to high-draw electrical loads.



An OE alternator is generally designed for a short duty-cycle supplying the truck’s factory electrical load. Its capacity to handle additional electrical loads from upgrades is small.

So long periods operating at its max output to try and meet those electrical demands create a lot of heat – and electrical components like alternators don’t like high heat.

Also, because you may be drawing on the battery more often in these cases, the repeated partial discharges may shorten the battery life.

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