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Old 09-27-2009
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Installing new AGM Batteries


I’m in the process of replacing the house batteries (2) and the engine battery (1) for new all AGMs. The battery charger can be set-up to manage AGM batteries. The mechanic tells me that before we do this we need to find out if the engine's alternator’s regulator can handle AGM batteries.

Is this correct?

How can I find out if I already have the right one or how to get the right one?

La Bestia

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Old 09-27-2009
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What kind of regulator do you have right now? Is it an external regulator, or the stock internal regulator that came with the alternator?

What kind of batteries are you replacing?

All battery types will benefit from a "smart" external voltage regulator that will customize the charging profile to the chemistry of the battery type.

But one of the advantages of AGMs is that they are fairly forgiving when it comes to charging. You will get optimal performance with the custom charging profile, but you will still get very good performance with the same internal regulator used to charge standard wet cell deep cycle batteries.

So if what you have right now is a standard internal voltage regulator, which has been charging a bank of wet cells, you will be fine with the new AGMs.

If that internal voltage regulator ever fails, consider upgrading to a "smart" external voltage regulator.

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Old 09-27-2009
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One concern to think about is that AGM's can accept a much larger charge (amps) than can flooded batteries. Depending on your regulator, this can mean that the alternator will be taxed more heavily with AGMs than it was with flooded batteries. In some cases, where alternators were not designed for full output for more than a short time, the alternators themselves can be damaged.

Bottom line: you need to evaluate the whole charging system -- alternator, regulator, size of battery bank, etc.

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