Alternator Replacement

[Don Bradner]

I would imagine that the wiring is a limiting factor, although hard to say for
sure. These are new AGMs, which have a low resistance compared to wet cells. The
most-likely primary cause for only getting 100 amps of charge is simply that the
batteries weren't particularly low, and therefore the voltage was quickly high.

On 3/5/2007 at 9:44 AM Chuck Wheeler wrote:

>Don,
>
>I believe that you will se the benefits of two alternators when you are
>using a lot of the 12 volt systems on your coach such as moving out after
>spending the night dry camping on the the batteries. When just charging
>the
>batteries there are several things that will come into play limiting the
>charging current. First you have the internal resistance of the batteries.
>This increases as they age and the charging current will go down no matter
>how much they are discharges. Then there is the resistance in the charging
>circuit, wiring, ammeter shunts , etc.. Also no two regulators are exactly
>the same. So one alternator will take the load first. It will be somewhat
>balanced by the resistance in the wiring between the two. When I would
>check out construction equipment with two alternators I would test one at a
>time by disconnecting the battery wire from one alternator at a time.
>Sometimes we would discover problems in one circuit. As I said at the
>beginning the real benefit will be under heavy load. Just charging the
>batteries this current will be limited by the alternator and wiring. Up to
>the point that you overload the alternator the charging current will remain
>the same for a certain amount of battery discharge no matter how large an
>alternator you install.
>
>- Chuck Wheeler -
>82 FC 31 SB
>Fort Worth, TX
>
>
> _____
>
>From: WanderlodgeForum@yahoogroups.com
>[mailto:WanderlodgeForum@yahoogroups.com] On Behalf Of Don Bradner
>Sent: Sunday, March 04, 2007 11:07 PM
>To: WanderlodgeForum@yahoogroups.com
>Subject: [WanderlodgeForum] Alternator Replacement
>
>
>
>My alternator replacement job is done, I'm happy to say.
>
>For memory refreshment, I had Alternator 1 with zero output, and Alternator
>2 with max 50-amps and unable to maintain voltage with headlights on.
>
>Replacing the top-front one (under the bed) was easy. That one was a
>130-amp
>Prestolite. After replacement, and with the power cables removed from the
>back one, the engine was started and showed 100 amps on Alternator 1 at
>idle, zero on Alternator 2. Voltage was above 13.5 and amps dropped quickly
>as the start drop was replaced, even with the headlights on.
>
>Replacing the back alternator was not easy at all. It sits under the A/C
>pump, so I tried to drop it out the bottom, but there just wasn't room to
>make it. The way the A/C pump is bracketed it was a B***h to remove, and
>similar to replace, but I eventually got it done. The removed alternator
>has
>no apparent markings anywhere, so I don't know what it was or its rating.
>
>Running with the two new Leece-Neville 160-amp alternators the output after
>startup is still 100 amps, shared equally between the two. I guess that
>makes sense, but I had thought it would be higher. I wish I had a way to
>draw down the batteries and still have enough to start the engine, so I
>could see if it would show a higher charge rate.
>
>Overall it was an interesting learning experience. I also replaced the
>belts
>on Alternator 1, which showed some wear, but the others - alternator 2 and
>the A/C pump - looked like new so I left them.
>
>Don Bradner
>90 PT40 "Blue Thunder"
>Eureka, CA
>
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>[Non-text portions of this message have been removed]
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>Yahoo! Groups Links
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Don Bradner
90 PT40 "Blue Thunder"
Eureka, CA