Altenator upgrade?

Submitted: Wednesday, May 24, 2006 at 22:18
ThreadID: 34230 Views:2839 Replies:6 FollowUps:1
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How many of you have yours upgraded to 120 amps? Or what ever, size you wish. Just wondering if it is "really" necessary to have it done to charge a 120 amp AGM in the camper trailer? Everything is working ok so far?? any feedback welcomed.
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Reply By: Gerhardp1 - Wednesday, May 24, 2006 at 22:39

Wednesday, May 24, 2006 at 22:39
It depends if you really have to charge your dead flat 120 amp battery in one hour.

If you have to do this, it would be essential to have the alternator capacity.

But if you have say 55ah alternator, your AGM would charge from half flat to full in about 1.5 hours or a bit less of driving/fast idle. If you are using more than 60 amps out of your battery in a short time I would say you probably need another battery rather than a bigger alternator capacity.

AnswerID: 174572

Reply By: Glenn (VIC) - Wednesday, May 24, 2006 at 23:17

Wednesday, May 24, 2006 at 23:17
Hi Uncle,

I have a 120ah alternator now, as my original one died on me. I had already had it repaired twice before, and gave me heaps of trouble when a long way from Coober Pedy, only to die as I reached the caravan park. I decided that when I returned home it was time to replace and the auto elec recommended the 120ah. I am glad I have done this, as it now works on charging three batteries, two in the vehicle and one on the camper. The extra grunt makes life easy when bush camping as I do not have to run the vehicle too long to recharge the aux batteries.


AnswerID: 174580

Reply By: Flash - Wednesday, May 24, 2006 at 23:29

Wednesday, May 24, 2006 at 23:29
I haven't but plan to some time in the future......
This mob are usually unbeatable on price- I bought an alternator off them a few years ago for another vehicle (mate's cruiser)

I have heard of alternators supposedly dying prematurely from overheating whilst charging aux batteries- but not first hand.
AnswerID: 174582

Follow Up By: Member - uncle - Thursday, May 25, 2006 at 07:31

Thursday, May 25, 2006 at 07:31
Thanks for the site link Flash, had a look and they have some great goodies there too. It seems my standard alt is 90amps,so I think for the time being i'll just leave as is.cheers
FollowupID: 430676

Reply By: Member - Craig D (SA) - Thursday, May 25, 2006 at 07:50

Thursday, May 25, 2006 at 07:50
An alternative is to fit a alternator management system (AMS) to enhance the alternator output. The following is an extract from a Merlin brand AMS sold by Bainbridge Technologies

"The alternators fitted to most
vehicles are standard units designed only to
recharge an engine start battery and run a fan,
heater, wipers etc. Therefore, they are fitted with
a fixed voltage regulator designed to maintain
voltage at 14V.
Due to the internal resistance of deep cycle
batteries and voltage drop across split charging
systems; Standard alternators are incapable of
quickly and fully recharging battery banks. The
problem is exacerbated with larger battery banks
and extreme temperature fluctuations.
The AMS is designed to work alongside your
alternator's standard regulator. When required,
it will take over alternator operation to ensure
that batteries receive correct charging voltages
and maximum possible alternator current. AMS is
not a booster (which can damage the alternator)
- it is an advanced regulator that compliments
the alternator and adapts it's charge profile to
suit the needs of the specialist vehicle or cruising
vessel. The AMS ensures that the alternator
continues to work within it's design parameters -
therefore, it won't shorten engine or alternator

Their site link is

No idea how much they cost.

AnswerID: 174608

Reply By: Geoff (Newcastle, NSW) - Thursday, May 25, 2006 at 11:06

Thursday, May 25, 2006 at 11:06
Or you could use one of these,

Work a treat and optimise what you already have rather than the same shortcomings with a bigger alternator.

Landcruiser HDJ78,
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AnswerID: 174661

Reply By: Member - Doug T (QLD) - Thursday, May 25, 2006 at 11:39

Thursday, May 25, 2006 at 11:39
I don't know what make of 4x4 you have but check out the link i have done for this subject

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AnswerID: 174665

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