Merlin AMS Alternator controller

FullCircle

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I have mine for sale as I am getting a twin alternator Adverc unit this year.

This is a 2007 unit, and has been whirring merrily for last 3 seasons.

New cost £170

£100 posted to UK.

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The alternators fitted to today's marine engines are basic, automotive units designed to simply recharge a small engine start battery and run minor loads like windscreen wipers. They do not have the ability to rapidly recharge high capacity battery banks or cope with the demands of a marine application.

The problem is not the alternator itself, it is the alternator's built in regulator. The standard regulator provides a single stage charge with voltage "clamped" at around 14V. The following charging problems usually result:

* Batteries require around 14.4-14.8V to charge properly. The standard regulator does not allow charging beyond 14V - therefore batteries never become fully charged
* Due to the lower charging voltage, the alternator is not able to develop it's full output, extending charge times
* Voltage drop across split charging systems, battery switches etc reduce voltage further - sometimes by as much as 1.5V making the above two problems even worse
* There are no adjustments for battery type, temperature etc.

The Merlin AMS is designed to work with the existing alternator regulator to overcome these problems. This is a short list of the main benefits (download our information packs for further details):

* AMS is universal and designed to work with all European Alternators (DO NOT use with Balmar or other high output marine alternators!)
* AMS provides up to 14.8V at the batteries to assure faster and fuller charging, while also making up for voltage drop across diodes, switches etc
* AMS provides a 4 stage smart charge to the batteries for faster, safer recharging
* AMS provides built in temperature compensation and battery type selection (flooded lead/acid or Gel/AGM)

Installation Note:

Installation of the AMS unit is within the abilities of a competent DIYer. In order to make the unit work, a wire is to be soldered or attached to the alternator's internal field wire. Instructions are provided to help you do this. However, if you do not feel that you can competently install this product, we recommend that you engage the services of a marine electrician.
 

Cantata

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Ah, the device with the delightfully named 'RTFM LED'. They say it stands for 'Real Time Fault Management', but we know better don't we...
A good piece of kit, just fit and forget as I have found.
 

prv

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The RTFM light has just caused great hilarity around my office :)

I'd be tempted by this, except that I'm concerned about charging both a deeply-discharged house battery and a nearly-full engine battery on the same aggressive regime. Won't I cook the engine battery?

Pete
 

FullCircle

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The RTFM light has just caused great hilarity around my office :)

I'd be tempted by this, except that I'm concerned about charging both a deeply-discharged house battery and a nearly-full engine battery on the same aggressive regime. Won't I cook the engine battery?

Pete

Suggest that you invest in a Voltage Sensitive Relay setup, mine is from BEP.
Besides, isn't that the scenario you are living with now, having a plain vanilla alternator setup?
 

prv

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Suggest that you invest in a Voltage Sensitive Relay setup, mine is from BEP.

Got one. It'll common the batteries together while charging, hence the problem.

Besides, isn't that the scenario you are living with now, having a plain vanilla alternator setup?

No, because the plain alternator charges at a constant moderate level that won't cook a full battery.

That introduces a different problem, the battery never getting a really full charge, which an advanced regulator like this is designed to cure. And so it does, if you're only charging one (bank of) battery. However, I've never seen a convincing answer to the question of connecting it to two banks with different needs.

Pete
 

FullCircle

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Got one. It'll common the batteries together while charging, hence the problem.



No, because the plain alternator charges at a constant moderate level that won't cook a full battery.

That introduces a different problem, the battery never getting a really full charge, which an advanced regulator like this is designed to cure. And so it does, if you're only charging one (bank of) battery. However, I've never seen a convincing answer to the question of connecting it to two banks with different needs.

Pete

OK.Suggest you read the BEP website, they would differ from your opinion of how the system works, and why is doesn't common them up as you suggest.
 

prv

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OK.Suggest you read the BEP website, they would differ from your opinion of how the system works, and why is doesn't common them up as you suggest.

I've just read the page on the BEP VSR and the suggested wiring diagram. It appears to work in much the same way as the Smartbank VSR I have - it connects the batteries together while charging, and disconnects them otherwise. That's just as I would expect.

To avoid the problem I'm worried about, they would need to also disconnect when the starter battery was full but the charging system was still in bulk charge mode trying to shove charge into the house bank. That doesn't seem impossible to do if the situation can be detected (I'm not an expert) but I couldn't see any indication that either VSR actually does it. They only disconnect when the voltage drops as the engine is stopped.

I'm not trying to "do down" the AMS you're selling, by the way - I think it's a good bit of kit.

Pete
 

FullCircle

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I've just read the page on the BEP VSR and the suggested wiring diagram. It appears to work in much the same way as the Smartbank VSR I have - it connects the batteries together while charging, and disconnects them otherwise. That's just as I would expect.

To avoid the problem I'm worried about, they would need to also disconnect when the starter battery was full but the charging system was still in bulk charge mode trying to shove charge into the house bank. That doesn't seem impossible to do if the situation can be detected (I'm not an expert) but I couldn't see any indication that either VSR actually does it. They only disconnect when the voltage drops as the engine is stopped.

I'm not trying to "do down" the AMS you're selling, by the way - I think it's a good bit of kit.

Pete

Well, its going on ebay now. If you have these technical queries perhaps you would be good enough to put them on PBO forum.

Just to be clear, I don't think your fear has any basis.
I completely flattened my bank of 3 domestics in 2 weeks by leaving the fridge on accidentally, leaving the engine battery OK.
The alternator charger brought all 4 batteries back to their charged condition after a long motor up the coast. No long term damage.
 

joybennett

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I don’t suppose you’ve still got the manual for the Merlin AMS by any chance? We’re in the process of replacing it with a sterling alternator to battery charger but need to remove the existing system and can’t find any info on it
 

Cantata

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I don’t suppose you’ve still got the manual for the Merlin AMS by any chance? We’re in the process of replacing it with a sterling alternator to battery charger but need to remove the existing system and can’t find any info on it

I might have one somewhere still but I'm not sure where!
If you are simply removing the device, you just need to disconnect all its wires. There are no other changes that I remember..
 
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