FW: inverters/chargers

Mark Erdos


With best regards,


Super Maramu 2000

Hull #275


From: Mark Erdos [mailto:mcerdos@...]
Sent: Wednesday, January 28, 2015 9:26 AM
To: 'amelyachtowners@...'
Subject: inverters/chargers

This is why I like this forum so much. I was about to replace an inverter/charger installed by the previous and original owner of Cream Puff. The pass through AC power has become intermittent and the Heart Interface unit is no longer manufactured (so the identical replacement is not an option). Olivier’s comment below has made me stop and rethink this!

The unit I was about to purchase is http://magnumenergy.com/ms-pe-series-invertercharger/ Model MS4124PE

I am assuming the unit needs to be “isolated” somehow. I also assume the unit ground must only be grounding the metal cover and not connected in any way to the 24vdc Neg. to ensure the Amel ground system remains unconnected.

What questions should I ask of the manufacturer to ensure I will not compromise the integrity of the ships grounds system?

Has anyone installed a unit like this and can you offer some forethoughts?

Many thanks!

With best regards,


Super Maramu 2000

Hull #275


From: amelyachtowners@... [mailto:amelyachtowners@...]
Sent: Wednesday, January 28, 2015 3:39 AM
To: amelyachtowners@...
Subject: Re: [Amel Yacht Owners] Re: Prop Shaft Electrolysis

Good morning Kent,

what lies in you very long message makes me think that your electrician knows what he's talking about.

Some combined inverters/chargers have internally a connection between the negative DC and their metal body. This is why you want to measure the resistance between negative DC and "corrosion bonding system".

This resistance must be infinite (no connection).

Amel never installed inverters/chargers (in the same device) on purpose.

The second spot you may have a problem is on your new engine:

With the DC ON (12V and 24V), there must not be any power (+12, -12, +24,-24) on the engine's body, while the engine is running and while it is OFF.

Only for a few seconds (pre-heating plugs, starting and stopping) the 12V negative is connected to the engine's body through a solenoid switch. Other than that, the engine's body must be isolated from the 12V negative.

All engines are not designed/connected like that. Your engine's wiring must be an isolated one. The alternators too.

I'm sure you're on the way to find the fault.

Best regards.


On Tuesday, January 27, 2015 10:42 PM, "'Bill & Judy Rouse' yahoogroups@... [amelyachtowners]" <amelyachtowners@...> wrote:


I think the suggestion to use a small bulb is to ensure that the voltage measured by a meter continues. Using a bulb will remove any capacitance (stored electricity)...you could also remove any stored electricity by touching the two poles that you are measuring together.

I wish I could help more, but it sounds like your electrician will find your problem.


BeBe 387

On Tue, Jan 27, 2015 at 2:52 PM, Kent Robertson karkauai@... [amelyachtowners] <amelyachtowners@...> wrote:

We're not sure yet, Alan. It's not the negative DC, but the one drawing we could find shows it connecting to the AC ground as well as the bonding system...



From: "divanz620@... [amelyachtowners]" <amelyachtowners@yaho ogroups.com <http://ogroups.com/> >
To: amelyachtowners@...
Sent: Tuesday, January 27, 2015 3:09 PM
Subject: [Amel Yacht Owners] Re: Prop Shaft Electrolysis

Wow, thats a lot of info....

The ground on the Sterling device is it just a ground for the metal case or is it the actual DC negative ??

If it is the negative and its connected to the boning system and / or the AC ground, that could well be the cause of your problem.

Sounds like Mike knows what he's doing....

Good luck


SV Elyse SM437

Gulf Harbour

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