Inverter / charger loop

[mrplastic]

I am fitting a 1kw PSW inverter to my beneteau 331 and am wiring it into the main supply box using a DPDT 30A
relay with a 12vdc coil. Shore power is supplied via the normally closed contacts and invertor output via the N/o contacts with the relay energised with a remote switch. My concern is the possible damage to the onboard battery charger. What if anything is likely to happen if the charger is supplied by the inverter output and resultant charging loop? Obviously this will consume more power than it outputs but is it likely to cause any damage?

Also, how do I address the earthing?

Any advice is appreciated

 

[Jabs]

I would suggest that you power the charger 'upstream' of the change over relay so it cant feed from the inverter.

It sounds as if you might be intending to leave the inverter running??

Think of the quiescent current. Might not be a good idea.

Best of luck.

Tony.

 

[mrplastic]

I would suggest that you power the charger 'upstream' of the change over relay so it cant feed from the inverter.

It sounds as if you might be intending to leave the inverter running??

Think of the quiescent current. Might not be a good idea.

Best of luck.

Tony.

The relay actually has 3 sets of contacts, the 3rd set being used for remote switching of the inverter. So activation of the coil will disconnect the shorepower and connect and activate the inverter. I chose this method so that i would be impossible to have the inverter running at the same time shorepower was present. The relay coil is powered via a panel mounted rocker switch which illuminates when on showing that the inverter is connected.
The charger is an integral part of the mains distribution board so not easy to move its feed, i would prefer to power the whole board directly from the inverter as it means that all the sockets will receive power without any additional wiring.
I can easily swictch off the charger before activating the inverter but would be keen to find out potential issues that would arise if it was left on. The reason for fitting this system is to make it possible to use low wattage mains devices when at anchor, and occasional use of a microwave (I have done the sums and have sufficient battery power for its intended use) this is not intended to be a full mains replacement system.

 

[prv]

The charger is an integral part of the mains distribution board so not easy to move its feed

It's not right next to the batteries, then? Seems an inefficient way of doing things, resulting in the need for thick 12v cables instead of thin 240v ones.

I'd be surprised if the battery charger supply can't be separated from the panel, as I'd have expected the panel builders to simply package up an existing design of charger.

this is not intended to be a full mains replacement system.

Best make sure it isn't also trying to supply the calorifier immersion heater, then

Pete

 

[Richard10002]

If you merely want to know the downside, it's flat batteries. The more you do it, the more likely your batteries won't recover... They might not recover after only one flattening - Ask me how I know

I can't see it damaging your charger, (although it might), All you would be doing is reducing the voltage to the charger until either of them reached their low voltage level, and activated their low voltage protection..... Which might be a cut out.

I have an inverter charger, and a separate charger. I usually use the inverter charger but there are situations where I would use the separate charger, (e.g. If I left the boat on mains charge for days/weeks while I left it).

To avoid your problem, I have 2 Consumer boxes. The mains shorepower inlet feeds the first unit which has outputs to the inverter charger and the separate charger. The inverter charger then feeds the second unit, which has one output to the 240v sockets around the boat.

The separate charger can't be fed by the inverter.

In your case, you might need some kind of 1-0-2 switch to avoid feeding your 240v ring from both the inverter and the shorepower mains - you might already have this?

 

[mrplastic]

It's not right next to the batteries, then? Seems an inefficient way of doing things, resulting in the need for thick 12v cables instead of thin 240v ones.

I'd be surprised if the battery charger supply can't be separated from the panel, as I'd have expected the panel builders to simply package up an existing design of charger.



Best make sure it isn't also trying to supply the calorifier immersion heater, then

Pete

What makes you think its not next to the batteries? Its actually just 600mm away and connected using 20mm2 cables. The remote switch is on the panel and that just activates the relay, so not inefficient at all....not that inverters can ever be termed efficient!

 

[mrplastic]

I have carried out some tests with the inverter in a loop and with the charger isolated, barely any difference measured when using low wattage mains devices, the rub comes when powering up the microwave, the charger kicks in within a few mins and the batteries voltage falls off a bit faster then it does when the charger is isolated but not as much as i expected. The charger itself shows no signs of distress so other than a faster drain so not a huge problem.

 

[rosssavage]

When I forget to turn off my Waeco charger before switching off the gennie (gennie / inverter auto changover system) the inverter makes a funny squealing noise then turns itself off.

The squealing noise is part of the inverters protection system, but I haven't worked out if it's under volts or overload. Either way, turn the charger off, reset the inverter and all is good. Probably really bad for the inverter, but having done it a few times now no harm done (yet...).

Future mod is to fit a charger / calorifer interlock. Relay with 240v coil powered from changeover relay, inhibiting the charger and immersion heater when the inverter is supplying power to the boat.

 

[GrahamM376]

In your case, you might need some kind of 1-0-2 switch to avoid feeding your 240v ring from both the inverter and the shorepower mains - you might already have this?

I've fitted a 1, 0, 2 switch mainly because without it the shore power socket was live whenever the inverter was on, which could spoil someones day. I've occasionally forgotten to switch the charger off when powering up the inverter, battery monitor instantly shows up the excessive load.