question

Dosheimer avatar image
Dosheimer asked

MultiPlus 12/3000/120/50: battery disconnection bad for inverter?

Hello!

I am just before installing a MultiPlus 12/3000/120/50 into my sailboat wich shall be connected to an existing 4x100Ah AGM battery bank.

The connection shall go via a main battery switch which I would like to always disconnect when leaving the sailyacht as I do not want to leave the boat connected with something to the batteries for security reasons and to avoid discharge.

Now someone told me that this disconnection would be bad for the inverter electronic and could cause damage at it as it always should be connected to the batteries.

Could you please give me some advise here?

Many thank in advance for your support!
Dirk

MultiPlus Quattro Inverter ChargerPhoenix Inverter
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

2 Answers
JohnC avatar image
JohnC answered ·

Hi @Dosheimer

This shouldn't hurt the Multi, and many people do this.

One issue though to be aware of is when turning it back on. The unit carries a lot of capacitance and can severely spark with the inrush current, even enough to damage your isolator switch if you do it often. Perhaps a 'precharge' circuit with just a small wire and 12V globe (with some Amp capability) would be more gentle, the fading globe indicating when it's time to throw the main switch. It won't take long.

This will happen even if the Multi is turned off, and at 48V can be quite spectacular, as you can hear and see the flash from within the main switch on my system. I shan't do that again..



2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Dosheimer avatar image
Dosheimer answered ·

Thanks JohnC for your comment.

Is there a main switch existing - ready to buy - including this precharge circuit?
Many people seems to use the Blue Sea Systems 6006 main battery switch (300A permanent, 1500A for 10 sec.). But I am not able to identify if there is a precharge circuit included within this switch.

Maybe someone have a recommendation?

3 comments
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

JohnC avatar image JohnC ♦ commented ·

@Dosheimer

I don't know of any. But you just gave me an idea, hey. I use a 4-position switch similar to Blue Sea's HD, but swung around from it's original purpose, to switch one battery to two loads (one of which doesn't spark). All I'd need is a resistor (globe?) between each side (#1 & #2), and of course remember to switch the off-Multi side first.

If this makes sense, maybe you could try similar? At 12V though it's not really as serious an issue for you as it is for me. The 4-position switch might be useful though if you have 12V dc loads like lighting as well.

0 Likes 0 ·
gbntx avatar image gbntx commented ·

I saw a switch with precharge idea on diysolarforum.

https://diysolarforum.com/resources/inverter-disconnect-switch-with-precharge.60/download
0 Likes 0 ·
JohnC avatar image JohnC ♦ gbntx commented ·

Good find. That's exactly what I meant with the 4-position switch.

0 Likes 0 ·