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Connecting Victron To Batteries


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I need to connect a Victron Multiplus Inverter/Charger to my batteries.

The manual says wire it through a switch and a fuse to the batteries.

Their wiring diagrams show it wired straight to the batteries.

The unit itself has a large fuse in it so why do I need another one? Is that just to protect the cable between the batteries and the Victron? All 4ft of it?

The Victron gives a healthy spark when you connect it to the battery poles, even when switched off, so presumably it contains a capacitor device across its inputs. I don't like the idea of leaving such a thing live when I am off the boat as I've had capacitory things fail before at home. So I should have a switch in the circuit, but then I understand that that would not be a good thing from the charging point of view as every extra resistance is bad news.

Finally I have the nasty battery isolator switches with the red fall-off-at-the-most-inconvenient-moment handles and the suppliers leaflet tells you everything except their maximum load. Could an inverter overload it (a general question as I've not given full details)?

 

So, how should I wire it please? And how do you do it (If different!)

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Fuse .... as close to the batteries as possible

 

Isolator yes....scrap that red thing and get a proper one

 

If the isolator is a good one the volt drop will be minimal

 

Make sure your cables are big enough, it is in the manual but I think 50mm2 is minimum. To big is better than not big enough.

Edited by bottle
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I sometimes fit an MRBF at the battery end too, the cable is then fully protected against shorts, with an internal fuse in the Vicky if there is any problem in the cable causing a short, though the Vicky one will blow there is still a path to ground from the battery bank unless a fuse is fitted both ends. If the cable is really short and well protected it is probably belt and braces.

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I think I'm right in saying you fuse to protect the cable not device.

 

Otherwise make sure you use at least the minimum cable. On my Victron it requires 2 for each the + & - wires. I can't remember the size now but each as thick as my index finger. I then have a 400amp isolator and a 400amp fuse.

 

Victron 12/3000/120-50

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You need the fuse at the battery end & the inverter end as they are both power sources feeding into the wire from different ends.

 

Re the spark when connecting the inverter.

 

You should remove the internal fuse then connect the bat wires then refit the internal fuse.

 

Our 12/3000/120/16 is wired using 120mm2 cable.

Edited by Justme
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You need the fuse at the battery end & the inverter end as they are both power sources feeding into the wire from different ends.

 

Re the spark when connecting the inverter.

 

You should remove the internal fuse then connect the bat wires then refit the internal fuse.

 

Our 12/3000/120/16 is wired using 120mm2 cable.

 

On the early Victron's it wasn't a fuse but a removable high current jumper you disconnected. Connecting main input terminals to the batteries you then got a green LED if the polarity was correct, allowing you to replace the jumper with the knowledge that battery polarity was correct.

 

A 400 or even 500 amp fuse close to should be fine as well as 70mm² battery cable for a run under 1.5 metres or 90mm² up to 4 metres. If you use an isolator then it should be well overrated. I use a 600 amp continuous (popular size) BEP one with a 3200 watt inverter.

 

As suggested the initial spark on connection (avoided with an isolator) is from an internal capacitor charging.

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Don't know about the latest models but Victrons are/were not polarity protected, so remove fuses just in case you get it wrong, then double check connections are the correct polarity before refitting fuses.

 

They are not. Don't ask me how I know this. Ever heard a 400amp fuse blow?

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Not sure what it does but I am sure that it is the recommended method.

 

I did see in one inverters instructions to use a large resister to make a jumper to fit before making the final connection to allow the capacitors to charge up slowly. That then stops the big sparks.

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On the early Victron's it wasn't a fuse but a removable high current jumper you disconnected. Connecting main input terminals to the batteries you then got a green LED if the polarity was correct, allowing you to replace the jumper with the knowledge that battery polarity was correct.

 

A 400 or even 500 amp fuse close to should be fine as well as 70mm² battery cable for a run under 1.5 metres or 90mm² up to 4 metres. If you use an isolator then it should be well overrated. I use a 600 amp continuous (popular size) BEP one with a 3200 watt inverter.

 

As suggested the initial spark on connection (avoided with an isolator) is from an internal capacitor charging.

Be aware that fitting an isolator switch does not eliminate the spark, just moves it to the switch contacts. Heres the internals of a BEP 600A after just a couple of months of the "switch off every night" routine.

 

4847068173_0c0405e000_z.jpg

 

We now leave the Victrons on 24/7, but I have fitted a 470 ohm resistor across the switch terminals in series with a small push button switch. If the Isolator has been turned off, then pressing the push button for 20 seconds will charge the capacitors; that will eliminate the arcing and protect the isolator.

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