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Connecting up an Inverter


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A quick question . I am just about to connect an 800 Watt Sterling inverter to my twin leisure batteries. I realise that the positive goes to one battery and the negative to the other battery as they are wired together in parallel with thick cables.


Is there any sequence in connecting ? Negative first then positive ? I know with engine batteries there is.


Spanner in hand waiting !!!!

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Unless the inverter has its own 12V on/off switch, you do not want to do this!

You first need to insert a suitable capacity 12V switch in the live feed to the inverter, otherwise its quiescent current will take a heavy draw on your batteries.  Then, providing the switch is in the off position, it won't matter which order you connect.  If the inverter has an on/off switch on the 12V side, switch it off before connecting.

As a general rule it is good practise to connect first to the negative battery terminal, and last to the positive terminal, with all other terminations being made before either of the above are connected, so that any odd ends of cable aren't left live and flapping around.  Make sure the 230V mains is isolated before connecting to the batteries, in case you upset the on board charger.  You ought really, in the interests of the charger, to install some kind of relay protection to ensure you can't accidentally switch on the inverter with mains connected.  The inverter will suddenly pull around 75-80Amps from the batteries if worked at capacity, which might frighten the charger into submission!

Once connected and tested, switch the inverter 12V feed off until 230V current is required, and turn it off again as soon as the 230V use has ended.  It would be a good idea, unless the inverter is so equipped and visible, to stick a large, bright red LED, somewhere annoyingly visible, to indicate that the inverter feed is live.  Then, you'll be unlikely to forget, it and accidentally leave it on.

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Thanks for the replies.

I have connected to the negative first, positive second and the inverter has a switch and light on the 12 Volt input side.The van is not plugged into a hookup.

The inverter has a lead up into the van cab with a red LED light showing on a 240 volt socket when live.


So hopefully I have covered all of your recommendations. Everything working OK. Very useful to be able to get an answer from the forum !!

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Thought it was going too well !!!

Fitted the inverter next to the batteries. Connected red to positive on one battery , black to negative on second battery. They are fitted in parallel with thick cables.

Switched on the inverter .Plugged in a bedside light to the three pin socket and eureka, all working !

Turned the inverter OFF and left the job of running a cable through to the cab for today. Switched on the inverter this morning and a red light was showing low battery . My Schaudt control panel was flashing CHARGE on the leisure batteries and the solar regulator was flashing a code meaning low battery.

So I disconnected the inverter from the leisure batteries and plugged the van in to my electric hookup.

Tonight the Schaudt control panel has stopped flashing alert and the batteries are recharged. The solar regulator is still flashing showing low battery .


So I am perplexed. Any ideas ?

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Thanks Brian,

I have rung the supplier of the Sterling inverter who reckons the switch on the inverter definitely cuts the 12 Volt supply to it.

I have been told to cover the solar panel over and pull the fuse from the solar. This should reboot.

This morning my Schaudt was flashing and showing 15.7 V on the engine battery and 16.5 on the leisure !! I think the solar regulater and the Schaudt are compromising each other.

When connecting the inverter the other day I must have temporarily disconnected the solar regulator which needs to reboot.

If all else fails its back to Highbridge(Somerset) and let Adventure motorhomes sort it out

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Does your solar regulator automatically detect 12 or 24 volt systems (batteries). If so I think it has got inself in a dissy. If so Solar regulators have to be connected to teh battery 1st and then teh solar panel. In effect coerng te panel as suggested by dealer and disconnecting battery and reconecting will effect a cure...or should.


I suspect when you connected up the invertor you caused the solar panel regulator to get confused as it will have lost battery power but remained with some power from the solar panel.


If your batteries are in poor condition, in other words quite old or well used, then adding something like an invertor with its massive peak currents can be the last straw for the batteries.

Good luck.




edit- typos.

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Covering the solar worked and regulator showing 100 %.

Disconnected the hookup and reconnected the invertor.

Thats working and have managed NOT to disconnect the solar this time !!


BUT I have upset the Schaudt control panel which is flashing and needs resetting date and time.


Batteries are 6 month old


So thats the next problem to sort.


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Many thanks for all your advice.

Touch wood everything is back to normal and the inverter is connected. Schaudt and solar regulator all showing full charge and no flashing alerts.

But I can recommend Adventure Motorhomes at Highbridge ,Somerset for the original solar fitting,supply of the Sterling Inverter(much cheaper than any on-line supplier) and a lot of advice over the phone.

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