Inverter woes

Golwgymynydd · Jul 11, 2022

I have built a campervan and am keen to avoid propane - preferring to use an induction hob.

But it is giving me some issues.

I have 610w of solar on the roof and use a Victron mppt charger (set to spiral) to charge 2x brand new Leoch 110ah AGM leisure batteries wired in parallel.

I bought a cheap Chinese 2000w(4000w peak) pure sine wave inverter but it alarms and cuts out when the induction hob is pulling 1200w or higher.

So I bought a Renogy 3000w inverter (6000w peak) that is better quality. But I get the same result - alarming and cutting out but at any current draw.

Talking to Renogy they suggest I need more battery power. Talking to the battery supplier they say an additional identical battery wired in parallel will make no difference (I guess they feel their batteries should be able to provide the constant 170A required to drive the induction hob for 30 minutes.

So I am stuck.

Looking at voltages across the shunt - the inverter drops the batteries from 13.79v down to around 12v when loaded at 1600w and the tech specs suggest the inverter should only shut down when it drops to 10.7v

There is a 250A breaker in line that is not tripping.

The cables are heavier than supplied by the inverter manufacturer and should be good for 500A so I can’t see the cabling as being the issue. No cable is over 500mm in length.

The cables linking the batteries are 25mm2 as are the cables feeding the inverter.

So now I am scratching my head

Any thoughts gratefully received.

binky · Jul 12, 2022

so many of htose inverters seem to specced on the 'optomistic' side. I've not had much to do with such things, but the experiences I've had have mostly been 'disappointing'. I would have a look at Victron gear, and possibly talk to their technical helpline before purchasing anything.

johnb2713 · Jul 12, 2022

What is the spec of the induction hob?

Lots of induction hobs and microwaves take a huge load to get them started, I had a microwave in my caravan that took over 3kW at startup, settled to around 1100w after 1 second or so. I had a dreadful time finding a suitable inverter, I did eventually sort one, pure sinewave with remote on/off 3.5kW constant 7kW peak. Try your setup with a resistive load around same value as the hob and see if that operates if it does you know it's a momentary draw getting started.

binky · Jul 12, 2022

johnb2713 said:
What is the spec of the induction hob?

Lots of induction hobs and microwaves take a huge load to get them started, I had a microwave in my caravan that took over 3kW at startup, settled to around 1100w after 1 second or so. I had a dreadful time finding a suitable inverter, I did eventually sort one, pure sinewave with remote on/off 3.5kW constant 7kW peak. Try your setup with a resistive load around same value as the hob and see if that operates if it does you know it's a momentary draw getting started.

that's interesting, perhaps nursing the hob on would work? IE start at a low heat and then turn it up.