Inverter/Electrical question

[Lokken86]

So I've got a little solar system all set up now with 300w of panels connected to a (currently) single 100ah 12v battery and I'm doing a little testing putting it through its paces. My problem is the circuit breaker keeps tripping if I run something like a kettle which uses about 2000w.

The inverter I have is a 2500w pure sinewave 12v connected to the battery via 70mm2 (0/2awg) wire approximately 1meter for the ground and 70cm the live with a 250amp circuit breaker in between.
To my understanding 2000w/12 = 166amps, not enough to trigger the circuit breaker.

Am I asking too much from a single battery? I did see quite a hefty voltage drop as the controller was reporting less and less volts until about only 25% capacity before the breaker popped open.

Would more batteries wired in parrallel help me or a bigger circuit breaker or both? I guess the inverter itself isn't an issue since the breaker is going off before the inverter does.

 

[bremen1874]

Your calculation assumes 100% efficiency. It obviously won't be, so there's additional current there.

If the output stays constant and the input voltage is dropping then the current will be increasing (I think).

Your '2000W' kettle could be pulling more current than you think.

 

[Lokken86]

Your calculation assumes 100% efficiency. It obviously won't be, so there's additional current there.

If the output stays constant and the input voltage is dropping then the current will be increasing (I think).

Your '2000W' kettle could be pulling more current than you think.

I see. There is actually a recommendation of using 300amp circuit breakers for a 2500w dc inverter I didn't understand why before. I also preferred, due to the length and size of wire I originally had, to keep it lower not realising there would be so much losses over the line . Now that I have the 70mm2 I could try a 300amp breaker and see how it goes.

 

[LuckyBenski]

I'd suggest that 150+ amps is a ****load to actually draw from a single battery. Losses will be big but also as you have seen it will create a big voltage drop through internal resistance. It's simply more current than a battery like that can deliver continuously.

I could be wrong as most of my experience with this gear was supercapacitors, but car batteries aren't known for limitless current.

I'd also suggest that a 2kW heating element isn't really the idea with car batteries or inverters at this scale but I'm sure you've done some research. You could certainly consider a caravan kettle though - direct 12V will be more efficient. They're usually just a reduced power.

 

[Rroff]

Depending on what kind of battery it is but a typical 100ah 12V battery isn't really designed for sustained loads over 30-50 amp ~600 watt max so more useful for a travel kettle or the likes though they can do 100s of amps for short periods if a car battery, etc.

IIRC a typical kettle can peak at near 3kw as well (depending on model and circumstances).

 

[Terminal_Boy]

Vehicle batteries are designed to supply high currents, but only for short durations.

I suspect that the OP has a marine/leisure battery which aren’t designed for high current discharge at all.

It’s far more efficient to power 12V DC equipment from such an arrangement as the DC>AC conversion losses are significant in all but the most expensive inverters.

 

[wandgrudd]

So I've got a little solar system all set up now with 300w of panels connected to a (currently) single 100ah 12v battery and I'm doing a little testing putting it through its paces. My problem is the circuit breaker keeps tripping if I run something like a kettle which uses about 2000w.

The inverter I have is a 2500w pure sinewave 12v connected to the battery via 70mm2 (0/2awg) wire approximately 1meter for the ground and 70cm the live with a 250amp circuit breaker in between.
To my understanding 2000w/12 = 166amps, not enough to trigger the circuit breaker.

Am I asking too much from a single battery? I did see quite a hefty voltage drop as the controller was reporting less and less volts until about only 25% capacity before the breaker popped open.

Would more batteries wired in parrallel help me or a bigger circuit breaker or both? I guess the inverter itself isn't an issue since the breaker is going off before the inverter does.

Same issue ???

https://youtu.be/SVLGHB2IxxU

 

[Lokken86]

Same issue ???

https://youtu.be/SVLGHB2IxxU

My inverter is already a soft starter. I actually think the main issue is the circuit breaker is junk and going off well below it's rating so I bought some inline mega fuses to replace it with and I'll test it soon.
I did add a second battery also to see if it made an improvement.. to the voltage drop it didn't drop quit as much but improved only buy +0.2v.

 

[Lokken86]

Installed this bad boy and it works a treat.

Spoiler: Fuse

Boiled the kettle with it

Basically don't buy those cheap Chinese circuit breakers. Bit of a shame I thought because they could have been super handy. Unless of course you want to use a 250 one as a 150.

I'm still going to go for some lower power consuming appliances just to keep the strain on the system to a minimum but I'm glad it can be used full power for short periods of time if I wanted it.

 

[jpaul]

... as commented multiple times your lead acid batteries probably not spec'd for kettle current draw, and it may cause battery damage, or safety issues.

 

[Lokken86]

... as commented multiple times your lead acid batteries probably not spec'd for kettle current draw, and it may cause battery damage, or safety issues.

Yes and I said I am going to buy a low wattage one but also if you have multiple batteries in parallel it will actually increase the discharge rating.

 

[FRM2005]

Hi I've have a 2000w pure sine wave inverter in my van. Its currently connected to 2 100ah 12v batteries wired in parallel. My issue is when running my 800w microwave the voltage drops considerably sometimes causing the unit to alarm and shut off. I also have a voltage sensitive split charge relay which is connected to the main battery of the van and the two leisure batteries. The system works OK when the van is running and the relay is engaged however the relay constantly clicks on and off when the microwave is on. The input voltage drops to 10.3volts and the output to 192volts causing the microwave to slow and sometimes stop completely. Any advice would be really appreciated. Cheers Daz

 

[LuckyBenski]

So you're looking at about 66 amps at 12V nominal, to pull 800W. Plus any inefficiency I'm the inverter. That's 35 amps or so per battery, not insignificant.

What type of batteries are they? Lead acid/gel/other?

And what's their charge state before the load is applied? IIRC 12V is actually quite low for a car battery.

As the sine wave inverter will be constantly switching on and off I would expect a capacitor on the batteries might help smooth out the loading.

 

[bremen1874]

And an 800W output microwave will be pulling 1200W+ from the wall.

 

[FRM2005]

Hi thanks for posting, the batteries are around 13.5v when the relay switches over to charge state.
It drops down to 10.3v and fluctuatates 10.3 10.4 when the load is applied. This is also when the relay is engaged.
Both batteries are 12v 110ah lead acid wired in parallel.