Is the 1150 watts, input or output?

If it is output the microwave will use a lot more for input. Let's say about 1600 watts input. 

At 15% inverter & wiring inefficiency, you are looking at about 133 amps if the batteries are in top notch condition. Probably more likely 150 amps at the lower voltage as the battery is gasping for life.

If you have a few batteries in parallel it will be a lot easier on each battery.

Even though I have small batteries, the 4 of them will provide 360 amps for 5 minutes.

Not to forget that when you draw a very high current from a battery it's effective capacity drops by half, or worse. 

& if you only every want to drain batteries to no more than 50%, at a very high draw rate the battery effectively only have a capacity of 25% of it's rated AH at best.

So basically for very high current appliances, at least double your battery set-up. So if you already have 2 batteries, you should have 4. At the very least, add another battery to spread the high current load.

A similar issue, a Birko 750 watt kettle is a lot more friendly on batteries than a typical 2000 watt kettle.

Slower wins the race!

Also, what is the total length of wire from batteries to inverter?

Wire resistance is the total length of + & - so in other words if you have a 1m cable. It's actually 2m for calculating wire resistance for + & - wire length & thus the cross sectional area of the copper.

So let's say 2m at 150 amps (because the inverter is sucking the life out of the battery), & we are at 11 volts.

You are looking at about 3.6% voltage drop in the wire resistance. Doesn't sound a lot, but it is actually about 0.4v. On a 12v system, this hurts!

Use at least 4awg, or double up your 6awg cable.

The data sheet for my 26AH battery:

93 amps 5 minutes (7.8AH)

or 

43 amps 20 minutes (14Ah)

or 

17 amps 60 minutes (17AH)

or 

4.6 amps 300 minutes (23AH)

or

2.6 amps 600 minutes (26AH)

So on the really high draw situation (I have 3 air compressors in parallel to pump up tyres quickly), so with 4 batteries I get basically double the battery AH. Or from a single battery point of view I don't have half  the AH (& a shorter battery life).

Batteries will appreciate the load amortised across all 4 of them.

Some of the older microwaves tend to draw more current on startup.  As suggested try using a lower power setting. Also if your fuse is a resettable type some of the cheap ones can case issues.  I use ANL fuses so try a 150A but make sure you upgrade your wiring.

https://www.jaycar.com.au/150a-gold-anl-wafer-fuses/p/SF1995?pos=4&queryId=fa1a07e87170681b0c01dcf3feb5cefc

Tim

The value in these threads is for the ones who are actually capable of usimg the search function instead of asking the same old question ad nauseam. 

Use quality products & build in redundancy. Switches to isolate each solar panel for quick testing. Who wants to be urgently looking for parts on the Gibb River Road.

Benchmark your system as soon as you buy it or inherit a second hand system.

If you don't already have a few tools. Buy some measuring devices. The cost of any system includes maintenance devices & regular checking. No difference to getting the car checked regularly.

I have handed out quite a few fuses to the brain dead in the outback & a few containers of fuel... gifted!

Looking at the Victron 3000VA (2400 watts at 25°C, 1700 watts at 65°C) inverter. 533 x 285 x 150mm 19kg.

Input voltage range 9.3 to 17 volts. 92% efficiency, double pair of M8 bolts for 12v connection (no mucking about!).

https://www.victronenergy.com/inverters/phoenix-inverter-smart 

Disclaimer, all my gear is Victron, couldn't be stuffed with cheap failed products in the outback. Not worth the cost.

yobarr wrote:

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 NO sympathy for those who buy El Cheapo and then cry when it turns out to be rubbish. So Sad, Too Bad, Poor Lad. Cheers

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 I learnt many moons ago from Wifey, make sure thing don't fail. Simply not worth it, you will be reminded & suffer beyond eternity plus some. Not worth it. A Victron 3000VA inverter looks cheap to me.

jeepnudger wrote:

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I appreciate all the comments, HAVE WAITED TO READ ALL COMMENTS BEFORE ANSWERING. The 3000w inverter had that it could handle peak 6600w, said it was pure sine wave. I did buy on line as relatively cheap compared to say Jaycar. The leads into inverter were less than 1/2 metre to parallel  AGM 120A batteries. The microwave is a LG smart inverter.

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 Welcome back Jeepnudger.

Ignore the unhelpful stupid comments about the inverter you have bought.

I have mentioned the fuse but a good way to test your inverter is to run different wattage appliances through it.  Start off with something small and then step up to higher wattage appliances without motors if possible.

Also the cables that come with many inverters are not large enough, I like many others increase the cable size and fuse appropriately.

Can you PM me the link to the inverter you have bought.

Good luck

Tim

When your income relies on a system that works you are keenly aware of lost customers forever... Optus FU.

I do not use the Chinese 3th rate rubbish. I have redundancy having 2 solar controllers (1 backup), 2 DC-DC charterers (1 backup), 2 battery chargers (1 backup). Also have 6 solar panels (5 backups) which I can reconfigure for redundancy, not to forget 4 auxiliary batteries (3 backups).

Can charge & jump start myself (have jump started more than half a dozen cars, with 1040 amps on tap with welding cable with 2mm solid copper clamps).

The best failed report fit is fire & brimstone from Wifey!

TimTim wrote:

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jeepnudger wrote:

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I appreciate all the comments, HAVE WAITED TO READ ALL COMMENTS BEFORE ANSWERING. The 3000w inverter had that it could handle peak 6600w, said it was pure sine wave. I did buy on line as relatively cheap compared to say Jaycar. The leads into inverter were less than 1/2 metre to parallel  AGM 120A batteries. The microwave is a LG smart inverter.

---

 Welcome back Jeepnudger.

Ignore the unhelpful stupid comments about the inverter you have bought.

I have mentioned the fuse but a good way to test your inverter is to run different wattage appliances through it.  Start off with something small and then step up to higher wattage appliances without motors if possible.

Also the cables that come with many inverters are not large enough, I like many others increase the cable size and fuse appropriately.

Can you PM me the link to the inverter you have bought.

Good luck

Tim

-- Edited by TimTim on Thursday 9th of November 2023 09:19:37 AM

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Ditto.

Use the process of elimination by trying low load electrical appliances like mixers/beaters and TV's/chargers to toasters/air fryers. Even try a different microwave.

And make sure the AGM batteries are fully charged.

It appears the inverter is capable and is connected correctly but power source may be insufficient.

TimTim wrote:

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Whenarewethere wrote:

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TimTim wrote:

Ignore the unhelpful stupid comments about the inverter you have bought.

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 Really!

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 Yes really!

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 IMHO some regular poster here forget that other people have a right to their opinion and to make their own decisions also. I think this post shows that well !! My suggestion is to be more respect-full of other peoples opinion.

We get enough of pushing some agendas on weights and WDHs to put off the average posters from ever asking questions and seeking friendly information. IMHO. Gees ain't big egos hard to handle !!

Jaahn

For anyone else wondering don't believe all the victron hype, I have one of their 1300dollar dc dc chargers that struggles to do 29amps in 40degree heat. Victron make their stuff for europe climate. Their datasheets on some products use Shenzen amps.... Also power factor of the microwave may be an issue causing the inverter to have to muster up more va. By the sounds the inverter is a pile of junk and is the culprit, soo many electronics dont work properley its staggering. My victron inverter doesn't like a load with poor power factor, it just says nope....try again... Really for such loads you want a minimum of 400amp hours of AGM, agm suffers from ridiculous voltage drop and the worse it is with the myriad of cheap junk out there. Forget using ohms law... You need some serious capacity.

jeepnudger wrote:

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I appreciate all the comments, HAVE WAITED TO READ ALL COMMENTS BEFORE ANSWERING. The 3000w inverter had that it could handle peak 6600w, said it was pure sine wave. I did buy on line as relatively cheap compared to say Jaycar. The leads into inverter were less than 1/2 metre to parallel  AGM 120A batteries. The microwave is a LG smart inverter.

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I have a cheap Chinese inverter 3000/6000W pure sine wave bought on Ebay and cannot fault it. Lives up to its specifications.

That is why I recommended to jeepnudger to check the battery source charge state.

My battery bank is 405AH so plenty of source reserve.

Even the Brand Name inverters are made in China.

I went through this cheap Chinese notion when I sourced LiFePO4 batteries and also settled on cheap Chinese batteries on Ebay. Fabulous batteries!

Not everything cheap is of poor quality if you shop around.

And you can return the product on Ebay if you are not satisfied with it.

jeepnudger has not found the source of his dilemma and already the blame game is about cheap Chinese products.