12V inverter issues

[Thematrix12]

Hi all

Having a few issues with a 12V inverter powering a 240V TV (2A max). It kept coming on for a few minutes before then going off and the inverter throws up a red light. Purchased a new inverter and it's doing exactly the same thing - although this one indicates overheating/fan does not run (according to manual) - weird when it's only been on a few mins. These were both modified sine wave inverters.

The battery is fine. Voltage is fine. Cable is fine. I've just ordered a pure sine wave inverter to give it a whirl but I am of the distinct impression that what I'm trying to do should work fine on a MSW inverter.

Does anyone have any prior experience or any ideas to suggest?

 

[JTQ]

It could as you no doubt question be that the electronic circuitry of the TV, might not cope with a modified sine wave?

I assume both, the Wattage ratings are adequate, and the wiring to the inverter is amply heavy enough not to cause too large a voltage drop?

 

[Thematrix12]

It could as you no doubt question be that the electronic circuitry of the TV, might not cope with a modified sine wave?

I assume both, the Wattage ratings are adequate, and the wiring to the inverter is amply heavy enough not to cause too large a voltage drop?

Thanks for the super quick reply.

The inverters were rated at 150W/200W respectively (more than enough for the 25W the TV draws including an overhead). Wiring to the inverter is 3mm (brand new stuff put in last week) and can carry 33A. Voltage difference between the 12v terminal and the battery is 0.01.

It might be the TV. I was hoping to find something else around the house with a similar power draw to test it but no luck. Weird as the TV used to work fine on the 150W inverter on the bog standard factory fitted 6A socket (until you turned the pump on!).

I'll try the PSW inverter. If it's still not good then I'll have to dig deeper and try a carousel of different cabling, inverters, devices etc

 

[ProfJohnL]

It's impossible to remotely give you a cast iron answer because I cannot test the appliances in question, but from other experiences I have had with various devices, that some of them do not like MSW inverters despite the apparent rating capability.

It's the impurity of the waveform that can upset loads that have a high inductance input. Having said that I have not found MSW that indicate a fault when connected to these loads, so something else is going on for you.

The common factor for you seems to be the inverters, and the fact that they both fail but in different ways does suggest one or possibly both are faulty.

There are now loads of cheap Chinese inverters swamping the markets, they are cheap because they often don't have the same quality of design and strength of components, and there are examples where the unit falls well short of their stated capacity. We have seen similar poor situations with Audio amplifiers where they may be quoted as offering 1000W but that's a peak capacity where the actual true RMS rating is more like 25W.

Generally PSW inverters produce fewer failures, but the compromise is PSW inverters are typically 30% less efficient than MSW's .

 

[Thematrix12]

It's impossible to remotely give you a cast iron answer because I cannot test the appliances in question, but from other experiences I have had with various devices, that some of them do not like MSW inverters despite the apparent rating capability.

It's the impurity of the waveform that can upset loads that have a high inductance input. Having said that I have not found MSW that indicate a fault when connected to these loads, so something else is going on for you.

The common factor for you seems to be the inverters, and the fact that they both fail but in different ways does suggest one or possibly both are faulty.

There are now loads of cheap Chinese inverters swamping the markets, they are cheap because they often don't have the same quality of design and strength of components, and there are examples where the unit falls well short of their stated capacity. We have seen similar poor situations with Audio amplifiers where they may be quoted as offering 1000W but that's a peak capacity where the actual true RMS rating is more like 25W.

Generally PSW inverters produce fewer failures, but the compromise is PSW inverters are typically 30% less efficient than MSW's .

Thanks John. I've ordered a PSW to try.

My understanding was that PSW is more efficient than MSW? I must have these round the wrong way.

IT certainly is strange why both MSW inverters are having issues. I'm going to do more digging over the weekend to nail it down and experiment trying from the car too. I have a feeling it's something to do with the caravan wiring/battery but as voltage/connections are fine I'm struggling to nail it down.

 

[JTQ]

I have a feeling it's something to do with the caravan wiring/battery but as voltage/connections are fine I'm struggling to nail it down.

Were your "tests" done with or without the van on an EHU?

The thoughts here are if the van's battery was not "fine" as stated, but "iffy", and that factor played a part, then being on the EHU ought give it some support.

 

[Guzzilazz]

A 2A 240V inverter is near enough 500 W. I have a 350 W Belkin inverter on the boat that I use to run a 38W soldering iron primarily, and that pulls hell out of my 330AH domestic battery bank, indicating low voltage within less than a minute. I have to run the engine to run the inverter....

 

[Thematrix12]

Were your "tests" done with or without the van on an EHU?

The thoughts here are if the van's battery was not "fine" as stated, but "iffy", and that factor played a part, then being on the EHU ought give it some support.

Without EHU. The voltage didn't waver too much.

A 2A 240V inverter is near enough 500 W. I have a 350 W Belkin inverter on the boat that I use to run a 38W soldering iron primarily, and that pulls hell out of my 330AH domestic battery bank, indicating low voltage within less than a minute. I have to run the engine to run the inverter....

Sorry, meant 2A at 12V.

Think you may have an issue with yours too. 38W at 12V (even with overheads) is less than 5A. 330Ah battery should be able to run that for quite a considerable amount of hours!

 

[Woodentop]

Forget amps. The wattage is essentially the same whether running at 12V or 240V. Therefore the 38W soldering iron will also draw 38W from 12V and allowing for, say, 80% efficiency in the inverter you would be pulling 38/0.8 or about 48W off the battery.

 

[Thematrix12]

OK, tests so far.

New inverter is having same problem running the TV from leisure battery and from car battery. So unless the TV is somehow ruining the inverter then it is the new inverter at fault. I suspect the fan in it is broke as it never seems to come on and the inverter is warm.

Now trying old inverter (MSW) and seems fine at the moment. PSW arriving tomorrow so going to try that too.

 

[ProfJohnL]

Certainly based on what you have told us, the wiring should be OK, but with inverters its always best to keep the low voltage wiring as short as possible, to minimise current heating losses. It better to extend the high voltage side.

Sorry Woodentop You can't forget the Amps, because you must ensure both the battery and the 12V wiring are capable of carrying the current required. Agreed an invereter is notionally a constant power converter, but its approximately a conversion ratio of 1:20 so a 230V device needing 1A translates to 12V at 20A plus a bit for losses.

Guzzilass - If a 38W soldering iron flattems a 330Ah battery in less than a minute, then you have a problem somewhere. 38W at 12V is less than 4A!

 

[Thematrix12]

Certainly based on what you have told us, the wiring should be OK, but with inverters its always best to keep the low voltage wiring as short as possible, to minimise current heating losses. It better to extend the high voltage side.

Sorry Woodentop You can't forget the Amps, because you must ensure both the battery and the 12V wiring are capable of carrying the current required. Agreed an invereter is notionally a constant power converter, but its approximately a conversion ratio of 1:20 so a 230V device needing 1A translates to 12V at 20A plus a bit for losses.

Guzzilass - If a 38W soldering iron flattems a 330Ah battery in less than a minute, then you have a problem somewhere. 38W at 12V is less than 4A!

Thanks John.

Now trying old inverter and lo and behold it's been fine for 30 mins so far. If the PSW one works fine then I'm going to keep that and use that instead.

 

[Guzzilazz]

Certainly based on what you have told us, the wiring should be OK, but with inverters its always best to keep the low voltage wiring as short as possible, to minimise current heating losses. It better to extend the high voltage side.

Sorry Woodentop You can't forget the Amps, because you must ensure both the battery and the 12V wiring are capable of carrying the current required. Agreed an invereter is notionally a constant power converter, but its approximately a conversion ratio of 1:20 so a 230V device needing 1A translates to 12V at 20A plus a bit for losses.

Guzzilass - If a 38W soldering iron flattems a 330Ah battery in less than a minute, then you have a problem somewhere. 38W at 12V is less than 4A!

It doesn't flatten the battery but because I use a "conservative " lower 12V limit setting on the inverter the alarm goes...

 

[ProfJohnL]

It doesn't flatten the battery but because I use a "conservative " lower 12V limit setting on the inverter the alarm goes...

It still seems very odd that a modest 4A 12V load for 1 minute on a 330Ah system (assumed the batteries are fully charged) should cause a low voltage alarm to go off.

 

[Thematrix12]

Thanks John.

Now trying old inverter and lo and behold it's been fine for 30 mins so far. If the PSW one works fine then I'm going to keep that and use that instead.

New PSW inverter has arrived. All works fine. No noisy fan. Have used it today with a battery charger to charge my car as a test and 10 hours later all is still good. 👍🏼

 

[Beachball]

New PSW inverter has arrived. All works fine. No noisy fan. Have used it today with a battery charger to charge my car as a test and 10 hours later all is still good. 👍🏼

i am pleased everything working fine as i said they are great bunch on here any more questions you will get some answers