Help required with new inverter only working on low wattage (1 Viewer)

[celticmini]

Can anyone help?


I have just had two new liesure batteries fitted now a total of 260ah onboard. I have a claimed 1500w inverter fitted professionally with 25mm sq cable, cable run as short as possible about 900mm.

The inverter works at about 800w but anything more results in a beep and shut down.

Any ideas BEFORE I return the inverter as faulty for a refund ?

The inverter is rated as 1500w peaking at 3000w pure sine wave.
I want it to run hair drier for my wife ( I don't have any hair) coffee maker and microwave all rated at under 1500w.

Batteries are fully charged and I have a 150w solar panel to keep them topped up.

 

[Stealaway]

I would say you still don't have enough battery capacity for the hair dryer.

A 1000w element will pull over a 100A from you battery's while it is switched on. They will all be total flat within a few minutes.

Although I do think your inverter is faulty and I love inverters, I wouldn't use them for any thing with a big element ever.

 

[Minxy]

First things first, what is the charge level of your leisure batteries?

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[funflair]

I dont think that your cable size is big enough, or your batteries are crap!

Martin

 

[DBK]

Does it last any longer if the engine is running?

 

[funflair]

Does it last any longer if the engine is running?

That was my next question

Martin

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[celticmini]

Batteries are fully charged!

Cable is rated at 170a, running 100a for five minutes will not deplete 260ah batteries to anything g like the 60% charge level!

Have not tried with engine running, will try tomorrow.

Anything less negative would be appreciated. Thanks.

 

[Teuchter]

I would say you still don't have enough battery capacity for the hair dryer.

A 1000w element will pull over a 100A from you battery's while it is switched on. They will all be total flat within a few minutes.

Although I do think your inverter is faulty and I love inverters, I wouldn't use them for any thing with a big element ever.

The inverter op is 230/240 v so 1000w element will draw a little over 4 amps (IxV=W) plus the losses due to the inverter say 2 amps so total of just over 6 amps

The op says it works up to 800w so a tad under 4 amps plus inverter losses - at 1500w rating it should be ok for up to 6 amps plus losses

 

[funflair]

We had a 2kw inverter on two 110ah Elecsol batteries and as soon as they were put on load they just imploded to about 10.5 or 11 volts, refitted the original old 2x80ah GEL's and all was OK, that is with something like 70mm sq cable.

Martin

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[Bart]

my 1500 Pure sine inverter beeps when the battery voltage drops low , then if you continue draining the batteries the inverter will stop.

 

[funflair]

The inverter op is 230/240 v so 1000w element will draw a little over 4 amps (IxV=W) plus the losses due to the inverter say 2 amps so total of just over 6 amps

1000 watts might be drawing about 4 amps at 240volts but that is more like 80 amps at 12volts, the inverter losses will only be a couple of amps at 12volts so pretty insignificant in the grand scheme of big current draws.

Martin

 

[Minxy]

Taking into consideration all that has been said it sound like the inverter is either duff OR has been misleading advertised (fraudulently claiming) that it can handle the capacity stated, I'd say its the latter ... sorry if that's negative, I see it more as finding a logical answer ...

What IS the inverter you've bought? Do you have a link to it?

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[celticmini]

Minxy girl that is not negative at all. Thank you!

It is Chinese but the supplier has offered a refund d so will send it back!

I will look for another one, any recommendations?

 

[funflair]

OK what are your batteries?

Martin

 

[celticmini]

Not sure, will look tomorrow. Bought off internet on recommendation of a friend who has used them.

I would consider buying two new ones if I was sure it was batteries.

I don't mind throwing some more cash at it I just want a working solution.

Not sure how I can load the batteries to text if they are ok?

I have been away all week running lights and TV off batteries and solar panel shows full no charge being taken.

I will try to run the hairdryer at 800w for a while and see if battery voltage drops significantly.

Thanks again.

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[JeanLuc]

I think the cable size is the most likely culprit. At 800 watts the inverter will be drawing about 70 amps (allowing for a bit of inefficiency) but at 1500 watts that will go up to 125 amps. (Forget about using the peak power reserve!)
According to the Sterling website, you need 35 sq mm cable, or possibly 40 sq mm for extra security. The problem is not the cable's absolute power handling capability but the voltage drop that is happening along its length. Thicker cable offsets this problem. When an inverter senses a low supply voltage, caused by drop along the cable, most will sound a warning.

Here is the cable size guide https://cdn.shopify.com/s/files/1/0658/7343/files/cablelengths.jpg?12413006777598578016

 

[Minxy]

Minxy girl that is not negative at all. Thank you!

It is Chinese but the supplier has offered a refund d so will send it back!

I will look for another one, any recommendations?

Unfortunately it's not unusual for some of the Chinese ones to make 'false' claims about the 'capacity' of inverters ... I assume you got it from Ebay? If so, make sure you aren't charged for the postage for them sending it to you and that you see if you can use the Ebay returns facility to get it sent back FOC. If the seller won't play ball then you could tell them you'll be leaving negative feedback ... it's the ONE thing that is sure to get them to play ball with you as they really do NOT want anything negative!

As for what to go for, I'll let others comment on that as we've never needed anything but a basic low powered one so can't say what would be best for a higher power requirement.

 

[funflair]

We run a 2kw pure sine wave Merlin inverter on 2metres of close to 80mm2 copper cable,

Martin

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[GaryH61]

Based on the fact an invert will not run at 100% efficiency therefore I estimate 85%. To calculate the current drawn by the battery we divide the load in watts by the battery voltage and the efficiency thus; 1000/12/0.85= 98A. A fully batteries with no other load rated at 230A/hr will discharge in about 2.5hr. However going back to 85% efficiency 1500 x 85%=1275W due to the inductive load of the motor and the element of the hair dryer you may be exceeding the max supply current at start up of the hair dryer and the overload protection circuit is kicking in and shutting down

 

[Minxy]

Based on the fact an invert will not run at 100% efficiency therefore I estimate 85%. To calculate the current drawn by the battery we divide the load in watts by the battery voltage and the efficiency thus; 1000/12/0.85= 98A. A fully batteries with no other load rated at 230A/hr will discharge in about 2.5hr. However going back to 85% efficiency 1500 x 85%=1275W due to the inductive load of the motor and the element of the hair dryer you may be exceeding the max supply current at start up of the hair dryer and the overload protection circuit is kicking in and shutting down

I did wonder about the 'start load' but more in terms of the microwave than the hairdryer. Interesting.

 

[tonyidle]

Simple answer is to connect a meter across the 12v feed to the inverter, at the inverter itself, to see what voltage is available to it when loaded. If it is seeing a low voltage, for whatever reason, it will beep & shut down. If the voltage holds up the fault is with the inverter. If it doesn't you need to look at the feed (batteries, cable, connectors).

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[celticmini]

Thanks Tony, that is the sort of help I was looking for.

I will get on the case tomorrow!

Thank you all for your help, I knew I could rely on you all!

Thanks again!

 

[celticmini]

The plot thickens!

I have been out taking a good look and measuring voltage across batteries, inverter not under load and under load!

I can't see where the auto electrician has taken the negative from, I will have to ask as it doesn't appear to come from battery directly which is what I expected using similar lengths of the same 25mm cable?

Voltage of battery 12.9v, back of inverter 12.9 V, under load of 500w 10.5v!!!!

I think I need the auto electrician to explain his mysterious wiring and to run additional cables, if I double up the 25mm would that be ok in everyone's view? As access is an issue he may need to add another 16mm cable making it 25 + 16 ( 41mm)???

I will take it back at the end of the week as it is booked in for more work then and see what they say before sending inverter back, does this seem the best option?

 

[hilldweller]

Voltage of battery 12.9v, back of inverter 12.9 V, under load of 500w 10.5v!!!!

Sorted then, 99.9% certain of poor installation.

If you can measure between inverter neg and battery neg which should read near zero and you see a few volts you have proved the problem.

There is a small change you have an existing fault, batt neg to chassis is poor and the inverter is showing this up. Again, meter from bet neg to chassis will prove this, obviously should be zero.

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[Reallyretired]

Your setup will run your hairdryer without problem if everything is working as we have used a similar set up for years with no problems.
Your wiring is the most likely suspect. At a metre length you need really substantial cable for both positive and negative connected directly to the batteries and similar cable between the two batteries. Check the connections too as high resistance can occur there if not well made.

 

[celticmini]

Thank you for your reassurance, I was beginning to think I had spent hundreds of pounds for nothing!

I will get the auto electrician to beef up wires with additional ones straight off battery!

 

[Minxy]

I would be extremely wary of using this 'auto electrician' for ANYTHING ELSE! It appears he doesn't know what he's doing possibly because he's used to only working on standard car wiring rather than on items that will draw higher power ... hopefully he will replace the existing wiring with something more suitable and ensure it is installed correctly which at present appears to be questionable ... oh yes ... and you should NOT have to pay any more as he's supposed to be an expert I assume.

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[Jeff and terri]

I have just fitted a 2500 invertor and would not have even considered doing it without two new batteries . My thinking was all new or don't bother I was worried and did a lot of research before finally purchasing pure sine wave invertor from a seller with 100 per cent feedback and pictures of the components inside the invertor as there are two many cheap and nasty copies

 

[Jeff and terri]

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[funflair]

Don't know what is happening duplicate posts so I Edit and then end up wth nothing

Anyway what I said was I don't know how your electrician would fuse two cables, dangerously most likely.

Get him to run 50 or 80mm sq cables straight from batteris +ve of one battery and -ve the other with a heavy interconnection cable and a suitable fuse close to the battery.

Martin

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