Inverter issues

[Reallyretired]

How many batteries have you and what sort. A single lead acid battery will struggle to provide the 120A draw fo your hairdryer, the voltage will drop and the inverter shut down until the voltage rises again

 

[lorger]

Personally I think that the cable is well undersized, OK it's a short run but that's the same size as I have on my solar install running a lot less amps, doesn'r sound right to me.

The guy fitting it did say it might struggle but that’s what came with it and what they recommended, not a big job to change it.

 

[lorger]

How many batteries have you and what sort. A single lead acid battery will struggle to provide the 120A draw fo your hairdryer, the voltage will drop and the inverter shut down until the voltage rises again

I have a lithium 125ah battery, I monitored the battery as the device was running and it never dropped below 12.9v

 

[DBK]

A stab in the dark but my guess is a connection between the batteries and inverter either hasn't been tightened or one of the cables has a dry joint. Worth giving everything a shake and check for tightness of connections.

We have a "cheap" inverter and it has never given any trouble.

 

[lorger]

A stab in the dark but my guess is a connection between the batteries and inverter either hasn't been tightened or one of the cables has a dry joint. Worth giving everything a shake and check for tightness of connections.

We have a "cheap" inverter and it has never given any trouble.

I’ve never said I have a cheap inverter everyone just assumed, I deliberately didn’t name it as I wanted to find out the general thoughts no matter what inverter I have as people tend to see that and become blinkered with their answer.
I’ll check the cables tomorrow

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[Googlebot]

I’ve never said I have a cheap inverter everyone just assumed, I deliberately didn’t name it as I wanted to find out the general thoughts no matter what inverter I have as people tend to see that and become blinkered with their answer.
I’ll check the cables tomorrow

I had a Victron do that to me.

Was gutted as it was very expensive. :-(

 

[Tombola]

When you plug in and run the hairdryer for a minute check the trip isn't getting hot. Mine did and inhad exactly the same as you and I changed it to a proper fuse and it's fine.
The weak.link was the trip.

I had 200ah of iKS lithium at the time

 

[paddymcc]

If the limit is the BMS max current discharge, doubling the battery (2x110Ah in parallel) will doubling the max current your system can cope with.( But more expensive than changing the inverter )

 

[lorger]

If the limit is the BMS max current discharge, doubling the battery (2x110Ah in parallel) will doubling the max current your system can cope with.( But more expensive than changing the inverter )

Thanks, we’re thinking of adding a battery anyway.
If the battery BMS is the issue surely a new inverter wouldn’t solve it?

 

[paddymcc]

Thanks, we’re thinking of adding a battery anyway.
If the battery BMS is the issue surely a new inverter wouldn’t solve it?

No it wouldn't. But I guess from comments already received that it could still be an inverter issue rather than a BMS one. So you could get a 2nd battery and still find the inverter doesn't work properly

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[Jimbohorlicks]

Cables are the ones that came with it and although they recommend them I am doubting they are, here are the cables. The fuse has a trip on it.
Battery is full according to my van monitor my Victron monitor and the battery app plus the inverter has battery reading.

Can you advise what the inverter cost?

 

[SeanF1]

I would start by changing the cables. My inverter came with 16mm cables but they went in the bin and I fitted 35mm. It works fine so far and runs the Nespresso machine (1,250w) without issues. I have 2x 110ah agm batteries

 

[Tombola]

came with 16mm cables but they went in the bin and I fitted 35mm.

so did i, and fuse to suit

 

[cmcardle75]

Battery has 150a output and I think if I remember correctly the device was drawing 155a, I assume that’s the issue.

Sounds very possible. Doubling battery in parallel would definitely help. You can't quite double the BMS capacity, but you can nearly so, as there will be some natural balancing of current flows at high draw. You need to match battery chemistry (i.e. buy the same battery type). Get the batteries to the same state of charge before introducing the new one.

 

[gerry mcg]

Personally I think that the cable is well undersized, OK it's a short run but that's the same size as I have on my solar install running a lot less amps, doesn'r sound right to me.

16mm2 cable is only rated to 110A - so the Inverter needs to be fused at well below that (80A?) -
25mm2 cable is rated at 170A
35mm2 icable is rated at 240A

https://www.12voltplanet.co.uk/stranded-single-core-plain-copper-cable.html

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[Jezter]

Did you say a KS125?
Max discharge current of the BMS/Battery is 100A. Recommended 80A.

Figures from their website below:

Maximum continuous discharge current: 100A
Peak surge discharge current: 300A for 5 seconds
Max continuous charge current: 100A, charge type: CC/CV
Recommended charge current <65A
Recommended discharge current: <80A

 

[Jezter]

Did you say a KS125?
Max discharge current of the BMS/Battery is 100A. Recommended 80A.

Figures from their website below:

Maximum continuous discharge current: 100A
Peak surge discharge current: 300A for 5 seconds
Max continuous charge current: 100A, charge type: CC/CV
Recommended charge current <65A
Recommended discharge current: <80A

Sorry. Just noticed that you'd figured this out already!
Good luck with the fix. Another battery/cabling sounds a good idea. Hope the current one hasn't been in too long so you don't drag the new one down.

 

[cyberyacht]

Probably any current draw over 100A is asking a bit much from any 'single' battery, however big and powerful.

 

[lorger]

Thanks for all the replies the problem has been solved, the fitter got in touch and all working fine.
You might be surprised to find out it wasn’t the inverter so all the assumptions about a cheap inverter were wrong and he had changed the cable for thicker stuff just hadn’t mentioned it, it was actually a faulty fuse/holder, new fuse and holder and all fine.

If you read the replies you will understand why I didn’t mention the type of inverter as some folk get blinkered with that and don’t really solve the problem. I won’t say what make it is but it wasn’t cheap but there again my expensive might be your cheap.

Thanks again folks