Inverter failure.

[Callum4878]

Hi all, 

my Mastervolt 2KW inverter/charger has blown up, so I’m going to replace it with another from the same manufacturer, as it has lasted 14yrs without many issues. Decided upon a 3kw this time, just wondered if anyone had been through this process and has any words of wisdom for me, like any pitfalls in the change process, cheapest place to buy etc. I’m obviously researching it myself, but would be grateful for any useful input.

Keith

[OldGoat]

11 minutes ago, Callum4878 said:

Hi all, 

my Mastervolt 2KW inverter/charger has blown up, so I’m going to replace it with another from the same manufacturer, as it has lasted 14yrs without many issues. Decided upon a 3kw this time, just wondered if anyone had been through this process and has any words of wisdom for me, like any pitfalls in the change process, cheapest place to buy etc. I’m obviously researching it myself, but would be grateful for any useful input.

Keith

Probably not directly germain to your request,

BUT what are / what is your battery capacity?

 

The reasons may become apparent later...

[Alan de Enfield]

20 minutes ago, Callum4878 said:

Hi all, 

...........would be grateful for any useful input.

Keith

You may well need to re-wire from the batteries to the inverter if they were 'wired' for 2Kw.

Having 3Kw means that you (or someone) may one day use its full capability so you need compatible cabling.

 

Check the size of existing wiring, but you will need something capable of carrying 300amps, and, then also take into the possibility of volt drop if the inverter is any distance from the batteries.

 

If your inverter is 3 metres from the batteries, running at 300amps will require 95mm2 wiring, this will give you a volt drop of 0.3 volts (2.97%) which is acceptable.

 

If you have only 25mm2 cable then the volt drop will be 1.23volts (10.25%) which is not acceptable.

 

 

Mastervolt 3.5Kw = £1500

https://www.cactusnav.com/mastervolt-master-12v3500w-inverter-with-outlet-wired-p-30463.html

Edited October 2, 2020 by Alan de Enfield

[Jen-in-Wellies]

In addition to cable sizes, the fuse to the batteries may need increasing in capacity, depending. If there is an isolation switch between the batteries and the inverter, is it rated for 300A continuous?

Jen

[Higgs]

 

As an aside; The Victron 3kw inverter I have has a 400amp fuse installed. It was Victron that packaged it, to fit in the fuse holder. 

 

 

Edited October 2, 2020 by Higgs

[Callum4878]

Battery capacity I’m not sure is the honest answer, 3 deep cycle agm’s replaced the original 4 Mastervolt, but I can’t find any capacity reference in my paperwork, will have to crawl into the compartment to check. Cable size is 70mm and the batteries are less than a metre from the inverter.

[Alan de Enfield]

2 minutes ago, Callum4878 said:

Cable size is 70mm and the batteries are less than a metre from the inverter.

No problem that'll give only 0.15v volt drop at 300a

 

As Jen says - check fuses and switches are sufficiently rated.

[Tracy D'arth]

12v then if you have 3 batteries.

 

Check that the battery interconnect cables are 70mm sq  too.

If these 3 are 110Ah or 125Ah batteries that are going to suffer at 3kw.

[Callum4878]

Leisure batteries are 3x210Ah isolator cabling is all 70mm.

[Higgs]

 

In my limited experience; If the demand is high and the inverter cannot draw the current it needs, because the cabling is too small, the inverter will shut down and 'report/signal' the batteries are not up to the job. 

 

 

Edited October 2, 2020 by Higgs

[OldGoat]

I asked about battery size, because - as I thought - 3three small batteries is just not enough to run a large inverter (whether or not it's used occasionally / not for long / whetever) and that may be the reason why the inverter failed.

 

Doubtless I'll be contradicted - but that's the way it goes...

[TheBiscuits]

3 minutes ago, OldGoat said:

I asked about battery size, because - as I thought - 3three small batteries is just not enough to run a large inverter (whether or not it's used occasionally / not for long / whetever) and that may be the reason why the inverter failed.

 

Doubtless I'll be contradicted - but that's the way it goes...

 

I'll bite - a 3kW inverter doesn't always deliver 3kW.  If there's only a few hundred watts being demanded, that's all it will be delivering.  In this case it's making the same demands of the batteries as a smaller inverter.

 

I do agree that running big electrical loads off a small battery bank isn't good for them, but it's not the maximum possible inverter power rating that causes this.

[Richard10002]

14 minutes ago, OldGoat said:

I asked about battery size, because - as I thought - 3three small batteries is just not enough to run a large inverter (whether or not it's used occasionally / not for long / whetever) and that may be the reason why the inverter failed.

 

Doubtless I'll be contradicted - but that's the way it goes...

1) it was 14 years old.... thats why it failed!

 

2) i have a 2500w inverter to run my vacuum cleaner for 10 minutes or so at a time. It runs from a bank of 3 110Ah batteries, with a depleted capacity. 300A for 15mins is 75Ah, so the bank is always able to cope from a capacity point of view. Clearly, hoovering for an hour wouldn't be sensible. I also run a lawn mower from it, no problem.

[Higgs]

3 minutes ago, Richard10002 said:

1) it was 14 years old.... thats why it failed!

 

It's always possible it wanted to give up the ghost, but.., if it had been slightly abused, it might have hastened that event. 

 

 

[GUMPY]

8 minutes ago, Richard10002 said:

I also run a lawn mower from it, no problem.

You have a turf roof on your boat? Wow

 

[Jen-in-Wellies]

37 minutes ago, Loddon said:

You have a turf roof on your boat? Wow

 

Turf carpet inside. A turf roof would just be silly. ?

[Callum4878]

Thanks to all, think it’s going to be a 3000va model.

[cuthound]

4 hours ago, Callum4878 said:

Hi all, 

my Mastervolt 2KW inverter/charger has blown up, so I’m going to replace it with another from the same manufacturer, as it has lasted 14yrs without many issues. Decided upon a 3kw this time, just wondered if anyone had been through this process and has any words of wisdom for me, like any pitfalls in the change process, cheapest place to buy etc. I’m obviously researching it myself, but would be grateful for any useful input.

Keith

 

Might be worth giving Mastervolt (or their UK agent) a phone to see if they will offer a discount on a new one as your old one is obsolete and beyond possibly repair.

 

Their biggest competitor Victron do this, and will give existing customers a 25% discount against a new one.

[Callum4878]

Well worth a try, thanks for that, will let you know how I get on.

[Slim]

13 minutes ago, cuthound said:

 

Might be worth giving Mastervolt (or their UK agent) a phone to see if they will offer a discount on a new one as your old one is obsolete and beyond possibly repair.

 

Their biggest competitor Victron do this, and will give existing customers a 25% discount against a new one.

Some years ago when my Mastervolt inverter went belly up I tried to get MV to repair it (at my expense) but all the wrinkles involved including shipping at my expense to Holland made it unviable. The best discount they would offer to replace was well beaten by a number of UK suppliers. 

[Callum4878]

Tried Mastervolt uk, discounts are given for failures within 10years apparently. Worth a try though.

[dor]

I would ask myself if I really needed 3000VA.  It is a lot of load on the batteries.  The quiescent current is probably higher than a smaller one.

 

I've had a 1800VA Powermaster inverter for the last 13 years.  Run everything I needed including a decent vacuum cleaner, a microwave and a lawn mower.  Most electric kettles now are 1700W, but then I don't need an electric kettle.

[Callum4878]

Truth is probably not,  2kw has been fine to date, but I'm thinking it's better to have too much than just enough, and my system doesn't need any wiring upgrading. Also I'm guessing 2kw comes easier to a 3kw inverter than a 2kw, might be totally wrong in that one?

[Sea Dog]

1 hour ago, Slim said:

Some years ago when my Mastervolt inverter went belly up I tried to get MV to repair it (at my expense) but all the wrinkles involved including shipping at my expense to Holland made it unviable. The best discount they would offer to replace was well beaten by a number of UK suppliers. 

Also my experience, as I recounted in another thread a few days ago.  Thoroughbred kit, but when it gets sick or injured it appears that, all too frequently, your only sensible course of action is to shoot it.

 

 

[Detling]

You may find the standby current on the 3000 is significantly higher than the 2000. Not an issue if you switch it on and off as required but if you leave on 24/7 you could be adding 24 amp hours to your daily load.