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Had one of my fuse links blow yesterday after a long drain on the battery from 100% to 20% at 3kW.

Not being familiar with these units is it a case of buying another 40Amp, 500V gG or do you open the blown unit and re wire with appropriate fuse wire ?

I’m thinking it’s the former rather than the latter but I don’t want to bin the old block if it’s capable of re-use ?

Guidance much appreciated

Moxi

Moxi wrote: ↑Mon May 08, 2023 12:20 pm Had one of my fuse links blow yesterday after a long drain on the battery from 100% to 20% at 3kW.

Not being familiar with these units is it a case of buying another 40Amp, 500V gG or do you open the blown unit and re wire with appropriate fuse wire ?

I’m thinking it’s the former rather than the latter but I don’t want to bin the old block if it’s capable of re-use ?

Guidance much appreciated

Moxi

40AMP is too low surely, 3000W at around 51V (average) is 58 amps, so no wonder the fuse blew - just as it was designed to do ( I am assuming "standard" 48V battery system and the fuse is in the battery lead). That fuse is really there for effectively short circuit protection, or fault currents which will generally be way in excess of normal operating currents. (000's of AMPs). To be honest I would replace with 75 or even 100Amp fuse.

As far as I know, and would think, NH00 fuses are not rewireable and nor would I advise trying. They are designed to be able to "break" literally 10's of 000's of amps DC. They are "sand filled" to prevent any arc "taking hold" which would enable the current to continue to flow.

Thanks marshman, they were supplied with the system which is four of 3500 pylontechs and now you mention the low value I think I recall Nowty saying something similar to someone.

I’ve sorted news ones at city electrical and Parker’s and of course good old r/s components so I will go online now and see who’s got stock and best price.

Thanks again

Moxi

If you are using a single pair of the standard Pylon leads they are IIRC rated at 100A so to protect them your fuse shouldn't be any bigger than that.

Fortunately my Force L2 BMS module has a 100A DC breaker which solves the problem as the inverter at the other end cannot produce more than 70A.

Ordered a pair of 63 Amp fuses, the 40’s lasted more than a year and only gave out after I drained the house battery into the car so a prolonged run at about 3 KW followed by a sharp disconnect by the bms at 20 % which I am guessing was too much for one of the fuses. Normally the stack doesn’t get used like that so I worked on the 63 Amps being man enough whilst retaining their protective duty with plenty of headroom.

Happily a grey low solar day here and fuses arrive tomorrow to put me back in operation as the suns back and I can lift the stack back up to pick up its duty serving the house only

Moxi

**Update**

Fused links arrived today and are now fitted, note to self and other solis inverter users, upon re-start of system the batteries immediately began to charge from the grid at 3.3kW and I discovered that I had to go back into the system menu and reset the user parameters via the advanced settings.

Now charging from solar only at a more leisurely 1.2kW

I have a spare set of fuse links coming from a separate source as it took longer than I had appreciated to get hold of them (maybe because of where I live ?) but I don't fancy a few days without the system another time if I am unfortunate to break a fuse in the future.

Thanks again for the support, most appreciated.

Moxi