MPPT install issue blown fuse?

[MrD]

Just replacing a cheap PWM solar charger with a MPPT Victron 75/15 as recommended here. However the unit seems dead (no leds) and the app can’t see it on Bluetooth. It’s wired correctly to PV and Battery as per previous controller.

So checking fuses I have found a 30A blown so replaced that and it blew again , I did briefly see a led light up on the mppt .

Any ideas from the more experienced?

 

[MrD]

3rd blown fuse as soon as it inserted, sparks away a lot on trying to install the fuse. I don’t understand what the issue is as it was a straight swap over.

Maybe a loose cable happened when I was installing ?. Or faulty MPPT charger?

 

[True Romance]

Have you removed the victron and unplugged any solar cables? If so does the fuse still blow?

 

[MrD]

Have you removed the victron and unplugged any solar cables? If so does the fuse still blow?

Not currently as the heavens have opened here. Will do when drier.

Before I removed the old charger there was normal status led on as usual on the battery .

 

[MrD]

Ok just disconnected the victron from the panel and battery. Replaced the fuse no sparks and not blowing.

 

[TallPaul_S]

How have you got the Victron wired up?

It has 6x wire inputs - 2x for battery +/-, 2x for PV +/-, and 2x (optional) for DC load +/-.

Battery +/- should be connected first and given 10 seconds to detect the voltage, according to the manual.

What's that fuse for? Is it the solar controller to battery fuse?

 

[MrD]

I literally have no idea what that fuse is for tbh but isn’t sparking now the controller is disconnected and the cable at rear of it seems quite large (Red) .

I did wire up battery +/- waited then panel +/- . No DC Load req.

The victron didn’t do anything no leds etc with the battery connected.

I did mistakenly put the +/- from panel wires in the wrong way on mppt for a few seconds until I realised my error (I initially just copied the battery +/- order my mistake). Could that have buggered it?.

I bought it from Amazon as per recommendation on here. On opening it “smelled” a little strongly (not burnt just electrical) but didn’t look like it was fitted previous so proceeded.

The 20a fuse in the Victron is fine not blown

 

[Dellmassive]

thats not right. . .

post some pics of the vic` mppt connections,

and some pics of the battery if you can.

 

[MrD]

thats not right. . .

post some pics of the vic` mppt connections,

and some pics of the battery if you can.

The battery I believe is quite buried and requires some panel removal to get to it which I started earlier today.

By connection do you mean the cables leading to the mppt as they are just red black cables with exposed ends (bit scruffy exposed ends TBF).

Oh and should I cover the solar panels when working on the system?

 

[Dellmassive]

a pic of the blue vic` 75/15

 

[MrD]

Here you go ……

 

[Dellmassive]

sorry, i ment with it all wired up - to see if there was a installation problem causing the fuses to blow.

 

[TallPaul_S]

(bit scruffy exposed ends TBF).

This might have caused a short or a high resistance connection which is never good.

Best to cut and restrip the wires if there's any stray strands or they're not neat and tidy.

 

[MrD]

This might have caused a short or a high resistance connection which is never good.

Best to cut and restrip the wires if there's any stray strands or they're not neat and tidy.

Yes agreed was planning on this , possibly even getting a crimper tool maybe

 

[MrD]

sorry, i ment with it all wired up - to see if there was a installation problem causing the fuses to blow.

I see. I just installed it with Red + Black - for Battery then Black - Red + for panel in that order . Except when I wrongly got the panel wires in wrong terminals (my fault making assumptions). Same as previous PWM solar charger it replaced

 

[MrD]

I reconnected it earlier with just battery and this did not blow the fuse. Not tried attaching the panel again though yet.

Photo from install earlier today…..

 

[Dellmassive]

Ok. Use a multimeter to double check the polarity from the PV, itay be the other way round.

The pic above looks ok.

The unit will power up with just the battery connection, and show a slow pulse blue led... Showing no PV.

You will then be able to connect via BT to get to the settings.

 

[MrD]

The unit will power up with just the battery connection, and show a slow pulse blue led... Showing no PV.

This didn’t happen when installing no leds. Even with new fuse not blown and no PV connected it was lifeless. I have ordered another unit to try and will check the PV today as you suggest. Will also try to find the battery access to have a nose.

 

[MrD]

Update

With my limited knowledge using a multimeter (very basic) I tested the panel cables .

Black cable with Black probe and Red cable with Red probe .

The panel iirc is a 100w semi flexible.

In mostly full sun but clouds blowing over blocking then unblocking.

Got these results ( had to decipher the multimeter instructions if honest and tested DC volts DC A and AC volts)

DC 12.4 6.2A
AC 26.2


If these make no sense please feel more than free to discuss here as I may have missed something?.

Also image of panel not that it means much but someone may know something. Not looked for battery access as tbh I am fed up with it all :-(

Oh and the test set I used

 

[MrD]

UPDATE…..

Well what a complete dick ……

30a fuse was blowing because numb nuts here was wiring up the battery to the PV terminal and the PV cables to the battery terminals . Which absolutely explains the 12.4 DC readings off what I thought was the PV cables.

Double checked old PWM charger and it was confirmed I was indeed a tw$t . It was opposite termination points.

Stripped all cables, used bootlace end crimps and crimp tool to rewire the Victron all good Blue led slowly flashing and BT connection to phone all ok. Sun is in at minute so waiting to see the PV working or…….. fingers crossed.

There is a lesson to be learnt here and that is check, check again , understand what your doing then check it again!!!!!

I am -3,000,000 man points and the wife is currently surfing Tinder as we speak …..gutted .