Probably a good idea because when removing the fuse to check it, it could arc and blow the fuse anyway. Same applies if inserting a new fuse.
I would suspect making and breaking the battery terminals could potentially cause more "arcing" and sparking with a possibility of surges than cleanly pulling and inserting a fuse. With that's risks to electronics. If the fuse had blown there had to be a current to do it which might reoccur making the connection.
In addition to this any spark would be in the battery box on a terminal so as close to the battery as it is possible to get, and that is not good practice. In safety focused practices you don't make and break a current carrying connection close to any LA battery.
So, unlike the advice so far tendered I would not touch the battery connection to remove and refit the supply fuse.
What I would definitely do in addition, is make sure all the power is isolated, so done with the panel shut off & the EHU cable is unconnected.
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For the OP.
If you do disconnect, ensure you do the negative ( earth) first then the positive . Reconnect positive first then negative
If you do disconnect, ensure you do the negative ( earth) first then the positive . Reconnect positive first then negative
That is correct as then no sparking etc. Also after disconnecting it may be wise to wait a couple of minutes before doing anything on any electrical system. This allows the system to discharge any components that may still hold a small charge.
Then remove the fuse connecting the solar controller and battery, however, in present light energy times, the over cast and deep winter of today, the current involve will be low.
Your safest option as I stated early is simply cleanly pull out the battery to main panel fuse, check it and then cleanly reinsert a viable fuse, all done with the panel switched off.
That's way "cleaner" than making a battery post clamp connection, and more remote from the battery
You can't know there will be no current making the final connection completing the circuit, so its quite wrong to state there will be no possibility of a spark.
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If there is no practical alternative to making connections at the battery where the system can't be isolated, removing the negative first & connecting last is right practice as it removes the "ground" connection.
This is so a spanner back end ever making contact with the "ground" can't cause a mega short.
It however gives no protection of possible sparking when making or breaking that connection.
The very physical nature of taper battery connections make "clean" single break make connecting nearly impossible, another good reason not to do it, particularly where electronic kit is also involved.
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I must have been very lucky in the past as never experienced sparking when I have disconnected negative first, then positive and then the other way around when reconnecting. Never seen it happen when battery is changed by a qualified fitter. However it could possibly happen if person is making a hesitant connection?
More probably, if with cars, you were unaware of any sparking, as with our cars these days there is typically some level of maintained current feed to the computers, radios etc in our cars.
That said with our cars its difficult to do a battery swap without breaking and making contact at the battery post, so the routine of breaking negative first and connecting last is adopted. As said, avoiding the risk associated with all the ground metal around near battery locations, of the spanner ever shorting.
Again here with a question on the viability of the main power fuse having been blown one has to consider why, and that opens the possibility that the final connection could be made at the high current that blew the fuse. There the last safe place to do that reconnection is on the battery itself, the more so with another option being way safer.
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There is no right or wrong , if there is a fault , then replacing the faulty fuse with a good one will just cause it to blow again, same with removing a wire off the battery, changing the fuse and reconnecting will also just blow the fuse . One thing with removing the fuse , you don't have to expose any bare terminals. Also looking at the fuse if it looks like its blackened , then the cause of the failure should be investigated before replacing.
Doesn't matter which terminal you disconnect first, same current flows through both terminals. Disconnecting Neg on cars is good practice to avoid shorts to chassis by loose Pos cable. In case of caravan battery box which is plastic this isn't issue.
Shouldn't be any sparks if all 12v circuits are isolated/turned off. The small current draw from systems that can't be isolated shouldn't result in a spark. Make sure any solar panels feeding a solar charger are isolated.
All I know is there are no lights on this at all, I don't know if I have a solar charger as such or how this thing actually works.
My service engineers told me as it no longer functions the best thing to do is to disregard it.
I'm on a permanent ehu all season and don't go off grid.
I'm going to remove the battery and stick it on the AA, 4 amp charger that has been suggested.
But thanks for all your input peeps.
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If there is solar panel just cover it then it won't produce any power.
How on earth would you cause a short if the positive cable touched the chassis after it has been disconnected and the negative is still connected to the battery or have I misunderstood you?
The things some people get fired up over really amazes me, talk about being risk averse as opposed to being risk aware 
If there are multiple batteries eg 4WD and hybrid, also jumper leads when trying to jump start a car.
It's not the positive cable touching the chassis that is the risk, it's the spanner you're using to loosen the battery clamp. If it touches the nut on the positive terminal and simultaneously touches the body / chassis you create a dead short with the risk of the battery exploding. Not so much of a risk on a caravan due to the plastic battery enclosure, bur a real risk on car.
I know someone who shorted the battery positive to the chassis (via the battery retaining clamp) with his metal watch strap and suffered serious burns to his wrist.
I understand that, but if they are clumsy with a spanner, maybe they should not be working on a motor vehicle?
However dexterously proficient, it is only an idiot who courts any risk where the ramifications can be life changing, but they are out there.I understand that, but if they are clumsy with a spanner, maybe they should not be working on a motor vehicle?
Here, there is a much safer way.
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I find there is often insufficient room for a socket or ring spanner . Open Enders are not the safest even in our careful hands 😉I understand that, but if they are clumsy with a spanner, maybe they should not be working on a motor vehicle?
No, but there could have been, IMO though it was self evident and already spelt out, but your are probably right, reading some contributions!
"Here" refers to the safer advice given in the thread itself.
Exemplified by #68, repeating the substance that had previously been posted.
Just be careful and there is no issue!!
Too many people see deadly danger in everything these days. I have lost count of the batteries I have disconnected/connected over the years, and yes I HAVE on occasions touched both terminals without any untoward ramifications other than making me nearly jump out of my skin.
The chances of a battery exploding are present, but exceedingly unlikely in any reasonably ventilated location. But if it makes you feel happy to take all of the above precautions then I am not going to try and stop you!
Too many people see deadly danger in everything these days. I have lost count of the batteries I have disconnected/connected over the years, and yes I HAVE on occasions touched both terminals without any untoward ramifications other than making me nearly jump out of my skin.
The chances of a battery exploding are present, but exceedingly unlikely in any reasonably ventilated location. But if it makes you feel happy to take all of the above precautions then I am not going to try and stop you
!
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