Hab electrics help please

[Riverbankannie]

We have received our replacement battery and it reads 12.7 volts at the terminals before installing.
When attempting to reconnect the wires to it, husband connected positive and then tried negative but got a spark. I suggested removing the battery fuse and he has has now connected the negative terminal safely but he is confused as to why there is a voltage difference of 12 v which gave the spark.
The solar regulator PV wire is still disconnected
We have a battery master - is this giving 12v from the cab battery ??
Does it sound like something is wrong?
Is it ok just to stick the fuse back in.
We are now on day 7 of trying to put this battery back in and I have MOT tomorrow and would really like the van back together as it has been dismantled since first week in October just for this battery change.
Husband worried and confused - could be an age thing.

 

[Lenny HB]

Nothing to worry about, several things will be connected to the battery leads, the spark just shows a bit of current is being drawn.

 

[Riverbankannie]

Nothing to worry about, several things will be connected to the battery leads, the spark just shows a bit of current is being drawn.

He says that’s reassuring (maybe a bit hesitantly) however he has put if off once again by going out to lunch !

 

[Pausim]

I always get a bit of a spark when I reconnect my leisure battery. I think it is just charging up a few capacitors in things like the inverter. May get a bit of a spark when he puts the fuse back but it has to be done.

 

[Riverbankannie]

I am sorry Lenny but it is another AGM as Leoch collected old one and sent a direct replacement all free of charge so would be silly not to use it. However I suppose the old one failing at just one year old, proves your point about them. It failed their bench tests as I was sure it would knowing that we had not killed it ourselves.

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[Gromett]

Nothing to worry about. As Pausim says just a few capacitors charging up.

 

[Silver-Fox]

Riverbankannie if I wasn’t just post op I’d have fitted it for you.

Is there no other funsters close by that can sling it together for you??

 

[Riverbankannie]

Riverbankannie if I wasn’t just post op I’d have fitted it for you.

Is there no other funsters close by that can sling it together for you??

Thank you but I am sure it is just nervousness, he doesn’t like to do things without understanding all of it and he won’t let me do it as , well you know, electrics a man’s job.
I arranged to have the converters original swopped by an auto electrician last year so we didn’t touch it ourselves as too heavy. This time John has made a new base so it just slides in and I bought 2 straps, each with 2 strap holders, to tie it in place.
Hope your post op recovery goes well, I am currently sitting in eye hospital waiting room for yet another check. It’s packed

 

[VXman]

I am sorry Lenny but it is another AGM as Leoch collected old one and sent a direct replacement all free of charge so would be silly not to use it. However I suppose the old one failing at just one year old, proves your point about them. It failed their bench tests as I was sure it would knowing that we had not killed it ourselves.

Not sure one example of one battery failing proves a point. My 3 are nearly 4 years old and have performed faultlessly.

 

[Riverbankannie]

Not sure one example of one battery failing proves a point. My 3 are nearly 4 years old and have performed faultlessly.

Well yes, my first one performed faultlessly for 8 years and that is why I went for another hoping for another 8 years which would definitely see our MHing days out.
Unfortunately it didn’t work out that way and at 45kg and an awkward fit, a real nuisance just to send back.

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[autorouter]

Thank you but I am sure it is just nervousness, he doesn’t like to do things without understanding all of it

If he wants to understand that spark, think of it like this. If you turn all your house taps off, then turn the water stop tap off, all water stops flowing. If you turn the stop tap back on again, still no water flows through the stop tap. Until you turn a tap on of course.

Now turn the water stop tap off again. But this time, flush the toilet. The cistern flushes, but can't refill because the stop tap is off.

So when you turn the stop tap on again, water flows immediately, to fill up the cistern.

There are some electronic components called capacitors that act like a cistern. They take in electric charge, ready for when they are asked for a sudden rush of charge. Typically chargers, inverters and power supplies contain capacitors.

When they are connected, they take an inrush of amps to charge themselves up. That can result in a spark as soon as the wires are connected. As others have said, it's quite normal for these items, and is nothing to worry about.