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lucyboatgirl

sparks fly when rewiring battery terminals???? Help???? Thank you

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Hi friendly helpful boaters, I have a bit of a confusing question that might be too vague to get your help with about my batteries. But any help or advice you could send me would be amazing.

I was re-wiring my leisure batteries to swap the negative terminals around. By this I mean to swap the negative connectors from one battery for the negative connectors on the other battery. So the batteries would still be wired in parallel but the load would be coming off the other terminal. Another boater out here told me this would be a more efficient use for the batteries.

So I switched the isolators off so there should be no circuits running. and popped BOTH negative connectors off BOTH batteries. As I have been told to take the negatives off first to avoid big sparks. However as I moved the cables around. I accidentally touched  one of the negative connectors onto the positive terminal of one of the batteries. I got a sparks display for a second and a fright. I am a bit confused because I thought as BOTH negative connectors were not on the battery terminals there would be no completed circuit?

I am just learning this stuff so any help would be amazing. I am trying to understand why this happened before I try to rewire my batteries again. There is a starter battery in the circuit, could it be this that caused the spark? I just don't understand how the battery connector when not connected to the battery at all can cause sparks when touched to the other terminal. I understand that my knowledge is pretty low on this stuff and would appreciate any tips or advice going and I'm sorry if I'm asking a super stupid or obvious question. And I also know you guys don't know anything about how my batteries are wired up or my boats electrics so its super vague. But thank you for any help you can chuck my way. Thanks so much you lot. Stay safe and healthy out there. x x x x x x x

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6 minutes ago, lucyboatgirl said:

I accidentally touched  one of the negative connectors onto the positive terminal of one of the batteries. I got a sparks display for a second and a fright. I am a bit confused because I thought as BOTH negative connectors were not on the battery terminals there would be no completed circuit?

You disconnected 'one end' of the negative cable, but where was the other end ?

 

If one end touched the 'positive' and the other end was still connected to another battery negative, or to 'earth' then you had made a circuit and got your 'flash'.

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Hey Alan thanks for the reply. I disconnected BOTH negative connectors from the negative terminals. I am pretty sure the other end was not touching the negative terminal or any metal part of the boat when the sparks flew. Thats why I am confused because I didn't think there was a circuit.

 

But thinking about it maybe I accidentally dragged the other negative connector onto one of the negative terminals at the same time by accident. I mean that would make more sense to me as to how it happened. If thats what I've done do you think I have done any damage to my batteries????

 

Thanks for your help Alan. Hope you are marred up somewhere beautiful for the quarantine. Thanks so much x x x x x x

 

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Inverter-chargers are often wired bypassing the master switch so if you have one and if it was turned on that could explain the sparks. They also have big capacitors in them so such things charging up or discharging can cause an impressive spark.

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Don't worry, it happens. Did it myself a couple of weeks ago on a car, batteries and wires everywhere and then a big flash and sparks. And yes, I should know better and I do but I still did it.

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Hi Tony thanks for the reply.

I am not totally sure what an inverter-charger is? Does this mean like a 240V ac inverter? I am pretty sure there is not one wired into this boat, because they have a packaged inverter in its box in the cupboard.

Or do you mean something else. Thanks 

Thanks Bee, thats re-assuring. I gave myself a fright and really trying to be safe.

Thanks for the support matey x

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Just now, lucyboatgirl said:

Hi Tony thanks for the reply.

I am not totally sure what an inverter-charger is? Does this mean like a 240V ac inverter? I am pretty sure there is not one wired into this boat, because they have a packaged inverter in its box in the cupboard.

Or do you mean something else. Thanks 

 

Yes an inverter with an inbuilt battery charger. Sometimes called a combi-unit. Hard to help without knowing exactly how the boat is wired and what kit you have. The most likely explanation is that you dragged the other terminal onto a negative post.

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Aye Tony, I know its a bit abstract and vague because you don't know the circuit and stuff but I just thought I'd ask incase there was something really obvious. I'm leaning towards thinking I must have dragged the other connector onto the negative terminal like you say. It would explain the sparks and obviously I wasn't paying enough attention to where the terminals were anyway if I let it touch the positive so it makes sense.

 

I'm kind of thinking the mystery has been solved here. Thanks for your help though. It took you guys saying to make me think it through that I must've made a mistake.

 

Thanks for your help fellas. Really appreciate you taking your time to help me trouble shoot this even if it was just my own dumb mistake.

Thanks for your help. It is very much appreciated. You guys always help out us less knowledgable boaters and it is a mighty kind and generous thing yous do. So thank you x x x x x x x x

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1 hour ago, lucyboatgirl said:

*moored up somewhere beautiful

 

*I hope you are not married in anything

I misread your mail Lucy - it did seem an odd question at first, and I wondered if you were seeking a full-time electrician   🙄   Then I re-read it.

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Sparks need a source of power this could be -

1 Engine start battery if charged from the same alternator as the ‘house’ batteries.

2 Solar panels.

3 A remote battery for a (Example) bow thruster.

4 Shore line battery charger left on.

5 Smoothing capacitors in an inverter

 

If a smallish spark, capacitors in 12v usb chargers, some led lights, ‘car’ radio etc.

 

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thanks chew baka and everyone. I've rewired them now. all fine. lights all going on. engine starting. solar panels charging. all good. no sparks at all this time. tustve been that I touched the connector onto the negative terminal without noticing. thanks for all your help everyone. your all the best x

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2 minutes ago, lucyboatgirl said:

thanks chew baka and everyone. I've rewired them now. all fine. lights all going on. engine starting. solar panels charging. all good. no sparks at all this time. tustve been that I touched the connector onto the negative terminal without noticing. thanks for all your help everyone. your all the best x

You may have been getting volts from the solar hard to say without knowing which cables were touching what at the time but positive and negative would have shorted the solar if it was still connected or the battery charger if it was still on

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As you mentioned solar, I will advise you that in future you must disconnect the solar panels from it’s controller before disconnecting the batteries and reconnecting the panels AFTER reconnecting the batteries.  You will also need to cover the panels with a blanket or similar or wait till dark (so as to drop the panel output) before messing with your panels.  I don’t know how your panels are wired, but solar panels can in some installations generate about 100v (or more) which is dangerous, so take care.

 

added - as always with electric stuff it’s best to seek advice before doing the job if you are not confident in what you are doing.  Someone here will usually be happy to advise.

Edited by Chewbacka

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Batteries creat hydrogen gass when used hevily I manages to blow on up catching a spanner on the hull to make a circuit luckily I had the cover between my face and the exploding battery 

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To minimise accidental sparks it is good practice to insulate tools with a couple of layers of insulating tape, remove all rings, watches etc, surround the hull near the batteries with cardboard and tape up connections as you take them off.

 

Wint stop sparks from capacitors charging though!

 

 

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As long as you had the presence of mind to yank the shorting wires away...some folks would get a fright and let go of the wire, leaving it to start welding...

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