# Leisure Battery Negative Voltage Reading?



## mfrancer (Sep 27, 2012)

I have installed a second leisure battery in my Swift Sundance 532 LP. I connected positive to positive and negative to negative terminals. When I take voltage readings using a multimeter, the original battery is reading minus 12.80 volts and the new battery is reading plus 12.80 volts. I do not understand this. Is it normal? Should both not be reading plus 12.80 volts?


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## trevorf (May 16, 2005)

There is no way that could be true if you have connected then correctly. Are you sure you have your meter leads the correct way round?


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## bigcats30 (Aug 13, 2012)

you are putting the wrong connections on if you get minus on a multimeter (IE you have + on -)


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## WildThingsKev (Dec 29, 2009)

If you have connected them with decent size wire (as you should have) then they will read the same voltage anyway. 

+ & - is probably just that you have inadvertently crossed your wires, are the batteries not adjacent?

Kev


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## mfrancer (Sep 27, 2012)

The batteries are adjacent. The original battery is a Yuasa with the positive terminal on the left. The new battery is a Banner with the positive terminal on the right. When I switch the leads on the meter, the battery that was giving a positive voltage reading now reads negative and vice versa. The Banner may be intended for marine leisure use. Would that make a difference?


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## Stanner (Aug 17, 2006)

> The batteries are adjacent. The original battery is a Yuasa with the positive terminal on the left. The new battery is a Banner with the positive terminal on the right. When I switch the leads on the meter, the battery that was giving a positive voltage reading now reads negative and vice versa. The Banner may be intended for marine leisure use. Would that make a difference?


No - it can only be that you are not putting the correct probe to the correct terminal in both instances.

If they are connected as you say, the voltages CANNOT be different as each pair of positive and negative terminals are connected to each other and so MUST be at the same voltage.


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## BillCreer (Jan 23, 2010)

Could be an Australian battery?


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## readyforoff (Dec 28, 2013)

Is this a leg pull by Barryd ? If the two batteries are adjacent and connected in parallel why are you taking two readings or even how are you taking two readings? There can only be one common reading :?


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## missbusybusy (Jun 11, 2010)

start again disconnect each one and take a reading, then re connect and check


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## Jeannette (Aug 7, 2012)

ROFL..... :lol: :lol: 

When you connect the batteries together like that they become a single battery. To check the battery put your test probe positive on the positive of one battery and the negative on the negative of the second battery. the reading then gives you the total voltage of the 'battery pack'.

If you want to check the batteries individually then disconnect them from each other.

Cheers
Steve


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## BrianJP (Sep 17, 2010)

BillCreer said:


> Could be an Australian battery?


Nah must be cause its Irish ??


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## mfrancer (Sep 27, 2012)

readyforoff said:


> Is this a leg pull by Barryd ? If the two batteries are adjacent and connected in parallel why are you taking two readings or even how are you taking two readings? There can only be one common reading :?


No, not a leg pull. I was taking readings to check that both batteries were being charged by the van's charger. I put the negative meter probe on the negative terminal of battery 2 and the positive probe on the positive terminal of battery 2 and got a reading of +12.80. I got the same reading by putting the positive probe on the negative of battery 2 and the positive of battery 1. However when I put the negative probe on the negative terminal of battery one and the positive probe on the positive terminal of either battery 1 or battery 2 the reading is -12.80.

However, I will check again tomorrow and take missbusybusy's advice and disconnect both batteries and see what the readings are.


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## barryd (May 9, 2008)

> *readyforoff wrote: *Is this a leg pull by Barryd ? If the two batteries are adjacent and connected in parallel why are you taking two readings or even how are you taking two readings? There can only be one common reading :?


Not me this time!


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## mfrancer (Sep 27, 2012)

BrianJP said:


> BillCreer said:
> 
> 
> > Could be an Australian battery?
> ...


I was waiting for that!

One of the batteries is Japanese and the other appears to be Austrian.


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## erneboy (Feb 8, 2007)

Obviously one is an anti-battery.


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## trevorf (May 16, 2005)

Do you see a + sign for positive and - for neg on the battery or are they colour coded?

The reason I ask is that the Germans and Austrians use Brown as -ve and Blue or Black as +ve which is the opposite of the UK normal.



Trevor


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## Stanner (Aug 17, 2006)

mfrancer said:


> I put the negative meter probe on the negative terminal of battery 2 and the positive probe on the positive terminal of battery 2 and got a reading of +12.80. I got the same reading by putting the positive probe on the negative of battery 2 and the positive of battery 1. However when I put the negative probe on the negative terminal of battery one and the positive probe on the positive terminal of either battery 1 or battery 2 the reading is -12.80.


IF the batteries are connected as you say that is impossible because if the positive terminal of battery one is connected to the positive terminal of battery two and the negative terminal of battery one is connected to the negative terminal of battery two the voltage will be the same at BOTH terminals.

If however you have disconnected the links (and so isolated the batteries from each other) AND then get that result when reading meter + to battery + and meter - to battery - on each battery - you have some serious problems and it's a wonder you haven't had some serious sparks.

Indeed it's a wonder you are still around to ask the question.


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## bigtwin (May 24, 2008)

Batteries connected in series?


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## rayc (Jun 3, 2008)

> bigtwin said:
> 
> 
> > Batteries connected in series?
> ...


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## bigtwin (May 24, 2008)

Agreed. 

But it's evident there is something amiss. If they're connected in series +'ve and -'ve get connected together and could explain the odd readings.


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## mfrancer (Sep 27, 2012)

trevorf said:


> Do you see a + sign for positive and - for neg on the battery or are they colour coded?
> 
> The reason I ask is that the Germans and Austrians use Brown as -ve and Blue or Black as +ve which is the opposite of the UK normal.
> 
> Trevor


No colours. Just positive and negative symbols


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## alexblack13 (Feb 10, 2013)

Scotty..........

You canny change the laws o' phisics captain.....


Al' ....


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## rayc (Jun 3, 2008)

Is there any reading when you put the meter across both negative terminals?


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## pippin (Nov 15, 2007)

Many years ago when I was a TV repairer I would be inundated with faulty 12V portables in the holiday season.

This is a seaside town and caravanners would arrive in the dark and connect their tellies up to the battery a4se about face.

Result - blown fuse at best. A nice little earner!

One summer a lady kept on bringing back her set with the fuse blown.

I told her she must be connecting the croc clips the wrong way round.

She was quite adamant that she was not so eventually I went to the caravan armed with my test meter.

Sure enough she was connecting the TV +ve to the battery +ve and the -ves correctly as well. 

Yet the fuse blew! Eh?

I couldn't believe it but what had happened was that over the winter the battery had gone flat.

She had connected up the battery charger (you know, the old simple type) back to front and the battery was reverse charged! 

I had no idea that a lead acid cell could be reverse charged - and I know a lot about batteries.

I had to totally discharge said battery with a car headlamp before I dared reconnect the charger - this time the correct way round.

I am not suggesting that this has happened in this case because connecting two charged batteries back to front would result in a hefty explosion and battery acid everywhere.

But, if one battery happened to be totally discharged..............


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## trek (May 1, 2005)

As stanner and pippin have already mentioned , batteries can be very dangerous and can explode 

Please be very careful and perhaps get an auto electrician to look at your installation before you proceed.


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## BrianJP (Sep 17, 2010)

mfrancer said:


> readyforoff said:
> 
> 
> > Is this a leg pull by Barryd ? If the two batteries are adjacent and connected in parallel why are you taking two readings or even how are you taking two readings? There can only be one common reading :?
> ...


seems to defy all logic. Have you confirmed this with a second meter?


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## Penquin (Oct 15, 2007)

Logic says this is not possible, and it is certainly not something that any of us have encountered, perhaps because we haven't tried it BUT I would add my caution to that of many others about getting everything checked by a professional since the risks of a battery explosion are real and the damage that could be caused would be catastrophic - we have all seen the horrendous pictures of people (often young Indian girls) who have gad battery acid (sulphuric acid - UK spelling NOTE) thrown onto their skin.....

Sulphuric acid is VERY corrosive and will destroy metals such as steel and copper - which are commonly found in battery compartments, and fabric and rubber such as in seating, it's effects on skin are permanent as it reacts with the protein in the skin..... not a pleasant thought.....

So, please, proceed with VERY great caution.....

Dave


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## mfrancer (Sep 27, 2012)

Checked the batteries again this morning and still got the weird readings. The electric system was in "on" mode so I switched it to "shutdown" mode and the voltage readings were perfectly normal. Switched the system on again and the readings remained normal. 

Thanks for all the interest in this. Some may think that either myself or the meter are faulty, but I was certainly consistently getting illogical readings until I shutdown the system and switched it on again.


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## safariboy (May 1, 2005)

If you connected the batteries via fused wires and then connected them the wrong way round the fuse would instantly blow whatever its value. As the batteries are now disconnected they could read the opposite polarity.


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## pete4x4 (Dec 20, 2006)

I reckon you have a multimeter with deltaV on it and are measuring the difference between two readings.
That is the only way you can get the readings you describe.


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