Linking batteries in parallel

[pcatterall]

I fitted 2x domestic batteries last year. For various reasons it was difficult to link them as I normally would with the supply being connected to the neg of one and the positive of the other. Instead my power is taken from one battery with the other battery just connected to it (pos to pos and neg to neg).
Just inspecting the batteries today I notice that the 'slave' battery terminal are heavilly corroded whereas the 'active battery' terminals are quite clean.
Have I done a naughty thing connecting the batteries like that? Is it hand smacking time?

 

[sailorman]

I fitted 2x domestic batteries last year. For various reasons it was difficult to link them as I normally would with the supply being connected to the neg of one and the positive of the other. Instead my power is taken from one battery with the other battery just connected to it (pos to pos and neg to neg).
Just inspecting the batteries today I notice that the 'slave' battery terminal are heavilly corroded whereas the 'active battery' terminals are quite clean.
Have I done a naughty thing connecting the batteries like that? Is it hand smacking time?

i would suggest linking is ok just take a pos from one & neg from the other

 

[Cardo]

http://www.smartgauge.co.uk/batt_con.html
Method 2 is what I've gone with. Should cover your bases.

 

[ukmctc]

I fitted 2x domestic batteries last year. For various reasons it was difficult to link them as I normally would with the supply being connected to the neg of one and the positive of the other. Instead my power is taken from one battery with the other battery just connected to it (pos to pos and neg to neg).
Just inspecting the batteries today I notice that the 'slave' battery terminal are heavilly corroded whereas the 'active battery' terminals are quite clean.
Have I done a naughty thing connecting the batteries like that? Is it hand smacking time?

Not at all, mine are connected in the same way except I have 4 x 110, no corroded terminals so one would think its just a poor set of terminals on the slave battery. Take the connections off, clean them, grease them and refix terminals (after doing same) and all should be well.

 

[Plevier]

It is theoretically better to equalise the current paths but I can't honestly see that what you have done is responsible for the corrosion.
I always find it hard to believe it's very important. Even two nominally identical batteries are likely to differ more in internal resistance than the wiring resistance difference.

 

[the_wanderer]

Voltage?

Hi.

I am assuming that the two batteries you are using are both twelve volts and you require tweve volts for your requirements.

That said, linking positive to negative will give you twentyfour volts. Not good if your charging system is twelve volts and your equipment requires twelve volts.

Connect positive to positive and negative if you require twelve volts.

The corrosion problem is problably caused by stray battery acid. Clean it all up with bicarbonate of soda, swamp the terminals after cleaning with sandpaper with Vaseline.

That should sort it.


Best wishes.

Alan.

 

[vyv_cox]

Mine were connected for many years in the No.1 configuration on the Smartgauge page. When I reconfigured the battery arrangement I went for the No.2 layout. No detectable difference but maybe it's better for the batteries. No corrosion anywhere as the batteries are in a dry area and I'm careful to clean up after topping up.

 

[Martin_J]

Hi.

That said, linking positive to negative will give you twentyfour volts. Not good if your charging system is twelve volts and your equipment requires twelve volts.

Connect positive to positive and negative if you require twelve volts.

To clarify - I don't believe the original poster was doing this - in fact they even said +ve to +ve and -ve to -ve.

The question was about where to draw the power 'from' ....i.e.. from one battery (because I guess there was originally one battery and that's how long the leads from the fuse panel were)... or from the -ve of one of the new parallel batteres and the +ve of the other battery.. thus still getting 12v but across 'both'.

I assume the original leads were not long enough to stretch one far enough... but as said, should not cause the corrision.

 

[pcatterall]

Thanks guys, the corrosion just seemed odd. Perhaps its because the two corroded terminals are at the very back of the battery box where perhaps the 'corrosion climate' is worse. I think I must have read what Troubedour refers to about current paths.
Clean, and vasaline.... Thanks again