warm battery

[Odysseus]

I am embarrassed to bring this to the forum as I used to make batteries, but I am at a loss to to understand this.

I have 3 domestic wet  batteries all 115 amp, same year fitted, but one always is warmer than the others, I have thought about it but all of my thoughts have come to nothing.

The one that gets warmer is the first in the circuit, the others are linked by 10mm cable, only 9" / 14" cable run to each. The connections are in good order, and so far it does not appear to detrimental to the output, charging,  or sailing with instruments and autohelm all day long.

Any ideas?

Odysseus
Bav 38

[MIA]

Current always goes to the easiest path, therefore your theory could be feasible, might be a good idea to rotate the batteries about each year.

[Ripster]

I was going to suggest similar, though I suspect you have probably thought of it!  Is it a lot of hassle to swap one over and see if that one then gets hot and first one then runs cool.  If the previously cool batt then gets warm in its new home, you know its do with cabling.

[Tony]

In my experience, if it's not a cabling issue, the warm battery can be a good one trying to compensate for others

[Odysseus]

Thanks for that, I agree, however I have measured inputs and outputs, there is I slight difference but not enough to warrant the heat. Also the cable is big, short, and clean.
I am taking a thermometer out to see if I am having a cell issue.
Odysseus
Bav 38

[Nigel]

Do the charge and discharge leads run from opposite ends, as is recommended? I've gone one step further, my three batteries are linked by a delta shape of cables.

[Odysseus]

Always prepared to look at any and all ideas, however can you discribe your interpretation of "delta" wired configuration please. 
I am going to visit "Barden UK" next week.
Odysseus
Bav 38

[MarkTheBike]

Hi Nigel

Like Odysseus, I am intrigued by your 'delta' arrangement; would a photo be possible, or even an envelope sketch?

Also - what do you mean by 'opposite ends'? Are you referring to batteries that have their +ve and -ve terminals at either end? Why would that be preferred? Is it to do with heat dissipation? I've got 2x140aH and they were only available with terminals at one end. Only just replaced them so a bit loathe to bin them...! 

ATB

Mark (B34 "Figaro" Plymouth)

[Odysseus]

http://www.smartgauge.co.uk/batt_con.html

I think this is the answer to the problem, and it's very interesting. All should read it.
Odysseus
Bav 38

[Bavnav]

Many thanks for the link about methods of connecting batteries - very informative and interesting.
Fair winds,
Bavnav

[Salty]

From a former disbeliever but now converted, many thanks Odysseus for that web link. I've been thinking of changing my domestic batteries (2x 140ah) and perhaps adding a third battery as they don't seem to hold their charge for long. Also, the trusty hydrometer gets some very strange readings at times from the different battery cells. With the information from that web site I will also be changing the method of hook up from the charger to each battery to try to ensure a properly balanced system. Recently I purchased and fitted a Marlec Rutland 914i wind turbine and one of their HRDi charge controllers. The controller came with a battery temperature sensor which I have not yet fitted, but from the above thread, fitting the heat sensor has just become a prime job to be done.
Thanks guys.

[Nigel]

By "Delta" I mean that my three batteries have three wires linking each terminal (rather than the normal two), so they look like a Greek Delta: Δ

Sorry for the jargon, it's a fairly common term in electronics.

[MarkTheBike]

Cheers, Nigel. I had a feeling that's what you meant, having read the bumf supplied by Odysseus's link. Extremely logical, but not necessarily obvious to the electrically challenged. I'll be going through my setup this week to see if it needs balancing (ps. I bet it does).

Mark