Battery connections

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emnick

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I intend replacing the batteries in the picture below. The bottom right one failed getting very hot and filling the saloon with hydrogen, this could have been very nasty!

Is there a better way of connecting said batteries, I appreciate that the wires from the charger should be moved so as not on the same battery but looking at the 'smartgauge' website they pay alot of attention as to how batteries are connected I cant seem to be able to see any way of improving this but my guess is, there is? Over to the experts
Thanks
 
The bottom right one was doing most of the work, as explained in the Smartguage page. I think the general comment in the article about each battery having to go through the same number of bridging links (either side) is the way to go.

Method 2 would seem to be the way to go. With 3 batteries it will give the same number of bridging links for all batteries.
 
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You would appear to have space to fit all three parallel to one another across the box like the one at the top. This would make it simpler to link them electrically in parallel without so many cables over the batteries. The vents would all be at the same side too. If you bridged the positive and negative terminals down each side and connected the main positive and negative cables diagonally opposite one another then the cable lengths would be balanced for all three batteries.
 
Had the battery bank worked OK prior to the battery failing? The interconnecting cables appear to be securely terminated, and the lengths are so short that I can't see any great improvement would be achieved by moving the main connections. It's probably just the case that the bottom right battery developed a fault and failed. I'd replace it, like for like, and see what happens.
 
genuine question, bcs I started this morning at 0300, and am not feeling bright...

Can someone remind me, please, of the accepted way that electrons 'flow' in a simple circuit ? AFAIR, physicists got it wrong in the 19th century, and our clever bods with bigger telescopes, now say that the real flow is the other way round.

So, is it from + to -, or - to + ?
 
Yes, This caused a lot of problems during WW11 when the Americans helped with radio type circuits as we (Brits called it + and they used electron flow when designing circuits, as far as I remember.
 
As Philip says.

The electrons flow from negative to positive but the conventional direction for current flow is positive to negative.

.
 
The thing which puzzles me is the production of hydrogen, which is unusual unless the charging system was grossly overcharging causing gassing. The fact that the battery was hot seems to confirm over charging.
Question is, how did it happen?
 
If a cell in one battery went short-circuit it would now only have 5 cells, giving a nominally 10 volt battery on a 12 volt charging circuit. Hence it gets overcharged and hot and produces hydrogen (and oxygen).
 
pappaecho said:
The thing which puzzles me is the production of hydrogen, which is unusual unless the charging system was grossly overcharging causing gassing. The fact that the battery was hot seems to confirm over charging.
Question is, how did it happen?
Click to expand...

I was also concerned but reasoned that all of the batteries would be hot. When i say I could not leave my hand on it.

I am told that I should leave the charger always on, which I do. But I am considering making or buying some type of thermal switch perhaps put something on each battery that would disconnect the charger if it happened again. Is there any such device on the market?

Thanks again
 
Thermal cut out switch

This kind of monitoring is common on aircraft using wet NiCad batteries as they have a habit of reducing voltage as they get hot so encouraging more current in a constant voltage charging system. Called thermal run away it can be very disastrous.
I have not heard of similar in Lead acid battery systems however some smart chargers use temperature to determine actual charge conditions. It might be simpler if you want to leave the boat with charger on to use just a trickle charger ie about 1 amp continuous for 3 batteries. Or fit a solar panel and don't leave charger on.
re filling the cabin with hydrogen I imagine you mean the smell of sulphuric acid fumes as I think Hydrogen is odourless. Just goes bang with a flame.
good luck (or maybe you have had good luck) olewill
 
emnick said:
I am told that I should leave the charger always on, which I do. But I am considering making or buying some type of thermal switch perhaps put something on each battery that would disconnect the charger if it happened again. Is there any such device on the market?
Thanks again
Click to expand...
I was intrigued to note that the batteries you were replacing are identical to those I've just had to replace on our Swedish manufactured boat. These are no longer being made, it would seem Exide took them over.
When I started to take them out, a little block with an attached wire was stuck on the top of one out of the four. I am told this was the thermal device you inquired about. We just stuck it back on again.
One other point: Unlike you, I have always disconnected mains power whenever I leave the boat, I am aware most others do not, but I can see no point. Being that my batteries appear to have outlasted most other boats of this age, I reckon my policy to be the best one.
 
PhilipF said:
I was intrigued to note that the batteries you were replacing are identical to those I've just had to replace on our Swedish manufactured boat. These are no longer being made, it would seem Exide took them over.
When I started to take them out, a little block with an attached wire was stuck on the top of one out of the four. I am told this was the thermal device you inquired about. We just stuck it back on again.
One other point: Unlike you, I have always disconnected mains power whenever I leave the boat, I am aware most others do not, but I can see no point. Being that my batteries appear to have outlasted most other boats of this age, I reckon my policy to be the best one.
Click to expand...

I think I may start doing the same. Ours were also Swedish. I think the charger (mastervolt 12-40A) has the facility to connect a thermal protection device, but IIRC only one, this I presume is to protect from over charging, not a battery defect.
 
If you leave the charger always on, it is essential that when it reaches about 13.6 to 14.0 volts that it switches to float charge.
I suspect that your charger basically cooked your batteries
 
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