Maitenance free batteries not maitenance free.

[rayke1938]

In my dam boat I have 2 X 6volt 165 amp hour maintenance free lead acid batteries mounted under the front seat.

I have always charged them after use using a 3 stage intelligent charger. I also put them on charge the day before fishing to top them up.

Last time the charge light turned green ( Indicates charged) immediately.

Used inbuilt battery tester on minnkota and it told me battery needed charging so I left battery on charge overnight.

Next day motor ran for about 15 minutes and slowed right down so I just used stern mount motor which is on a different battery bank.

Tiday I removed front seat and removed the batteries so that I could check them out.

On the voltmeter ind battery read 6.3 volts and the other 4.8 volts.

As i was able to check the voltage of each cell individually O located the faulty cell which was only reading .8 of a volt.

Oh well up for another battery thinks I.

Scrooge raises his ugly head and I have a good look at the battery construction and I see that there seems to be some removeable plugs on the top of each cell. [img size=500]http://www.australianfishing.com.au/media/kunena/attachments/legacy/images/IMG_9885_AFO.jpg

[rayke1938]

This is what i found under the plug. [img size=500]http://www.australianfishing.com.au/media/kunena/attachments/legacy/images/IMG_9886_AFO.jpg

[rayke1938]

So i removed the plastic strap and rubber plug. If you are doing this be carefull as the rubber plug had pressure behind it. ( Most likely hydrogen gas which is explosive so be carefull no sparks ) [img size=500]http://www.australianfishing.com.au/media/kunena/attachments/legacy/images/IMG_9889_AFO.jpg

[rayke1938]

Looked down the hole to check how much electrolite it could see and the battery plates were bone dry.

I then removed the plugs from all cells on both batteries and topped up all cells with distilled water. Both batteries took 2.5 litres of water so they all were in a very sad state.

I have had the batteries on charge for over 6 hours now and the specific gravity of the electrolite has only risen to around 1170. Fully charged should be over 1260 so at this stage i do not know whether the batteries will recover as the plates must have been dry for quite a while.

The batteries are around 4 years old. I have not moved or checked them since installation and it is a couple of years since I have given them a good workout.

When I reinstall them I will be making provision so that o can access the terminals so that O can check them with a load tester.

Cheers

Ray [img size=500]http://www.australianfishing.com.au/media/kunena/attachments/legacy/images/IMG_9884_AFO.jpg

[ellicat]

Interesting read Rayke1938. Let us know the end result.