Thursday, 11 December 2014

It's the time of boat chores. (1)

Cold days are not good for working in the the boats engine bay. Well not unless you run the engine for a while to create a nice warm engine block to sit on. I like to do this in cold weather when I top up the battery bank with water. Yes, its that time of the year - its battery maintenance time. 
But at several hundred pounds a time to replace the batteries in the bank, it makes good sense to nurse them along to get the maximum life out of them.  I routinely check and top up the batteries at about three month intervals. I start by clean the connections and add a little spray of WD 40, this is the first little chore.

The batteries always need water, but the fluid level is still above the plates. I use de-ionised or distilled water only. Using tap water will shorten the life of a wet cell by encouraging the build up of furring around the plates. De-ionised or distilled water is very pure with any trace elements removed.

There are automatic battery filler systems available. But looking at them and especially at their cost. It seems like a very expensive way to avoid an hours chore.

In the auto top up system the battery plastic filling screws are removed and a water injector is fitted in their place. Inside each water injector is a precision level-sensing valve enclosed in a strong protective housing. 

When the electrolyte level rises to reach the tip of the injector, the valve shuts off instantly. There are no exposed parts to stick or break and injectors are strong enough to withstand many years of use.

Some people use a hydrometer to test the condition of the batteries. Then proceed to assume a contortionists positions to try and visually check the fluid level in each cell. 

I prefer to just top up using my special little battery filler can.  It has a special regulator valve and sleeve which means no more spillages and at the same time the level is topped up automatically. No short filling or over filling of the cells. The batteries between them seem to consume about a litre and a half of water each cruising year.

You can find the fillers for sale on on eBay. Search for 'Sealey JBF1 Battery Fluid Filler'.



  1. We opted for sealed batteries for Naughty-Cal. Where the batteries are located is pretty much impossible to get at them to check the levels, which is how we killed out first battery, and yes that was just one domestic battery!

    We replaced the one with two sealed batteries which lasted about four and a half years which seemed like a reasonable time frame for them considering the use they get. We replaced them again mid this year as they were getting a bit unreliable but far from dead.

    Hopefully this set will last just as long.

  2. Hi where did you get your batteries fully thing from sounds like I could do with one. Clinton


Please put your name to your comment. Comments without a name may automatically be treated as spam and might not be included.

If you do not wish your comment to be published say so in your comment. If you have a tip or sensitive information you’d prefer to share anonymously, you may do so. I will delete the comment after reading.