Britannia has eight golf-cart lead-acid batteries, (also called float batteries), in the house bank. They are mounted low down under the saloon floorboards in two rows, on either side of a 6.5 Kw diesel generator, a large water heater, and the usual conglomeration of pipes, pumps, and filters, not to mention the mainmast compression post. She also has two 12-volt batteries, one in the bow for the windlass, and the other aft, as a dedicated engine start. That's a total of 36 cells to check and fill from time to time. The process usually took over an hour, because the battery caps were not easy to reach, deep down in the bilge. Yet batteries are the beating heart of all boats, sail and power, and should be one of the most accessible of items.
You would think a boat with a 14’foot beam would have lots of space for batteries, but the large capacity water and diesel tanks on each side of the hull, 280 gallons of fuel and 325 gallons of water, reduces the middle space to only 36" inches. Just to inspect the water level in the cells I had to first dismantle the saloon table and roll up the carpet, then lift up four large heavy plywood floorboards and insulation, then lay flat over the floor-beams with a flashlight to unscrew the battery caps. If any cell needed water, I used a long narrow funnel which I stuck in each cell, then poured water in from a gallon bottle of distilled water. It was simply guesswork how much went into each cell, and I know I sometimes over-filled them, but how else could they be topped-up?
Britannia is not the only boat with awkward-to-reach batteries. I was once the skipper of a 77’foot ketch, with full standing headroom in the engine room. That voluminous boat had ten large 12-volt batteries sitting in a big custom-made box—60 cells in all. The problem was that it was necessary to clamber over the front batteries to get to others at the back, even to just test the specific gravity and see if they needed water. I didn't do that very often.
It is of course advantageous that heavy batteries be mounted as low as possible, (Britannia’s weight over 500 Lbs), but batteries that are difficult to reach often result in a lack of attention and maintenance. Nor is it usually practical to relocate them to give better access, due to cable lengths and the boxes they usually sit in.
The water level in lead-acid batteries alters during charging and through evaporation, especially if batteries are in warm engine compartments. The battery charge is tested by drawing the electrolyte up into a hydrometer, then reading the specific gravity on the scale. If water is required, this can be poured in through a funnel or special filling jug. In both instances good access is necessary.
I hated to even test my batteries, and what I really wanted was to change the whole lot for sealed AGM batteries, (Absorbent Glass Mat), which don't need any maintenance at all, but there was one slight problem with that bright idea—$1600. I would have needed to rob a bank to consider lithium!
I wondered if there was some sort of automated filling system, and indeed, a search for "automatic battery filler systems," on the web brought up a multitude of different devices.
A cheap simple method was a half-gallon bottle with a special valve on the spout, which when inserted into a cell delivers water if needed, then shuts off at the correct level. There are several other inexpensive filling systems to be found under these search keywords, but I would still have to go through the same rigmarole of removing floorboards, etc., so I discounted those products.
I continued to look for an automatic system, that I might install permanently on the batteries themselves and that would work without removing the floorboards.
I found a company appropriately called, Water My Battery, www.watermybattery.com advertising water filling systems for golf carts, RVs, and boats. Under the system selector on their website I found, "marine battery watering systems." Bingo!
The principle is simple enough when you think about it. The battery caps are replaced with special valves interconnected with plastic piping. The valves open when the water level drops, allowing new water to enter the cell, then they shut when the required level is reached. The valves are all interconnected to a common feed-pipe, leading to a tank of distilled water high enough above the batteries to give the required gravity pressure, and the system self-feeds. Unfortunately, in practice, it's not quite as easy as that.
The website offers a lot of ways to find the best combination of valves and pipework, but I still had questions specific to Britannia.
Unfortunately, testing the specific gravity of each cell with a hydrometer still requires the removal of the valves.
The valves set the water level at 1" inch below the filler cap level, which is well above the plates on my batteries, so even if the boat remains heeled for some time, it is unlikely the plates will be exposed.
In answer to the forth question. The company makes a special valve, connected to a neon light which blinks green when the level is satisfactory and changes to red when the battery electrolyte level needs filling. I also fitted a battery voltage meter on my power distribution panel, showing the voltage of each battery bank, that gives me a rough idea of the condition of the charge.
Valves are made to fit the caps of all types of batteries, and the warranty is five years.
I subsequently ordered 24 valves for my 6-volt golf cart batteries, and 12 valves to fit the two 12-volt batteries, along with the hand pump. Ms. Flores has offered Cruising World readers a 10% discount by using this discount code, EASYWAY, if they order anything for their own batteries.
I planned to arrange my pipework into separate feeds on each bank of batteries. The port side run will also feed the 12-volt engine start battery, and the starboard run will likewise feed the windlass battery.
The system must be installed when batteries are fully charged since this is when the electrolyte is at its highest. Mine had been on charge for three weeks without use and were fully charged.
The valves come pre-assembled in threes with tubing and just snap into the batteries. All I had to do was inter-connect each set with the tubing supplied, to form a string, I used a pipe cutter, which produces a clean straight cut with no burred edges. The tubing is then just pushed over the barbs to join it to the next bank of valves and the end valve in the run is capped off with a plug. I routed my two fill-tubes at the other end where I kept a gallon of distilled water, and where I could easily get to them without ever touching a floorboard. All connections and pipes should obviously be free of kinks and tight bends.
METHOD OF OPERATION.
To fill the batteries I connected the fill-tube to the end of one of the battery banks, with the quick-connect plug, and the other end was placed in the water bottle. When the bulb was squeezed a few times, it pumped water along the tubes and into the valves. I could see water passing through the pipes and as I continued to squeeze the bulb it became harder, indicating that all the cells had been filled and the valves had closed. The quick-connect was then disconnected and the end of the pipe capped off—it's that simple.
It took less than five minutes to fill both battery banks, and I was kicking myself that I had spent the past ten years lifting floorboards and scrambling about in the bilge, servicing my batteries by hand. This system also fills the cells more accurately.
This is another really good idea to make life easier on a boat.
Costs: The valves are sold in kits, and pricing for various battery configurations is on the company website. One kit for four of my golf-cart batteries was $107.00. The manual pump was $25.00 and the water level indicator $55.00.
WITHOUT EVEN TOUCHING THEM