Friday, January 22, 2016

Master Of All Trades

"Jack of all trades, master of none" is how the phrase goes, I think.  But on a boat, it seems you need to be more than a jack of several trades, at least if you don't have unlimited funds to pay someone to maintain it.  And certainly if you insist on things being done right. From engine repair to fiberglass, it certainly helps to know how things work and how to fix them, even if you have to learn how as you go.

On our trip south we've discovered a few items that we will need to deal with.  One of them is the house battery bank.  It seems that our house bank isn't holding much of a charge anymore. So begins my deeper education in marine batteries and complex charging systems (if I do any upgrades, I want them to be compatible with the eventual addition of solar). Things I wanted to learn about anyway...but learning under the gun of a needed repair is not as fun.

I'm somewhat familiar with variants of lead-acid batteries and multi-stage chargers from my previous stewardship of an airplane.  In the airplane case, the batteries are small due to weight concerns and expensive (because they are a certified airplane part) and yet need power to crank the engine and run electronics for a while if an alternator failure occurs in flight. So, squeaking out as much life from them as possible was always a goal, and 3~5 years was considered a good lifetime for those batteries. But marine is a bit different environment.  Much larger batteries wired into banks.  The need to run things like refrigerators, lights, and equipment without a charging source for days on end (deep cycling) is a bit different than running a few airplane instruments.

I started my investigation with the obvious...take a look at the house battery bank.  I try to take a peek at all the boat systems periodically, but the house bank sits at the bottom of a locker in the cockpit and isn't the easiest to access. Add in the fact they are AGM VRLA batteries (what was once touted as maintenance-free batteries) and they were a bit out of sight - out of mind.  Well, when i dug all the stuff out of the locker and removed the access panels to the batteries, I could tell that the batteries were not in good shape.  Each of the 3 group 4D (20 inch x 9 inch x 10 inch or so) batteries showed minor signs of swelling.  The two usual causes of this are heat related: Either a sudden rapid discharge (short) or overcharging of the batteries.  Since I haven't experienced any shorts, my immediate assumption was that it was the result of overcharging.
The West Marine Battery that makes up our current house bank.

A year or so ago I had one alternator's voltage regulator fail and it was overcharging...but that problem was identified rather quickly and resolved.  Since the boat is configured so the engines charge their start batteries and then any leftover energy is used to charge the house bank, I would expect the start battery to have failed first. Since it was OK, I doubt it was the culprit.  The original charging system for the boat works in a similar manner, charging the start batteries and then letting power "overflow" from there to charge the house bank.  That left only one culprit - the Xantrex inverter/charger.

The inverter is wired to the main house bank, and it includes a smarter multi-stage charger that is supposed to do a better job of charging and maintaining batteries.  As a result, the charger needs to be set up with parameters for the type and size of the battery bank.  I guess I shouldn't have trusted how the thing had been set up when we bought the boat.  I found the parameters were set for a 3000Ah bank of wet cell batteries.  Since the actual bank is only 600Ah of AGM batteries, this is probably the cause.

Of course, this means we need to replace the main house bank. The batteries currently on the boat are from West Marine and when I checked were about $700 each.  Ouch.  Looking around, I found similar 4D AGM batteries for a little over $400 each.  Continuing my research, I found that many of these batteries aren't true deep cycle batteries and, as a result, likely won't last as long as other options. Reading a number of articles on marine batteries and deep cycling batteries, it seems that some of the best bang for the buck are golf cart batteries.  It sounds like they are better designed for deep discharges than the big batteries.  They also seem to have higher amp-hour ratings for a given size than the ones I have now.  The down side is that each battery is smaller and is only 6 volts, so I would need two batteries connected in series to equal one of the batteries I have now.

Trojan T-105 225Ah, 6v battery option.
US Battery 2200 232Ah, 6v battery option.

Two group size GC2 batteries sitting next to one another are the same length, slightly taller, and just a bit narrower in width than a 4D group size so they should fit my battery locker.  Wired in series, I would have a 12 volt equivalent with between 210 and 225 Ah (compared to the existing batteries at 198Ah). The wet cell batteries seem to be around $110 each (or $220 for the equivalent to one of the 4d's), and the AGM versions are around $200 each (about the same as the cheaper 4D's that I've found). Since these produce a slightly higher amp-hour bank that is more accepting of deeper discharges (to 50%), this may be the way to go.  It would require I get 3 new cables to wire two 6-volt batteries in series, but it seems to me the advantages may be worth the limitations.

Trojan AGM 217Ah, 6v battery.
US Battery AGM 213Ah, 6v battery.
The other question is do we go with AGM or traditional wet cell batteries.  Due to cost, I'm not interested in going with the newer lithium options (my time in the software industry has taught me the value of "trailing edge technology") and these two seem like the best choices.  Each has advantages and disadvantages.  I guess one thing that worries me about the standard flooded battery bank is if we can keep on top of maintenance.  I know they need to be checked and filled with water periodically.  With the location of the house bank being at the bottom of one of our large storage lockers, will we dig everything out and check them as often as we should?  And what is that interval anyway?  But my wallet sure likes the price point of the flooded ones, and they do have higher capacity.

Decisions, decisions...if anyone has any advice, leave a comment.


  1. Hi Mike,
    Sorry to hear about the batteries, however you may be able to restore more of their capacity. That info with link and other comments are in email I sent to you.
    Doug in VT

  2. Hi Mike
    We replaced our house bank during our refit a couple years ago. One thing to consider is where the bank will reside. This is important for two reasons. One, these things need to breath, and hydrogen gas is given off. Also, the flooded type have to be watered very regularly, or there is a risk of a dry cell getting cooked during a vigorous charge cycle. The risk of explosion in a closed compartment filled with hydrogen gas from a battery is a scary thought... I once blew up a van battery while jump starting it. The sound was scary, like an M80, and it blew the top of the car battery over the house into the back yard. We bought the AGM sealed batteries and we have not had any problems. We found AGM Duracell golf cart batteries at Sams Club, and they have been fine for us. 6 of them, wired as you described, and we have about 630 amp/hours for the house bank. For us, the AGM batteries were the way to go.
    SV Saltrun

    1. Hey Chris,

      The house bank sits under a false floor in our cockpit settee. I believe, just like the propane locker across from it, has vents below that lead under the bridge deck of the boat. Hard to tell for sure as there are currently 350+ lbs of battery sitting on a tray in there and too much rain at the moment to go hop in the dink and slide under the boat to take a look. ;-)

      I wonder who makes the Duracell batteries...and if I can find someone with a Sams Club card...or maybe Costco sells them...will look into it.

      Thanks for the input. The AGM is appealing from the maintenance and safety standpoint, but the added capacity with the flooded cells is nice too. Do you know what "wattered regularly" actually is? Is it monthly? I never could get a good answer on that as most everyone says it depends on I guess I want to know what it should be in the Caribbean. Of course, not an issue with the AGM versions.

  3. Mike,

    We have as a family 4 electric golf carts. I use one at the shop to move planes around, etc. I get about 10 years on the batteries. At first I can go weeks between charges (I have a charge meter in the carts). Near the end, a day or so, and if it sits for a week fully charged, will need it in a few hours.

    Costco usually has the best prices on the golf cart batteries (wet cell) so you need to check them every 3 months at first and monthy after 5 years.

    Whatever type of battery you get, always replace a whole bank. Charger work best this way, and the battery pack last the longest.

    The biggest difference between car and golf cart batteries (sans voltage) is that car batteries are to be charged slowly and then discharged rapidly for a brief period. Golf cart batteries charge quickly and can sustain a steady and very long duration draw.

    Been studying up for solar. Solar tip, wire panel in series to get the voltage up, this reduces inverted cost and give charging at first light.



    1. Thanks Roscoe. As for series versus parallel wiring, the one catch on a sailboat that shouldn't exist as much in a fixed land-based system is shading. Booms and sails can shade randomly and series wiring kills everything in the series circuit. Parallel with an MMPT controller is the typical best-case solution for I understand it.

  4. Mike,

    When people say 'on condition' they mean battery condition, not environmental conditional. Cold is the enemy of all batteries.

    Back in the early 90 I worked at a gov lab that deployed weather buoys (10, 11, 3, NOMAD meter) that used lead acid gold cart batteries, marine batteries and my job in software was to monitor battery condition in the weather reports. These buoys are never someplace nice. They are unmanned and on their own for 5-9 years. With yearly or less service.

    The Golf Cart batteries needed water level checks every 3 months for the first 5 years, and monthly thereafter in 99% of cases. Some might go on the monthly service schedule early, if battery conditions indicate.



  5. Mike if you can find an East Penn Manufacturing warehouse near you, they sell factory seconds AGM for less than new wet cells. We got our 8D that way and it's been doing fine for 2.5 years. No warranty, but at the price it doesn't matter. I know there's one in Ft. Lauderdale if you can wait that long.

    SV Kintala

    1. That is good to know. Wonder if they have any good deals on the GC2's. The idea of more, smaller, higher amp-hour batteries seems to be growing on me more every day.

  6. Sorry to hear Mike. We had the exact same issue. Splashed the boat at Stingray Point and realized, after disconnecting from shore power after 3 months, our house bank wasn't up for the task. Grabbed 6 West Marine Deka batteries. We now have 660 AH and they've been working well.

    I don't expect much more than 2-3 years of service before we have to replace again. Partly that's me not willing to risk our auto pilot failing on passage. We'll consider Lithium in 2-3 years simply for the fact you can almost fully discharge them.

    Rainy, cloudy & windy in Florida. Don't rush down here too fast ;)

    1. Hey Ben,

      Yeah, lithium seems like a good idea...but I'm going to wait until the tech is a bit older. As I mentioned, I've learned that being an early adopter can be a costly proposition but once they become a bit older, they might well be worth it.

      The thing that bugs me is that these batteries really should last more than 3~5 years if taken care of...yet most practical experience says otherwise. I have heard that the GC batteries have a greater chance of living up to their life potential.

      It is cold here today...right now 32 and yesterday was raining it is still warmer down there, even if the weather isn't perfect. Hope we can catch up some time soon.

  7. The Dekka batteries are what East Penn makes.

    SV Kintala

    1. Yep, they make Dekka and I think they are the ones that are re-branded for West Marine (in case you want to spend way too much for the same battery). ;-)