Why does it seem like we’re always having to replace our batteries? Maybe because we’ve owned the boat almost 15 years and replaced them now 3 times? But when you read the specs online, it doesn’t really seem to matter whether you opt for gel cells, AGMs or flooded lead acid batteries, all of them have lifespans of somewhere between 3 – 8 years.
These are 4 1/2 years old. But life aboard a sailboat is hard on batteries – especially if you’re really out cruising. It’s literally impossible to charge them fully “out cruising” and this set of batteries endured our 157 night straight anchored out never going to a dock adventure. So, maybe it’s time.
While we were anchored out for a week just before the holidays, the batteries indicated 12.25 (basically a dead battery) in the morning – when they were only down about 30-50 amp hours. They should be FINE all the way down to 120 amp hours when the yellow “time to charge” light illuminates on our Link 10 monitor. David checked each battery — 5 of the 6 were showing 6.1-6.2 volts after overnight – one showed 4.8. So we knew we had one dead battery.
When we returned to the marina, David borrowed our boat electrician friend’s fancy diagnostic tool and we found that every battery said either “weak” or “bad”. Now what to do.
When we left the US to go cruising, we had 8D gel cell batteries. We found, at that time, we could not replace gel cells in the Western Caribbean when they were bad after 5 years. So in LaCeiba, Honduras, we converted to Trojan T105 flooded lead acid batteries because they were readily available.
We replaced them in Panama in 2009 and now we can either replace them again or convert to a different type of battery – preferably one that doesn’t require maintenance and watering. Despite our diligence in having a caretaker check the batteries monthly while we’re away, there have been times when we’ve come back to dry cells in the batteries – severely shortening battery life. 🙁
But after doing the research, and having most people recommend AGM’s, we found between the price difference – it would cost us approx $1000, plus installation if we couldn’t do it ourselves, to convert. PLUS the leading AGM manufacturer, Lifeline still says on it’s website that AGM’s must be recharged to 100% every time – here’s the link: LifeLine where it states: “Once you have selected and installed your battery bank (s), there are some simple tips to insure a long cycle-life. After you have discharged your batteries, be sure you fully recharge them.” We have a cruising buddy boat that was an electrician and was severely disappointed in only getting 3 years out of his AGM batteries – when he contacted LifeLine, he was told it was because he wasn’t 100% recharging them. Out cruising, it’s next to impossible to recharge to 100% even with our little Honda 2000 generator, let alone solar & wind.
So after checking pricing and comparing lifespan, we’ve decided to replace the Trojan T105’s. We found them for $91 each at a golf cart shop locally. The big catch is that everywhere these days requires you to bring in the old battery or they charge you … in this case $23 more per battery. So we lugged old batteries in and brought new Trojan T105’s home.
One other important consideration — make sure if your boat is knocked down or lays on its side that your batteries don’t become 62 lb (each) lethal missiles. If you look closely at the photo below, you can see the white bar that bolts down, holding our batteries in place. It’s not perfect, but it works. Don’t forget to make sure your batteries aren’t going anywhere!
Two important steps before we removed the batteries … first, we photographed exactly how all the connections went and then David drew himself a little diagram so he knows where to put the cables back. Sure saves alot of hassle when putting them back in!
Don’t forget to use the liquid electrical tape – black & red – to cover all the connections in an attempt to keep out the corrosion.
Voila! We’re $589 dollars poorer, but the house battery bank is good to go! We recently replaced the starter battery and checking the windlass battery shows that it’s still good, so no need to replace it.
One more unexpected project finished successfully!