In part one and two of this series on the care and feeding of batteries on a live-aboard voyaging boat, we talked about what batteries need for a long life. In the next few posts we will move on to how to actually get those battery needs met.
We now have a fair, but certainly not great, battery charging system; however, getting here was anything but easy. The story of our long and costly struggle on Morgan’s Cloud and the lessons we have learned will, we hope, help you.
I start the story with some bozo (that would be me) plugging in a heavy chop-saw while forgetting that the shore power was off and that our venerable Heart Interface was on—end of that charger/inverter.
First Lesson
Inverters may claim to have over-current protection, but they are not idiot proof. Think about what you plug into them, particularly tools with heavy electric motors that produce very high start loads.
Perhaps we could have got the Heart Interface repaired, but since the inverter produced square waves, which some modern electronics don’t like, and not sine waves, and because the charger was not fitted with temperature sensors allowing automatic temperature compensation (required for AGM batteries), we decided to replace it.
After carefully studying the specifications, we bought a Xantrex 2000 watt inverter/charger, and so commenced a two year saga of frustration: The first unit had unstable charge voltage and, we suspect, AC ripple superimposed on the DC charging voltage. The result was the death of a brand new pair of AGM batteries in just six months.
The second unit worked fine, but had a 30 amp draw limit on the AC side when charging (in direct contravention of the published specification) which meant that we could not run our fridge and charge the batteries properly at the same time while running our generator. Not only was this a waste of fuel, it also meant we could not fully load the generator at any time during our daily charge cycle—very bad for it.
After much letter writing, Xantrex agreed to upgrade us to the 3000 watt model free of charge. But the 3000 watt unit had a design error resulting in the AC and DC grounds being tied together, an absolute no-no on an aluminum boat.
Each iteration required wrestling the 70lb units out of and into place and then shipping the defective one across the continent. The light finally went on in our heads:
Second Lesson
Don’t combine the charger and inverter functions since you end up with one very complex and heavy single unit. And when any part of that machine fails you lose your entire electrical system.
We managed to convince Xantrex to take back the last inverter charger and give us a 1800 watt sign wave inverter (which has worked well for three years) and two 40 amp three stage chargers in return.
Why two chargers you ask? Because, at least at the time, charger manufacturers had decided, for reasons that escape me, not to make large chargers unless integrated with inverters.
This deal meant that we now have three (we already had one) Xantrax TrueChargers. Each of the two 8D batteries that make up our house bank has its own charger wired directly to it with a temperature sensor and the third is wired to the “Both” side of the battery switch.
This is a reasonably good system that allows all three chargers to be used together to pump a theoretical 120 amps into the batteries and also allows us to equalise one battery while using the other.
Also, we have lots of redundancy, always a good thing on a cruising sailboat. We even have a small portable inverter to backup the big one.
So now we have reached battery charger nirvana, right? Sadly not. Due to limitations in these, and we suspect most, chargers, this is anything but a turn on and forget system.
In the next post we will write about a fundamental weakness of almost all of the readily available charging systems, both AC and alternator based, and how these systems must be managed if you want a decent life from your batteries.
If you have any questions, or thoughts on our hard earned lessons, please leave a comment.
{ 6 comments… read them below or add one }
John–
Regarding, “Inverters . . . are not idiot proof. ” My daughter–a professional stage manager–tells me that nothing is idiot proof because idiots are so inventive.
Do the makers of the Xantrex charger/inverter also make Xantex: a “Homeopathic product containing natural ingredients to be used as an aid in achieving performance in racing horses.” Who knows–perhaps Xantex also would improve battery performance.
Regards,
Westbrook
Hi Westbrook,
That’s me, nothing if not inventive. It was a huge chop saw too!
About your batteries, Get a wood burning stove on board (fed by drift wood) and get your perfectly OK batteries working again at a temp where the tech has a chance to work.
David
I’m eagerly following the account of your experiences . . and wonder why you chose Xantrex over Mastervolt ? … was it because they combine the charger/inverter in one sgl unit? Where am I coming from?…The bareboat charter industry in The Whitsundays…that’s probably one-rung up the ladder in terms of Degrees of Difficulty…that is from the single vessel/private live-aboard situation. 20 years ago a bareboat was just that…today the punters want everything from surround-sound (and moving pictures) to hair driers…it sucks…I often wonder why we choose to charter in an area that has a World Heritage Listing!!! Regrettably, we have to deal with fools (rather than idiots) on a daily basis! Cheers from DV
We chose Xantrex because they had taken over the old Heart/Link line that we had had years of trouble free service from. Also because the Mastervolt would not fit in the space the Heart had vacated.
However, I don’t think the brand is so much the point. Rather, for me anyway, the key take-away, was that having the inverter and charger in the same unit was a bad plan–just too many eggs in one basket.
I hear you on the trend to too much stuff on boats. Although we do have three computers and a network on MC, so maybe I should not point the finger. But then again, she is our home, not a boat to sail on for a couple of weeks.
John:
I also had a year of frustration with the Xantrex 2000 installed with a 4 – 8 D battery system. From time to time the charger function would simply cease to work. Xantrex could not diagnose over the phone. The solution was a separate charger entirely and using the Xantrex only for the inverter function.