Project 2 - Solar: 2016 Update

The batteries and solar worked great throughout the summer of 2015, we never plugged in to shore power just like on old Trekker, all was good.  Then we went out for a cruise in mid September and had the pleasure of usually crowded anchorages all to ourselves!  After two nights and one partly cloudy day  at anchor we woke up to house batteries reading 10.9 volts, which is effectively dead. This didn't make any sense to me as the only serious electrical draw we have on the boat is the refrigerator, which draws an average of 2 amps per hour.  Lights are all LED (and we use them as though they are incandescent), we turn off instruments, didn't watch the TV ... you get the picture. In fact, we baby the batteries, only using our electric winches when the engine is running and generally being anal about taking care of them. So, if the batteries were 320 Ah, and we had been sitting for 40 hours using, to be conservative, 4 amps per hour we should only have used 160 Ah. And that was assuming no solar charging, and we knew there had been some.  So, on went the engine, we charged up and because I was now nervous about being caught out with no electricity, motored home.  We spent the balance of our vacation at the dock and prepared for, and hauled out a day early.  I completely disconnected the batteries for the winter. Pat Sturgeon came up and checked them with a cranking battery tester and declared them to be fine, and season done, I spent the winter trying to figure out why they appeared to be dead that morning!

In the spring I had Brian and Mike Kelly of Bayland Enterprises check the batteries with their deep cycle battery tester, and sure enough, one had only 105 Ah and the other 93 Ah.  

I spoke to Pat and we decided I would take the batteries back to Ontario Battery, that is a Victron dealer and they would check them too.  They got nearly the same results, so new batteries were in order.  Pat very kindly agreed to split them with me and we decided to get two more as well since we had decided we need more freezer space which would effectively double our draw.

We ordered and installed 4 new 165 Ah Victron AGM batteries and wired them up with the help of Mike Kelly at Bayland. While he was at it, I had Mike give the electrical system a "once over" and he was satisfied with the system architecture. He couldn't identify anything in particular that would have caused the early demise of our original batteries.  Pat Sturgeon helped with sleuthing a potential cause, and about all we were able to come up with was that the batteries were manufactured in the fall of 2013, sat in stock at Hanse for 6 months until they were installed in our boat early 2014, shipped to Canada,  and used to demo the boat for the summer.  We're not sure how well they were maintained at Hanse before they were installed, and I expect they were used hard on the boat to demonstrate the electric winches, the windlass etc. during the summer prior to our taking ownership.

I was still concerned that we hadn't found a clear cause for the original batteries being pooched.  After much internet research, apart from deciding that batteries and electrical systems are more of a black art than science, I learned that AGM batteries do not take well to being overcharged.  I decided that there was a chance that the batteries were being overcharged by our 115 amp alternator, since it seems to charge at 14.1V whether or not they were fully charged (which they usually are, being connected to solar). Victron states that the float voltage for the batteries is 13.5 to 13.8V.  At the same time I realized that we do not have a smart regulator like we did on old Trekker.

Mike at Bayland recommended a Sterling Alternator to Battery charger, which in addition to maintaining the float voltage at the recommended level also includes a "boost" function which is supposed to increase the amps going into the batteries and recharge them faster than the alternator can on its own. It also includes an alternator temperature sensor, which I thought would be a good idea, since our battery bank is really too large for the size of the alternator. 

The alternator to battery charger seemed to work well until  we went on holiday and started to discharge the battery bank to about 70% at which point, after 20 minutes it would trip due to excessive alternator temperature, supposedly greater than 90 degrees celsius. As a result we were losing the "boost" function, although it still maintained the absorption and float voltages at the correct values.  I bought an infra-red thermal gun and checked the alternator and found that it was getting nowhere near to 90C (65 was more like it), so now we had another puzzle to figure out.  It turned out that the alternator is mounted on a bracket which comes off the exhaust manifold, which is where Mike had installed the temperature sensor, so he moved it to another mounting point, and we'll see how it goes this summer.