Battery balancing

For those who have the inclination and the patience, the SmartGauge website technical pages are a good read, even though they haven't been updated in years. I first came upon discussions about the SmartGauge on the CanalWorld forums. It excited a lot of debate between those who simply knew that it couldn't possibly work, and those whose experience had shown that it did. In the end I read most of the content on the website, quite enjoying the fact that Chris Gibbons never presented himself as a detached observer. He argued his case(s) passionately, sometimes rudely, and always with an eye to selling one of his products!

A reader quickly realises that, while it's a promotional website, it also has many pages that are simply interesting (if you like that sort of thing) technical info. On one of them I found a discussion of battery wiring and its effect on battery balancing, and the calculations made a lot of sense. This is the wiring that results:

With this configuration, each battery is connected to the charge sources and loads via one short and one long lead, and all charge sources and loads are connected to the same point. If you're interested in why this matters, see the discussion.

Erin Mae's batteries were connected to each other the more "obvious" way, with links straight between batteries 2 and 3 in the diagram. In addition, I found that the charger / inverter and the 12 volt systems were attached to opposite ends of the bank. I decided that no harm could come from re-jigging the wiring, and that anything which benefited the batteries in the harsh environment of a narrowboat was bound to be a Good Thing. So that was one more job completed over the winter.

It looks a bit more complicated than it did, and the various sensor cables add to the confusion. Chris Gibbons says: "I think I am right in saying that this is the only example I have ever come across where doing something the correct way actually looks less elegant than doing it incorrectly."