A bit over a week ago I posted an electrical quiz question.

A couple of members came close in the comments, but no one got it exactly right.

Answer

I had the volt meter connected between a reference anode, immersed in the water next to the boat, and the boat’s bond system, and was looking to see if the meter kicked when I disconnected and reconnected loads and charging sources from the main positive busbar.

If the boat had been metal I would have been connected to the reference anode and the hull.

The clues to the right answer were that I was measuring volts, not amps or continuity, and that neither of the meter probes are present in the picture.

I’m pleased to say there was no kick, but if there had been, that would have indicated stray currents flowing from the battery positive, through the connected piece of gear, through the water, and back to the bond system, and eventually the battery negative—we must always think about circuits.

This is a good test to perform regularly on any boat and that goes triple for metal boast and those with saildrives.

Further Reading

• More on how to do this important test
• And more on metal boat care

Quiz is closed, here’s the answer.

Why am I methodically disconnecting each load from the battery, and then reconnecting it while looking at a volt meter? And what’s the meter connected to?

Answer in the comments:

First right answer wins an Adventure 40 T-shirt.

While researching for an upcoming article I noticed something interesting:

Victron rate their Long Life Gel batteries at 2500 50% cycles, as against their AGM Super Cycle Battery at 1000 cycles, and not a lot less than their much more expensive lithium batteries at 3000 cycles.

Could it be that the pivot away from gel cells toward AGM that occurred in the sailing community some 20 years ago was a giant mistake?

I do know that both members Dick and Ginger Stevenson, and Phyllis and I, had very good service from Prevailer Gel batteries back in the day.

Now before we get too excited it’s important to note that gels have one Achilles’ heel: they can’t be conditioned to get rid of sulphation from being left in a partial state of charge, as is common on cruising boats.

Hit ’em with any more than 14.2 volts and they are toast in very short order.

Whereas AGMs from both Victron (14.9V) and LifeLine (15.5V) can be charged at higher voltages to blow off that nasty battery wrecking stuff.

Still, these days, with cost effective and efficient solar, fully charging a lead-acid battery regularly without shore power is a lot less of a problem than it once was.

Should those who want to avoid the expense and complications of lithium be thinking of poor old neglected gels?

Don’t know, but it’s worth thinking about.

Anyone out there using gels?

Our new-to-us J/109 was filled with wire ties like the one on the left. Horrible things because when changes and additions are made people tend to just add more wire ties over the existing bundle.

So, as I clean up the wiring, I’m replacing the ones on the left with those on the right (first photo). Way better, because when I make changes at a later date I just snip the old tie and replace it with new, like so:

Question

Member Kimbal asked:

I’m looking at an ad on Yachtworld for a boat that has “New Victron Super Cycle AGM batteries – 3 x 125ah (2022) – Note: These batteries are a new type of AGM which approach lithium in some respects, and matches the Carbon Foam Firefly batteries performance – capable of up to 100% depth of discharge occasionally, and 60-80% frequently without damage.” Have you heard of this, and does it sound legit?

Answer

Yes, in fact that’s what we have installed on our new-to-us J/109, and testing at Ocean Planet seems to indicate that they do very well on deep discharges.

So far we have not used them enough to say anything really useful, although they are looking good after one season.

That said, it’s important to understand that Victron have two offerings with different strengths:

• Super Cycle, which we selected because we have a very small bank and occasionally will need to take it a long way down, say when aboard for a weekend, but will be able to bring up to fully charged at our wharf when we get home.
• Carbon Foam, which might be better for a long-distance cruising boat since they are more resistant to being left in a partial state of charge.

Do note though that all discharge cycles of all batteries (lithium included) reduce life to some extent (batteries are expendables) so claims like “and 60-80% frequently without damage” are simply not true. Like with Firefly, it’s important to read the fine print.

It drives me crazy when sales people suggest that installing their lithium batteries automatically means we don’t need a generator.

Batteries are a storage device, generators are…wait for it…a generation device. They are different things.

Sure, installing a larger capacity battery bank (of any chemistry) might mean that we can anchor for longer, or sail for longer, without starting a charging source, but eventually, and in some way, those batteries will need charging…duh.

And if we have enough solar to never need a generator, then we might not even need lithium batteries.

Point being that confusing this basic difference between batteries and generators, sets us up to make bad system design decisions…and often spend our money unnecessarily.

Navico should know better.

More on the generator decision here (needs updating).

The way I read this, batteries with BMSs that do not communicate are now obsolete:

If a shutdown condition is approaching a battery system should notify the operator with a visual and/or audible alarm before disconnecting the battery from the DC system.

ABYC E13-7

I think ABYC should have required all BMS to be able to communicate with charging sources. This could be as simple as a set of contacts, but CANBus is better. More here on why. And here on ways to do that.