Monday, March 11, 2013

The Equaliser!

That’s what I need, apparently. Not Edward Woodward playing Robert McCall in the 80s detective series, but something to “equalise” my batteries!

Seriously, though. Thanks to Tom on NB Waiouru for his advice I researched battery equalising and it appears that this is what I should have done. I say “should”. Now we’re no longer on shore power I don’t have that option.

For the technical people – ignore if you’re not interested, but if you have open cell lead acid batteries you should be – if a battery of the above type is subjected to long periods of minimal discharge and charge (i.e. not used much), a build up of sulphate crystals occurs on the internal plates which reduces the plate area and thus the overall capacity of the battery. Periodically batteries should be equalised, which consists of applying a higher than normal charge voltage (typically 15.5 to 16.5 Volts) for a period of time. This has the effect of forming bubbles upon the plate surfaces which stir the electrolyte and break down the coating of crystals. However, this should only be performed on unsealed wet cell batteries, those that you can top up.

Tom pointed out that my Mastervolt Mass Combi has this function built in, and I should have used it while still in the marina. Now we’re out I can’t, you need a mains supply for the charger.

This is a first for me, in the past I’ve been able to identify and replace individuals in our four battery bank with the use of a digital voltmeter and hydrometer and a degree of common sense. But this one had me stumped. The only thing I can think of is that our break in Barton Marina, plugged in on shore power, has resulted in this sulphation because of the low consumption/recharge cycles required. And this has affected all four batteries.

Why has it not happened before, I wondered. Well, I guess that in “cruising mode” we discharge the batteries more deeply overnight, and therefore charge at a higher rate when the engine is running. This will discourage sulphate formation.

So the last week has been a bit of a learning curve. I know now that when I have the chance (on shore power), I should, and will, equalise my battery bank.

Incidentally, some chargers have this function built in automatically. Terry, on The Rooster’s Rest, told me that whilst they were on shore power, once a week their Smartgauge reported battery overvoltage for a time, which implies that their Victron charging unit was equalising.

I am going to replace all four batteries, so at least I will be starting from fresh, with a bit more knowledge (and a bit less cash!) than I had.

Thanks to everyone who has commented, texted and emailed with ideas and solutions. Particularly Tom for pointing me in the right direction.

We were intending to head down the canal to Streethay today, to collect and install the new batteries, but frankly I wimped out. It was so cold in that Siberian easterly, and the snow flurries didn’t help… Tomorrow now, for definite.

The weather didn’t stop Sue (No Problem) dragging Meg and I for a walk around the fields for over an hour this afternoon.

Sheltering from a howling gale and snow shower near Alrewas HayesDSC_0078

Meg and Penny having a “discussion” over ownership of a stick….DSC_0083

We should be able to get to Streethay, pick up and install the batteries, and be back here in the afternoon. So long as it’s not too cold. I am being a wimp, aren’t I!

Locks 0, miles 0


No Direction said...

Yes, our Victron gauge shows 15.5v now and again, then settles back to 13.5v.

Alf said...

Keep the "old" batteries, Equalise them when power next available, then reconnect them = mega capacity !!!
Though you probably don't have room them all ?

Tom and Jan said...

A couple of thoughts for you to ponder.
1. Do you know a fellow boater with a generator who would be prepared to lend it to you for 24 hours to run the charger. Or have you considered booking into a marina for 24 hours to use their shore power.
2. If the problem with your batteries is sulphate crystals on the plates have you considered purchasing a charger like the CTek MSX5.0 (£51 Amazon). Apparently tt has a "pulse" function that can "recover" sulphated batteries back to new.

You may not need to purchase a new set of batteries!


Geoff and Mags said...

Hi Ray, I wish my Mastervolt did that...
Alf, that did cross my mind, or maybe just buy two new ones and zap the old ones when I can. But then I measured the battery compartment....
Hi Tom, thanks for your help. I did consider the marina option, but I still might be wrong about the problem, so I thought I'd be done with it and just change the blessed things!