Equalisation charge for sealed lead acis battery ?

[Boo2]

Equalisation charge for sealed lead acid battery ?

Hi,

I have a couple of sealed lead acid batteries of the type Alphaline XV31 seen here http://www.batterymegastore.co.uk/product/XV31/ and as my boat has been out of the water for nearly 3 years I was wondering about doing some preventative maintenance on the batteries. I have kept them charged during this time by occasional use of an automotive style charger set to the "sealed" setting, they have never taken more than 20 minutes or so to top up but have not had a proper dis/charge cycle during the whole period ashore, neither have they been maintained at a float voltage of 13.6V during this time.

I have read about doing an equalisation charge which AFAICT is a constant current charge at 4% of nominal capacity / hour (4.6A for my 115Ah batteries) at a voltage limited to 14.4V or 14.8V though I have also heard of permitting the voltage rise as high as 15.5V during this process. My understanding is that this counteracts any sulphation that may have occurred during the period of disuse and I just wondered if anyone here has any comments ? Please bear in mind that my batteries are not top-up-able so I must at all costs avoid boiling off the electrolyte.

Anyone prepared to quote voltages / times / currents to suit my purposes ? Or should I leave well enough alone ? My intention is to use a bench power supply that has settable voltage & current limits rather than a charger and I will be present to supervise the whole process.

Many thanks,

Boo2

 

[macd]

I'm not expert but everything I've read (including battery and charger manuals) says you do not equalise sealed batteries. Equalisation charges are always above gassing voltages, and rather higher than the 14.4 to 14.8 you mention.
It's possible that your 'sealed' batteries actually have the facility for topping up under a big sticker on their top (some do, some don't); if that's the case, they can be topped up.
On the other hand, if it ain't broke...

P.S. All lead acid batteries benefit from a periodic full charge with a multi-stage charger (rather than the "car-type" one you mention): yours would very likely benefit from that.

 

[Plevier]

Mike

Bluntly that's a bottom of the market thin plate product as shown by its weight and its cranking current capability. Basically it will be a vehicle battery with different separators.
There's a bit more detail at http://www.alphalinebatteries.co.uk/leisure-batteries.html
They claim 115Ah, 750CCA (1000A MCA) from a 23kg battery costing £77.
For comparison an Exide ER550 115Ah weighs 28kg and costs about £100.
The Alphaline is not sealed lead acid in the correct use of the term, i.e. one without free electrolyte, it's a sealed maintenance free wet battery with liquid in, you just can't top it up. (In fact you may find a removable strip under a label or something where you can top it up.)
If they are 3 years old and you haven't been looking after them properly - they should have been put on a decent charger at about 13.8/14V regulated for 24hrs every 3-6 months, that's what guards against sulphation - I can't imagine them being up to the ambitious cruising plans you have.
Yes you could try a constant current charge at up to say 10A voltage limited at 14.4V or so, definitely below 15. It will wake them up a bit. They will lose a bit of water during this, I would reduce to 13.8 3 or 4 hours after they hit the voltage limit or if they get hot and leave them on at 13.8 for a couple of days.
You'll only know what capacity they have by doing a test discharge at a sensible current, say 10A to an end voltage of 10.5V. High rate tests mean little. Remember every full capacity test shortens the life. Recharge immediately.

 

[Boo2]

...All lead acid batteries benefit from a periodic full charge with a multi-stage charger (rather than the "car-type" one you mention): yours would very likely benefit from that.

So what voltage / current regime would that be, dyk ?

Boo2

 

[macd]

So what voltage / current regime would that be, dyk ?

For sealed, probably no higher than around 14.4V during absorption charging. A good multi-stage charger will probably have a setting for SLA, as opposed to open led acid batteries; with the same device, amps should take care of themselves. Troubadour sounds like he knows what he's talking about.

 

[Boo2]

Bluntly that's a bottom of the market thin plate product as shown by its weight and its cranking current capability. Basically it will be a vehicle battery with different separators.
There's a bit more detail at http://www.alphalinebatteries.co.uk/leisure-batteries.html
They claim 115Ah, 750CCA (1000A MCA) from a 23kg battery costing £77.
For comparison an Exide ER550 115Ah weighs 28kg and costs about £100.
The Alphaline is not sealed lead acid in the correct use of the term, i.e. one without free electrolyte, it's a sealed maintenance free wet battery with liquid in, you just can't top it up. (In fact you may find a removable strip under a label or something where you can top it up.)
If they are 3 years old and you haven't been looking after them properly - they should have been put on a decent charger at about 13.8/14V regulated for 24hrs every 3-6 months, that's what guards against sulphation - I can't imagine them being up to the ambitious cruising plans you have.
Yes you could try a constant current charge at up to say 10A voltage limited at 14.4V or so, definitely below 15. It will wake them up a bit. They will lose a bit of water during this, I would reduce to 13.8 3 or 4 hours after they hit the voltage limit or if they get hot and leave them on at 13.8 for a couple of days.
You'll only know what capacity they have by doing a test discharge at a sensible current, say 10A to an end voltage of 10.5V. High rate tests mean little. Remember every full capacity test shortens the life. Recharge immediately.

Hi Mike,

Thanks for the advice and the voltages, our posts crossed and I didn't see your reply until just now.

I knew they were low end batteries when I bought them so it's no problem to replace them when they go. It was always my intention to replace them with a pair of Trojans before I try my round GB trip but that's been put back another year now as my new engine is still not nailed in yet

I will follow your advised 14.4V regime and try a test discharge on another charger that does capacity measurements during discharge to see how they've held up.

Thanks again,

Boo2

 

[Plevier]

I'll be interested to hear the results.
When I was in the industry I would have rated Exide and Varta as best of the basic types but a lot has changed, most of them just come from anonymous Korea/China manufacturers and get labelled now.
Trojan are a bit different. T105s will undoubtedly give more life but at higher cost, more space and more maintenance. Of course you can get other makes of floor sweeper/golf cart batteries interchangeable with T105s but Trojan do seem to have got the best name.

 

[JohnGC]

I'll be interested to hear the results.
When I was in the industry I would have rated Exide and Varta as best of the basic types but a lot has changed, most of them just come from anonymous Korea/China manufacturers and get labelled now.
Trojan are a bit different. T105s will undoubtedly give more life but at higher cost, more space and more maintenance. Of course you can get other makes of floor sweeper/golf cart batteries interchangeable with T105s but Trojan do seem to have got the best name.

I have just "upgraded" to a pair of T105s for my service battery. I'd be most grateful to know what you consider to be a "good" maintenance regime. I have a shore power multi-stage charger which I've set to "traditional wet", a bottle of de-ionised water, a NASA BM-1 and good intentions.

 

[Plevier]

Just follow Trojan's charging instructions and if you are regularly cycling and fast charging, keep an eye on the topping up. They will use water a bit quicker than "maintenance free" lead calcium. It's the penalty of having a fairly high antimony content for better cycle life. (Calcium is not as good for cycling, or for high temperature tolerance, despite what the advertising tries to make you think.)

 

[JohnGC]

Just follow Trojan's charging instructions and if you are regularly cycling and fast charging, keep an eye on the topping up. They will use water a bit quicker than "maintenance free" lead calcium. It's the penalty of having a fairly high antimony content for better cycle life. (Calcium is not as good for cycling, or for high temperature tolerance, despite what the advertising tries to make you think.)

Thank you. I will follow your advice.

I spent a long time working out how to fit more service Ah into my existing battery compartment and I'd like to get the best from them.