Changing from Top up to Sealed Batteries

[lancelot]

Hi,
Would there be a problem changing from the top up batteries to the sealed type and still use the existing original boat battery charger which is left on constantly, boat in marina on shore power. The boat is a Bavaria 30c 2006. I may go for two Varta 140ah to replace the original Exides. However, I do not want to risk damage the new batteries with the charger if it is not compatible.
Any thoughts?
Fair winds,
Lancelot

 

[pessimist]

I think it'll depend on the charger. As I understand it you charge sealed at a "lower rate". When we made the switch we had to adjust our charger (Sterling) accordingly. Is your charger adjustable?

 

[lancelot]

I think it'll depend on the charger. As I understand it you charge sealed at a "lower rate". When we made the switch we had to adjust our charger (Sterling) accordingly. Is your charger adjustable?

Not sure, so I will find out.
Many thanks,
Lancelot

 

[prv]

Depends what you mean by "sealed". Gel ones need to be charged more gently, but my new AGMs permit a surprisingly high charge voltage (can't remember the exact figures).

If they are bog standard "maintenance free" batteries, they're much the same as traditional flooded lead-acid except that the caps are glued shut so you can't top them up. If you didn't need to top up the old batteries then the new ones will be fine; if they did need topping up then you need to back off a bit or the new ones will die quite quickly without that maintenance.

Pete

 

[ditchcrawler]

I have Numax sealed batteries as domestics and a Red Flash AGM starter battery.The advice from the marine electrician was to adjust my Sterling alternator charger to 14.4 volts.My mains charger does it automatically alledgedly

 

[rivonia]

Our sterling battery charger has THREE settings so able to charge any type of battery. We changed from top up to sealed lead acid and never looked back. So it will depend solely on the type of charger.

Good luck

 

[Richard10002]

I think the general concensus is that you should charge sealed lead acid at about 14.4V. You can generally charge open lead acid up to around 14.8/15V

The higher the voltage, the more Amps flow .... Although some of them always get converted to heat, rather than being stored in the batteries.

 

[Plevier]

Depends what you mean by "sealed". Gel ones need to be charged more gently, but my new AGMs permit a surprisingly high charge voltage (can't remember the exact figures).

If they are bog standard "maintenance free" batteries, they're much the same as traditional flooded lead-acid except that the caps are glued shut so you can't top them up. If you didn't need to top up the old batteries then the new ones will be fine; if they did need topping up then you need to back off a bit or the new ones will die quite quickly without that maintenance.

Pete

That is spot on.
However AGMs do vary (don't use gel); follow what the manufacturer says. e.g If you get Lifeline they need a boost charge over 15V occasionally but that's unusual.
My friend's 2006 Bav 30 has a Bav badged Quick charger similar to http://www.quicknauticalequipment.com/resources/downloads_qne-prod/1/SBC_MINI-LOW_NRG_R01B.pdf maybe a slightly older version. It's very good but I don't think it will do the 15V+.
Remember more batteries fail from undercharging than overcharging.

 

[lancelot]

That is spot on.
However AGMs do vary (don't use gel); follow what the manufacturer says. e.g If you get Lifeline they need a boost charge over 15V occasionally but that's unusual.
My friend's 2006 Bav 30 has a Bav badged Quick charger similar to http://www.quicknauticalequipment.com/resources/downloads_qne-prod/1/SBC_MINI-LOW_NRG_R01B.pdf maybe a slightly older version. It's very good but I don't think it will do the 15V+.
Remember more batteries fail from undercharging than overcharging.

Thanks for all the info. I will check the charger.
Fair winds,
Lancelot

 

[VicMallows]

Eleven years later and the maintenance free battery is still going strong but I've had to replace the house bank of batteries twice - go figure?

That's obvious! The 'maintenance-free' (engine) battery hardly does any work. As long as it remains in good condition it will absorb very little excess power even at 14.8v and therefore loose little water. Your house batteries will be regularly cycled and will age accordingly. The problem then can be that as they age, if charged at 14.8v for a long period they gas and use up their store of electrolyte .... which if they are sealed you cannot replace.

 

[Interlude]

Changing the shore power and solar power regulators to allow the lower voltage for sealed batteries is OK, but what to do about the alternator - which with an integral regulator (as far as I can see) does not have any adjustment. Any ideas?

 

[vyv_cox]

FWIW I had used top-up batteries for years, being used to adding de-ionised water every couple of months in Greece, where my solar panels produce an excess of power at the height of summer. In something of an emergency I substituted sealed Bosch mixed use (leisure/starting) ones just over four years ago. I changed the charge voltage setting on my Sterling alternator controller, rarely connect to mains charging and have no adjustable output on the solar panel controller. The batteries are working perfectly well with no sign of deterioration so far.

 

[symondo]

We changed ours to all Sealed - 3x house batteries and 1 per engine.

As long as your charger from the shore power can convert to the right charge voltage as they are different you should be fine

It may be worth looking at the dry cell deep Cycle batteries for house use as they tend to have higher output and can take a bit more of a battering without any ill effect

 

[BabaYaga]

The replies to this thread so far have focused on the top voltage. Even more important for the OP might be whether his charger switches over to float voltage or not when the batteries are fully chargerd.
It's not clear why he leaves the charger permanently on, but if it's to supply some tiny load when the boat is not in use I think there could be a problem with sealed batteries. Some chargers are fooled by a small load and stay at absorbtion voltage. Sealed batteries will dry up regardless of whether that voltage is 14,8 or 14,2 – just a matter of time.

 

[VicMallows]

My point was that the sealed engine battery although obviously not cycled much has spent years of its life now at 14.8 volts. Although called 'sealed' it obviously has a vent. At 14.8v any battery will gas and boil off electrolyte. All the charger/regulator manufacturers and so called battery experts tell you to not charge sealed batteries (whether house or engine) at 14.8v as you will rapidly boil them dry and yet this appears to have had very little effect on mine.
So it's not quite as obvious as you seem to think it is!

You asked us to 'go figure?' .... so what is your explanation for the excellent life of your battery

 

[VicMallows]

Perhaps its capacity is massively reduced, I have never discharge tested it, nor does my engine put heavy loads on it so I wouldn't know.

I suspect that is indeed the case but that it was already in that condition when you bought the boat and before you fitted the 14.8v regulator. I have many times recycled old car batteries (which seemed fine until that particularly cold winter day!) with an old fashioned 'brute-force' charger. Many would achieve a terminal voltage of 16v or so quite quickly while accepting negligible current and hence gassing very little. (probably a result of sulfation). The batteries have often gone on to give years of use in undemanding applications.

 

[charles_reed]

If you have a standard OEM regulator built into the back of your alternator then it is most likely already set to 14.0 to 14.2V maximum output - so it can do no harm. It will also be fairly hopeless as a quick charging tool for heavily cycled batteries as it will take forever to put in the last 10 to 15% of battery capacity. Best to fit a 'smart' multi stage regulator if you think you will need to use your alternator a lot to charge your batteries.

Your assumption about alternator controllers is almost certainly wrong and based upon obsolescent technology.

Adverc have, in fact, told me that their controller is redundant and Sterling have told another poster the same.