Charging a sealed lead acid battery

[ColinR]

I have a Sterling Pro Digital regulator on my boat which fast charges the batteries. Its worked well for years. I have always had open lead acid batteries which can be charged up to 14.8v and the system has worked well because in normal cruising it generally takes about an hour to charge before dropping to a lower float voltage. I renewed all the batteries this year, two Trojan 130 AH deep cycle for domestic and an Exide 110 AH cranking battery. The banks are separated by a VSR. The Trojans are open lead acid, but I inadvertently got a sealed lead acid cranking battery and didn’t notice until it was a bit late to change it.
Sterling (and Exide) specify a maximum of 14.4v to charge a sealed lead acid battery. I can set the regulator to this, but it increases the charge time to about 4 hours which is way more than I want to be motoring unless there’s no wind. As I understand it, at a higher voltage there is more gassing and the acid needs topping up more frequently. I do top up the domestic bank now and again over the season, but the start battery never needs it. I assume this is because it is not doing much work and is permanently fully charged. The man in the battery shop said that the sealed battery is vented and the top can be carefully prised off to check if it needs topping up.
The boat is on a mooring and has a solar panel, so the batteries are always fully charged when I turn up.
Would it be safe to charge at 14.8v or should I reduce it to 14.4v.
Thanks!

 

[V1701]

You could take the start battery out of the equation which would mean the sealed might charge a bit quicker but to answer your question yes it'll be safe to charge the "sealed" at 14.8 as long as you top them up...

 

[Boater Sam]

Evan ae 14.8v you may find that the sealed battery never needs topping up. All my batteries are sealed and charge at 14.8 on a Sterling and they die after about 7 to 8 years through number of cycles reducing their capacity and never get topped up.

 

[ColinR]

Evan ae 14.8v you may find that the sealed battery never needs topping up. All my batteries are sealed and charge at 14.8 on a Sterling and they die after about 7 to 8 years through number of cycles reducing their capacity and never get topped up.

is the reason for charging a sealed battery at a lower voltage to avoid loss of acid as its harder to top up? If thats the case then its not really an issue for me as the start battery does so little work it never seems to need topping up.

 

[geem]

is the reason for charging a sealed battery at a lower voltage to avoid loss of acid as its harder to top up? If thats the case then its not really an issue for me as the start battery does so little work it never seems to need topping up.

That's my experience of sealed starter batteries. As liveaboards our batteries get more use than most. I would still pull the cap off and check the water level every few months. In four years I have topped up the sealed starter battery twice. Its not used much water but topping up is so easy there is no reason not to

 

[Graham376]

The boat is on a mooring and has a solar panel, so the batteries are always fully charged when I turn up.
Would it be safe to charge at 14.8v or should I reduce it to 14.4v.
Thanks!

We're also mooring based with solar and Trojans plus sealed engine battery. As the Trojans take 14.8v charge, the solar only charges those as I don't want the sealed engine battery charging for long periods at that voltage. An isolated engine battery in good condition can last for months without charging.

 

[ltcom]

It seems everyone agrees.
As do i, but i am a luddite and technophobe apparently.
But i agree with all posts.
System sounds fine.
Sail and enjoy.
Batteries are consumables, but I do agree that you should make them last as long as possible.
Enjoy the good weather, but the glass is falling where i am...... foulies at ready ....still go for it.

 

[geem]

It seems everyone agrees.
As do i, but i am a luddite and technophobe apparently.
But i agree with all posts.
System sounds fine.
Sail and enjoy.
Batteries are consumables, but I do agree that you should make them last as long as possible.
Enjoy the good weather, but the glass is falling where i am...... foulies at ready ....still go for it.

We don't charge our engine battery via the same solar as our domestic batteries. We have a folding 40w panel that we sit on the deck at anchor. This panel has its own solar reg connected to the engine batteries (2 of them as we are a 24v boat). One battery is open cell. The other battery is sealed. They are different sizes as well. The batteries are provided with a battery balancer that sends up to an amp from one battery to the other to keep them both in the same state of charge. They also have a desulphator installed. They have been going 4 years, mostly in the Caribbean brutal heat. We can access the sealed battery to top up. We do everything we can to keep batteries in good condition.

 

[ColinR]

We're also mooring based with solar and Trojans plus sealed engine battery. As the Trojans take 14.8v charge, the solar only charges those as I don't want the sealed engine battery charging for long periods at that voltage. An isolated engine battery in good condition can last for months without charging.

good point, but the solar goes through a regulator and the batteries are always at 13.1v when I arrive.

 

[Graham376]

good point, but the solar goes through a regulator and the batteries are always at 13.1v when I arrive.

Have you set up the regulator for the Trojan charge profile? ours floats T105s at 13.5. To stop the vsr (which is bi-directional) allowing solar to charge engine battery as well, I've connected it to the engine side of the isolator so solar only charges engine battery if it's isolator is switched to on.

 

[PaulRainbow]

good point, but the solar goes through a regulator and the batteries are always at 13.1v when I arrive.

You need to set the charge profile of the shore charger and the solar controller to that of the T105s. The engine battery doesn't need to be on charge all of the time, either leave it out all together, or find another way of charging it, post #10 is one good solution.

 

[ColinR]

Have you set up the regulator for the Trojan charge profile? ours floats T105s at 13.5. To stop the vsr (which is bi-directional) allowing solar to charge engine battery as well, I've connected it to the engine side of the isolator so solar only charges engine battery if it's isolator is switched to on.

my regulator is a bit more basic than that, its the one I had for a Rutland wind generator that also takes solar. I cant set profiles but it stops overcharging. All this raises new questions; While it may be ideal to set the Trojan profile, and to leave the start battery out of the equation, the set up I have has worked pretty well for my needs. Which is to have the batteries fully charged when I arrive, and in good nic . I replaced the batteries this year as a precaution as they were about 9 years old and although still going strong and showing no issues when checking with a hydrometer, I wanted to avoid a failure when in some remote place during the sailing season. So the current regime seems to work in practice. Not sure why I should change it... But very interesting to hear these views as I am no expert.

 

[Graham376]

I'm no expert either, tend to listen to and sometimes argue with others here. Batteries are expensive and I work on the theory that manufacturers publish ideal charge profiles to obtain the best performance and life from their product. I don't know your Rutland's profile but suspect it may not be ideal, being dual purpose. I do turn my Trojan's absorption charge rate down from 14.8 to 14.4v when leaving the boat for extended periods to minimise water loss.

As far as engine batteries are concerned I firmly believe car batteries are the most suitable and often cheapest option. When coming away sailing, I would just disconnect my "old tech car" battery and it would start first turn on my return, anything up to six months later so, I treat the boat the same. It's engine battery is isolated when I leave and is fine, often for several months. Being isolated also has the advantage that it won't be taken down if there's a fault on the house bank.

 

[ColinR]

You need to set the charge profile of the shore charger and the solar controller to that of the T105s. The engine battery doesn't need to be on charge all of the time, either leave it out all together, or find another way of charging it, post #10 is one good solution.

You say the engine battery doesn't need to be on charge all the time, but do you mean it shouldn't be or just it isn't needed? Its a 50w solar panel flat on the coachroof, goes through a regulator, and is also charging the two domestic batteries. They are each 110AH, so 330AH in total. I've had this setup for years and the batteries have lasted well, never had a failure.

 

[PaulRainbow]

You say the engine battery doesn't need to be on charge all the time, but do you mean it shouldn't be or just it isn't needed? Its a 50w solar panel flat on the coachroof, goes through a regulator, and is also charging the two domestic batteries. They are each 110AH, so 330AH in total. I've had this setup for years and the batteries have lasted well, never had a failure.

If the Trojans need 14.8v that's high for a sealed battery. If you set the charging profile to 14.4v, that's low for the Trojans. The engine battery doesn't have to be on charge all of the time, so leave it out. You could rig the VSR so that it only closes when you are onboard, or when the engine is running etc.