A battery as flat as Norfolk...

[Kukri]

I have just exchanged contracts on a boat which had been carefully laid up by a yard a few months ago. Unfortunately the yard had not spotted that the gas detector was hard wired in and could only be taken out of circuit by removing the fuse. The charger had not been hooked up to shore power and whilst the starter batteries were sitting at 12.6v the house bank were south of 11.1v, thanks to the gas detector.

All the batteries are Rolls deep cycle sealed type, and there are six in the house bank.

After a couple of days of shore power, the Sterling 1250 CED charger declared itself satisfied for the moment and the house bank were at 12.6v

Will any permanent damage have been done?

 

[DownWest]

Read somewhere that even plain old car batteries can be completely flattened around 20 (?) times and still hold a decent charge. A DS type should be OK if at not much under 11v. esp as it was being gently discharged and not just age related.

Wot's the boat Minn? Thought you already had a nice project.

 

[burgundyben]

What boat have you bought?

 

[Kukri]

I am not willing to tempt Providence until I have completed the transaction! She is my lifetime Ultimate Dream Ship, she popped up unexpectedly and I now have a composite Ohlson 38 for sale in a tearing hurry!

Thanks for the advice.

 

[NealB]

She is my lifetime Ultimate Dream Ship, she popped up unexpectedly and I now have a composite Ohlson 38 for sale in a tearing hurry!

Sorry, I can't offer any useful insight into your battery state, but I wait with bated breath for news about this "ultimate dream ship".

How exciting.

ps I must keep Joscelyn away from Levington for a while: she was cooing about a fine looking Ohlson 38 just last week.

 

[macd]

Quality deep-cycle batteries such as your Rolls shouldn't be harmed by being flattened. But, like all lead-acid batteries, damage can certainly be caused by leaving them in that state for an extended period. Granted that doesn't answer your question in any quantitative way. The only way of telling is an actual capacity test. There are various methods. The simplest is to put them on a known load for a period calculated to take them down to 50% of nominal capacity. Then check the actual state of charge with a hydrometer. If you don't have a hydrometer, do buy one: your Rolls batteries will thank you.

 

[GHA]

After a couple of days of shore power, the Adverc declared itself satisfied for the moment and the house bank were at 12.6v

Will any permanent damage have been done?

Almost certainly, just how much damage you'd need to do a proper load test to see what's left in them (not an auto drop test) . If they were sitting empty for a while then maybe toast, might be OK if it was a one off discharge then recharged again but sitting empty for extended periods is about as bad a thing you can do to a battery. Shame if they are trashed, 6 rolls is a high end battery bank.

12.6v - take that is with the charger not connected?

 

[Stemar]

I've had problems that have flattened my batteries to around 1v. The first time, the domestic battery survived several more years, but the starter battery, which had been on the boat for a few years and was second hand anyway, didn't. The second time, both appear to have survived, but I've no doubt I've reduced their capacity and their lifespan.

If this is your dream boat, I wouldn't worry about it. If they survive, fine; if not, new batteries are likely to be a small part of the cost of getting her just right.

 

[Richard10002]

Which model of Rolls batteries are they? Could be worth an email to Rolls... I’d guess they have a department or desk that deals with this kind of stuff.

 

[Kukri]

Almost certainly, just how much damage you'd need to do a proper load test to see what's left in them (not an auto drop test) . If they were sitting empty for a while then maybe toast, might be OK if it was a one off discharge then recharged again but sitting empty for extended periods is about as bad a thing you can do to a battery. Shame if they are trashed, 6 rolls is a high end battery bank.

12.6v - take that is with the charger not connected?

Correct - 13.3v with the charger in line. But I didn't wait a full hour before putting the multimeter across, so it could be illusory. The charger is probably on the small side for the installation at 50a.

 

[TQA]

Yess there will be damage, a permanent loss of capacity.

But as they appear to be taking and holding charge I would keep using them. If they are designed with solid plates they cope well with deep cycles unlike starter batteries that have grids with different makeup of plate material.

 

[Allan]

If they were mine, after checking that the whole bank of six seemed OK, I would disconnect them and check them individually. I'm a bit anal about batteries and would do that anyway, if I bought a boat with a battery bank. Five good and one bad battery is not as good as five good batteries.
Allan

 

[Kukri]

If they were mine, after checking that the whole bank of six seemed OK, I would disconnect them and check them individually. I'm a bit anal about batteries and would do that anyway, if I bought a boat with a battery bank. Five good and one bad battery is not as good as five good batteries.
Allan

Thanks. I was thinking that. Load test each one and use a hydrometer.

(My late father would have appreciated this - I inherited his hydrometer. Not that I can find it, now that I need it!)

 

[lw395]

I have just exchanged contracts on a boat which had been carefully laid up by a yard a few months ago. Unfortunately the yard had not spotted that the gas detector was hard wired in and could only be taken out of circuit by removing the fuse. The charger had not been hooked up to shore power and whilst the starter batteries were sitting at 12.6v the house bank were south of 11.1v, thanks to the gas detector.

All the batteries are Rolls deep cycle wet type, and there are six in the house bank.

After a couple of days of shore power, the Adverc declared itself satisfied for the moment and the house bank were at 12.6v

Will any permanent damage have been done?

I'd look at the current draw of the alarm and see if that statement stacks up.
As Allan says, properly charge and test each battery.
I trust the cost of some new batteries would not be the end of the world.
The batteries are used batteries. They are not as good as new, the question, are they good enough. That depends on your needs.

I think Norfolk is flatter than 11V.
I've found batteries on motorbikes down in single figures and they've given further service after a good charge.

 

[macd]

Thanks. I was thinking that. Load test each one and use a hygrometer.

(My late father would have appreciated this - I inherited his hygrometer. Not that I can find it, now that I need it!)

No point in finding it unless it's actually a hydrometer. A hygrometer measures humidity.

Whether you find it or buy one, do use it on batteries as precious as you have. An anal (or Allanal?) relationship with your batteries will be good for them if not always for you

 

[Kukri]

No point in finding it unless it's actually a hydrometer. A hygrometer measures humidity.

Whether you find it or buy one, do use it on batteries as precious as you have. An anal (or Allanal?) relationship with your batteries will be good for them if not always for you

duh..!

 

[GHA]

Correct - 13.3v with the charger in line. But I didn't wait a full hour before putting the multimeter across, so it could be illusory. The charger is probably on the small side for the installation at 50a.

Hmm, might not have actually got to full charge ... maybe..
My t105's will hold a high voltage after charged for ages, like 24H. And 12.6v sounds possibly a bit low for fully charged n summer. Maybe the Adverc switched to float too early. Might be worth doing another charge cycle, can the adverc do an equalizing cycle?
One way to check if they are toast would be to connect a hefty load and just see what happens - If you connected a load of bank Ah/20 in Amps (say 600Ah would be 30A) and the voltage didn't plummet within a few hours or so then at last you'd know there was still a bit of life left in them.

 

[Allan]

Hmm, might not have actually got to full charge ... maybe..
My t105's will hold a high voltage after charged for ages, like 24H. And 12.6v sounds possibly a bit low for fully charged n summer. Maybe the Adverc switched to float too early. Might be worth doing another charge cycle, can the adverc do an equalizing cycle?
One way to check if they are toast would be to connect a hefty load and just see what happens - If you connected a load of bank Ah/20 in Amps (say 600Ah would be 30A) and the voltage didn't plummet within a few hours or so then at last you'd know there was still a bit of life left in them.

I've just thought, I assumed the drop from charge voltage was due to the alarm. If not, I think the batteries need fully charging again and leaving for a while before checking.
Allan

 

[Kukri]

Hmm, might not have actually got to full charge ... maybe..
My t105's will hold a high voltage after charged for ages, like 24H. And 12.6v sounds possibly a bit low for fully charged n summer. Maybe the Adverc switched to float too early. Might be worth doing another charge cycle, can the adverc do an equalizing cycle?
One way to check if they are toast would be to connect a hefty load and just see what happens - If you connected a load of bank Ah/20 in Amps (say 600Ah would be 30A) and the voltage didn't plummet within a few hours or so then at last you'd know there was still a bit of life left in them.

Thanks. I just ran out of time. The charger might well have had plans to carry on, and was probably just doing a float phase before resuming its efforts, but I didn't care to leave it connected. The two starter batteries, which must also have had six months un-charged, were at 12.6 and 12.5

 

[AntarcticPilot]

Norfolk isn't all that flat - it even has hills and cliffs in places! Try Cambridgeshire and Lincolnshire for REALLY flat fenland!