Batteries not holding their charge

[Chambo]

On an earlier trip this year I had a problem with my batteries not holding a charge overnight. At the time I was having trouble with my 12v fridge, this was changed for a new 240v fridge freezer unit. The batteries were all took of the boat once fully charged, left for a few days and then tested, they all showed 13v. One thing I did discover was a broken clamp on the battery bank which was replaced. Thinking that might have been the problem we planned to go out for an autumn cruise this week, the boat has been plugged in to shore power for the last two days to get the fridge freezer down to temperature. I disconnected the shore power at 1630 this afternoon and by 2130 this evening the inverter cut out because the voltage had dropped below 12v. I have a battery bank of 4 12v 110 amph batteries for leisure, sterling 2kw inverter, all led lighting, small 240v TV and a water pump. The inverter is over ten years old but not showing any alarms and works perfectly until the volts drop then it cuts out as it should. I'm at a bit of a loss to understand what's happening, has anyone got any ideas?

[MtB]

How old are your batteries? They don't last for ever. This sounds as though they have simply expired.

 

 

[nicknorman]

Yes just because they showed 13v after a period of no load, doesn’t mean they are ok. Knackered batteries can often behave like good batteries that are 100th the nominal size,

 

But first perhaps check that they are being charged properly in case there is some issue with the charging. What means do you have for monitoring battery current and voltage?

[Chambo]

13 minutes ago, MtB said:

How old are your batteries? They don't last for ever. This sounds as though they have simply expired.

 

 

The batteries are probably 4 years old, they were tested by Streethay wharf boatyard on the Coventry with their "all singing" tester and I was assured they were in good health.

 

11 minutes ago, nicknorman said:

Yes just because they showed 13v after a period of no load, doesn’t mean they are ok. Knackered batteries can often behave like good batteries that are 100th the nominal size,

 

But first perhaps check that they are being charged properly in case there is some issue with the charging. What means do you have for monitoring battery current and voltage?

Just a volt meter and an ammeter when the engine is running 

[blackrose]

Sounds like your batteries are cream crackered.

5 hours ago, Chambo said:

On an earlier trip this year I had a problem with my batteries not holding a charge overnight. At the time I was having trouble with my 12v fridge, this was changed for a new 240v fridge freezer unit. The batteries were all took of the boat once fully charged, left for a few days and then tested, they all showed 13v. One thing I did discover was a broken clamp on the battery bank which was replaced. Thinking that might have been the problem we planned to go out for an autumn cruise this week, the boat has been plugged in to shore power for the last two days to get the fridge freezer down to temperature. I disconnected the shore power at 1630 this afternoon and by 2130 this evening the inverter cut out because the voltage had dropped below 12v. I have a battery bank of 4 12v 110 amph batteries for leisure, sterling 2kw inverter, all led lighting, small 240v TV and a water pump. The inverter is over ten years old but not showing any alarms and works perfectly until the volts drop then it cuts out as it should. I'm at a bit of a loss to understand what's happening, has anyone got any ideas?

 

What was actually running from the inverter when it cut out? Just a mains fridge?

[MtB]

8 hours ago, Chambo said:

The batteries are probably 4 years old, they were tested by Streethay wharf boatyard on the Coventry with their "all singing" tester and I was assured they were in good health.

 

This is curious as there is no way I can think of to genuinely test a leisure battery for capacity and sulphation without a right load of faffing about over about a ten hour period. Generally cheaper to buy a new battery than pay someone to carry out a meaningful capacity test giving a result you can actually rely on.

 

"All singing" one minute testers are little more than theatre, used as a tool to sell batteries, as in. "Oh look, the printout says your battery is goosed, you need a new one Sir. We just happen to have a row of them of the shelf here Sir." So I'm not sure what went wrong at Streethay, or what it was that their "all singing" tester would actually have been measuring. Did it print anything out? What did it say?

 

 

 

 

 

 

 

 

[Chambo]

4 hours ago, blackrose said:

Sounds like your batteries are cream crackered.

 

What was actually running from the inverter when it cut out? Just a mains fridge?

The mains fridge, which was "at temperature" and the TV.

47 minutes ago, MtB said:

 

This is curious as there is no way I can think of to genuinely test a leisure battery for capacity and sulphation without a right load of faffing about over about a ten hour period. Generally cheaper to buy a new battery than pay someone to carry out a meaningful capacity test giving a result you can actually rely on.

 

"All singing" one minute testers are little more than theatre, used as a tool to sell batteries, as in. "Oh look, the printout says your battery is goosed, you need a new one Sir. We just happen to have a row of them of the shelf here Sir." So I'm not sure what went wrong at Streethay, or what it was that their "all singing" tester would actually have been measuring. Did it print anything out? What did it say?

 

 

 

 

 

 

 

 

It didn't print anything out and I didn't see what it said. The lad using it just said they were ok.

[MtB]

7 minutes ago, Chambo said:

The mains fridge, which was "at temperature" and the TV.

It didn't print anything out and I didn't see what it said. The lad using it just said they were ok.

 

Lead acid batteries fall in capacity as they grow older. Three or four years is a typical life for basic, el cheapo leaisure batteries. The decline is accelerated by not keeping them 100% fully charged ALL the time. Boaters who are not fully familiar with how to look after batteries tend to destroy them quicker. 

 

I think its a racing certainty yours are due for replacement. A long read of the "Battery Primer" here will get you up to speed on how to look after a new set, should you decide to get one. Its here:

https://www.canalworld.net/forums/index.php?/topic/95003-battery-charging-primer/

 

[Tony Brooks]

I agree with the others, definitely sounds like unserviceable batteries. My guess would be sulphation rather than internal shorts.

 

Have the ends of the batteries developed an outward bow by any chance?

[Bee]

Horrible things batteries, hard to tell if they are accepting a meaningfull charge and you can't repair the brutes anyway if there is a problem. If they are being charged but go flat quickly with nothing much connected then they are worn out.

[Peanut]

I've noticed this too, as you get older you get worn out quicker, have less energy, and take longer to recharge.

[jonathanA]

depends how much buggering about you want to do (before biting the bullet and buying new batteries).

 

you could try isolating each battery in turn and put some sort of load on the disconnected battery noting the voltage  ( I use an old car 55W bulb) before you start and then either give it an hour and then see what the voltage is or time how long it takes until the light is decidedly dim.  my guess is your batteries wont keep the light on very long.  its just possible one (broken clamp?)  is knackered and taking the bank down so it might be some of the others are better than others (long shot TBH)

 

I'd suggest at this time of year (now the indian summer has ended) you could leave your fridge off overnight.  I tend to turn my fridge 'up' (cooler) when the engines running and then back it off a bit  (warmer) when we stop.  if you have the freezer nice and cold and don't open the door too much it should stay frozen for 8 hours or more I'd have thought. 

 

just one further thought - are you sure there is no other load on the batteries or inverter ?  For instance a battery charger plugged into the inverter trying to charge the batteries - I thought i'd invented perpetual motion doing that once 🙂

 

or an immersion heater running off the inverter that sort of thing. 

Edited September 18, 2023 by jonathanA
clarity / further though

[Chambo]

1 hour ago, Peanut said:

I've noticed this too, as you get older you get worn out quicker, have less energy, and take longer to recharge.

Helpful, but true🤣🤣

[mrsmelly]

Batteries are like diesel, a consumable. At four years for bog standard so called leisure lol batteries they are very likely cream crackered. Bin and replace, repeat.

[LadyG]

1 hour ago, mrsmelly said:

Batteries are like diesel, a consumable. At four years for bog standard so called leisure lol batteries they are very likely cream crackered. Bin and replace, repeat.

Depends what you do with them: for historic reasons I have an excess of batteries, and they are all AGM because I was not going to top up seven rather inaccessible batteries with special water, checking with mirrors etc 

I am a bit fanatic about keeping them charged when the sun has got his hat on, and they seem to work ok , four years since purchase them, and they still work .

If course I am frugal, and only have fridge on for a few hours in winter. I don't suppose it's about usage, I think it's all about recharging.

[Ronaldo47]

Does the battery have removable filler caps that allow you to inspect thhe plates?  Fully charged plates are chocolate -brown. Discarged plates are slate-grey. Knackered plates will often show signs of distortion.  Acid should be clear: muddy acid can indicate a short-circuited cell.