Help! left the electrics on! how long have I got?

[Jonkx]

So I managed to leave my boat in too much of a rush last night and forgot to switch the  electrics off. The boat has 3 x 110 Amp hour domestic batteries, which at the moment are powering a 12 volt fridge. I don't know the makes, but both are probably about 6 years old.

I'm not planning to be back on the boat before Saturday. Will the batteries be completely killed by then?

[mrsmelly]

3 minutes ago, Jonkx said:

So I managed to leave my boat in too much of a rush last night and forgot to switch the  electrics off. The boat has 3 x 110 Amp hour domestic batteries, which at the moment are powering a 12 volt fridge. I don't know the makes, but both are probably about 6 years old.

I'm not planning to be back on the boat before Saturday. Will the batteries be completely killed by then?

Very likely.

[rusty69]

1 minute ago, Jonkx said:

So I managed to leave my boat in too much of a rush last night and forgot to switch the  electrics off. The boat has 3 x 110 Amp hour domestic batteries, which at the moment are powering a 12 volt fridge. I don't know the makes, but both are probably about 6 years old.

I'm not planning to be back on the boat before Saturday. Will the batteries be completely killed by then?

They will likely be flat, unless you have solar. Killed will depend on the state of them, but may be ok once recharged.

[Jonkx]

Thanks. It's sounding like I need to try and get back there sooner of possible. What's the likely maximum time they'll last?

[system 4-50]

At 6 years it doesn't matter. Replace them anyway.

[Momac]

5 minutes ago, Jonkx said:

 

I'm not planning to be back on the boat before Saturday. Will the batteries be completely killed by then?

 Probably you will have 24hrs per battery. assuming they were fully charged when you left the boat. 

 

 

[mrsmelly]

3 minutes ago, Jonkx said:

Thanks. It's sounding like I need to try and get back there sooner of possible. What's the likely maximum time they'll last?

Its impossible to say as there are too many variables.

How cold is the fridge setting?

How much capacity is left in the batteries?

They will probably charge up again but I would expect them to be flat.

[rusty69]

4 minutes ago, Jonkx said:

Thanks. It's sounding like I need to try and get back there sooner of possible. What's the likely maximum time they'll last?

3 days tops,best case , from when you left (guestimate)

Edited September 19, 2017 by rusty69

[Jonkx]

Thanks, again, for all your advice. Especially those who've helped me before. Its very much appreciated. Cheers Jon

[mross]

Some 12v fridges will cut out automatically when the battery voltage gets too low.  So don't worry.  The damage is done but the batteries may not me totally goosed.

[MtB]

This raises an interesting question. At six years old the batteries are probably heavily sulphated anyway, and in my experience the more a battery is sulphated, the less susceptible it is to further sulphation so yours probably won't suffer noticably. Is this possibly true or just a matter of my distorted perception?

I suspect your batteries will drop to about 11v in about 24 hours given their age, at which point the fridge will lock out and stop drawing power anyway. So when you get back on saturday, a good recharge will probably return the batts to much the same condition as they were yesterday, i.e. still half knackered!

Edited September 19, 2017 by Mike the Boilerman

[DHutch]

How far away is the boat.

Unless it's reasonably close or you can't charge them when you get there could likely to worse than leave it till Saturday but then ensure a good 8+hr charge.

Daniel 

[David Schweizer]

I assume that you have a dual battery system, with a separate battery to start the engine, so even if the domestic batteries are completely flat, you will still be able to start the engine and re-charge the domestic batteries. As Daniel suggests, it will take a while. and eight hours is probably a bit optimistic for a 330 amp bank, but a couple of days should sort things out.

Of course it does also depends on what type of batteries you have, if they are bog standard  (so called) leisure batteries, they may not survive, but if they are deep cycle batteries they should recover without any problems, they are designed to be deeply discharged and then rapidly recharged.

Edited September 19, 2017 by David Schweizer

[Jonkx]

When I bought the boat, I suspected I might need to replace the batteries - I don't know the age to be honest, the boat is 13 years old but I think the previous owner replaced them in the last 6. However thus far they seem to lasted, I generally charge them for a good day - 5 to 7 hours - and just use them for an evening, lights and maybe the radio. The meter which I've had checked seems to indicate above 12 volts by the morning.

But we'll see. It's a 3 hour trip each direction up to the boat. Could go Thursday night, or wait till the weekend, and see if I need new batteries.

[rusty69]

2 minutes ago, Jonkx said:

I've had checked seems to indicate above 12 volts by the morning.

 

The important bit ,is by how much above.

[Jonkx]

7 minutes ago, David Schweizer said:

I assume that you have a dual battery system, with a separate battery to start the engine, so even if the domestic batteries are completely flat, you will still be able to start the engine and re-charge the domestic batteries. As Daniel suggests, it will take a while. and eight hours is probably a bit optimistic for a 330 amp bank, but a couple of days should sort things out.

Of course it does also depends on what type of batteries you have, if they are bog standard  (so called) leisure batteries, they may not survive, but if they are deep cycle batteries they should recover without any problems, they are designed to be deeply discharged and then rapidly recharged.

Thanks, yes have a separate (new) starter battery on a separate circuit / twin alternator. I think the domestics are a reasonable make, possibly sealed, but I just can't remember. Something the lad who serviced it said. Yes I need to learn more! 

[mrsmelly]

4 minutes ago, rusty69 said:

The important bit ,is by how much above.

Correct. After an evening online and the boss watching telly and the fridge on all night my batts are at about 12.5 in the morning and I then charge them followed by a further boost about 7pm for an hour.

[Dave Payne]

30 minutes ago, mrsmelly said:

Correct. After an evening online and the boss watching telly and the fridge on all night my batts are at about 12.5 in the morning and I then charge them followed by a further boost about 7pm for an hour.

where you moor must get all day sun, when it's shining, why no solar?

[ditchcrawler]

1 hour ago, Mike the Boilerman said:

This raises an interesting question. At six years old the batteries are probably heavily sulphated anyway, and in my experience the more a battery is sulphated, the less susceptible it is to further sulphation. Is this possibly true or just a matter of my distorted perception?

I suspect your batteries will drop to about 11v in about 24 hours given their age, at which point the fridge will lock out as stop drawing power anyway. So when you get back on saturday, a good recharge will probably return the batts to much the same condition as they were yesterday.

I go along with that. How often have you read "My fridge wont work in the morning unless I run the engine" The give up trying when the terminal volts at the fridge with the starting load drop to a pre set figure.  

[mrsmelly]

14 minutes ago, Dave Payne said:

where you moor must get all day sun, when it's shining, why no solar?

I usualy do have solar, but only 160 watts, it does help though but I should fit more. They are not connected at moment as I brought my boat out of paint dock yesterday and I need to get round to putting them back on

[Jonkx]

51 minutes ago, mrsmelly said:

Correct. After an evening online and the boss watching telly and the fridge on all night my batts are at about 12.5 in the morning and I then charge them followed by a further boost about 7pm for an hour.

Seems to be around 11.4 volts if the digital meter is correct. 

[mrsmelly]

12 minutes ago, Jonkx said:

Seems to be around 11.4 volts if the digital meter is correct. 

You will prob need new batts then so I wouldn't bother going back till the weekend. New batts will seem awesome then as the others will have very slowly got worse and worse without you probably noticing.

[David Schweizer]

If you do decide to get new batteris, may i suggest that you seek out US deepcycle batteries, they are not cheap, but will last at least twicwe as long as normal leisure batteries, and they will tolerate being run flat and being re-charge quickly, they are designed to operate heavuy demand vehicles  like golf trolleys and fork lift trucks. The first pair I had on Helvetia lasted more than 15 years, and the second lot were still going strong after nine years,

[LadyG]

3 hours ago, David Schweizer said:

If you do decide to get new batteris, may i suggest that you seek out US deepcycle batteries, they are not cheap, but will last at least twicwe as long as normal leisure batteries, and they will tolerate being run flat and being re-charge quickly, they are designed to operate heavuy demand vehicles  like golf trolleys and fork lift trucks. The first pair I had on Helvetia lasted more than 15 years, and the second lot were still going strong after nine years,

do you mean Trojan?

[Alan de Enfield]

3 hours ago, LadyG said:

do you mean Trojan?

 

3 hours ago, LadyG said:

do you mean Trojan?

Had he said 'buy a Mercedes', would you have said 'do you mean a Ford ?'