Unhappy batteries

[imranino]

Oh dear!

i only ever use my inverter to run power tools and my food processor. I turned it on to do some angle grinding the other day but then decided against it and forgot to turn it off. I spent the night away from the boat and left the inverter on for around 15 hours. 

Since then my batteries have been unhappy. They’d never usually go below 12.3V at night, but now they’re reading 12.1V. For my use, I usually only need to run my engine once or twice per week to keep them topped up. Is there anything I can do bring them back to health? Leave the engine on all day? 

Im a CCer and access to a shoreline is limited. 

Thanks!

[Chewbacka]

No easy way to say this, but if your batteries need charging, then they must be charged before they become damaged.  No easy way to recharge quickly, it just takes time.  Best get that engine running.  For the future, a few hundred watts of solar would cover your modest power needs for much of the year, though not so good in winter as there is not much sum and unless you can aim the panels at the sun, the sun is too low to give much output from horizontal panels.

So I'm not much help really.

[mrsmelly]

Can you nip into a marina for a day? For about a tenner for the day and hook up for the duration? of course assuming some decent battery charging kit. How old are the batteries?

[imranino]

8 minutes ago, Chewbacka said:

No easy way to say this, but if your batteries need charging, then they must be charged before they become damaged.  No easy way to recharge quickly, it just takes time.  Best get that engine running.  For the future, a few hundred watts of solar would cover your modest power needs for much of the year, though not so good in winter as there is not much sum and unless you can aim the panels at the sun, the sun is too low to give much output from horizontal panels.

So I'm not much help really.

Yep I’ve got a couple of panels that keep the batteries very healthy, it’s only during the very short days they they don’t quite cut the mustard!

i wonder if there’s a way to put a timer on the inverter so it turns off right after use? I only ever use it for max 1 hour at a time. 

5 minutes ago, mrsmelly said:

Can you nip into a marina for a day? For about a tenner for the day and hook up for the duration? of course assuming some decent battery charging kit. How old are the batteries?

Good idea, I’ll give a call to see if there’s space. 

[WotEver]

If charging with the engine, starting at 12.1V you’ll probably be looking at more that one full day’s charging (8am-8pm). 

What battery monitoring do you have?

[MtB]

2 minutes ago, WotEver said:

What battery monitoring do you have?

 

Great question.

I can see exactly where this thread is heading now!! 

 

[Rebotco]

1 minute ago, WotEver said:

If charging with the engine, starting at 12.1V you’ll probably be looking at more that one full day’s charging (8am-8pm). 

What battery monitoring do you have?

Yes. So best start straight away. At under £1/hr for diesel its gotta be the quickest and cheapest option.

[WotEver]

1 minute ago, Mike the Boilerman said:

 

Great question.

I can see exactly where this thread is heading now!! 

Yup, monitoring tail current. 

[imranino]

Ok, I’ll leave it running! I just spoke to the local marina and I can go in tomorrow morning. 

 

6 minutes ago, WotEver said:

If charging with the engine, starting at 12.1V you’ll probably be looking at more that one full day’s charging (8am-8pm). 

What battery monitoring do you have?

I’m just relying on the reading on the solar charge controller. I’ve not taken a reading directly from the batteries but as I always read from the controller I can see that it’s low

[Chewbacka]

26 minutes ago, imranino said:

Yep I’ve got a couple of panels that keep the batteries very healthy, it’s only during the very short days they they don’t quite cut the mustard!

i wonder if there’s a way to put a timer on the inverter so it turns off right after use? I only ever use it for max 1 hour at a time. 

Good idea, I’ll give a call to see if there’s space. 

For this type of timer job, I just use a little battery powered kitchen timer, the only problem is remembering what to turn off when it dings.

[Alan de Enfield]

1 hour ago, imranino said:

I turned it on to do some angle grinding the other day but then decided against it and forgot to turn it off. I spent the night away from the boat and left the inverter on for around 15 hours. 

If leaving an inverter on standby for 15 hours flattens the batteries, (maybe - 15Ah or 30Ah maximum)  then take it as a warning that your batteries are probably 'beyond their best' and plan to replace them soon.

You say you 'top them up once or twice per week' - how do you know when to stop charging ?

 

54 minutes ago, Chewbacka said:

For this type of timer job, I just use a little battery powered kitchen timer, the only problem is remembering what to turn off when it dings.

Not much help when you have left the timer on the boat and gone away for a few days (or whatever).

[mrsmelly]

Another thing that may assist in the future is that with my inverter I can alter the voltage at what it cuts out at, mine is set to 11.5 volts. Ok 11.5 volts is already into damaged battery territory but some verters go lower before shutting down and this is worse still.

[cereal tiller]

3 minutes ago, mrsmelly said:

Another thing that may assist in the future is that with my inverter I can alter the voltage at what it cuts out at, mine is set to 11.5 volts. Ok 11.5 volts is already into damaged battery territory but some verters go lower before shutting down and this is worse still.

Is the 11.5 reading with a Significant Load on?if so the Voltage may recover to to 12 and a Nidge once Unloaded.would allow you to Sleep Better.

[mrsmelly]

5 minutes ago, cereal tiller said:

Is the 11.5 reading with a Significant Load on?if so the Voltage may recover to to 12 and a Nidge once Unloaded.would allow you to Sleep Better.

Yes it is with a significant load on, quite significant so in practical terms never shuts down but would if I left summet daft on.

[smileypete]

The more info you can give the better the advice will be.

If you feel up to it there's a list of questions on this topic:

'When you post about your battery problem, please include the following information. If you don't know how to get it, then by all means post asking how to find it, but this info is essential before anyone can give any meaningful help diagnosing a battery problem.

1) Type of battery. Open cell, sealed, AGM, something else

2) Number of batteries in your bank, and the make, model and age of them

3) Exact make and model of any monitoring device(s) you have. Or say if you have none.

4) The method you use to charge them. Engine alternator, generator and charger, shore line and charger, solar, something else

5) The make and model of your engine alternator, charger, generator etc.

6) The voltage at which your batteries are being charged, assuming you have a voltmeter

7) A brief description of your charging regime, i.e. how long you charge for, how frequently

8) A brief description of how you know when your batteries need to be charged. I.e. when do you start charging?

9) A brief description of how you know when to stop charging them. I.e. how do you decide when they are full?

10) A brief description of how the batteries are seen to be underperforming or failing.

 

The board will probably still come back with further questions, based on the info above you supply, but this will speed an answer to your problems by several days, probably. Many thanks!

Sorry it's either 'question hell' or 'expert hell', the choice is yours... The less information given then the more disparate and confusing the advice may be, being based more on speculation about the problem.

Edited December 14, 2017 by smileypete

[Ex Brummie]

Can't post a link, but scan pneumatic time lag switch on ebay.  There is an adjustable one from 1 second to 2 hours, about £13.

[ditchcrawler]

1 minute ago, Ex Brummie said:

Can't post a link, but scan pneumatic time lag switch on ebay.  There is an adjustable one from 1 second to 2 hours, about £13.

Often used in stair wells, the big round button you push in

[Ex Brummie]

Saw that one, but time lag is quite short, but like the ebay one that gives two hours.

When I can be a***d tospend the time, I'll learn how to copy and paste into posts.

[philjw]

Where in the inverter circuit would you connect such a timer switch?  Is there a remote switch cable that you can interrupt? Clearly it can't go in the main supply cable.  Or is it to energise a hefty relay?

[Bewildered]

I would think a 200amp 12v heavy duty relay in the battery feed to the inverter coupled with the aforementioned vacuum switch to activate the coil would do the job

[imranino]

23 hours ago, Alan de Enfield said:

If leaving an inverter on standby for 15 hours flattens the batteries, (maybe - 15Ah or 30Ah maximum)  then take it as a warning that your batteries are probably 'beyond their best' and plan to replace them soon.

You say you 'top them up once or twice per week' - how do you know when to stop charging ?

 

Not much help when you have left the timer on the boat and gone away for a few days (or whatever).

I was thinking of something that would cut power to the inverter after a fixed time (say 1 hour)

16 hours ago, Ex Brummie said:

Can't post a link, but scan pneumatic time lag switch on ebay.  There is an adjustable one from 1 second to 2 hours, about £13.

Excellent idea! I’ll place it before the inverter and leave the switch on the inverter on. 

[imranino]

58 minutes ago, Bewildered said:

I would think a 200amp 12v heavy duty relay in the battery feed to the inverter coupled with the aforementioned vacuum switch to activate the coil would do the job

If I understand correctly, I’d need to put the relay between the batteries and the inverter, then attach the pneumatic time lag switch to the relay?

[Alan de Enfield]

17 minutes ago, imranino said:

If I understand correctly, I’d need to put the relay between the batteries and the inverter, then attach the pneumatic time lag switch to the relay?

It would be simpler and much less expensive to have a 'leaving the boat' checklist stuck onto the exit door, it can also be used when making sure the boat is ready for departure.

eg:

Battery charger can checked that it is 'connected' when you leave the boat, and checked it is disconnected when you depart to go cruising (you don't want to be running your charger from your inverter)

Here is mine :

 

 

 

DepartureChecks.docx

Edited December 15, 2017 by Alan de Enfield

[rusty69]

14 minutes ago, Alan de Enfield said:

It would be simpler and much less expensive to have a 'leaving the boat' checklist stuck onto the exit door, it can also be used when making sure the boat is ready for departure.

We have a departure checklist on both our boats. It eliminates the "did I turn the gas off?" question that inevitably would occur without it.

Edited December 15, 2017 by rusty69

[WotEver]

Do you have a checklist to remind you to check the checklist?