Battery Issues?

[Nattysw]

Hi, I’m new to boating. Yesterday I noticed my water pump was continuously on, and feared I had a leak somewhere. After checking and finding no leak, and noticing my lights were also flickering, I found my battery output was at 9V. We’re plugged into shore power, so the charger should be charging the leisure batteries to at least 12V. I’ve checked the reading on the charger and it reads that the battery is charging but near 100%. We have solar panels, and when the sun is out it goes to 12.5V, but when it goes behind the clouds we’re back down to 9 or 10, with it intermittently changing between the two. Our leisure batteries are the same type, but 2 and 5 years old respectively. How can I diagnose what the issue is? From my research it seems it’s either the batteries aren’t holding charge, or the charger isn’t working, or some fuse or wiring is gone. I don’t want to buy new batteries to find out it’s the charger and ruin brand new batteries too. I’m going to buy a voltmeter today, and I’m just wondering if anyone has any advice on how to diagnose the issue. TIA!

Edited April 23, 2023 by Nattysw

[Alan de Enfield]

At 12 volts you batteries are almost flat

At 10v your batteries are totally knackered

At 9v they are totally useless.

 

Once you have purchased your multimeter, come back and you'll get information of how to do the tests,

 

In the meantime - DO NOT BUY any more batteries until you have read this :

 

 

 

You can easily kill your new batteries within a couple of weeks so you need to learn how to manage them.

 

Good luck.

Edited April 23, 2023 by Alan de Enfield

[MtB]

2 minutes ago, Alan de Enfield said:

At 9v they are totally useless.

 

 

Not necessarily.

 

I once returned to the boat to find the batts at approx 0.01V. Yes!

 

I recharged them and two years later, still no ill effects. 

 

 

[Nattysw]

Thanks Alan, I’ll give this a good read. I’ve just checked my batteries with the voltmeter and they’re both reading 11.5V. I’m not sure what to think of this as it’s higher than the reading in getting indoors, but clearly not high enough for them to be being charged through the charger properly. I think the next step is to try me rest the charger. I’ll take the time to read this first though.

[Tony Brooks]

No charger, solar controller, or many well known battery monitors can give an accurate %  charged, so your 100%, whatever that means, in better ignored.

 

What are you using to measure the 9V. If it is a battery monitor then the % will be a downright lie UNLESS you have set it up properly, have regularly resynchronised it, and fully understand how to use it.

 

A lead acid battery showing 9V on any sort of meter will take many, many hours to recharge, assuming they have not been damaged, so if you have only had it on charge an hour or so you will have done very little to recharge it.

 

Do any of the following apply?

 

Shorting cells

 

Individual cells getting hot, gassing more, or dryer than the rest.

Charging taking much longer than "normal" and discharging faster.

These are a result of old age, excessive-discharge charge cycling, to a too deeper level of discharge.

 

Sulphated cells

Ends of batteries bulging out or the lid lifting.

Batteries charge far faster than normal but also discharge faster.

This always happens but is hastened by leaving the batteries partially or fully discharged for long periods.

 

In both cases new batteries are required but heed the advice to read the topic linked to, otherwise you WILL ruin the new set.

9 minutes ago, Nattysw said:

Thanks Alan, I’ll give this a good read. I’ve just checked my batteries with the voltmeter and they’re both reading 11.5V. I’m not sure what to think of this as it’s higher than the reading in getting indoors, but clearly not high enough for them to be being charged through the charger properly. I think the next step is to try me rest the charger. I’ll take the time to read this first though.

 

I think that you have simply not had them on charge long enough. You need to see nearly 13V with the batteries off change and no significant loads.

 

Battery chargers do silly things like reducing the charging voltage long before they should, so when you think the batteries are charged, start and rev the engine. If the voltage is not in excess of about 14.2 volts, the batteries are not yet fully charged.

 

NOTE 14.2V + in no way indicates the batteries are fully charged, it just shows they are starting to get there and probably needs several hours more charging at a voltage in excess of 14.2V. You can't determine that they are fully charged without measuring the charging currant and until we know what is giving you that % figure we can't say if you can measure that.

[Nattysw]

We’ve been plugged into shore power for a week now, would that really not be long enough to fully charge them? We’ve had no issues until last night. Just put the voltmeter across the charger and couldn’t get anything, although the charging light isn’t on where it is when it’s hooked up to the batteries.

[Alan de Enfield]

2 minutes ago, Nattysw said:

We’ve been plugged into shore power for a week now, would that really not be long enough to fully charge them? We’ve had no issues until last night. Just put the voltmeter across the charger and couldn’t get anything, although the charging light isn’t on where it is when it’s hooked up to the batteries.

 

Is this a properly installed 'smart marine' battery charger with the cable correctly attached to the battery posts, or is it a 'Halfords' cheapo car battery charger 'hooked up' to the battery with crocodile clips ?

Edited April 23, 2023 by Alan de Enfield

[David Mack]

Probably obvious by now, but the water pump is running continuously because the voltage is too low for it to pump the water system up to the pressure switch cut out pressure. So not only are your batteries flat, but the water pump is drawing a continuous current which makes matters worse.

So first switch off the water pump (or pull the fuse/trip the circuit breaker if it has no separate switch). While your batteries are charging you can still turn on the pump manually for short periods while you turn a tap on, then turn it off again.

[Nattysw]

Hi Alan, this is the exact charger as far as I can tell: https://www.halfords.com/motoring/battery-maintenance/battery-chargers/ring-rcb320-20a-workshop-battery-charger---up-to-12l-329109.html

 

Thanks David, last night we turned off the water pump and we’ve only had it on when using the taps since then. Good to know that was the right call.

[Tracy D'arth]

That battery charger will kill any batteries you connect it to. Its a crude workshop charger for getting a car battery up to start a car, no care for the battery, its useless for marine use when you are living in a boat and using power all day.

[Bod]

19 minutes ago, Nattysw said:

We’ve been plugged into shore power for a week now, would that really not be long enough to fully charge them? We’ve had no issues until last night. Just put the voltmeter across the charger and couldn’t get anything, although the charging light isn’t on where it is when it’s hooked up to the batteries.

You have checked the shore power is actually working?

Not run out of credit on the post, other post for other boats are working?

Some clever systems will automatically switch from shore line to battery power, if the shore line is not reconnected before the batteries go "flat" the lights go out.

 

Bod

[David Mack]

9 minutes ago, Nattysw said:

Hi Alan, this is the exact charger as far as I can tell: https://www.halfords.com/motoring/battery-maintenance/battery-chargers/ring-rcb320-20a-workshop-battery-charger---up-to-12l-329109.html

It does say not for long term connection or for use with AGM batteries. But it does drop to low voltage mode when the battery is fully charged, so I would have thought that offers some protection against battery wrecking.

[Tracy D'arth]

It will drop to a low voltage far too soon leading to undercharged batteries and their demise.

[Nattysw]

Thanks guys, maybe we’ll get another charger then. After unplugging the batteries and charger and plugging them back in to 240V they’ve magically gone up to 13V now…we unplugged them after and the boat ran off the batteries at 12V fine, (albeit maybe losing charge faster than we’d like), and then when plugging them back in it’s back to 13V. Not really a clue what that means…maybe a rusty connection?

[ditchcrawler]

5 minutes ago, Nattysw said:

Thanks guys, maybe we’ll get another charger then. After unplugging the batteries and charger and plugging them back in to 240V they’ve magically gone up to 13V now…we unplugged them after and the boat ran off the batteries at 12V fine, (albeit maybe losing charge faster than we’d like), and then when plugging them back in it’s back to 13V. Not really a clue what that means…maybe a rusty connection?

Are you connecting them to the batteries with crocodile clips, if so that could be why you are not getting a good connection.

[Rob-M]

Probably the charger switching to float too quickly, each time you turn the charger off and back on it puts a bit more charge in before switching to float but needs to be charging at 14.2v for quite some time before batteries will be fully charged.

[ditchcrawler]

7 minutes ago, Nattysw said:

Thanks guys, maybe we’ll get another charger then. After unplugging the batteries and charger and plugging them back in to 240V they’ve magically gone up to 13V now…we unplugged them after and the boat ran off the batteries at 12V fine, (albeit maybe losing charge faster than we’d like), and then when plugging them back in it’s back to 13V. Not really a clue what that means…maybe a rusty connection?

You wont have put any charge in worth talking about in 15 minutes.

[Nattysw]

The connection is bolted on, no crocodile clips in sight! So we think the charger is the culprit and I’m likely to need to get a proper marine charger? Yes it doesn’t seem likely it’s charged up in 15 mins so I’m not really sure what’s happened there. Also the voltage on our readout is quite erratic and not stable, not sure if that helps diagnose the issue.

Edited April 23, 2023 by Nattysw

[beerbeerbeerbeerbeer]

Sorry if Ive missed this one but have you tried charging with the engine running?

See what results you get. 

[Tracy D'arth]

7 minutes ago, Nattysw said:

The connection is bolted on, no crocodile clips in sight! So we think the charger is the culprit and I’m likely to need to get a proper marine charger? Yes it doesn’t seem likely it’s charged up in 15 mins so I’m not really sure what’s happened there. Also the voltage on our readout is quite erratic and not stable, not sure if that helps diagnose the issue.

Have you checked through for a poor connection which is causing the erratic readings?  Do not trust the percentage of charge or remaining energy readings on a battery management display, they lie unless you have reset them within the last few days.

You may well have killed your batteries already, you may find that they hold charge for a short time but not long.

[Tony Brooks]

55 minutes ago, Tracy D'arth said:

That battery charger will kill any batteries you connect it to. Its a crude workshop charger for getting a car battery up to start a car, no care for the battery, its useless for marine use when you are living in a boat and using power all day.

 

I don't think this is the case, the specs say it drops to a low voltage when the batteries are fully charged. For truth, it should say when the charger thinks the batteries are fully charged.

 

It is very unlikely that it can provide an accurate assessment of state of charge, almost impossible unless it has infringed copyright. Even if it has, which I doubt, it will still not be accurate whilst charging.

 

It says 20 amps so should cover most daily electrical loads unless the OP is using some form of electric heating.

Edited April 23, 2023 by Tony Brooks

[Alan de Enfield]

32 minutes ago, Nattysw said:

The connection is bolted on, no crocodile clips in sight! So we think the charger is the culprit and I’m likely to need to get a proper marine charger? Yes it doesn’t seem likely it’s charged up in 15 mins so I’m not really sure what’s happened there. Also the voltage on our readout is quite erratic and not stable, not sure if that helps diagnose the issue.

 

Stand by for a bit of 'price sticker shock' when you look at proper battery chargers (compared to a cheapo one)  - however - even if you pay (say) £300 for a charger that is only 3 batteries that you could have destroyed in a week or two, and (hopefully) now you won't.

 

Victron BPC122042022 Blue Smart Battery Charger 12V 20A (asap-supplies.com)

 

Having one of these does not remove the obligation for you to PHYSICALLY TAKE AN ACTIVE PART IN MANAGING THE BATTERIES.

Edited April 23, 2023 by Alan de Enfield

[Tony Brooks]

54 minutes ago, Nattysw said:

Thanks guys, maybe we’ll get another charger then. After unplugging the batteries and charger and plugging them back in to 240V they’ve magically gone up to 13V now…we unplugged them after and the boat ran off the batteries at 12V fine, (albeit maybe losing charge faster than we’d like), and then when plugging them back in it’s back to 13V. Not really a clue what that means…maybe a rusty connection?

 

Neither have we until you tell us what you are getting this voltage reading from.

At the least, you need a digital multimeter set to DC volts across each battery in turn.

 

 

39 minutes ago, Nattysw said:

The connection is bolted on, no crocodile clips in sight! So we think the charger is the culprit and I’m likely to need to get a proper marine charger? Yes it doesn’t seem likely it’s charged up in 15 mins so I’m not really sure what’s happened there. Also the voltage on our readout is quite erratic and not stable, not sure if that helps diagnose the issue.

 

See above answer re the "read out".

If the 9/12V figures were fairly stable but the 13V one is erratic hen it may be the charger "hunting" or pulsing the output. That may or may not be a charger fault.

 

30 minutes ago, Goliath said:

Sorry if Ive missed this one but have you tried charging with the engine running?

See what results you get. 

 

This ^^^^^.

The alternator should provide up to perhaps 14.6 or 14.7 volts as the batteries charge up, so run the engine at about 1500 rpm for several hours and see what the voltage rises to. The alternator will not play silly beggars and drop the charging voltage at a whim.

 

As a rule of thumb, the higher the charging current, the lower the charging voltage the charger can supply so your 13 volts could be from a faulty charger or a charger that has dropped into the low float voltage or, more likely, in your case, a high charging current into very discharged batteries or possibly shorting cells.

 

I don't think I can help much more until you start answering questions to aid the diagnosis.

 

Have you checked the things I listed a while ago that may help identify shorting cells?

 

Do you have a digital multimeter with a decent battery in it?

 

For the third time, what is giving you the voltage and 100% charged readings. If you don't know, post a photo.

Edited April 23, 2023 by Tony Brooks

[nb Innisfree]

5 hours ago, MtB said:

 

 

Not necessarily.

 

I once returned to the boat to find the batts at approx 0.01V. Yes!

 

I recharged them and two years later, still no ill effects. 

 

 

I once accidentally left the immersion heater on for several hours which totally flattened our already knackered batts, a full recharge restored them to full working order for several more months. 

[Tracy D'arth]

6 minutes ago, nb Innisfree said:

I once accidentally left the immersion heater on for several hours which totally flattened our already knackered batts, a full recharge restored them to full working order for several more months. 

The inverter did not shut down on low voltage?