Low/Flat Batteries, charging and replacements Questions

[JollyRodgers]

Just when you think you get your boat 'perfect' something goes wrong .. Atleast I'm never bored anymore..

Anyway, was sleeping down on the boat the other week. Usually I disconnect from shorepower when I leave, plug in a small solar panel (I imagine it is something like this; http://www.amazon.co.uk/Solar-Batte...1441095841&sr=8-22&keywords=solar+panel+boats but cant be sure without checking next time I am down) and then turn off the batteries.

This time the solar panel wasnt plugged in properly and therefore was not keeping the batteries on trickle charge whilst I was away. I came back to the boat, and connected shorepower and even then the batteries were slowly dying and when they dropped below around 10V , the fridge turned off and wouldnt start up. We wanted to go out for a little sail, but couldnt start up the engine - which is when we found out the batteries were flat. I was hoping that the engine starting up would give some life to the batteries - but did not.

I also hoped that being connected to the shore power would charge up the batteries - but that did not.

When I left the boat, I had the batteries turned off and solar panel plugged in and shorepower disconnected. Hopefully when I go down on Friday they will be a little higher up.

The batteries are around 6 years old and on the survey when I bought the boat she said that they were old and would need replacing soon and were only just showing 11-12V, which was low. The owner said he had to switch to Batteries 1 and 2 to start up the boat and it was always fine.

I have 3 batteries on board. They are Exide PP75 / 75Ahr.

Does it sound like the batteries are just knackered and I will need 3 new ones? If so, what would be best? I presume that the batteries I have on at the moment are low-end/budget ones.

Questions:
1) How come shore power doesnt charge up my batteries.
2) How come my fridge stopped working, despite being connected to shore power? Surely it runs directly through to the shore? How does that work?
3) What "volts" should my batteries ideally be at, 12-15V?

I also had an issue with my engine running when I took the boat out a couple of months ago. It was running along fine and then all of a sudden (without any spluttering or anything) it just cut out silently. Could there be a correlation between this and the batteries being in poor health? I posted about that a while ago and people seemed to think it couldve just been an air bubble or something going through and not a big deal. I managed to start up the engine after a 10 second pause and it ran okay after that.

Many thanks,

Alex

Sorry the pics are big and the boat is dirty. Haven't refurbed these areas yet
Battery 1 Health

Battery 2 Health

Batteries 1, 2 and 3

 

[VicS]

Starting with the batteries .
I would get them off and charge them independently with a good mains powered automatic multistage charger with a maximum output current of at least 8 or 10 amps until fully charged according to the charger.

Let them stand for 12 hours then check the voltage. If not around 12.7 ish try charging some more but probably regard them as defunct. If you can get them to 12.7 after a 12 hour rest monitor them to see how well they hold their charge. Expect them to fall towards 12.6 fairly quickly but if good should take several weeks to fall to 12.5 ish

You obviously need to unravel the mysteries of your charging system, check the charger for correct operation, check the alternator too perhaps.

Your solar panel is too smal to give you any serious recharging capability but should maintain a well charged battery with no load on it while you are away. Consider a larger solar panel if you want recharging capability.

The fridge may or may not automatically switch to mains operation when the shorepower is connected .......... RTM.


As an aside check that you have a galvanic isolator if you leave the shorepower connected , unless the earth is not bonded to the the anodes, DC negative etc. ( If it isn't then consider bringing this up to modern standards at sometime)

Exide is a well known reputable make of battery. The world's second largest battery manufacturer I understand. I have one in one of my cars replacing a similar one which lasted 10 years. You could consider an ordinary automotive battery, rather than a leisure battery, for engine starting and deep cycle batteries for the house battery bank but there is some merit in them all being the same.

 

[JollyRodgers]

Just got back from the boat today. The solar panels had charged up both batteries to just ever so slightly under 12V on the gauge. We decided to bring home the batteries and properly charge them up and will see what they're like after that.

I think we have a galvanic isolator. I googled what it looks like and remembered seeing it somewhere. Also got the anodes too. Do these not work unless there is power connected/batteries are left on then? I haven't really thought about it properly to be honest.

 

[Sniper]

I had a similar problem recently and found that two of my three batteries were dead. Get them drop tested once fully charged and if they fail that, they'll need replacing.

 

[macd]

Just got back from the boat today. The solar panels had charged up both batteries to just ever so slightly under 12V on the gauge.

Assuming the batteries maintain that value with no further loads or charging being applied, it suggests they're about 40% charged. If the reading drops significanlty over the next few hours (again with no load or charging) they're probably knackered. Incidentally (clearly what happened wasn't through choice), allowing a battery to regularly drop beyond 50% discharged will significantly shorten its life.

As Vic suggests, read the fridge handbook. Yours may run on 12 or 240V. But most yacht fridges run on 12V only: when on shore power it's common for the battery charger to be running, which will top up everything the fridge takes out = no effective drain on the batteries. It's equally normal for the fridge controller to shut the compressor down below a particular voltage; if it didn't, you'd be at risk of the batteries draining to zilch. The handbook will tell you what this voltage is.

To answer your earlier question about battery voltage, a healthy 12V lead acid battery should show around 12.7V if fully charged. The same battery would show rather more after just being charged (by engine, battery charger, panels etc), but will then settle to a 'true' value.

 

[JollyRodgers]

Assuming the batteries maintain that value with no further loads or charging being applied, it suggests they're about 40% charged. If the reading drops significanlty over the next few hours (again with no load or charging) they're probably knackered. Incidentally (clearly what happened wasn't through choice), allowing a battery to regularly drop beyond 50% discharged will significantly shorten its life.

As Vic suggests, read the fridge handbook. Yours may run on 12 or 240V. But most yacht fridges run on 12V only: when on shore power it's common for the battery charger to be running, which will top up everything the fridge takes out = no effective drain on the batteries. It's equally normal for the fridge controller to shut the compressor down below a particular voltage; if it didn't, you'd be at risk of the batteries draining to zilch. The handbook will tell you what this voltage is.

To answer your earlier question about battery voltage, a healthy 12V lead acid battery should show around 12.7V if fully charged. The same battery would show rather more after just being charged (by engine, battery charger, panels etc), but will then settle to a 'true' value.

Thanks for that, it was helpful. My girlfriend reckons that last time the fridge wasn't working because we hadn't actually flicked the switch on (lol), but I thought I had. So between us were not sure if it was definitely not running due to the batteries or if we just didn't turn it on properly. I will keep an eye out for that next time.

I'll see how the batteries respond to the proper charging at home and how they respond when back in the boat. If they are being iffy I will just replace them. One less thing to worry about to be honest. They are quite old anyway (I think 5-7 years) so could do with replacing in the near future.

I'm toying with the idea of putting the boat onto a swinging mooring at some point, so if that's the case I will probably get a couple of bigger solar panels or a wind generator to keep the batteries topped up, as well as automatic bilge pumps.

 

[macd]

I'll see how the batteries respond to the proper charging at home and how they respond when back in the boat.

Sorry, but I'm bound to ask what you mean by "proper charging". If it's with a regular car battery charger it will never get your batteries to 100% in your lifetime; mind you, your boat alternator probably won't either. Without 3- or 4-stage charging, the best they'll reach is around 85%. So, since draining below 50% is bad news, you get little more than a third of your batteries' nominal capacity to play with.
That's a sobering thought, but a useful one if you want to be kind to them.

 

[ghostlymoron]

In my experience (limited), once you start worrying that your batteries are defunct, they probably are! Replace them and review your charging equipment. I recently bought a Hankook deep cycle (?) 75ahr. They don't quote a CCA so it is a Leisure rather than starter. I should get 2 of them for your domestic supply and a cheaper car battery for your starter.

 

[JollyRodgers]

Sorry, but I'm bound to ask what you mean by "proper charging". If it's with a regular car battery charger it will never get your batteries to 100% in your lifetime; mind you, your boat alternator probably won't either. Without 3- or 4-stage charging, the best they'll reach is around 85%. So, since draining below 50% is bad news, you get little more than a third of your batteries' nominal capacity to play with.
That's a sobering thought, but a useful one if you want to be kind to them.

Ahh.. yeah, I was planning on just using a car battery charger..

So what batteries would you recommend to replace the existing 3? I don't know much about 75ah/125ah/300ah batteries. I don't want them to risk running low again in future, but to be honest I don't use the batteries much.

Only need them for waterpump,fridge and possibly in the future an automatic bilge pump. And of course actually starting the engine. Presumably 75ahs will suffice.

I really don't have a problem with spending money if it saves me inconveniences down the line or hassle, so I guess that replacing all 3 batteries now would be a good idea.

In my experience (limited), once you start worrying that your batteries are defunct, they probably are! Replace them and review your charging equipment. I recently bought a Hankook deep cycle (?) 75ahr. They don't quote a CCA so it is a Leisure rather than starter. I should get 2 of them for your domestic supply and a cheaper car battery for your starter.

I had a similar feeling to be honest too. Do you remember how much the hankook cost per battery? I'm seeing results on google for £50 - but it seems cheap?

Is this the 'modern' equivalent of my existing batteries - https://www.tayna.co.uk/Exide-ER350-DUAL-Leisure-Battery-Porta-Power-PP75-P7640.html ?

For some reason I had in mind per battery costing £120 each, so £50-70 is a bit nicer.

 

[macd]

So what batteries would you recommend to replace the existing 3? I don't know much about 75ah/125ah/300ah batteries. I don't want them to risk running low again in future, but to be honest I don't use the batteries much.

Only need them for waterpump,fridge and possibly in the future an automatic bilge pump. And of course actually starting the engine. Presumably 75ahs will suffice.

I really don't have a problem with spending money if it saves me inconveniences down the line or hassle, so I guess that replacing all 3 batteries now would be a good idea.

Your "only" is quite a big one if it includes a fridge. They're quite power-hungry.
For an engine starting battery, as ghostlymoron suggests, you just need an automotive one. Your engine handbook may well specify a minimum CCA (Cold Cranking Amps): chose something that meets or exceeds this. In a well-regulated system starter batteries get a pretty easy life.

For domestic batteries you have lots of choice and a whole array of quality, but for occasional use maybe ghostly's suggestion is also OK. Ah capacity may depend, as much as anything, on the amount of space available in your battery compartment. While you're in there, double-check that the cabling and connections are clean, sound, not subject to chafe and fairly hefty.

Whatever you choose, remember that lead acid batteries hate to be left partly charged for extended periods. They adore being full.
You might also consider a more sophisticated battery charger on board, or a 'smart' regulator. That will keep them happier, too.

 

[santelmo]

The best investment that I ever made for my boat was Nigel Calder's Boatowners Mechanical and Electrical Manual. Read and learn

 

[earlybird]

Re. the voltmeter shown in your pictures. Is it turned off when the batteries are switched off? I once tried a meter of that type, it consumed 2-300mA IIRC.
Seems small, but if left on 24/7, 250mA will drain >40 Ah./ week from your fairly aged batteries, much more than your solar panel can put back in.
Just a thought!

 

[Poecheng]

Jolly, you don't actually say that you have a charger on board - just that you have shorepower. I assume you do have a battery charger?

Sounds to me like you need to sort out your system: boat battery charger, your batteries and your solar system.

Check that the alternator is charging - the voltage at the battery terminals should be >14v when the engine is running. This is a whole topic in itself but for the moment just check your alternator is working and charging the batteries.

OK guesswork here but am I looking at the battery compartment of a Sadler 34? In which case you are confined to what will physically fit within the compartment and cannot extend it - you are just stuck with it.

I will tell you what I think is a good system for your boat without giving you much options. In fact, there are lots of options and different views but sometimes (if you are not confident in an area) it is just easier to be told one person's view and then decide whether you want it or not ! If it sounds dictatorial it is meant to be so that you are not swamped with options.

Battery charger: check what you have on board and whether it is a modern, stepped charger. For your set up you need one that puts out 15A or more and I do not think a 10A charger is sufficient. If you need to change then buy a CTEK M200 or M300. THese are fairly expensive because they are very good. PRices vary significantly so do do your searches though I wandered into Foxs, Ipswich and got an M200 at the lowest internet price I could find.

Batteries: you are governed by the space you have available (including height) and so the dimensions of the battery and the layout and type of terminal are critical to the job. Loads of types to chose from but that doesn't help you! Try these https://www.tayna.co.uk/Numax-Marine-Batteries-S527-1.html or the Exides.
Extra option: you can only get three batteries in the space photographed. If you could get a small starter battery stored elsewhere (engine compartment?) then your three batteries in the compartment can be domestic batteries. This will significantly improve your position as you are drawing down from a bigger source and therefore a) either draw down for longer or b) draw down less as a percentage. In reality it is a bit of both but the extra domestic battery - when you have a fridge - will improve things for you.
Smaller starter battery: ideal is a Red Flash 1000 (assuming engine no more than 35hp) but you could also use a normal car battery for small car such as Toyota Yaris if your engine is not knackered and doesn't requires churning away !

Solar: Start with a decent controller. You can get cheap ones on Ebay if you want (and most do happily ) but I chose Victron 75/15 (it can take max input of 75v/15A) which is an MPPT. It acts like a multi-stage battery charger. Then the biggest panel you can fit on your hatch garage or other suitable flat space available. I recently bought a 50W semi flexible from Photonic Universe for about £95 and it is excellent.
Option: When doing the wiring, allow for a branch (or Y connector) so that you can add in further solar panels. Depending on your storage and funds you could store a couple of panels so that, when moored or at anchor in summer (using fridge) you can get them out and plug them into the system. I picked up a couple on Ebay and when plugged in together with the one above they were more than keeping pace with the fridge and other usage.

Rough costs
Charger: M200 (15A) = £130
Batteries: 3 x 85A Numax CXV24MF (as an example) = £192 (but if you look at the particular product then Tayna tell you the other labels for same battery and the price of those- see bottom left of page).
Engine start battery: say £50 for small lead acid battery and £20 for box and straps etc.
Solar charger (Victron =£75) and panel £95

Then you have a good system when on shorepower, when afloat and using it and when on swinging mooring and not using it.

You can improve it by, as Mac says, a smart regulator for the battery in due course if it needs it.

 

[ghostlymoron]

Ahh.. yeah, I was planning on just using a car battery charger..

So what batteries would you recommend to replace the existing 3? I don't know much about 75ah/125ah/300ah batteries. I don't want them to risk running low again in future, but to be honest I don't use the batteries much.

Only need them for waterpump,fridge and possibly in the future an automatic bilge pump. And of course actually starting the engine. Presumably 75ahs will suffice.

I really don't have a problem with spending money if it saves me inconveniences down the line or hassle, so I guess that replacing all 3 batteries now would be a good idea.


I had a similar feeling to be honest too. Do you remember how much the hankook cost per battery? I'm seeing results on google for £50 - but it seems cheap?

Is this the 'modern' equivalent of my existing batteries - https://www.tayna.co.uk/Exide-ER350-DUAL-Leisure-Battery-Porta-Power-PP75-P7640.html ?

For some reason I had in mind per battery costing £120 each, so £50-70 is a bit nicer.

I've a feeling mine was about £70 from battery megastore including delivery.

 

[yotter]

+1 for Nigel Calders book, it s the bible. Although I have to confess that I see it before me, temporally supporting my PC screen
Angus

 

[ghostlymoron]

Mine was a hankook DC24MF 88ahr price from megastore £51.50

 

[JollyRodgers]

The best investment that I ever made for my boat was Nigel Calder's Boatowners Mechanical and Electrical Manual. Read and learn

Will look into it. Many thanks.

Re. the voltmeter shown in your pictures. Is it turned off when the batteries are switched off? I once tried a meter of that type, it consumed 2-300mA IIRC.
Seems small, but if left on 24/7, 250mA will drain >40 Ah./ week from your fairly aged batteries, much more than your solar panel can put back in.
Just a thought!

The voltmeter has a switch on the bottom of it. Up 1 one battery, down is another battery and middle is 'off'. I would prefer one of those digital displays which give the volt to the nearest decimal point because they are more accurate to read I think - but the current setup works too.

Jolly, you don't actually say that you have a charger on board - just that you have shorepower. I assume you do have a battery charger?

Sounds to me like you need to sort out your system: boat battery charger, your batteries and your solar system.

Check that the alternator is charging - the voltage at the battery terminals should be >14v when the engine is running. This is a whole topic in itself but for the moment just check your alternator is working and charging the batteries.

OK guesswork here but am I looking at the battery compartment of a Sadler 34? In which case you are confined to what will physically fit within the compartment and cannot extend it - you are just stuck with it.

I will tell you what I think is a good system for your boat without giving you much options. In fact, there are lots of options and different views but sometimes (if you are not confident in an area) it is just easier to be told one person's view and then decide whether you want it or not ! If it sounds dictatorial it is meant to be so that you are not swamped with options.

Battery charger: check what you have on board and whether it is a modern, stepped charger. For your set up you need one that puts out 15A or more and I do not think a 10A charger is sufficient. If you need to change then buy a CTEK M200 or M300. THese are fairly expensive because they are very good. PRices vary significantly so do do your searches though I wandered into Foxs, Ipswich and got an M200 at the lowest internet price I could find.

Batteries: you are governed by the space you have available (including height) and so the dimensions of the battery and the layout and type of terminal are critical to the job. Loads of types to chose from but that doesn't help you! Try these https://www.tayna.co.uk/Numax-Marine-Batteries-S527-1.html or the Exides.
Extra option: you can only get three batteries in the space photographed. If you could get a small starter battery stored elsewhere (engine compartment?) then your three batteries in the compartment can be domestic batteries. This will significantly improve your position as you are drawing down from a bigger source and therefore a) either draw down for longer or b) draw down less as a percentage. In reality it is a bit of both but the extra domestic battery - when you have a fridge - will improve things for you.
Smaller starter battery: ideal is a Red Flash 1000 (assuming engine no more than 35hp) but you could also use a normal car battery for small car such as Toyota Yaris if your engine is not knackered and doesn't requires churning away !

Solar: Start with a decent controller. You can get cheap ones on Ebay if you want (and most do happily ) but I chose Victron 75/15 (it can take max input of 75v/15A) which is an MPPT. It acts like a multi-stage battery charger. Then the biggest panel you can fit on your hatch garage or other suitable flat space available. I recently bought a 50W semi flexible from Photonic Universe for about £95 and it is excellent.
Option: When doing the wiring, allow for a branch (or Y connector) so that you can add in further solar panels. Depending on your storage and funds you could store a couple of panels so that, when moored or at anchor in summer (using fridge) you can get them out and plug them into the system. I picked up a couple on Ebay and when plugged in together with the one above they were more than keeping pace with the fridge and other usage.

Rough costs
Charger: M200 (15A) = £130
Batteries: 3 x 85A Numax CXV24MF (as an example) = £192 (but if you look at the particular product then Tayna tell you the other labels for same battery and the price of those- see bottom left of page).
Engine start battery: say £50 for small lead acid battery and £20 for box and straps etc.
Solar charger (Victron =£75) and panel £95

Then you have a good system when on shorepower, when afloat and using it and when on swinging mooring and not using it.

You can improve it by, as Mac says, a smart regulator for the battery in due course if it needs it.

Awesome post, thanks so much for this. I owe you a beer if you are down in Chichester way

I'm not sure if I have a battery charger on board actually. i will look next time I am down. There were lots of wires going onto the batteries, which then went into the engine bay way, so I'll have a look and see if there are any in there next time I am down. If not I will purchase the one you said to.

Solar panel, I need to have a look and see what model it is and the output. It's only a very small one about the length of my arm or so and my forearm in width.

Battery compartments are limited. IWill have to check the sizes/dimensions of the 85A to see if they match my current ones. There is an empty compartment that would fit a battery in behind the battery ones, so could stick that in there - or in with the hot water tank or engine bay - loads of options.. I would however need to figure out how to connect it all too. E.g. how would I switch onto the engine start battery when I turn the ignition key. I have a battery twistyswitch bit ,which allows me to select battery 1,2 or 1 and 2. Previously, I have been starting the engine on batteries 1&2 as per the previous owners recomendation. Confuses me a bit actually because does that mean I am never selecting battery 3? lol..

Engine is a Beta Marine 28hp and it's pretty new. The volts also go up when the engine is running.

I've done so much work to the boat and learnt such a ridiculous amount - very satisifying actually. However, the one part that my knowledge lacks on is batteries/electronics, diesel engine maitenance is a bit iffy (I know the basics..) and actual sailing practice needs work lol. BUT - i'm trying to learn as much as I can and speak to as many people as I can about things.

Maybe a bit of a generalisation and obviously it's not true for everyone, but i've noticed that the majority of people in my marina tend to just pay for people to do the work, so when I speak to them in the yacht club they aren't too helpful for maitenance stuff. That's why I like this forum I heard Dell Quay has a very tightly knit community and everyone seems to be very practical and hands on.

Boat is a Sadler 32 btw.

 

[Poecheng]

Hi Jolly,

Glad you took it all the right way and I was right on the Sadler but wrong model !

OK - firstly your Beta is an excellent engine and the alternator will charge the batteries as well as anything without a special regulator. It will charge at about 14.4v which is fine (at least for the moment.)

Sounds like two of the batteries are linked together as "1" (or "2") and the single engine start battery is the other. That explains the third battery.

The starting on "both" banks either is the previous owner's practice (fair enough and no bad thing particularly to spread the load) or because the single engine battery was not considered upto it. If you adopt the system I suggest with a separate engine battery then that can become "1" and the three new ones combined together to become "2". You might need some help getting that sorted because a) you are not confident and b) the wires to make it all up are large and need to be crimped and the equipment is generally beyond DIY. Depends who is around ? It is not the end of the world though to get someone to link it all up and to the battery switch.

WHen that is done, to start the engine you turn switch to "1", give it heat and it will fire away. Practice varies thereafter but reasonable to allow it to charge "1" for say 10 mins and then move the switch to "2" (moving the switch via "both") to charge up the domestic bank. Then when you are sailing, anchoring etc or otherwise not using the engine, keep it on "2" so that, if that gets run down you always have "1" to start the engine.

Your solar panel, I am guessing, is about 10w which is no use with the bank of batteries you have. If you get a decent solar panel then you will always come back to happy batteries.

There are refinements after this - special regulator for the alternator, getting rid of the battery switch etc but ATM you need a basic but good and working system so suggest they come later if you need them.

Beta again: make sure that the heat exchanger is cleaned properly every year (the cooling system is fine if clean, not if it is not) and change your cooling system anodes every 6m/season as they go through them quickly.

Good luck