Battery chargers for beginners

[MissFitz]

I see there are lots of threads about battery chargers already, but have to confess that I don't understand a lot of them. Also, they mostly seem to cover much larger electrical systems that I will have on my boat.

What I will have is one 12V battery running (for the moment) one set of nav lights only. What would be the best type of charger for this system? I'm hoping the answer will be a very small & cheap one that's available from Halfords or similar, but am prepared to pay up if necessary.

Also, I understand that these battery chargers can themselves be charged from shore power. Is that right? If so, how often are they likely to need to be charged from shore power? And what will I need to do so apart from a shore power electrical cable?

Again, I would note that at present my ignorance of these matters is lamentable, so answers for idiots would be much appreciated!

 

[Tranona]

You really don't need a battery charger unless you have access to shorepower. For your modest needs you need a 12v battery of around 75AH such as used in larger cars. Keep topped up with a solar panel. If you do run it down then it is small enough to take off the boat and take home to charge. Then you will only need a modest charger plugged into your electricity at home.

You will, of course need a fused 12v circuit with switches to distribute power to your lights, instruments etc. Plenty of ready made switch panels in chandlers or on ebay. Make sure battery is well strapped down - dedicated boxes available for this.

 

[{151760}]

I think you're confusing battery chargers and power packs. They're both useful in different ways. A battery charger is a device that pumps electricity into a battery. It doesn't require charging itself, but it does need a mains supply in order to work, so it's useful in a Marina or mooring with a mains supply. Yes, for your needs a cheapie charger from Halfords will do the job, but to recharge a 75ah battery will take overnight.
Power Packs or Jumpstarters are much more expensive and are essentially a battery combined with a charger. They're useful as a way of getting a car or inboard engine started but, they then need recharging themselves from a mains supply. I would say they're not particularly relevant to your situation at the moment.

 

[MissFitz]

I think you're confusing battery chargers and power packs.

That is indeed precisely what I was getting confused about, thanks for clarifying. So would a 12A charger be sufficient? Or even a 4A one?

 

[VicS]

That is indeed precisely what I was getting confused about, thanks for clarifying. So would a 12A charger be sufficient? Or even a 4A one?

A Rule of thumb often applied to choosing a charger is to get one with a max output in amps equal to 10% of the battery capacity in amphours
You do need an automatic charger that will reduce its output to a float mode once the battery is charged

So for the 75 Ah battery Tranona suggests an automatic 8 amp charger would be about right.

Larger will be not be of any great benefit because the battery will not accept a higher current for longer the first few minutes or so.

Smaller will mean that the battery will take too long to recharge if significantly discharged.

However if you will have equipment operating at the same time as you are trying to recharge increase the size of the charger to supply the current that requires in addition to charging the battery.

Some chargers do not like loads being applied so also make sure that it is one that will charge and supply a load at the same time.
My Ring charger goes into "recondition mode if a load is switched on while it is charging!

Some do not resume charging after a power interruption.... you want to avoid those My little 3.8amp Lidl charger is like that. My Ring resumes but defaults to its lowest (2amp) output setting

If I was looking for a charger specifically for the boat, where my needs are similar to yours, I would look at the Ctek range and probably choose one of the marine chargers.

http://www.ctek.com/products

Halfords chargers are probably Ok for the car/ home workshop, otherwise best left in Halfords

 

[{151760}]

A Rule of thumb often applied to choosing a charger is to get one with a max output in amps equal to 10% of the battery capacity in amphours
You do need an automatic charger that will reduce its output to a float mode once the battery is charged

So for the 75 Ah battery Tranona suggests an automatic 8 amp charger would be about right.

Larger will be not be of any great benefit because the battery will not accept a higher current for longer the first few minutes or so.

Smaller will mean that the battery will take too long to recharge if significantly discharged.

However if you will have equipment operating at the same time as you are trying to recharge increase the size of the charger to supply the current that requires in addition to charging the battery.

Some chargers do not like loads being applied so also make sure that it is one that will charge and supply a load at the same time.
My Ring charger goes into "recondition mode if a load is switched on while it is charging!

Some do not resume charging after a power interruption.... you want to avoid those My little 3.8amp Lidl charger is like that. My Ring resumes but defaults to its lowest (2amp) output setting

If I was looking for a charger specifically for the boat, where my needs are similar to yours, I would look at the Ctek range and probably choose one of the marine chargers.

http://www.ctek.com/products

Halfords chargers are probably Ok for the car/ home workshop, otherwise best left in Halfords

Good advice.

 

[halcyon]

What I will have is one 12V battery running (for the moment) one set of nav lights only. What would be the best type of charger for this system? I'm hoping the answer will be a very small & cheap one that's available from Halfords or similar, but am prepared to pay up if necessary.

Until you get more equipment, I would go with a solar panel and regulator, free to run and works at sea or shore side. If you get more equipment later, fit more battery power and engine and mains charging, the solar panel will keep battery topped up when not on the boat, so no money wasted.

Brian

 

[anoccasionalyachtsman]

For what it's worth, I pondered all of this and took a different route. My dayboat hasn't got proper yacht power demands - an echosounder sometimes, like you the possibility of nav lights a few nights a year, but I definitely need to be able to charge an hh vhf, mobile 'phones and run some sort of music player/amp/speakers. I don't have a charge facility on the outboard but don't want to run an engine for charging anyway.

I'm assuming that I can recharge every day, but if I can't I don't want to kill a lead acid battery by running it flat, so I've gone for a lithium car 'jump starter' with 18 amp hour capacity. If that turns out to be a bit light I'll buy another. They'll fit in an oilie pocket and come with mains and car chargers, so rechargeable in a marina office, pub etc.. if we ask nicely. Under £70 with charger, has USB output and will start the car if that battery is flat.

 

[MissFitz]

Thanks guys, lots of really helpful info & suggestions. Sounds like I want a solar panel and/or a Ctek but will wait to splash out on those until I've decided what I want to put on the boat in terms of electrics. To keep me going in the meantime I've bought a 4A smart charger, clearly too small for the 110 Ah battery I've been given by a friend but will at least mean I can put a bit of charge in it while working out a longer term solution.

 

[Sailingsaves]

You are all wrong and I am right.

I'll tell you the correct arrangement needed because I am all-knowing: You just need LOTS of AA Duracells (terrible AA batteries actually).

Seriously though, Halcyon said it;

You have the battery already, just buy a 20W solar panel (25 quid, maximum for a new one on ebay) and cheap controller and you are sorted.

I don't know a lot about controllers because I make my own, but if they don't come with a voltmeter, buy a cheap multimeter.

If a wet cell battery, keep an eye on the electrolyte levels and if possible mount the battery so it lies with the 6 'screw' caps athwart ships (that is from an article in PBO magazine - someone will correct me if I am wrong there - I sailed for years with a simple car battery lying t'other way around and took it from swinging mooring home for a charge regularly with no trouble), but the alignment reason is so when heeling no lead is exposed (according to PBO article).

And read lots online; it is easy and fun to pick up info. 5 years ago I didn't know what an LED was and now I make all sorts of electronic things and I tinker with solar, windturbines, towed turbines, nav lights MOSFETS and even an electronic lighter that melts the end of rope in a F8 Gale.

Happy illuniation

 

[PaulRainbow]

You really don't need a battery charger unless you have access to shorepower. For your modest needs you need a 12v battery of around 75AH such as used in larger cars. Keep topped up with a solar panel. If you do run it down then it is small enough to take off the boat and take home to charge. Then you will only need a modest charger plugged into your electricity at home.

You will, of course need a fused 12v circuit with switches to distribute power to your lights, instruments etc. Plenty of ready made switch panels in chandlers or on ebay. Make sure battery is well strapped down - dedicated boxes available for this.

This would also be my advice.

 

[Uricanejack]

Thanks guys, lots of really helpful info & suggestions. Sounds like I want a solar panel and/or a Ctek but will wait to splash out on those until I've decided what I want to put on the boat in terms of electrics. To keep me going in the meantime I've bought a 4A smart charger, clearly too small for the 110 Ah battery I've been given by a friend but will at least mean I can put a bit of charge in it while working out a longer term solution.

An ordinary run of the mill charger will work just fine and dandy.
you might find an extension cord and possibly an adaptor to fit marina power sockets comes in handy.
A small LED cabin light might be quite nice to have should you stop in anywhere particularly if you can charge up.

 

[PaulRainbow]

An ordinary run of the mill charger will work just fine and dandy.
you might find an extension cord and possibly an adaptor to fit marina power sockets comes in handy.
A small LED cabin light might be quite nice to have should you stop in anywhere particularly if you can charge up.

Not great advice. Connecting to "An ordinary run of the mill charger" and leaving it won't necessarily do the battery an favours.

 

[Uricanejack]

Not great advice. Connecting to "An ordinary run of the mill charger" and leaving it won't necessarily do the battery an favours.

If not why not?

All she needs is a battery to power some lights for a while if it gets dark or she runs into poor vis on the way home. Which will work just fine till she gets there. Once she has boat at home marina mooring or dock she can set up a permanent electrical system.

Nobody suggested it as a permanent fitting. Or going away and leaving it. She has a ordinary smart charger which will work just fine to charge up a car battery at home or in this case on the boat while you are there.

Once she does set up a system she will probably want a deep cycle battery anyway.

 

[ghostlymoron]

"Halfords chargers are probably Ok for the car/ home workshop, otherwise best left in Halfords"
Amen to that. I once left my 2 85ahr batteries on charge all winter with a Halfords 'automatic' charger and they were totally wrecked by Easter.

 

[PaulRainbow]

If not why not?

All she needs is a battery to power some lights for a while if it gets dark or she runs into poor vis on the way home. Which will work just fine till she gets there. Once she has boat at home marina mooring or dock she can set up a permanent electrical system.

Nobody suggested it as a permanent fitting. Or going away and leaving it. She has a ordinary smart charger which will work just fine to charge up a car battery at home or in this case on the boat while you are there.

Once she does set up a system she will probably want a deep cycle battery anyway.

Sorry, but i don't understand what you are suggesting. When will she be using this "run of the mill charger" ?

A deep cycle battery will be totally over the top and pointless for what she describes.

 

[PaulRainbow]

Thanks guys, lots of really helpful info & suggestions. Sounds like I want a solar panel and/or a Ctek but will wait to splash out on those until I've decided what I want to put on the boat in terms of electrics. To keep me going in the meantime I've bought a 4A smart charger, clearly too small for the 110 Ah battery I've been given by a friend but will at least mean I can put a bit of charge in it while working out a longer term solution.

Put the 110ah battery on the boat. For less than the price of a smaller battery you can fit a solar panel and regulator.

 

[jac]

Put the 110ah battery on the boat. For less than the price of a smaller battery you can fit a solar panel and regulator.

+ 1 ( ish)

Assuming your ob is a recoil start this will be the only battery you need. Find a patch of deck with minimal shading and fit the biggest panel that will go into the space. You might have room for a 50W panel on a sonata. That will give you about 12Ah of charge of day in the summer - more than enough to keep your battery topped up and bring back to 100% over a week if you hammer it at the weekend.

Go and buy a simple fuse panel and which ever electrical items you decide and run it from there. Plenty of time to worry about all the complicated bits later.

 

[RupertW]

"Halfords chargers are probably Ok for the car/ home workshop, otherwise best left in Halfords"
Amen to that. I once left my 2 85ahr batteries on charge all winter with a Halfords 'automatic' charger and they were totally wrecked by Easter.

Used Halfords chargers on all my boats - whatever was cheapest to deliver the most amps. I have tended to change batteries every 10 years or so (or for a current boat after 13 years and they weren't new then).

I have never had a problem with a battery being left unattended for 6 months over Winter. I don't charge them or leave them with anything on to run them down.

That doesn't mean I've got anything against expensive chargers, just that I am sure they don't make a noticeable difference to battery life. I will become much more interested in alternator ability and solar panel controls once I get enough time off to be able to spend more than a week away from a marina and don't want to burn through fuel for hours each day, but "good" mains chargers will never be a priority I think.

 

[LadyInBed]

You may think that at the moment you only have a need to power your nav lights, but you will soon realise that it would be handy to recharge your mobile phone and I believe you also have a h/h VHF which can probably also be recharged from a 12v battery