Battery chargers for beginners

The problem with cheap battery chargers is not that they are cheap, but they have the ability to destroy boats !!

Yours might be ok but if its not a totally isolated battery charger and your neighbour has a mains connection without a galvanic islolator you could start to dissolve his sterngear and anything else that is earthed.
 
raymondmcm said:
The problem with cheap battery chargers is not that they are cheap, but they have the ability to destroy boats !!

Yours might be ok but if its not a totally isolated battery charger and your neighbour has a mains connection without a galvanic islolator you could start to dissolve his sterngear and anything else that is earthed.
Click to expand...

There may be some truth in that ..... but I don't really think that one can be expected not to use a shore-charger just because your neighbours have not fitted GIs. Your boat will presumably be the primary victim anyway, unless you have a GI fitted.

Richard
 
PaulRainbow said:
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.
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She has a borrowed car battery. She has bought a 4 amp smart charger.
All she needs is access to an AC socket. For a couple of hours. And she is good to go. She can do this at home before she leaves to go to the boat yard. Or in any marina along the way that has AC sockets available.
Why would this be a hard concept to grasp?

It's Simple, It will meet her needs.

The simplest (perfectly safe ) solution would be a set of battery operated lights. The forum has talked her out of this and into fitting a set of permeant navigation lights and a battery

I am presuming boat tokens are limited. Boat is long way from home. She has to make a series of round trips to boat to get it ready for the delivery home. Each trip to the boat will be an added expense. Each additional job to get the boat ready will take both more time and money.

When she goes to make the delivery she will be making a one way trip to the boat.

Now you are suggesting she by and fit solar panels. Which might be a good idea for an electrical system down the road but she does not need a solar panel to get the boat home.

Halfords sell battery chargers, I presume consumer protection laws in UK require the chargers sold by Halfords or any other car part store. Conform to British safety standards and can be safely plugged in to a standard UK AC plug , used with an extension cord, and even used outside to charge a car battery.

I fail to understand why putting said car battery on a small boat and using it to charge the battery. Would make be unsafe or unwise.

All I am suggesting is she get the simplest working lights she can up and running and bring the boat home.
 
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Uricanejack said:
She has a borrowed car battery. She has bought a 4 amp smart charger.
All she needs is access to an AC socket. For a couple of hours. And she is good to go. She can do this at home before she leaves to go to the boat yard. Or in any marina along the way that has AC sockets available.
Why would this be a hard concept to grasp?

It's Simple, It will meet her needs.

The simplest (perfectly safe ) solution would be a set of battery operated lights. The forum has talked her out of this and into fitting a set of permeant navigation lights and a battery

I am presuming boat tokens are limited. Boat is long way from home. She has to make a series of round trips to boat to get it ready for the delivery home. Each trip to the boat will be an added expense. Each additional job to get the boat ready will take both more time and money.

When she goes to make the delivery she will be making a one way trip to the boat.

Now you are suggesting she by and fit solar panels. Which might be a good idea for an electrical system down the road but she does not need a solar panel to get the boat home.

Halfords sell battery chargers, I presume consumer protection laws in UK require the chargers sold by Halfords or any other car part store. Conform to British safety standards and can be safely plugged in to a standard UK AC plug , used with an extension cord, and even used outside to charge a car battery.

I fail to understand why putting said car battery on a small boat and using it to charge the battery. Would make be unsafe or unwise.

All I am suggesting is she get the simplest working lights she can up and running and bring the boat home.
Click to expand...

Hat's with all the "bringing the boat home" comments ?

Did i miss a post ?

You might want to read post #1 again.

Fitting any old "run of the mill charger" is not a good idea. The 4a smart charger should be OK, but that isn't a "run of the mill charger" it's a smart charger.

No one has talked the OP into fitting a battery and nav lights, that is what they said they had/planned.

You sure you're reading the same thread as the rest of us ?
 
PaulRainbow said:
Hat's with all the "bringing the boat home" comments ?

Did i miss a post ?

You might want to read post #1 again.

Fitting any old "run of the mill charger" is not a good idea. The 4a smart charger should be OK, but that isn't a "run of the mill charger" it's a smart charger.

No one has talked the OP into fitting a battery and nav lights, that is what they said they had/planned.

You sure you're reading the same thread as the rest of us ?
Click to expand...

We were trying to talk the OP into a solar panel at the start, if they really wanted a charger for the battery, saves the need for mains and saves lugging a battery around.

Brian
 
PaulRainbow said:
Did i miss a post ?
Click to expand...

I posted a whole load of threads on related subjects, hence the confusion. Started with what I need in the way of equipment to get my Sonata back from Brixham to Southampton, progressed to what sort of lights to fit on it & then on to battery chargers to power said lights. The idea was to keep things simpler by splitting out separate topics, unfortunately has been some thread overlap. Sorry!
 
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ghostlymoron said:
"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.
Click to expand...
Any particular reason you though that was a good idea?
 
RichardS said:
My batteries are on permanent 365-day charge using a decent smart charger. That's what they are for. :)

Richard
Click to expand...

If you are talking about your boat batteries Richard, when you fit the solar panels you should turn the shore charger off, or there won't be anything for the panels to do.
 
Hi,
Not going to add the good advice above, with an unusual amount of consensus too!
However, if your boat has minimal electrics/toys you can live off a big battery for a week or more without wrecking it, which was common not so very long ago. Even easier now led lights are so good & cheap. And they can be run from their own batteries.
There's a valid argument for keeping it simple.
Sail first, get out there & enjoy and add gear as you go.
 
mogmog2 said:
Hi,
Not going to add the good advice above, with an unusual amount of consensus too!
However, if your boat has minimal electrics/toys you can live off a big battery for a week or more without wrecking it, which was common not so very long ago. Even easier now led lights are so good & cheap. And they can be run from their own batteries.
There's a valid argument for keeping it simple.
Sail first, get out there & enjoy and add gear as you go.
Click to expand...
I believe the OP has got her boat back home now.
 
For a small boat 12v power. Firstly if you are going to use nav lights much then fit LED nav lights. Plus LED inside lights.
A fixed VHF radio will draw on receive around 300ma (1/3 amp) so needs a decent battery for operation beyond about 12hours. Even then a small battery might suffice. One that is convenient to put in your bag and take home. SLA lead acid are fairly cheap and start at around 7 amp hour and are deep cycle. That is one option to take battery home to recharge. However an excellent idea is to fit a solar panel and regulator. Not expensive.
A battery can not be recharged from another 12v battery. This is because a 12v battery needs around 14v to push a reasonable current into the battery to recharge. It would need a voltage boosting device to be able to decant from one battery to another. Power packs can only substitute or add to a flat battery for engine start.
Mains powered battery chargers have evolved over the years. Originally they had a transformer and rectifier such that the charging waveform had a peak voltage of perhaps 17 volts and an average of about 13 volts such that it pushed current into the battery at a rate of 50 times per second for a period depending on charge state of the battery. The end effect was almost a constant current charger. A large charger could put a lot of charge into a battery in a few hours but could if left on destroy the battery by over charging. However I like this type.
With electronics so cheap the regulated charger became the norm. This has a constant voltage such that current is large when battery is flat but diminishes as battery is charged. This means that left on long term the charge current becomes low
and no harm is done. It does however mean that it takes along time to get a full charge. This type of charger emulates a car regulated alternator. Then almost universal now is the smart charge where initially a large current is pushed into the battery by providing a higher charge voltage. When it senses the battery is near charged it reduces the voltage and current to a trickle or maintenance charge. olewill
 
William_H said:
.A large charger could put a lot of charge into a battery in a few hours but could if left on destroy the battery by over charging. However I like this type.
Click to expand...
Olewill, somewhat OT, but what do you like about these? I've seen that they *may* have a role in recovering mildly sulphated batteries .
Thanks
 
The OP doesn't say if he has mains on his mooring. If he doesn't, a charger won't do him any good and a small solar panel is what he needs. This is what I have although I have mains available if needed. I have no mains installation on my boat. The 20w panel keeps the battery nicely charged in summer and I use a small car charger at home in the winter every so often.
 
mogmog2 said:
Olewill, somewhat OT, but what do you like about these? I've seen that they *may* have a role in recovering mildly sulphated batteries .
Thanks
Click to expand...

Probably mostly because I have several home made from just an old transformer and rectifier. I would never leave one on over night or not monitored so suits me. Certainly the foolproof aspect of modern chargers is important for many people. olewill
 
William_H said:
Probably mostly because I have several home made from just an old transformer and rectifier. I would never leave one on over night or not monitored so suits me. Certainly the foolproof aspect of modern chargers is important for many people. olewill
Click to expand...

There is a big difference between transformer based and switch mode based chargers, as mentioned earlier, transformer systems run on a pulse charge. If you look on a scope you will see a straight line ( almost ) and a number peaks, these being the time that the battery is on charge. To fully a charge a lead acid battery you need around 15.5 volt to complete chemical reaction, a transformer buy design can give you 14.4 volt baseline and 15 plus on peakes, this and the 10% rule gives a full charge without major gassing. A switch mode being flat output goes to 14.4 v or higher, then uses absorption mode, meaning it is running continual high volts, thus high water usage and never makes full charge.

I would not recommend any old transformer and a few diodes, but a small transformer charger on a timer has a lot going for it for intermittent use. Plus the peak voltages will help limiting sulphation from low charge rates, ie regulated solar panels.

Downside, are these chargers still made ?

Brian
 
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