Battery Charging Safely....

Scubadoo

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Is it safe to charge my boat batteries while still connected to the boat's electrical circuit or should I disconnect before charging. I don't have a built in charger and use the normal car charger type from halfords.

I am only talking about charging while in attendance.

RM.
 

philip_stevens

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It is quite safe to charge them without disconnecting them. I top-up charge mine during the winter in this way - using a charger with float facility - while on the boat and in attendance.

I also have the radio on while working, and when necessary, the lights.

No problems.

regards,
Philip

regards,
Philip
 

brianhumber

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All batteries will produce explosive gas when being charged. This is why the MCA commercial small craft ACOP droned on about batteries must be situated in a well ventilated compartment. Just make sure yours are not in an air tight compartment when you are charging. Have a careful look from a safe distance at the electrolite through the top up plugs when the charger is on, any cell gassing more than the others normally means you are heading for a new battery in the near future.
 

johndf

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Re: Battery Charging Safely - ventilation....

I don't think that there is any ventilation for the battery compartment in my boat. This sounds like a bit of a concern, doesn't it? Is there any chance of a spark being produced by the charging process?
 
G

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There should be no problem in charging your battery using a Halfords type battery charger whilst other electrical items (loads) are switched on. The battery will act as a smoothing device and absorb most of the 'ripple' or noise that a cheap unregulated power supply such as your battery charger will produce. Many years ago before more modern electronic components capable of effectively smoothing a power supply were available, one method of smoothing was the inclusion of lead acid rechargeable batteries in the circuit. I would however not reccomend that the battery is taken out of circuit, in other words supplying your electrical appliances from the battery charger alone.
As for gassing, the lead acid battery will produce 3 types of gas during charging to a greater or lesser extent. If the charger is cheap then the chances of overcharging and therefore producing a lot more gas is much higher. If the battery is in an enclosed space then the build up of one of these gasses, hydrogen, is obviously highly dangerous. The battery should be allowed to ventilate. Hydrogen is lighter than air so a vent at the top of your battery compartment is reccomended or open the compartment and leave open whilst charging. The classic and horrible mistake is to disconnect a battery charger crock clip from one of the battery posts during or just after charging. The spark will ignite the hydrogen and not only will there be injuries associated with thermal burns and shrapnel but think of all that battery acid atomising and covering everything! Always arrange to have a battery charger switched off remotely (say via an extention lead) and even then I'd make sure the battery was allowed to ventilate a while longer before removing a crock clip.
If your battery is in an enclosed space I'd seriously look at improving the ventilation.
Info: Lead Acid Battery produces 60% Hydrogen (Lighter than air)
30% Oxygen
10% Hydrogen Sulphide (Heavier than air)
You can't smell Hydrogen or Oxygen but Hydrogen Sulphide smells like bad eggs. Since the production of all these gases is proportional, then if you smell bad eggs you can be pretty certain there is or has recently been a lot of Hydrogen around.
 
G

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All good technical point, one the practical side I keep a small (7a) charger permenantly plugged in on low setting on a small livaboard which work fine. The voltage is at gassing (14.2v) level so dosn't run into problems but its also a wooden boat so ventalation is kept at a steady howlig gale with no sealed lockers! I would be more cautious if you are thinking of leaving it on over the winter on a relitevly unattended boat. Car battery ones are not designed for this, don't have the safeties of installed one and could develope a falt and catch fire etc.

Roly, Voya Con Dios, Glasson, Lancaster
 
G

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On the point of H2S ..... if you can smell it, the Bad Eggs smell .... you are way over the safe threshold limit and your sense of smell will deaden on continued exposure. In severe cases where H2S is being produced, such as in sour crude oils .... it kills

Just thought you'd like to know that !
 
G

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I have a pair of batterys in the standard box under the bunk. I have a standard Halfords Charger.
I plug in the charger via a timer socket and leave all apliances / services connected etc.
I make sure that the bunk cushion and base is moved to allow the battery box to vent.

I leave the charger on the timer and change from one battery to another when the timer is off.

This way between visits to the boat, I am able to top-up the battery without expensive chargers etc.

But there is one point that people here have ignored / forgotten ..... many boats like mine have batterys under the bunks .... when the engine is running and the alternator is pumping in god knows how many amps replacing the starter useage .... the bunk is normally in place and venting not taken care of ...... just thought I'd mention that one !!
 

brianhumber

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Re: Battery Charging Safely - ventilation....

RON has given a detailed answer on this. As long as the compartment allows the gases to escape you will be ok as you will never produce enough gases to raise the concentration level to anywhere near danger levels. The 'Surveyor' doing the MCA exam was trying to get me to fit large ducts directly from the battery chamber to the outside! until I lost my rag and pointed out that after 18 years at sea, a C Eng and MIMarE I had forgotten more about the subject than he knew in the first place.
 

johndf

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Leaving the battery compartment lid up seems like a good simple safety measure, which I'll adopt in future. Thanks for the advice.
 
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