Wklkj wrote:
I have a cruiser with 3 - 12 volt batteries installed, the boat is twin screw
and has 2 battery switches (1,2,all,off) type, and finally a 30 amp battery
charger with terminals for all 3 batteries.
I always leave the charger on at the dock with shorepower but the past couple
of weeks I have 'cooked' 2 of the 3 batteries (maintenance free, probably 5
years old). Friends on the dock are guessing that the battery charger is
broken. Although it still charges fine, they suspect that it doesn't shut off
when the batteries are fully charged, causing them to boil over and eventually
dry up.
It's always possibly the chargers fault however 5 years isn't too bad
for boat batteries. So just the fact they lasted 5 yrs tends to make the
charger look OK.
Here's my questions:
I just purchased 3 'dual purpose' Exide brand marine batteries that are not
maintenance free so I can pop the caps and see if there's water in the cells.
Do you think I can continue to use the original battery charger and just watch
to see that they don't boil dry?
Yes but even better buy a cheap multimeter & verify what's actually
happening.
These batteries are new so after you've been for a run & they're
charged, let them sit overnight with one lead disconnected (so you rule
out any circuit leaks)
Next morning the multimeter should read around 12.6 volts when you put
the multimeter on each battery i.e. fully charged.
Now reconnect them & turn on the charger but don't have anything else
turned on. Leave the charger on for at lease a few hours again overnight
would be good.
To not risk wrecking your new little multimeter you could use a proper
auto accessory amp meter, but given the elcheapo multimeters are under
$10 these days & go to 10 amps anyway, take the risk:-) Following the
multimeter's instruction sheet, put it in series with each of the
batteries in turn (charger still on), set to read "amps". If the charger
is behaving it should have cut the charge rate back to 1 or 2 amps on
new fully charged batteries. If that's what it reads then all seems
well. Yes check the water regularly to be safe as you should anyway &
your old batteries died because they were ...um.......old.
A new charger which will charge 3 batteries is around $300. (ouch). I can get
a guest charger (2611) for $100 that is 10 amp on 2 circuits, for 2 batteries.
What will happen if I connect 2 batteries to one of the terminals in the
charger? Will that work or will I break something?
No you won't "break" anything but a 10 amp charger will not put out 10
amps for any time & will most likely be continuous rated at max output
more like 6 amps. I will charge 2 batteries (so long as the third is
totally isolated from the circuit) but it will take a while if they're
flat to begin. It would be OK as a way of "maintaining" well charged
batteries when the boat isn't used.
My other thought is to only hook up 2 of the 3 batteries to the new charger and
leave the 3rd one to charge when the engine is running, but not use that 3rd
battery for any accessories. This seems like a logical approach to me.
It is and you should always try to have the "start" battery protected
from discharge should someone (never you of course:-)) leave something
on, or a bad cell in any battery will milk the others in that circuit so
all are flat.
K
Any comments?
Thanks.
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