How do I find what's draining the power on my battery?
I use my boat twice a week for several hours. Two weeks ago neither battery
would start the engine. Battery 1 was low, but would hold a charge, so I had
it charged for an hour before launching while I went out and bought a
replacement for Battery 2 which was several years old, dead, and wouldn't
hold a charge.
Since then, I've used the boat several times, VM always indicates 13.5 when
running.
I forgot to turn off the master battery switch yesterday. When I checked it
today it was less than 11 volts, and nothing had been left on.
I have two batteries with a 1,2,both, none switch and combiner: that's not
new, I added the second battery, switch and combiner two years ago.
Before I added the second battery, I ran separate wires from Battery 2 for a
VHF radio and radar on the passenger side of the boat, because there was no
electrical wiring there. I've since added two utility plugs to that wire.
I'm tempted to disconnect the two utility plugs to see if they've been
draining power.
But I haven't done anything electrical for several months and have had this
problem for just the last two weeks.
Is there a simpler way of finding the drain? Am I going to have to
disconnect the wires for everything on the boat and add them one at a time
until I find one that's draining power?

The two immediate possibilities that come to mind are (1)
your older battery is somehow discharging your newer one,
despite the combiner; or (2) there is a "hidden" load
somewhere in your system.

Most likely scenario is that the battery you replaced may
have ruined its partner, which is now draining your new one.

Easiest thing to do is bring the batteries up to full charge
and then disconnect one lead from each battery, taking care
to secure the leads.

Give it as along as you can, and then monitor the voltage on
each. Put a 10 - 20 amp load on each one while you measure
the voltage if you can. If one is good and the other is not,
there's your answer. (old battery somehow draining new, but
that shouldn't happen if the combiner is working properly)

If both batteries are good, then connect them as before, but
this time, make certain your switch is in the "off"
position. Give that situation as long as you can and then
check voltages (remove one battery lead so they are not
connected via the combiner when you measure voltage.)

If both are good, then you probably have a "hidden" load. If
both batteries read low voltages, then you probably have a
bad combiner. I suppose one of the diodes could be shorted.

Good luck, and let us know what you find.

Chuck


William G. Andersen wrote:
How do I find what's draining the power on my battery?
I use my boat twice a week for several hours. Two weeks ago neither battery
would start the engine. Battery 1 was low, but would hold a charge, so I had
it charged for an hour before launching while I went out and bought a
replacement for Battery 2 which was several years old, dead, and wouldn't
hold a charge.
Since then, I've used the boat several times, VM always indicates 13.5 when
running.
I forgot to turn off the master battery switch yesterday. When I checked it
today it was less than 11 volts, and nothing had been left on.
I have two batteries with a 1,2,both, none switch and combiner: that's not
new, I added the second battery, switch and combiner two years ago.
Before I added the second battery, I ran separate wires from Battery 2 for a
VHF radio and radar on the passenger side of the boat, because there was no
electrical wiring there. I've since added two utility plugs to that wire.
I'm tempted to disconnect the two utility plugs to see if they've been
draining power.
But I haven't done anything electrical for several months and have had this
problem for just the last two weeks.
Is there a simpler way of finding the drain? Am I going to have to
disconnect the wires for everything on the boat and add them one at a time
until I find one that's draining power?

Unless the old battery is draining the new as Chuck supposed and the
combiner isn't working or was installed improperly, then you have a
continuing load on your batteries. It must be a significant load of a couple
of amps or more to run down a battery overnight. The easiest way to find it
is with a DC ammeter. If you can borrow a clamp on type, you can find the
culprit in a few minutes.

Otherwise some multimeters have a 3 or 10 amp setting (usually requires
separate sockets for the leads) that you can use. Disconnect each possible
load and then connect the ammeter in series with it and check if it is
drawing any current.

Lacking either of the two types of ammeters and if the unknown load is
significant as I suspect, you may be able to check it with just a good DC
voltmeter. First disconnect all loads and wait 30 minutes. This will let the
battery build up to full voltage. Then with your voltmeter on the battery
terminals, connect each load one by one. The culprit will cause a small
(maybe as little as a few tenths of a volt) drop in voltage at the battery
terminals due to the load pulling down the battery voltage a bit.

David

The other guys have given good advice.
I notice you said your voltmeter indicated 13.5 volts while charging.
Is that the voltmeter on the dash of the boat? If so use a good
voltmeter and check the voltage at the battery terminals of each
battery. If the charge voltage is really that low then that may be
part of your problem as they will never charge fully at that voltage.
You need 14 to 14.5 volts to charge.

Also if one of the batteries is weak it may be running down the good
one as the others have said. But it shouldn't do so if you do not
parallel them with the battery switch unless you have a shorted diode
in the combiner.

With the battery switch in the off position, check the voltage on each
battery with a voltmeter. You should have no need to run the battery
switch in the both position except if you have a starting problem.
Then return the switch to one.
They should both still charge through the combiner if it is installed
correctly. That way neither battery will run the other down and a load
on one will not drain the other.

Regards
Gary


On Sat, 2 Apr 2005 15:17:05 -0800, "William G. Andersen"
wrote:

How do I find what's draining the power on my battery?
I use my boat twice a week for several hours. Two weeks ago neither battery
would start the engine. Battery 1 was low, but would hold a charge, so I had
it charged for an hour before launching while I went out and bought a
replacement for Battery 2 which was several years old, dead, and wouldn't
hold a charge.
Since then, I've used the boat several times, VM always indicates 13.5 when
running.
I forgot to turn off the master battery switch yesterday. When I checked it
today it was less than 11 volts, and nothing had been left on.
I have two batteries with a 1,2,both, none switch and combiner: that's not
new, I added the second battery, switch and combiner two years ago.
Before I added the second battery, I ran separate wires from Battery 2 for a
VHF radio and radar on the passenger side of the boat, because there was no
electrical wiring there. I've since added two utility plugs to that wire.
I'm tempted to disconnect the two utility plugs to see if they've been
draining power.
But I haven't done anything electrical for several months and have had this
problem for just the last two weeks.
Is there a simpler way of finding the drain? Am I going to have to
disconnect the wires for everything on the boat and add them one at a time
until I find one that's draining power?

Thanks to each of you for the prompt replies. I hope to have time to check
it out next week.
Since I've had the batteries, switch and combiner installed for over a year
I don't put either of them high on my list of suspects. Although I did
wonder if combiners fail. I normally select only one battery, and change the
selection every couple of weeks.
As for the VM indicating 13.5 - that's on the instrument panel and I know
that those instruments aren't necessarily accurate. What's important is that
it did indicate the alternator was charging the batteries (right?)
I don't have a good VM, hopefully one of my friend does; another friend has
a battery charger, so I can borrow that, too.

"Gary Schafer" wrote in message
...
The other guys have given good advice.
I notice you said your voltmeter indicated 13.5 volts while charging.
Is that the voltmeter on the dash of the boat? If so use a good
voltmeter and check the voltage at the battery terminals of each
battery. If the charge voltage is really that low then that may be
part of your problem as they will never charge fully at that voltage.
You need 14 to 14.5 volts to charge.

Also if one of the batteries is weak it may be running down the good
one as the others have said. But it shouldn't do so if you do not
parallel them with the battery switch unless you have a shorted diode
in the combiner.

With the battery switch in the off position, check the voltage on each
battery with a voltmeter. You should have no need to run the battery
switch in the both position except if you have a starting problem.
Then return the switch to one.
They should both still charge through the combiner if it is installed
correctly. That way neither battery will run the other down and a load
on one will not drain the other.

Regards
Gary


On Sat, 2 Apr 2005 15:17:05 -0800, "William G. Andersen"
wrote:

How do I find what's draining the power on my battery?
I use my boat twice a week for several hours. Two weeks ago neither
battery
would start the engine. Battery 1 was low, but would hold a charge, so I
had
it charged for an hour before launching while I went out and bought a
replacement for Battery 2 which was several years old, dead, and wouldn't
hold a charge.
Since then, I've used the boat several times, VM always indicates 13.5
when
running.
I forgot to turn off the master battery switch yesterday. When I checked
it
today it was less than 11 volts, and nothing had been left on.
I have two batteries with a 1,2,both, none switch and combiner: that's not
new, I added the second battery, switch and combiner two years ago.
Before I added the second battery, I ran separate wires from Battery 2 for
a
VHF radio and radar on the passenger side of the boat, because there was
no
electrical wiring there. I've since added two utility plugs to that wire.
I'm tempted to disconnect the two utility plugs to see if they've been
draining power.
But I haven't done anything electrical for several months and have had
this
problem for just the last two weeks.
Is there a simpler way of finding the drain? Am I going to have to
disconnect the wires for everything on the boat and add them one at a time
until I find one that's draining power?

On Sat, 2 Apr 2005 15:17:05 -0800, "William G. Andersen"
wrote:

=How do I find what's draining the power on my battery?

I saw the phrase "VHF Radio" in your post, and it brought to mind a
service experience of many years back.

Customer was complaining that his battery was being drained every week
(weekend user). Checked with ammeter at batt terminal, and yes, there
was a load. Small, but still a load.

Turned out to be memory for an old VHF radio he had installed. Even
when off, unit consumed power.

I think newer units are designed somewhat better.

Worth a check?


Terry--WB4FXD
Edenton, NC

I guess it's worth checking almost anything to resolve the problem of a dead
battery: I want my boat ready to go at the first click of the key in the
ignition!

"Terry" wrote in message
...
On Sat, 2 Apr 2005 15:17:05 -0800, "William G. Andersen"
wrote:

=How do I find what's draining the power on my battery?

I saw the phrase "VHF Radio" in your post, and it brought to mind a
service experience of many years back.

Customer was complaining that his battery was being drained every week
(weekend user). Checked with ammeter at batt terminal, and yes, there
was a load. Small, but still a load.

Turned out to be memory for an old VHF radio he had installed. Even
when off, unit consumed power.

I think newer units are designed somewhat better.

Worth a check?


Terry--WB4FXD
Edenton, NC

(Terry) wrote in
:

Turned out to be memory for an old VHF radio he had installed. Even
when off, unit consumed power.


None of the VHF radios switch primary power. Their IC brick RF power amps
are continuously connected to the high current DC cables. The "power
switch" only switches off the basic walkie talkie circuit board the radios
use. I have a Standard Horizon Eclipse + in a box somewhere around here
that was in my jetboat. It draws a constant 3A at 13VDC when "off".
Seawater leaked in around the chinzy speaker sealing, ran across the main
circuit board destroying it and pooled up between the pins of the IC power
amp brick, biasing it into 3A of idle current.....which isn't enough to
blow the fuse or melt anything at 40 watts of heat for the heat sink on the
rear. It just gets hot while killing the hell out of the boat's battery so
dead you can't recover it.

Be sure to kill ALL power to ALL electronics at the primary power level
before storing your boat. A main disconnect is mandatory.

There are a number of different ways to attack this problem. Here are
the ones I'd use:

1. Fully charge the batteries and leave them completely disconnected
for a few days. Then check the voltage (or specific gravity using a
hydrometer) to see if they're still charged. This will tell you if one
or both of the batteries are dead. If you don't have a voltmeter you
can pick up a cheap one at radio shack for $15 that will be accurate
enough to tell you if you have problem.

2. Get an ammeter and check each wire to see if there's any load on the
batteries. We have one on our electrical panel and I always use it as
my final check to make sure that nothing is drawing power before I
leave the boat. Or if you don't have or want to buy an ammeter
disconnect all devices and methodically reconnect them (1 each day) to
see if there's a problem there.

3. If 1 and 2 still don't give you an answer I'd suspect a short or a
mis-wiring of the batteries.

This is obvious but if batteries are lead acid make sure the water
level is high enough that it's covering the plates. On our house bank I
have to add water to the batteries about 4 times a year.

My dad had the same problem your describing on his power boat and when
I started digging around the house bank I discovered that the boatyard
had mis-wired the batteries when they reconnected them in the spring so
that the alternator wasn't recharging the batteries.

-Todd

Free boat blogs: http://boatblogger.com

William G. Andersen wrote:
How do I find what's draining the power on my battery?