Battery and charging issues

[Fab1]

Hi guys,battery and charging issues are quite common and can lead to a bad day on the water.

Here are some basic checks and tests I do to try to avoid these issues.

The first thing I do is always keep my battery on a trickle charger to maintain its state of charge when not being used.

A common thing boaters experience is a slow crank/no start condition,if you experience this it can be caused by many things such as a dead battery(dropped cell/s),loose/corroded electrical connections,broken/frayed wires,fried stator,and the list goes on and on.

The first thing I do is check the electrolyte levels and if required top them up using distiller water until the water is covering the plates-

The next step is fully charging the battery using a battery charger-

Here is a graph that indicates when a battery is fully charged-

The next step is to set up a multimeter to test dc voltage-

You can clearly see I now have a fully charged battery by holding the red probe to the positive + and the black probe to the negative - of the battery-.

Now is a good time to clean the battery posts with a wire brush or sandpaper to make them nice and shiny.While your there give the case of the battery a wipe down.

Back at the boat give the terminals and wiring a good clean from the ignition switch to the starter motor to the battery terminals checking all wiring along its length for any issues and make certain all connections are tight-

Using the multi-meter connected to the battery as before we are going to check if the charging system is working.With the ignition in the off position you should see battery voltage-

Now start the engine on the muffs,a drum or in the water and look at the multimeter.The voltage should have increased by at least 1 volt indicating that the charging system is working.Preferably you want to see something like 14v-14.4v with the engine running at a fast idle as shown here-

To do a load test you want to keep the multi-meter set up as you have and turn the engine off.I disconnect the safety lanyard as you will be cranking the engine but you don't want it to fire,just crank.I then switch all electrics on as you want to put a load on the system such as nav lights,sounder,bildge pumps etc,anything that runs off the start battery and crank the engine for at least 30seconds noting the voltage on the multimeter.You will see the voltage drop a volt or so from battery voltage as shown here which is normal-Anything under 9.5v when performing this test is considered bad and the battery should be replaced.

This was just basic trouble shooting and we could go into checking various resistances,continuitys and checking voltage drops in various areas but these things will get you out of trouble 99% of the time.

Cheers.

[fragmeister]

Great advice and well presented information.

Cheers

Jim

[zmk1962]

Thanks for the great summary Fab1 !

[Fab1]

Thanks Fragmeister and zmk1962.