battery power problems

[penderboy]

I have a 2009 Hunter with continuing battery troubles.The batteries(three of
them)test as well charged,but the DC gauge shows only about 9-10 amps,and the motor struggles,but won't start.
I am mechanically and electrically challenged(I'm learning),but I am
stumped as to where to start.
I should say I suspect the battery charger,or a loose connection somewhere.
Any ideas would be welcomed.

 

[Bill Roosa]

Check the battery terminals

99.44% of all electrical problems on boats are corroded connections. Salt water, metal and electricity are not good friends.
Check the battery terminals. They should be tight and clean.
Also, I think you mean volts not amps. Volts is like water pressure, amps is like water flow. You are (I suspect) suffering from low voltage (pressure) that is causing all your equipment to not operate up to speed.

 

[Don12364]

Do you mean the gauge shows 9-10 VOLTS (rather than amps)? The engine will certainly not start with a voltage as low as this.
Voltage (Volts) is electrical pressure and insufficient pressure will not turn the engine over.
Current (Amps) is the flow of energy which results when you turn the starter switch. A loose contact can prevent this flow of amps.
Its just like your garden hose at home.

Your boat is only a year old so, unless it has been allowed to become very damp, it is probably not suffering from corrosion of the wiring or contacts.
What means did you use to measure that the batteries were well charged?
Also, when the shore power charger is on do you have any indication of how much current is being put into the batteries (in amps)?
From the present indications one would expect they would need charging for at least 24 hours to bring them up to 14.4 volts whilst on charge or at least 12.5 volts after charging and with the charger off.
Again, unless the batteries have been seriously misused, they should charge up okay.
If you can get any charge into them it will then be necessary to discover how or whether you are discharging them excessively.

The engine should have its own battery and nothing else should be connected to run from this so it ought be able to start the engine even if the other two 'house' batteries are low.

This raises the question of whether your shore power charger is actually connected up to charge the engine battery at all. Many are not. The boat manual should help here unless you are not the original owner and changes have been made.

Do you have one or two master switches?
Take a look to see how the batteries are connected to these battery master switch(es). The heavy red leads from the positive terminals should give you this information and you may also see wires from the charger to one or more batteries and whether these pass through the master switch(es).
If the charger goes direct to the batteries then you can switch the master switches off and still charge your batteries. This will eliminate any other current drains such as the refrigerator etc and allow the charger to do its job unhindered. The frig is the biggest thief of power on most boats.

If you do not already own one I suggest buying an inexpensive digital meter to measure the voltages of each battery.

At a later stage you should consider buying a battery monitor which checks how much energy you put in and deducts how much you have taken out. Thus it will show how the balance of how much is left in the batteries.

Think of it like your Bank statement and as if it is measuring your bank balance?
Everybody understands their bank balance!

 

[seadaddler]

Check

First check the batteries to make sure they are all good and fully charged,next make sure no loose connections and really tight on those battery terminals.
All three can't be bad and should only take one to start so maybe try each battery and see what happens and check each battery for good charge.
Nick

 

[tomgrigsby]

9-10 volts (not amps) shows partially discharged batteries and that won't start the engine. Not knowing your boat or the setup though, I don't know which battery you are reading or if it is the average of all of them. Can you select individual batteries on a Bat 1, Bat 2, Both, or off selector switch?
Please pardon my stupid questions since I don't know your boat. If so, select 1, check the voltage, then select the other and check the voltage. If one battery is way low and the switch is in the "both" position, the low battery will try to recharge from the good battery.
What position do you normally leave the switch in? Try selecting one battery and turning on the cabin lights. Then power up the charger and see if the lights get brighter. If they don't, your charger isn't connected to that battery. Also, as mentioned above, with the charger on a battery you will see 13 to 14 volts when the battery is fully charged, and something above 12 while charging.
Please note that all these tips are for a fairly simple system. If your system has complex controlling circuits to keep one battery from discharging the other, my advice is no good.