[firstlight]

2006 tiara 36 ft open.  I own the boat three years it has three batteries on the port and two on the starboard.  I believe port is engine bank and starb side is house?
Do know how old batteries are.
When I start port engine batteries are week , start starb they are fine. 
The question is do the engines have a designated battery when starting or are all three batteries working together and if so why week when starting port motor?
Do I need to replace all three batteries?
Thanks Frank

[sluggo]

I dont know for sure, but  I would question the assumption that the port side is the engine bank and the starb the house bank.

Can you turn the house bank off?  if so do so, and start the engines and see.

Now turn off the engine bank, and see if something starts (it shouldnt btw) and try and chase it down from there.

also if they arent sealed, I would check the water levels in each.  You said you know how old the batteries are, but for me, bumping up on 3 yrs or older in a boat makes them iffy, imho.

[firstlight]

Yes the starb is the engine and port side is house.
They are agm sealed batteries thanks

[Chris Burkard]

The two batteries are the engine starting batteries and the 3 battery bank is house I believe.

Here is the interesting thing. You say that one engine starts easy and the other starts slow. This should not be as both engines use the same batteries to start from. There are three possible causes for this. 1) there is a loose or corroded connection from the batteries to the starter on the slow staring engine. The starter cannot pull enough amperage through the loose or corroded connection. The solution is to clean and tighten all of the connections for that engine. 2) It is possible you have a bad starter on that engine. When a starter goes bad, it usually requires too much amperage to turn over. If the amperage needed to turn over the engine exceeds the batteries capacity, it will slow crank. The solution here is to replace the starter. 3) It is possible you have a bad battery/starter cable for that engine. If internally there is a partial break or corrosion, that cable may (either power or ground) may not be allowing enough amperage to pass, causing slow starting. This is the least plausible of the possible issues. The solution would be to replace the bad cable. There is a 4th possibility, but unlikely. 4) Possible internal engine friction (bad bearings, poor lubrication), but this would show itself as a poorly running engine that would not turn up RPM and would likely smoke badly. If your engines are running fine, This should not be the issue.

If this is above your head to track down the above issues, then I would have a qualified technician look at it for you.

Age of batteries - Most batteries either have a date stamp on them, or they have a coded date tag. The coded date tags are usually stickers that have a letter and a number on them. L4 would mean December of 2014.

Never replace individual batteries from a bank. You should replace the entire bank. Mixing new and old batteries is a good way to shorten the life of the new battery.

I believe the 2006 Tiara 36 used sealed flooded cell batteries. Make sure you replace batteries with the same size and Amperage as the original batteries. In most cases, flooded cell batteries may be replaced with AGM Batteries. Check with the battery company to be sure. Gel Cell Batteries may only be replaced by Gel Cell Batteries. They have a different charging rate. If the charging system is set up to charge Gels, then a Wet Cell or AGM will be constantly undercharged causing premature battery failure. If Gel Batteries are placed in a system designed to charge Wet Cell batteries, the Gel Batteries will be severely over charged and could explode! Dangerous!

Good Luck!

[jongott45]

Good post Chris,
I needed to change the sealed wet cell (Deka) batteries on my 2007 30 Open.  I replaced with AGM batteries.  On the back of my Charles charger is a switch that allows the charger to charge wet cell or AGM batteries.  Make sure the switch is in the proper position and you should be good to go.  FYI as Chris said ALWAYS replace all the batteries and never mix AGMs with wet cell.
Jon

The two batteries are the engine starting batteries and the 3 battery bank is house I believe.

Here is the interesting thing. You say that one engine starts easy and the other starts slow. This should not be as both engines use the same batteries to start from. There are three possible causes for this. 1) there is a loose or corroded connection from the batteries to the starter on the slow staring engine. The starter cannot pull enough amperage through the loose or corroded connection. The solution is to clean and tighten all of the connections for that engine. 2) It is possible you have a bad starter on that engine. When a starter goes bad, it usually requires too much amperage to turn over. If the amperage needed to turn over the engine exceeds the batteries capacity, it will slow crank. The solution here is to replace the starter. 3) It is possible you have a bad battery/starter cable for that engine. If internally there is a partial break or corrosion, that cable may (either power or ground) may not be allowing enough amperage to pass, causing slow starting. This is the least plausible of the possible issues. The solution would be to replace the bad cable. There is a 4th possibility, but unlikely. 4) Possible internal engine friction (bad bearings, poor lubrication), but this would show itself as a poorly running engine that would not turn up RPM and would likely smoke badly. If your engines are running fine, This should not be the issue.

If this is above your head to track down the above issues, then I would have a qualified technician look at it for you.

Age of batteries - Most batteries either have a date stamp on them, or they have a coded date tag. The coded date tags are usually stickers that have a letter and a number on them. L4 would mean December of 2014.

Never replace individual batteries from a bank. You should replace the entire bank. Mixing new and old batteries is a good way to shorten the life of the new battery.

I believe the 2006 Tiara 36 used sealed flooded cell batteries. Make sure you replace batteries with the same size and Amperage as the original batteries. In most cases, flooded cell batteries may be replaced with AGM Batteries. Check with the battery company to be sure. Gel Cell Batteries may only be replaced by Gel Cell Batteries. They have a different charging rate. If the charging system is set up to charge Gels, then a Wet Cell or AGM will be constantly undercharged causing premature battery failure. If Gel Batteries are placed in a system designed to charge Wet Cell batteries, the Gel Batteries will be severely over charged and could explode! Dangerous!

Good Luck!