Thread: Boat Battery Tech Tips

Good post thanks good info!!!!

very educational...thanks a bunch

Thanks

Battery gurus...looking for your expertise. I have 3 sears PM-1 Marine (enersys AGM Odyssey batteries with odyssey 31-PC2150 specs) in my boat . I have 2 on the TM that were purchased in late 2011, and are amazing batteries. I have an older one purchased in early 2010 that runs my starting motor and everything else. My last trip out, my starting battery was not up to snuff. I wasn't sure if something had drained down the battery while sitting or what happened. I have a 3 bank minn kota 330 charger that has 10 amps per bank and 30 total and recharge the batteries after every trip. I put the batteries on charge until the batteries charged to green status on the charger. I checked all batteries with a little minn kota 4 light tester and got 4 lights...fully charged. After 12 hrs had passed, I put a multitester on all three batteries and found the 2 trolling batteries to be testing at 12.8 V, while the starting battery was at 12.36 which I think would be approximately 65-70% charge or there about.

I called sears to check on my purchase date and unfortunately , this battery was over the 3 yr warranty date. The guy there said that these batteries needed to be charged with a 40 amp charger. I thought this was BS, so started looking at the odyssey web site and found the following in the odyssey owner manual:

To fully charge a 31-PC2150 battery that is routinely discharged deeply, a minimum of 40 amps are required with
charger voltage within the range of 14.1V to 14.7V. It is imperative not to exceed 15.0V as this will cause the pressure
valves to open and out-gas hydrogen, oxygen and water from inside the battery. This will shorten the life of the
battery and cause premature failure. Some portable chargers exceed 15.0V, especially two-wheel garage chargers, so
charging voltages should be verified by measuring the charging voltage during the time when the charging amperage
is reducing from full output. The deep cycle charging voltage must be within 14.1V minimum to 14.7V maximum.

So what do you guys think about this? Apparently Odyssey makes chargers specifically for these batteries, however , my minn kota charger had been doing a great job until now. I am wondering if somehow my battery got discharged so deeply, my charger would not bring it back to full charge, and if I took it to someone with the specified charger ....would this bring it back to full charge.... or should I cut my losses and just go buy a new battery?

Also, found a lot of good info in the tech manual on the odyssey web site, here's what they say on load testing:

LOAD TEST PROCEDuRE
This procedure should help determine whether the battery
returned by the customer has reached its end of life or simply
needs a full recharge. Depending on the time available one
may choose to perform either the longer load test (Step 4) or
the shorter ½CCA load test (Step 5).
The ½CCA test is quicker but less reliable than the longer test.
This is also the test that is performed when a battery is taken
to an auto store for testing.
An alternative approach to determine the health of the battery
is to use the ODYSSEY® battery PortAlyzerTM handheld tester,
specifically developed for these batteries. The test procedure is
shown in the flowchart in the section that discusses the tester.
1. Measure the open circuit voltage (OCV) of the battery.
Proceed to Step 4 or Step 5 if the OCV is equal to or more
than 12.80V; if not go to Step 2.
2. Charge the battery using the ODYSSEY OMAX-50A-1B
UltimizerTM charger until the green LED light comes on,
indicating the completion of the charge. Stop the test if the
red LED comes on indicating a bad battery.
3. Unplug the charger and disconnect the battery from the
charger. Let the battery rest of at least 10-12 hours and
measure the OCV. If it is equal to or more than 12.80V
proceed to the next step; otherwise reject the battery.
4. Long Test: Discharge the battery using a resistor or other
suitable load until the voltage drops to 10.00V and record the
time taken to reach this voltage. Let the battery rest for an
hour and repeat Steps 1 through 4. If the time taken by the
battery to drop to 10.00V is longer in the second discharge
than in the first discharge, the battery may be returned to
service after a full recharge; if not the battery should be
rejected as having reached end of life.
5. ½CCA Test: Battery OCV must be at least 12.60V to proceed
with this test. Connect the load tester cables and the voltage
leads of a separate digital voltmeter (if the tester does not
have a built-in digital voltmeter) to the battery terminals.
6. Adjust the tester load current to lad the battery to half its
rated CCA and apply the load for 15 seconds. Table 7 shows
the ½CCA values for all ODYSSEY® battery models. Use
Table 8 to adjust the battery end of test voltage temperature.


thanks in advance for your help.

HHD

Depending on your outboard, it may charge at a sufficient rate to meet the requirement when you are running. What outboard do you have?

It's unlikely that your cranking battery is routinely deeply discharged since the outboard charges it and it never has loads on it like a trolling motor, so you should have no issues keeping it topped off with the 10A charger.

I believe your battery is bad and I don't think charging it at a higher rate will accomplish anything, but I can't tell you for sure. If you want to try a higher charge rate, you could hook all three banks from your MK charger to the cranking battery and see if it helps. You may have to run the battery down some in order to get it to draw the full current of the charger though.

Before replacing the battery, you may want to check your outboard charging system. If the output is excessive, it could be causing venting of the battery and shortening its life. Just a guess, but with almost no effort to check and $250 at risk with a new battery it's worth doing.