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Boat Battery Tech Tips
POINTS TO REMEMBER
The battery is the heart of the electrical system. Always start troubleshooting at the battery. Never store a battery in a discharged state. Never add anything except distilled water to a battery.
IMPORTANT BATTERY FACTS
A good battery can provide four or five years of worry-free service with the right kind of care. Bigger is better! The battery you are replacing does not have to be the same size as the original. It is always better to have extra battery capacity.
DRY CHARGED BATTERIES MUST BE CHARGED BEFORE USING
Many small batteries are supplied with the electrolyte in a separate container. If you have to fill a new battery with electrolyte, you must place the battery on a quick charger. The charging system will never bring the battery to a fully charged state. The battery capacity will never be above 80%. Pulling the battery out later and trying to charge it will not work. The battery’s capacity has been permanently cut by 20% and there is nothing you can do about it.
BATTERIES WILL SELF DISCHARGE WHEN STORED
Batteries will self discharge when stored for long periods of time. This is a normal process with all lead acid batteries. Always charge the battery to full charge before storing. Also disconnect the negative battery able. This will keep the small system drains from accelerating the discharge process. The best way to avoid hortened battery life is use a SMART CHARGER (not a trickle charger) that will maintain the battery at a full state of charge by only charging the battery when the voltage drops to a specified level without overcharging.
ELECTROLYTE BECOMES WATER IN A DISCHARGED BATTERY
As a battery becomes discharged the percentage of sulfuric acid in the electrolyte becomes less. The sulfuric acid combines with the lead plates producing lead sulfate. As this happens the electrolyte solution becomes pure water. A discharged battery will freeze in cold climates, which will destroy the insulators and plates inside it.
LOOSE BATTERY TERMINAL ENDS CAN DESTROY A BATTERY
Loose or corroded battery cable lugs can cause all sorts of problems. When the starter is engaged the loose or corroded connection can cause a heavy arc which will melt the post right out of the battery. If the battery is gassing, the arc can cause the battery to explode. Never use the temporary type battery ends. These are only good for emergency use and will become corroded in a short period of time. Always use a crimped and
sealed battery cable end or replace the battery cable.
BATTERY TESTING PROCEDURES
WARNING! Batteries give off hydrogen gas constantly. Hydrogen gas is highly explosive. Always wear safety glasses or goggles and use caution when working with batteries.
OPEN CIRCUIT VOLTAGE TEST
Before you can properly test any battery it must be at FULL CHARGE. You can verify the state of charge with the use of a digital multimeter. Connect the digital multimeter to the battery terminals. A fully charged 12 volt battery will read at least 12.6 volts (2.1 volts per cell) on the multimeter. If your reading is 12.4 OR BELOW you must recharge the battery before testing.
Open Circuit Volts / Percent of Charge
11.7 volts or less / 0%
12.0 / 25%
12.2 / 50%
12.4 / 75%
12.6 or more / 100%
LOAD TESTING THE BATTERY
Before you can properly test any battery it must be at FULL CHARGE.
The only way you can thoroughly test a battery is to place a high amperage load across the battery terminals.
Starter motors have very high amperage requirements which can exceed 300 amps on certain engine applications. If the battery has to be recharged you must first remove the surface charge. This can be done by using the starter. Disable the ignition spark (consult manufacturer’s method to avoid electronic ignition) and crank the engine for 10-15 seconds. Once you have removed the surface charge, disconnect the battery cables and connect the battery load tester to the battery posts.
Determine the cold cranking amperage rating of the battery you are testing. If the cold cranking amp rating (CCA) is not known, use 450 CCA for four cylinder engines, 550 CCA for six cylinder engines and 650 CCA for V-8 engines.
Adjust current draw on the load tester to 50% of the CCA rating. Continue this for 15 seconds while viewing the voltage reading on the battery tester. The voltage should stay above the specified reading (see chart below) without falling off. If the voltage remains at the specified level or above, the battery would be considered good. If the voltage reading drops below the specified level, replace the battery.
Load Test Chart
Minimum Voltage / Temperature
9.6 / 70 F 21C and above
9.5 / 60F 16C
9.4 / 50F 10C
9.3 / 40F -1C
9.1 / 30F -7C
8.9 / 20F -12C
8.7 / 10F -18C
8.5 / 0F -18C
This information is from the ARCO Starting and Charging Catalog which can be found on this website.
http://www.marineengine.com/boat-for...7&d=1295993039
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Here's another site with some good technical info on batteries : Deep Cycle Battery FAQ
... cp :cool:
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Very good info on batteries. Thanks for posting it up for everyone.
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You guys are GREAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAT! as my boye Tony would say keep up the info!!!!!!!!!!!!!!
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My boat has set all Summer and now into fall. I have kept the batteries charged during the summer. Now that fall and cold weather has arrived I plugged in by on board charger and both batteries are down. One side showing redline, the other nothing, black. So I discconnected the on board charger and plugged in my 15amp shumacher marine charger and charged up my trolling motor deep cycle battery. It says after charging 6 hrs. at 10amps, it is 100%. So I plug in the starting battery and charge for 6 hrs and it says it is 100%. Next day plug in my onboard charger and both are showing full red line on both batteries. I leave them charging overnite and yesterday morning both have green lights, showing fully charged. Is this normal??? Or are my batteries shot because they didn't hold charge or is this normal?? How do I check them for voltage if they are charged at 100% without taking them out of the boat?
Thanks,
Bassky
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1 Attachment(s)
After they are fully chagred disconnect them and let them sit for 24 hours. Then using a digital meter measure the voltage(s).
Attachment 105821
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Bill,
My batteries tested at 12.67 and 12.66, so they must be OK. I measured a full 24 hrs after charging. Thanks for the table and suggestions.
Bassky
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Good info, Thanks for the post.
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Thanks for the chart and tips
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While fishing on 12/31/12 and getting ready to leave the lake I found my battery didn't have enough oomph to start my big motor. I found out my jumper cables weren't long enough to reach from the trolling batteries up front to the cranking battery in the rear. Fortunately a friend was fishing near by and we jumped my battery from his boat. This battery wasn't that old and I keep them plugged in with the on board charger all the time in the garage. I plugged the battery back in and since the place I bought the battery wasn't open the next day it was a week (on the on board charger all this time) before I was able to take it in.
When I took it in they checked each cell saying they are all OK but said they would hook it up to their charger overnight so I could pick it up the next day. When I went back into pick it up they said the battery was bad and fortunately it was still 21 days inside the window where they gave me a new battery. Just to praise Interstate Batteries here.
Now for the rest of the story here I'll talk about some clues that I ignored that probably should have told me I had a problem battery much sooner. It was probably early summer that my Lowrance graph on the front of the boat would at times shut off when I would start my big motor to move to another spot. This hadn't happened before but it didn't happen every time and when the graph did shut down I wasn't having any issues at getting the big motor started. The Lowrance X97 graph on the back never did shut down.
I'm just pointing out how I ignored this clue about something being different and if I had checked it out sooner I should have discovered I had a problem battery. It's my understanding that the graphs will shut down when they get a low voltage and I had ignored these clues and am passing it on to perhaps help someone else take notice about little clues that are telling us things we probably ought to be checking out.
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Good post thanks good info!!!!
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very educational...thanks a bunch
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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
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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.
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Thanks CatFan. As always, you give some good advice. I have an old 1976 115 HP Johnson (4 cyl), 2 stroke. I was doing ok in the Spring, and only got out a couple times in the heat of the Summer, and just recently started fishing again. I think I may have left something on sometime this summer that maybe put a draw on the battery. I typically don't run the big motor much. I am planning to take it out later this week when the weather warms up and see if I can get it started and run awhile and check to see what that does to it.
HHD