Bad battery or charging issue?

[z33tec]

In a previous post, I was troubleshooting an issue re-starting my motor once on the water. Went through and re gapped plugs. Put some seafoam in gas to maybe clean carbs out a bit. Checked fuel line for kinks, etc.

One thing I didn't check was the battery, since it's only about a month old. I assumed I could rule that out, being new and all.

I have been having intermittent tach issues. Sometimes it works sometimes it doesn't. Upon doing some reading, this can be due to a faulty charging system and may be a bad rectifier. That got me thinking, maybe my starting issues are due to battery being too low after initial crank since my boat is usually on the charger overnight prior to taking it out.

Here's the test results I have from my multimeter:

11.98v with boat off after just getting home from being on the water and having issues restarting.

With boat on and idling in driveway, 12.20+ and slowly climbing as it appears to be getting charged.

Turn boat off, drops back down to 12.0x and slowly dropping. Not sure where it settled but I'm guessing back around that 11.98 mark.

Just for kicks, I tested my OLD battery that was from the previous owner and was like 5+ years old. It's been sitting in my garage for a month or so now and that one tested at 12.50.

Did I get a bad battery? Did I buy the wrong battery? I'll attach pics of both the new and old batteries. I thought I had actually gotten a stronger battery if anything based on the rating.

The west marine battery is the new one and the diehard is the old one.

Also attaching pic of my boats voltage gauge as well, with boat off, which seems to correlate to multimeter reading.

Any help appreciated! Very frustrating not being able to start your boat when your out on the water. Luckily my trolling motor has gotten me back both times.

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[z33tec]

Oh, I should also add that it strangely starts without issue in my driveway on muffs at the 11.98v even though it wouldn't start in water.

Do muffs allow for easier starting due to no water pressure or something?

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[JL8Jeff]

You want around 12.6 volts from the battery and with the boat running it should be showing 13.8 to 14.4 depending on engine speed. I just had to replace my regulator/rectifier on my Mercury and it killed my 3-1/2 year old battery so I had to get a new one. If your West Marine battery is only holding around 12 volts, you should take it back and get another one while it might be under warranty or give you the most money towards another one. It sounds like your regulator/rectifier is bad, what year/model motor is it?

 

[CedarRiverScooter]

Put a charger on the battery without it being connected to the boat. When charger shuts off, then check volts. You could have a parasitic current draw that is constantly draining it. It is unlikely they sold you a bad battery.

 

[z33tec]

You want around 12.6 volts from the battery and with the boat running it should be showing 13.8 to 14.4 depending on engine speed. I just had to replace my regulator/rectifier on my Mercury and it killed my 3-1/2 year old battery so I had to get a new one. If your West Marine battery is only holding around 12 volts, you should take it back and get another one while it might be under warranty or give you the most money towards another one. It sounds like your regulator/rectifier is bad, what year/model motor is it?

1990 Johnson 70hp

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[JL8Jeff]

Try topping off the battery on the charger with nothing else connected to it. See if it holds around 12.6 volts sitting by itself. It does sound like your regulator/rectifier is bad and not charging but I'm not sure if the OMC stuff works the same as Mercury so check the manuals to see what the testing procedure is to verify it's good or bad. I think you need a multimeter that can test diodes to test it.

Here's a link Jim posted previously to the manuals https://www.tinboats.net/manuals/

 

[z33tec]

Try topping off the battery on the charger with nothing else connected to it. See if it holds around 12.6 volts sitting by itself. It does sound like your regulator/rectifier is bad and not charging but I'm not sure if the OMC stuff works the same as Mercury so check the manuals to see what the testing procedure is to verify it's good or bad. I think you need a multimeter that can test diodes to test it.

Here's a link Jim posted previously to the manuals https://www.tinboats.net/manuals/

Thanks. Testing that today. I have a 3 bank charger with my two other trolling motor batteries connected to the other two banks. I have heard some issues with chargers stopping when one of the batteries is full but another might not be. Not sure if that could be a factor too.

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[DaleH]

Few things ... otherwise to me it sounds like you got a bad battery.

CHARGING - I look for 12.7 VDC or use the electrolyte test when assessing battery charge but you NEED TO WAIT for 24+ hours after charging for the surface effect to dissipate or you get a false reading.

The auto settings have also changed so as to prevent battery fires, so what I do - but YOU take care if you do so too - is to switch from Auto to Manual mode once the charging is complete and I'll top it off for an extra hour or two, but I set a timer so I can't forget it. You do not want a battery fire ... a friend charged his tuna boat batteries manually last May in 2019 ... and it burned down the boat AND his house :shock: !

OB CHARGING - Your alternator won't charge it at idle and yes OBs run easier on muffs due to no exhaust back pressure. I myself do NO diagnosis anything on muffs other than she'll start or not. You need to be in the water with RPMs generally above 2K before any charging takes place and likely you'll see 14.3 VDC as a battery is charging on a good OB system.

BEST BUY in Batteries - Buy the Walmart ones for a 'best buy', as they are made by Johnson Controls, who also owns/makes the Optima brand gel-cel batteries. They also wear a 'made on' date code so you know when you are buying a newly made one.

For the best - buy an Interstate brand, arguably the best brand going!

CARE - Top them off at least 2X per season (beginning and mid) and keep them clean. If the electrolyte level drops the plate can sulfate and one sulfated - that area is dead and cannot be recovered.

Most OB makers advise putting a SS external toothed lock washer down on the post before affixing the battery cables and lock in place with nylok nuts - not wing nuts, as they can't get tight enough and can bring down expen$ive OB electronics like the stator and such.

Also watch out whilst using trickle chargers as they can 'cook' your battery ... I never use 'maintenance' chargers, either charge it fully or wait until it needs it.

 

[Sea Antsy]

??? WING NUTS...??? USCG no longer allows WING NUTS on battery terminals...

 

[airshot]

First off I hope your using a digital voltmeter and not the dash voltmeter on your boat. For 12v DC batteries you need to be 12.6 volts or above to be a full charge! At 11.98 you are almost dead. Normally you need 12.2 volts to get a motor started. Try a regular charger without the battery hooked up to anything and see if it charges fully. I always take a digital volt meter with me when I buy a battery, often had to go thru a number of " new" batteries to get a good one !! To each his own, but from all the different battery brands I have used in my 60 boating years, Interstate have been the worse, with walmart being better....DieHard were rhe best for me, back when they were made well, but that hasnt been the case now for many years!!

 

[airshot]

??? WING NUTS...??? USCG no longer allows WING NUTS on battery terminals...

On my recent inspection, they told me all about them, however, I ask him to loosen one with his fingers....which he could not as I use a tool to tighten them. He approved them but only because he couldn't loosen them by hand!!

 

[MrGiggles]

You probably just discharged it while having issues restarting. As mentioned a charged battery should read 12.5+ resting, charge yours up and I'm sure it'll be fine.

As Dale mentioned, you will not get much, if any, charging current at idle. And even at speed it is likely less than 10 amps, takes quite a while to recharge a good size battery with that especially when draw from electronics, lights, etc. are factored in.

 

[Ray Clark]

Good golly I love when old threads are resurrected as if they were written just yesterday.

 

[LDUBS]

No worries. I often learn something new from old threads.