Update on My Battery Issue (UPDATE) - What do you guys think?

[GraAlaMat77]

Okay, well I have an update on my battery issue. I went out tonight and tried to recreate my problem and find out where I was losing power. If you do not know what I am talking about, my problem is explained in depth in the thread "Battery Issue." Well here's how it went.

I had fully charged batteries. I cranked the boat up, and checked the voltage - 12.5. I let the boat run for about 5 minutes on idle, out of gear. After this time, voltage - 14V. So I turned her off and plugged in my Humminbird 787 and my Lowrance 510C. I left them on for 45 minutes running. I did not try to crank the boat again during this time (simulated fishing). While this was happening, I kept a voltmeter on the battery, checking it periodically. At the end of the 45 minutes of "fishing" voltage - 12.4V.

I cranked the motor up and it fired right up. I turned it off and cranked it up 5 minutes later, cranked right up again. I decided to crank it up and then turn it off and crank it right back up. I did this and it still fired right up. Finally, I turned it off and cranked it back up, this time choking it. The motor sputtered, and I pressed the gas and it turned over and cranked. I saw the hesitation in the motor, obviously from the added fuel. So I turned it right back off and tried to crank it up again. It spun, but no fire, even with the gas pedal.

So here is my question. Is my problem because of the repeated turn offs of the motor without time to charge, or is it because of "flooding." The reason I ask this is because I usually average at least 30-45 minutes of a fishing hole. Another question is can a flooded motor being hard to crank actually drop a battery that much so that it will barely turn the motor (even without firing)? I ended this experiment at 7:30 EST, and am going to let the motor sit for 30-45 minutes without charging and then try to crank it again and see if it will after flooding has had a chance to subside.

So, am I on the right track or am I thinking completely off base? Also, any suggestions or help will be GREATLY appreciated. I know you guys know your stuff. Thanks in advance.

- Grayson

 

[GraAlaMat77]

Re: Update on My Battery Issue (UPDATE) - What do you guys think?

After 45 minutes of sitting there after the flooding, I went back and cranked the boat. My voltage meter was now reading 12.4, when I left it, it was down around 11. Anyways, the boat spun over for a second and then it fired up. I left it running for about two minutes then turned it off. I cranked it right back up and it fired up right away. So, whats the deal here?

 

[Silvertip]

Re: Update on My Battery Issue (UPDATE) - What do you guys think?

How big is the battery (CCA) and what engine are we talking about? It may be the battery is undersized for the application. Your voltmeter reads 14 volts when the engine is running because the alternator output goes that high to charge the battery. When the engine is off, the battery voltage will return to 12.6 or so because its a 12V battery. Although the gauge shows 14 volts with the engine running, that does not mean you have a fully charged battery, or even that you have a "good" battery. Even if new, batteries can have a weak or dead cell. Have it load tested if you haven't already done so. At least you know that part of the system is ok. Next, you said "batteries". Are you using two batteries in this test?

 

[GraAlaMat77]

Re: Update on My Battery Issue (UPDATE) - What do you guys think?

It is a 1992 Yamaha Pro V 200. I have a Optima 34M. By "batteries," I meant the three that I have, only one is used for cranking. The Optima has 800 CCA and 1000 CA.

When on the charger or just coming off, the cranking battery has 13.3V

 

[Andrew Leigh]

Re: Update on My Battery Issue (UPDATE) - What do you guys think?

Hi,

it is not such a mystery at all, any lead acid battery has a recovery time.

When you start the motor the alternator will immediately charge at a nominal 14,4V for a 12V battery. The reason for the higher voltage is to overcome the back e.m.f in the battery. A lead acid battery acts like a capacitor and will accept the charge of the alternator and will climb to 14,4V. So if you were to immediately measure the voltage you will be deceived by the short term capacitive effect of the battery. It takes some 4 to 8 hours for the battery to settle after a charge or discharge cycle, which is what you are submitting the battery to.

In my opinion you will chase your own tail using voltage measurements, let me explain. Measure a good fresh battery in fully charged condition a day after a full charge cyle and you should get 12,65V if correctly charged and the battery is at room temp ~22?C. This is the correct voltage for a fully charged battery. Now crank the motor and measure the battery, you will read high 13's or even 14V as the electolyte in the battery changes temperature and the effect of the 14,4V of the alternator charges the battery.

The only reliable method is to measure the current draw of each component. Your battery is rated in Amp Hours and you will draw amps per hour from it, not volts. A ammeter in series with the component (make sure the range is sufficient) will give you a good idea. When it comes to electronics you can bet your bottom dollar that the current draw will be as per the manufacturers specification, if it were not your 12V accessories would have fried by now.

Your problems will be found with high draw items, incandecent bulbs etc. for example a 50W globe left burning at 12V draws 4,2A (or 4,2Ah) which is probably 15 times what a modest fishfinder would draw. 4,2A will not take too long to discharge a 50Ah 12V battery, probably about 10 - 12 hours. The problem is that after about 6 to 8 hours there will not be enough juice to crank your motor.

With regard to repeated starting of the motor, why after three successfull starts did you decide to choke the motor? You would not do that with a warm motor out on the lake would you? Successive starts will initially drain the battery significantly (remember the recovery time) so it would be best to allow the battery time to recover before restarting.

Idling is not the best engine speed for the alternator to charge, check your voltmeter on your dash when the speed lifts.
my 0.02c


Cheers
Andrew

 

[GraAlaMat77]

Re: Update on My Battery Issue (UPDATE) - What do you guys think?

Andrew, I appreciate your response. My only problem with what you said is, I don't have any electronics of that sort. No incandescent bulbs, no globes. It is a bass boat, my highest drawing item is two fishfinders. Amp and a half a piece. If they were anymore they'd blow the fuses. I'm thinking it may be a starter problem. When I flood the motor it drags the starter, which causes an increased drain on the battery. To answer your other question, the only reason that I choked the motor was to try and find a way to recreate the situation that I had on the water the other day (early morning, cold) so I could diagnose the problem. I appreciate the help and will keep ya'll updated.

 

[Coors]

Re: Update on My Battery Issue (UPDATE) - What do you guys think?

Have battery load tested.

 

[Andrew Leigh]

Re: Update on My Battery Issue (UPDATE) - What do you guys think?

What Coors said.

Do you perhaps have circulating water pump motors in the live wells?

Anyways good luck, a load test on the battery is free and quick, doing that will definitely remove one variable from the equation.

Just on a completely different tack, we may be treating the symptom rather that the cause. Picking up on what you have said perhaps your starting routine is incorrect, and perhaps you are stressing the battery unnecessarily. I had an Evinrude 115 on my last boat, because I used the boat infrequently I always battled to start it and also struggled with the battery. I knew I was stressing the battery.

Read this post, although we both have Yammie motors this thread helped me greatly with the starting routine. My new boat has a Yammie 130hp which I also battled to start in the begining.


http://forums.iboats.com/showthread.php?t=225510

Cheers
Andrew