Battery Question

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Originally Posted by Southeasttackle

No! You can't get a voltage spike from a battery! Each car battery only has six cells in total they produce 12.5 volts. ONLY 12.5 volts. They can not produce any more. That is basic electricity. And how do I know? Well, I am a ASE certified master auto technician and have been for 18 yrs.
If you think that a battery can produce voltage beyond 12.5 volts feel free to explain your "theory."
You can have a spike of amperage however. It happens often when a motor is started. But that is not related to the battery at all. You can connect a amp meter to a trolling motor and turn it on. You may often see a spike in amperage then a sudden drop to what is the normal running voltage. There is no difference in a car battery than a deep cycling battery other than a deep cycling battery is built for constant discharge and recharge.
They have no internal regulator!

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Well you are partially right. You don't get a spike from a battery. The trolling motor can cause surges in the way of start current and stall current. (and there is a difference between a spike and a surge) A battery doesn't produce anything, it stores it. A marine battery that measure 12.5 volts is 90% discharged. 12.6-12.7 volts, depending on the temperature, is fully charged. These are not my theories, its what the manufactures tell me.

Quote:

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Originally Posted by Southeasttackle

No! You can't get a voltage spike from a battery! Each car battery only has six cells in total they produce 12.5 volts. ONLY 12.5 volts. They can not produce any more. That is basic electricity. And how do I know? Well, I am a ASE certified master auto technician and have been for 18 yrs.
If you think that a battery can produce voltage beyond 12.5 volts feel free to explain your "theory."
You can have a spike of amperage however. It happens often when a motor is started. But that is not related to the battery at all. You can connect a amp meter to a trolling motor and turn it on. You may often see a spike in amperage then a sudden drop to what is the normal running voltage. There is no difference in a car battery than a deep cycling battery other than a deep cycling battery is built for constant discharge and recharge.
They have no internal regulator!

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I agree with Southeast .. The battery doesn't know if it's hooked to a boat, car , truck , tractor , lawnmower , motorcycle, nor does it care . Don't tell it that you're putting it in a boat:D:D

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Originally Posted by IBNFSHN

Well you are partially right. You don't get a spike from a battery. The trolling motor can cause surges in the way of start current and stall current. (and there is a difference between a spike and a surge) A battery doesn't produce anything, it stores it. A marine battery that measure 12.5 volts is 90% discharged. 12.6-12.7 volts, depending on the temperature, is fully charged. These are not my theories, its what the manufactures tell me.

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Thats pretty much what I was saying. As far as the voltage of a fully charged battery that will up for debate. The industry standard is 12.5 (not much difference in that and 12.7) whereas some think a battery that has 12.1 volts in fully charged when it is partially discharged. I don't agree that 12.5 volts of a 12.6 volts battery is 90 percent charged. .1 volt being 10 percent???? That would mean a battery that has 11.6 volts would be dead and deep cycle batteries are meant to be depleated to a point. I have run deep cycle batteries down to 5 volts just about everytime fishing so with that percentage standard I should have already been back home. The percentage should be left out of it as every battery will be different in terms of reserve. I just wouldn't assign a deep cycle battery voltage a percentage. It would be better to keep up with your battery voltage and know how long you can run your equipment.

This is from a battery manufactures web site and others show the same thing.

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Originally Posted by IBNFSHN

This is from a battery manufactures web site and others show the same thing.

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That is some intresting info for sure.

I used to work at the plant where the sear's diehard platinum marine battery is made, we checked the voltage after they came out of formation where they are charged and any battery that was below 12.5 got thrown in the trash if I remember right.

Quote:

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Originally Posted by IBNFSHN

This is from a battery manufactures web site and others show the same thing.

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I have seen that and I am not arguing with you about that. I just don't think the percentage is a good way of looking at a deep cycle battery.
According to the "chart" 10.5 volts is dead. Hook your trolling mtr up to a battery that has 8.0 volts at the lowest speed and it will run. You can run a depth finder even lower. How is that if the battery is dead???
It all depends on the draw that the item is placing on the battery.

BUT, we are getting way off topic.
Can a car battery work in place of a deep cycle battery?
Yes!!!!! And safely!!!!! Will it last as long? NO!
Very simple!

The main difference between a deep cycle battery and a car battery is how far you can draw the battery down before recharging. A car battery is designed to be drawn down while starting the engine, than recharged. Low draw down, referred to as a starting battery. While a marine deep cycle battery is designed to be drawn down further before recharging. Deep draw down. Regardless which battery your using, once you pass the recommended discharge rate you start to shorten the life of the battery, do it enough times and teh battery will fail/die.

One thing that hasn't been mentioned is the amp hours of the battery in question. If your using a small car battery it wont last as long as a fullsize truck battery. The smaller battery holds less amp hours becuase it doesnt take as much juice to crank/fire a 4 cylinder engine compared to a V8/deisel.

Than we could get into the whole dual battery scenerio, however that is for another time. :D

Can you use a car battery for trolling? YES! How long it will last depends on the amp hours, cold cranking amps, how much you draw it down before recharging it, the amp draw of your trolling motor, and the resistance against the trolling motor.

In other words, if your using a car battery in high winds with the trolling motor on full speed, your not going to be on the lake very long. Or rather on the lake trolling very long. If you cant get your main motor running due to a dead battery you could be stuck on the lake for a long time. :D