Battery question

[fishtank]

Asking a question out there. For "Deep Cycle" batteries, what is the best amperage to charge them? I have a charger that will charge at 2, 10 and 50 amps. I know 50 amps is just if you want it for starting (I think). I was told between 10 and 15 amps charging is the best. How long does it usually take a battery to fully charge? I know it all depends on battery capacity, but I am looking for norms.

[magnumthunder]

I do mine on 2 amps. It is my belief that slow discharge requires slow recharge. but that is what i do and has worked great for me.

[efgh]

I was told by someone, a slow charge will sink into the plates in the battery, a fast charge will be more of a surface charge on the plates and will not last long, so most of the time I charge using 2 or 4 amps, unless I;m in a hurry.

[lars0926]

I too always charge on the lowest amperage. This takes a while (I typically charge my deep cycle between 4-6 hours). After having charged two batteries at 10 amps, I quickly learned that you can fry the battery this way, especially if charged too long. At the lowest amperage you'll get a better charge and risk less harm to the battery should you put the charger on and accidentilty forget about it.

Also a couple other things that I learned: 1. The low amperage "trickle charge" will hold a charge better. 2. If you need to add liquid to the battery use only distilled water. 3. If you ever have a leak, be carefull as this acid is very corrosive (just ask the carpeting in my truck that was ate away from a battery tipping over). 4. If you have acid appear, it can be neutralized and cleaned with a 60/40 mix of distilled water and baking soda.

For those of you out there that, like me, didn't have a dad growing up, there is an amazing book out there published from the 1920's through the 1940's called "Fortunes in Formulas". It tells you how to do everything from making homemade soap to building a moonshine distillery. It's very useful and has tons of information about how to use stuff around your house to accomplish everyday tasks.

[mamohr686]

The above 3 responses are the exact opposite of all the information I have recieved when selling batteries when I used to work at scheels (from interstate reps). I would agree with adding distilled water to the cells (check every 3 months or so depending on use). Use a 10 amp charger/per bank with an automatic shut off. Trickle charges can cook your battiers and lead to burn off and more frequent maintence and addition of water. Chargers without an automatic shutt off can lead to boiling and battery acid overflow. Charge your batteries after every use, even if it's a couple of hours. The worst thing you can do to batteries is leave them discharged for a long period of time. This leads to builup on the plates and prevents the battery from being fully charged. Poor winter maintence is the leading cause of battery failure in the north. A battery has a set number of cycles which is the number of times a battery can completely be discharged and recharged. Running the battery completely dead will prevent the battery being able to take on the best possible charge (this is lead-acid only), Sealed gel cells have this as an advantage.

[Giant_Jackpot]

I agree that a 10 amp charger is the best as far as amount of current. If you are not using one of the new “on board” style chargers, then I would agree that the charger can hurt the battery if left on too long. Charge the battery until it hits about 14.8 volts and then disconnect it. Keep in mind that the “old style” chargers put out less amps as the voltage climbs so it will not be putting out 10 amps in the upper voltage ranges. The new “on board” automatic chargers hold their amperage output steady until it hits a certain voltage and then it goes to absorption mode and then into maintenance mode. You can leave these chargers connected indefinitely with no harm to the battery. A 6 amp “on board” style charger can probably charge the battery faster (and better) than an “old style” 10 amp charger.

[Farley]

Did the interstate rep tell you anything about battery memory? Like when you keep recharging your battery when it's at about half charge, after a while the battery will develop a "memory" and whenever you get down past half charge it will lose power faster than if you let it run all the way down before charging. That's why they tell you to always run a deep cycle all the way to dead before recharging.

[Giant_Jackpot]

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Did the interstate rep tell you anything about battery memory? Like when you keep recharging your battery when it's at about half charge, after a while the battery will develop a "memory" and whenever you get down past half charge it will lose power faster than if you let it run all the way down before charging. That's why they tell you to always run a deep cycle all the way to dead before recharging.

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Farley,

That advice is for NiCad batteries not lead acid. Trust me on this one as I used to work for a place that designed multi stage battery chargers. Lead acid batteries do not like to be completely run down and you have to charge them as soon as possible after each use no matter how long you used them.

[MuleSkinner]

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That's why they tell you to always run a deep cycle all the way to dead before recharging.

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I used to think this too, but there was a good 'In-Fisherman' 8 page article on batteries that I kept, which agrees with Giant Jackpot, that wet cell deep cycle batteries should be recharged as soon as possible after each use. Here is a quote from that article, May 2002:

They call 'em deep cycles, but they live longer with moderately shallow cycles. A battery discharged 50 percent every day lasts roughly twice as long as a battery run down 80 percent every day. Running batteries completely out of juice once in a while isn't necessarily a bad thing. But running them down 100 percent every time out is a prescription for annual battery purchase. Then again running batteries down only 5 percent each time isn't healthy either, because it tends to redistribute the lead dioxide (active material) on the plates in clumps.

All other publications that I have seen say the same thing. I used to think of my deep cycle in human terms: Give it a good tough work out, and it will grow stronger and tougher. But I have learned that it is just a mechanical/chemical device that just slowly wears out. And I am taking the advice of the experts in how to more slowly wear my battery out.

[lars0926]

These are all good "food for thought" points. I wonder how using certain equipment on this type of battery affects them, i.e. trolling motor vs. electronics. In my case, I only use the battery for the trolling motor.

[Macgyver55]

If you want to get real technical about battery charging here are the specifics.

The charging time of an average sealed lead-acid battery is approx. 12-16 hours. Higher charge currents and multi-stage charge methods will allow charging time to be reduced to 10 hours or less.

When charged at the proper rate it takes about 5 times as long to recharge a lead-acid battery to the same level as it does to discharge.

The best way to recharge a battery is with a multi-stage charger.

A multi-stage charger first applies a "constant current charge", raising the cell voltage to a preset voltage. This stage takes about 5 hours and the battery is charged to approx 70%. The next stage is called the "topping charge". The charge current is gradually reduced as the cell is being saturated. This is the most important part of the charging process. The topping charge takes another 5 hours and is essential for the well-being of the battery. If omitted, the battery will eventually lose the ability to accept a full charge. The final stage is the "float charge", which compensates for the self-discharge.

Overcharging is bad for batteries too. Continually over-charging causes grid corrosion on the positive plates. It also promotes gassing, which results in venting and loss of electrolyte.

Batteries should always be stored in a charged state. A topping charge should be applied every six months to avoid the voltage from dropping below 12.6 volts. Prolonged storage below that voltage causes sulfation, a condition that is pretty difficult to reverse.

Lastly, if you are going to err on one side or the other, it is better to charge too slow than too fast. Charging too fast builds heat and causes gassing and can be/is very explosive. It's a good idea to wear safety glasses even when just hooking up a charger. Take it from someone who has been there and done that first hand...it ain't fun when they "pop".

[Surface Tension]

Macgyver55 explained that pretty good. Look a the specs on your charger. It may be a 15 amp charger but it seldom charges at that rate. My charger is a 15 amp dual charger where I can select deep cycle or manual. It'll start tout charging at a high rate then taper down to nothing when the battery reaches its full charge. If I had to give an average life of my deep cycle batteries I'd have to say seven years. I've found brand makes little difference. All I do is keep them charged and the level up.

[MuleSkinner]

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I've found brand makes little difference.

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Truly words of wisdom. Just like my Momma. When I was little, she taught me how to wipe. But she didn't tell me what brand of toilet paper to use. (But my Northern Quilted is still the best, right? )

I have an old boat. Smartest battery thing I did was to hook up all my accessories/electronics to my trolling battery. Now my starter battery ONLY starts my engine. Before, I often had a dead starter battery, especially if I ran lights at night while electric trolling.

I have a cheap charger. Only 2 or 6 amp choice. Used to use 2 amp. But last few years, after reading battery articles and FM, I use the 6 amp, and will switch to 2 amp "at the end". But I never leave the charger on for more than 2 days.

[Surface Tension]

MuleSkinner, I like Charmin too.

Right, don't use a starting battery for anything but that, starting.