Battery issues

[MMS3rd]

For the past two summers, I have had a real problem with boat batteries. I use one 12 volt to run trolling motor and occasionally to fill live well, maybe run lights once in awhile. I have two, so I can switch without waiting for recharge. Problem is that after a few uses, I can't get battery to take full charge--or any charge. I have bought a second charger to see if that helped--didn't. A couple times batteries ended up bubbling through cell caps. The batteries are deep cycle and I put charger on deep cycle automatic recharge. Any ideas? Am I just expecting too much from batteries? Thanks.....Mike

[Northlander]

What kind of batterys are you running? Make sure you are using a deep cycle trolling motor battery for your trolling motor and a deep cycle starting battery for your outboard.
Your charger should say deep cycle trolling and starter. Use the correct one on the right battery. My charger shuts off when my batterys are fully charged so I dont have a boiling problem.
Make sure that the batterys have correct fluid levels if needed. Take them to a shop and have them tested for voltage etc.
I would recomend ya get some Interstates. They have been great for me in the past as well as some of the Champion shops batterys.
Sounds to me like your either charging too fast or too long or you arent using the right battery for the intended purpose.
What pound thrust trolling motor are ya using?

[This message has been edited by Northlander (edited 05-09-2004).]

[Mudcutter]

I have a buddy that works backup for generators at airports for landing lights and air traffic controler tower. The backup for the backup until the generator starts are about 96 12volt deep cycle battereis. According to him - anything charged at more than 6amp hours is reducing the plates and the life of the battery. Apparently the lead plates get warped with too much juice running throu...\
Keep your line tight.

[tman192]

I have found it important to run your batterys down, essentialy discharge them first completely before charging them back up again. This can create a problem as far as having power during your fishing trip but I carry 4 batterys on my boat so multiple batterys can solve this problem for anyone in any size boat. When I am done fishing for the day if my battery is anything more than 20% I leave it until I can drain it down on the next trip, and then when I get back and I want to recharge I drain more with a standered headlight assembly I rigged up to drain completly. New more modern batteries have eliminated some of the need for discharging, but I feel the longer the memory you give your battery the longer it will function and last. Just MO but it seems to work for me.

[MMS3rd]

Thanks for some ideas. The batteries are deep cycle, but are there deep cycle trolling v. deep cycle starting batteries? Cause if that is so, I probably have starting batteries (all but the original I got with the Tracker). I have tried several brands of batteries. The charger is supposed to be automatic and cut out when batteries are charged...still a couple have started bubbling over almost immediately when I hook up charger. I think charger has 2 and 10 amp settings and I use 10 amp. To be honest, I have a hel* of time reading charger....it appears to work backwards....it is charged when charger goes down to zero???...would that be right? Maybe I should go back to wooden paddle. Thanks. Mike

[tman192]

Yes when charger goes down to 0 then it is no longer taking a charge. I have a green indicator light on mine that tells me it's done.

[DuluthGuy]

Well, Where are the batteries located?
How much pounding do they take?
What trollig motor.
Unlike nickel-cadmium batt that have a 'memory' deep cell's should be charged up at every docking.

I will go into some detail. (gunna be a long post)

Many (most?) Marine batteries -
are usually actually a "hybrid", and fall between the starting and deep-cycle batteries, while a few are true deep cycle. In the hybrid, the plates may be composed of Lead sponge, but it is coarser and heavier than that used in starting batteries. It is often hard to tell what you are getting in a "marine" battery, but most are a hybrid. "Hybrid" types should not be discharged more than 50%. Starting batteries are usually rated at "CCA", or cold cranking amps, or "MCA", Marine cranking amps - the same as "CA". Any battery with the capacity shown in CA or MCA may not be a true deep-cycle battery. It is sometimes hard to tell, as the terms marine and deep cycle are sometimes overused. CA and MCA ratings are at 32 degrees F, while CCA is at zero degree F. Unfortunately, the only positive way to tell with some batteries is to buy one and cut it open - not much of an option.

Starting (sometimes called SLI, for starting, lighting, ignition) batteries -
are commonly used to start and run engines. Engine starters need a very large starting current for a very short time. Starting batteries have a large number of thin plates for maximum surface area. The plates are composed of a Lead "sponge", similar in appearance to a very fine foam sponge. This gives a very large surface area, but if deep cycled, this sponge will quickly be consumed and fall to the bottom of the cells. Automotive batteries will generally fail after 30-150 deep cycles if deep cycled, while they may last for thousands of cycles in normal starting use (2-5% discharge).

Deep cycle batteries -
are designed to be discharged down as much as 80% time after time, and have much thicker plates. The major difference between a true deep cycle battery and others is that the plates are SOLID Lead plates - not sponge. Unfortunately, it is often impossible to tell what you are really buying in some of the discount stores or places that specialize in automotive batteries. The popular golf cart battery is generally a "semi" deep cycle - better than any starting battery, better than most marine, but not as good as a true deep cycle solid Lead plate, such the L-16 or industrial type.

Using a deep cycle battery as a starting battery -
There is generally no problem with this, providing that allowance is made for the lower cranking amps compared to a similar size starting battery. As a general rule, if you are going to use a true deep cycle battery also as a starting battery, it should be oversized about 20% compared to the existing or recommended starting battery group size to get the same cranking amps. That is about the same as replacing a group 24 with a group 31. With modern engines with fuel injection and electronic ignition, it generally takes much less battery power to crank and start them, so raw cranking amps is less important than it used to be. On the other hand, many cars, boats, and RV's are more heavily loaded with power sucking "appliances", such as megawatt stereo systems etc. that are more suited for deep cycle batteries.

Now to the charging - and 'topping it off'.

Cycles vs Life
A battery "cycle" is one complete discharge and recharge cycle. It is usually considered to be discharging from 100% to 20%, and then back to 100%. However, there are often ratings for other depth of discharge cycles, the most common ones are 10%, 20%, and 50%. You have to be careful when looking at ratings that list how many cycles a battery is rated for unless it also states how far down it is being discharged. For example, one of the widely advertised telephone type (float service) batteries have been advertised as having a 20-year life. If you look at the fine print, it has that rating only at 5% DOD - it is much less when used in an application where they are cycled deeper on a regular basis. Those same batteries are rated at less than 5 years if cycled to 50%. For example, most golf cart batteries are rated for about 550 cycles to 50% discharge - which equates to about 2 years.

Battery life is directly related to how deep the battery is cycled each time. If a battery is discharged to 50% every day, it will last about twice as long as if it is cycled to 80% DOD. If cycled only 10% DOD, it will last about 5 times as long as one cycled to 50%. Obviously, there are some practical limitations on this - you don't usually want to have a 5 ton pile of batteries sitting there just to reduce the DOD. The most practical number to use is 50% DOD on a regular basis. This does NOT mean you cannot go to 80% once in a while. It's just that when designing a system when you have some idea of the loads, you should figure on an average DOD of around 50% for the best storage vs cost factor. Also, there is an upper limit - a battery that is continually cycled 5% or less will usually not last as long as one cycled down 10%. This happens because at very shallow cycles, the Lead Dioxide tends to build up in clumps on the the positive plates rather in an even film. The graph above shows how lifespan is affected by depth of discharge.

As a wrap-up Over-Charging once can kill it

Battery Charging
Battery charging takes place in 3 basic stages: Bulk, Absorption, and Float.
Bulk Charge - The first stage of 3-stage battery charging. Current is sent to batteries at the maximum safe rate they will accept until voltage rises to near (80-90%) full charge level. Voltages at this stage typically range from 10.5 volts to 15 volts. There is no "correct" voltage for bulk charging, but there may be limits on the maximum current that the battery and/or wiring can take.

Absorption Charge: The 2nd stage of 3-stage battery charging. Voltage remains constant and current gradually tapers off as internal resistance increases during charging. It is during this stage that the charger puts out maximum voltage. Voltages at this stage are typically around 14.2 to 15.5 volts.

Float Charge: The 3rd stage of 3-stage battery charging. After batteries reach full charge, charging voltage is reduced to a lower level (typically 12.8 to 13.2) to reduce gassing and prolong battery life. This is often referred to as a maintenance or trickle charge, since it's main purpose is to keep an already charged battery from discharging. PWM, or "pulse width modulation" accomplishes the same thing. In PWM, the controller or charger senses tiny voltage drops in the battery and sends very short charging cycles (pulses) to the battery. This may occur several hundred times per minute. It is called "pulse width" because the width of the pulses may vary from a few microseconds to several seconds. Note that for long term float service, such as backup power systems that are seldom discharged, the float voltage should be around 13.02 to 13.20 volts.
Chargers: Most garage and consumer (automotive) type battery chargers are bulk charge only, and have little (if any) voltage regulation. They are fine for a quick boost to low batteries, but not to leave on for long periods. Among the regulated chargers, there are the voltage regulated ones, which keep a constant regulated voltage on the batteries. If these are set to the correct voltages for your batteries, they will keep the batteries charged without damage. These are sometimes called "taper charge" - as if that is a selling point. What taper charge really means is that as the battery gets charged up, the voltage goes up, so the amps out of the charger goes down. They charge OK, but a charger rated at 20 amps may only be supplying 5 amps when the batteries are 80% charged. To get around this, Statpower (and maybe others?) have come out with "smart", or multi-stage chargers. These use a variable voltage to keep the charging amps much more constant for faster charging.

Some general rules -
Nearly all batteries will not reach full capacity until cycled 10-30 times. A brand new battery will have a capacity of about 5-10% less than the rated capacity.

Batteries should be watered after charging unless the plates are exposed, then add just enough water to cover the plates. After a full charge, the water level should be even in all cells and usually 1/4" to 1/2" below the bottom of the fill well in the cell (depends on battery size and type).

In situations where multiple batteries are connected in series, parallel or series/parallel, replacement batteries should be the same size, type and manufacturer (if possible). Age and usage level should be the same as the companion batteries. Do not put a new battery in a pack which is more than 3 months old or has more than 75 cycles. Either replace with all new or use a good used battery. For long life batteries, you can have up to a one year age difference.

The vent caps on flooded batteries should remain on the battery while charging. This prevents a lot of the water loss and splashing that may occur when they are bubbling.

When you first buy a new set of flooded (wet) batteries, you should fully charge and equalize them, and then take a hydrometer reading for future reference. Since not all batteries have exactly the same acid strength, this will give you a baseline for future readings.

When using a small solar panel to keep a float (maintenance) charge on a battery (without using a charge controller), choose a panel that will give a maximum output of about 1/300th to 1/1000th of the amp-hour capacity. For a pair of golf cart batteries, that would be about a 1 to 5 watt panel - the smaller panel if you get 5 or more hours of sun per day, the larger one for those long cloudy winter days in the Northeast.

Lead-Acid batteries do NOT have a memory, and the rumor that they should be fully discharged to avoid this "memory" is totally false and will lead to early battery failure.

Inactivity can be extremely harmful to a battery. It is a VERY poor idea to buy new batteries and "save" them for later. Either buy them when you need them, or keep them on a continual trickle charge. The best thing - if you buy them, use them.

Only clean water should be used for cleaning the outside of batteries. Solvents or spray cleaners should not be used.

Sorry such a long post.

B2

I run a dry cell for the pounding waves, charge, etc.

[This message has been edited by DuluthGuy (edited 05-10-2004).

[This message has been edited by DuluthGuy (edited 05-10-2004).]

[DuluthGuy]

MMS3rd - sorry, didn't really answer your question directly. I would say overcharged, old leadless (pounded and used) plates - leading to highly corrosive acid with nothing to burn. Lot of factors involved.
Could have been something like hooked up in reverse on accident once... seen-um smoke that one myself (I'm not perfect!)

B2

If you are in the Duluth area, I can bring one of my charger's and voltmeter and take a look?

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See Ya on the H2O

[Mudcutter]

Duluth Guy,
Nice post and info. Nice to hear confidence on such a wide ranging, dicey topic on deep cycle batteries. I'll keep your post bookmarked for future reference.

[DuluthGuy]

Glad to throw in my $.02.

Mudcutter? .... Mason? Rock mudder?

B2

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See Ya on the H2O

[MMS3rd]

Wow....well, now I know why I always tell my kid that I don't really know what I'm doing...cause I don't!

I have usually run the batteries down to the point that my 32 pound thrust trolling motor will not turn any more. I am curious why a couple of batteries started boiling over right after I hook up charger (and they feel warm). I really appreciate the info. I am looking at the Cabela trolling batteries and plan to go that way. I am posting another stupid question about trolling motors. Will appreciate help on that as well. Mike (a native waiting to retire so I can return to the state)