What is the proper way to charge a deep cycle battery?

[jibbs]

Deep cycle batteries are identical to automotive batteries with the exception of thicker lead plates which allows for a much increased reserve capacity (allowing it to run longer at lower draws) and lower cold cranking amps (needed for starting). There should be no reason to draw a deep cycle battery way down before recharging.

i agree..........i rarely draw mine all the way down unless i am fishing a tourney and the wind is howling.......i charge mine everytime after i fish...i have never had a problem.....my problem came when i had the automatic shut off charger.....it said it was 100% but it was only giving it a surface charge.....check those water levels as well

[sageur]

Pick up a quality on board charger. I have a 3 bank DualPro. Charges at 10 amps then when reaches full charge automatically switches to a float charge. Temperature compansates for winter storage also so no worries bout draining over winter. It cost more more than a MinKota, witch is a fine charger, but it is a step up in functionality.
10 amp is as low as you need to go I feel. Low enough not to create heat and gasses and sufficient to charge over night.
I feel one runs a risk at over charging if you do not have an automatic shut off or switching to a float charge witch can lead to the shortening of the life of the battery.

[rgfixit]

Battery charging 101
I've done a lot with batteries in my job. Lighting systems, emergency power, generator storage, electric lift equipment, pump systems....etc...etc...etc. My source for information at work has been the manufacturer. They know what to do with their batteries.

Deep cycle batteries (good ones) have solid lead plates as opposed to "sponge plates". Sponge plates allow for more surface area to provide higher cranking amperage, but less over long periods of time and a shorter life span. Deep cycles have less cranking amperage, but the thicker plates allow for a longer discharge cycle. The plates are not consumed as quickly ...they're tough.

Without getting into the chemistry of voltage production in a lead acid battery, charging reverses the effects of discharging a battery by removing lead dioxide from the positive plates and depositing it on the negative plates, thus restoring it's ability to produce the chemical reaction that creates voltage.

Whew!

The differences in construction means differences in charging methods.

"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." (From Wind/sun)

To properly charge a deep cycle battery you need a "smart charger"

We buy Charge Tek chargers for smaller applications.
http://www.batterystuff.com/

Hope this helps.
RG

[Grumpyoldman]

I understand the mechanics now, and the need for the right charger. Thanks very much. 

[trapper2000]

being ignorant of  the deep cell battery technology ....  i understand the  voltage  but  what about the amps? is it better for the battery to be charged a longer period  at a low  amp??

[rgfixit]

The higher the amperage, the harder the current is pushed into the battery.The initial charge (bulk) is quick. If you'll read the charging procedure above, you'll understand that regardless of the amperage of the charger, the rate of charge must be regulated properly. Whether it's a 2 map or 100 amp charger, you can ruin your battery if it's not regulated.

In other words, higher amperage chargers will perform better than lower amperage chargers, if regulated properly.

RG

[1fish@atime]

I was wondering if deep cycle batteries were like other rechargeables. If you don't totally discharge they will only go to where you start charging, and if you don't fully charge they loose peak charge limits?

[rgfixit]

No.
They're designed to be discharged to around 20% during a cycle. They should be recharged as soon as possible though, to prevent the plates from sulfating when sitting idle at a low charge. Again, it's the voltage put back into the battery that reverses the effects of discharging. All batteries discharge to a degree when idle.

RG

[pooley]

No.
They're designed to be discharged to around 20% during a cycle. They should be recharged as soon as possible though, to prevent the plates from sulfating when sitting idle at a low charge. Again, it's the voltage put back into the battery that reverses the effects of discharging. All batteries discharge to a degree when idle.

RG

that is what i was taught. that is what works for me. thanks RG!

[trapper2000]

my  charger is  a craftsman   automatic  6 amp to  2 amp with auto  shut off would you  recommend  just using it on 6 amp  then! i may have  been doing this wrong i been  using it set on 2 amps

[KingPerch]

My granddad and dad always taught me to trickle charge on 2 amp overnight. That way you are not putting the heat to the internal plates and taking life from the battery. Only my 2 cents, but has always worked.

[rgfixit]

Well,
I go by what the manufacturers say. A 2amp will certainly put some charge into the battery. Any DC 13 - 16v transformer will do that even at .5 amps. The problems come when the process is not followed completely. The battery will never be completely charged leaving lead dioxide deposits on parts of the positive plates. This will shorten the battery's effective cycle and degrade the plates shortening the overall life of the battery.

I have these types of problems with my bucket truck's heavy duty deep cycle batteries. The alternators will charge the batteries but never fully. It's not the best system.

RG

[SNAGGER]

   Thanks for the battery lesson!

[trapper2000]

rg  just a question  does your bucket truck have a altnator or generator?

[rgfixit]

The batteries are charged by the truck's dual 90 amp alternators. They're designed to run the boom , work lights and a hefty inverter as well. I try to use the battery pack as much as I can. That monster 454 sucks gas like a toilet flushing.

RG