Installing a New Deep Cycle Battery

It is good practice to charge any new battery before use. Even in storage they will loose a portion of their charge. Lead acid batteries have no memory effect which is what they use for most inverter power storage. If you have another type you need to give specs.

There are no batteries that benefit from a complete discharge. Most batteries will be damaged by deep discharge.

The "memory effect" that you mention is a phenomenon that occurs in the chemistry of Nickel-Cadmium (Ni-Cad) batteries. The deep discharge of a Ni-Cad battery may sometimes result in re-conditioning of the battery but more often it simply destroys the battery. There are charging techniques that will eliminate the effect and are more likely to succeed than a deep discharge cycle.

Read up on batteries. There's a lot to learn:

http://lmgtfy.com/?q=battery+basics

Discharging a LA or SLA will probably damage it.

Ive worked with Exide on high capacity batteries and on the particular battery, PERMANENT damage ocurrs below 10.5 VDC

Agreed, too vague.

Consult the battery manufacturer, not other sources, for advice, its their battery.

New battery before use, must be fully charged. If one starts with batteries not fully charged,it is likely to last for lesser period. Lead acid battery if cycled at lower charge, the life of battery will be very low. Lead- acid battery has biggest problem- that it gives much lower life if it is cycled at partial state of charge. For a flooded battery the gravity of electrolyte is indicator of full charge and not open circuit voltage. Sometime a discharged battery is sold with so low charge,for that, only charging is not enough.It may need an equalizing charge, before use.

Not saying you're wrong but aircraft ni-cad batteries are regularly reconditioned by deep cycling. When I was with NASA Langley and we bought our first ni-cad reconditioning system I got to go to a three day training class on the dang thing. That was circa 1975.

Hooker

Assuming you are using lead acid batteries you should charge them completely before placing in service. If it´s a 12V sealed lead acid battery you should not take it much above 14VDC paying attention to its´temperature. If you feel any overheating then back the voltage down to 13.9 or lower. Most 12V sealed batteries in the 80 to 100AH range will not overheat at 14 Volts as long as the charge isnt left at 14Volts for days on end. At the start of the charge the current will be high and as the charge progresses the current will fall. The charge is complete when the current flowing into the battery drops to nearly zero.

In my solar system my charge controller is set to 14Volts for 2 hours then it drops down to 13.67Volts for the continuous float charge. So after the night time partial discharge the batteries are topped up to 14V when the sun comes up then later held at 13.67 the rest of the day.

If you are using wet cells which are the kind you add water to then take the voltage up higher to say 14.6 or even 15Volts again watching the temperature. Using a hydrometer record the specific gravity of a test cell. Once this value does not increase for 4 hours the charge is complete. If you do not have a hydrometer the current can also be observed to estimate when the charge is finished. Add water, if required, during this high voltage charging period because it will mix better with the acid when the cell is bubbling and active. Adding water to a quiet cell makes mixing harder.

For my clients I perform a reference discharge test on just one of the batteries. In this test I place a load on the battery and use a recording device to watch the battery voltage falling over time. Do not take a 12V battery below 10.5VDC and at the end of the test recharge the battery completely. Now you have a reference graph which can be used in the yearly maintenance you perform on your system. As the battery ages you will find, when you repeat the test, the time gets shorter. Then at a prudent moment you can tell the client he will need new batteries next year and he can budget for this. You can write a note on the battery which was tested. It might read " Jan 12 2012 new 12.65VDC, charged for 24hrs to 13.9VDC, discharged at 50Amps, runtime to 10.5VDC 48minutes"

As was mentioned, lead acid batteries do not have memory affect so discharging them is not required or recommended. Only Nickel Cadmiums suffer from the memory effect however nickel cadmiums are getting rarer and rarer these days.

So in conclusion, charge as above and do the discharge test if the client wants a reference.

Regards

John

The two procedures are not mutually exclusive. This means that it is possible to completely discharge a battery and subsequently charge it. On the other hand, I've not heard that discharging a lead/acid battery prior to charging, accomplishes anything useful. I suspect you got some bad information. One thing for sure, you must charge the battery prior to use.

Thanks to you all. I got a lot of helpful information.

Lead acid batteries never get memory effect.

Most but not all LA batteries will be damaged if taken below 12.5 volts for a long period, recharge as soon as you can.

The trickle charge value for a battery is dependent upon battery size, manufacturer, age and previous usage. The only good method is to adjust the trickle charge voltage so that the battery does not gain a charge, it just retains its charge, or even loses it very slowly. Recheck every 12 months of so and re-adjust if needed.

Charging above 13.6 volts will cause any LA battery to gas, even a sealed one! This also reduces total life expectancy of the battery.

When sizing a battery, assuming you want it to last a long time, buy one that 70% of the capacity will cover all your needs, then only charge to 13.4 volts (around 70% capacity), it will last a long, long time and never gas.

Battery gas can be dangerous to life and limb when it gets ignited by a stray spark or similar.....so its far better not to gas......humans also!!