Battery Cycling vs. Life

[Nonchalant1]

I understand from battery manufacturers that one of the larger limiting things to battery life is "cycling" and that a battery may have 1,000 or 2,000 cycles in it's useful life. The bugaboo is that a "cycle" is when it's recharged for any amount, goes up to full charge and the charger goes off. The problem is that many chargers, left to their own devices will come on and "top off" the battery bank many times during a day as the battery bank power is used. This adds to MANY more cycles and huge decreases in battery life?

I'm not a battery engineer, but that's a bit counter-intuitive. I know it's good to occasionally use over 50% of the bank's capacity and than charge it back up, which keeps the lead suflites from hardening, but do a lot of little cycles really hurt lead acid batteries? I'd have to keep my charger off and then watch the voltage drop all the time. I'd rather just leave it on when we're on the boat and have it keep the bank fully charged.

Thanks,

Doug

 

[Genesis]

Not true.

A battery that remains at or near full charge is not "cycled".

 

[jim rosenthal]

I think this depends on whether you are using deep-cycle batteries, which are not harmed by repeated deep discharges, or starting batteries, which are. This difference is one of the reasons I just put a lot of time and effort into having Blue Note's battery systems rewired. True deep cycle batteries are okay to discharge and recharge; starting batteries will not take much of it. I suspect that starting batteries are not very resistant to sulfating, where deep cycle batteries are. Also deep cycle batteries can be conditioned, or refreshed, by equalizing them (a controlled overcharge) where I think starting batteries just get fried by equalizing them.
I know "smart" chargers aren't supposed to overcharge batteries and boil out the electrolyte, but maybe my smart charger's IQ isn't high enough. We'll see. In theory, we should be able to leave a smart charger on and it will float the batteries where they are supposed to be. In practice...well....
One thing that helps- I have learned to use only the warm or hot settings on chargers that have temperature adjustment switches. The cold setting raises the voltage too high and boils out the water over time. Also, it is worth it to check your batteries with a hydrometer fairly often- turn the charger off and let the surface charge dissipate, then see what they read. That will tell you whether they are fully charged.

 

[Genesis]

All L/A cells have a finite cycle life.

The deeper the cycle, the fewer of them you get.

With very shallow (basically float service), you get thousands (many) of cycles.

Draw down a starting battery to 80%, and you will severely damage it. Do that a few times and you're buying a new one. They are designed to be drawn down only a very small percentage (e.g. 10% maximum), and deliver higher starting currents.

Draw down a deep-cycle battery, and you get away with it more. However, if you regularly discharge more than 50%, you're not going to like the cycle life you get from any L/A cell, regardless of style (flooded, gel or AGM.)

Deep-cycle AGMs will withstand more of this abuse, but even they can be killed this way.

Deep cycle batteries should not be drawn down more than 50% of their amp-hour capacity. Starting batteries should not be drawn down effectively at all.

 

[34Hatt]

All good Info this is why many of us have 6 volt golf carts for our house bank and the 8Ds for starting. That set up with a good charger and a link that tells you battery amps taken out, floats and does equalizing will give you many years trouble free.

 

[SKYCHENEY]

I was really impressed by the service life of the gel-cells in a bus (coach) that I own. I had these gels as the house bank and ran 2-3300watt inverters with them. They lasted ten years in that application before I had to replace them. Not bad for any type of battery!