Battery Discharging - Less can be More
I think you meant C20. Most flooded acid batteries in the market especially the Tubular Battery form factor commonly sold are rated at C20. Although both of Sukam and Luminous have started to offer C10 batteries unfortunately none if them is sold in Nigeria (With exception of their AGM batteries which are rated C10). The example on the luminous site is just their attempt to explain in layman terms the peukert law which generally states the the relationship between battery discharge rate and current availability is exponential and not linear. If you take 11Amp / hour from a 220A battery rated at C20. The battery would be fully discharged after 20 hours. (20x 11= 220).
However if you discharge same battery at 20A per hour.. Rather than the battery lasting for 11 hours (which would be the case if discharge rate was linear) the same battery might only last 8 or 7 hours before becoming fully discharged.
On a flip side if you discharge a battery at a rate lower than its rated discharge rate. That is a 220AH battery being discharged at C40 or C30 which would be 5.5A or 7.3A respectfully. Then you could technically get more current from the battery than the rated 220A you might get close to 230 or 240A before the battery becomes fully discharged.
Ways to use the peukert effect to your advantage includes.
- Ensuring you use energy efficient devices which would allow you do more with less.
- Utilise opportunity loads i.e use most of your heavy loads in afternoons when you are at pick generation. This would put less pressure on your battery bank. Might also mean you solar array is a bit more over sized for the battery.
- Reduce night loads to minimum.
My offgrid setup is designed to take advantage of the peukert law. The combination of running heavy loads like freezers, fridge, Microwave Oven, Washing Machine etc during the day where 90% – 100% of the required energy comes directly from the solar panels and running a small and energy efficient load at night. I have ensured that my 220A battery is cycled daily at between 10 to 30% depth of charge. The shallow cycling of the batteries would ensure a longer shelve life.