Battery 101 - Calculating Battery Cost Of Ownership

Posted by Matthew Campbell on Apr 9, 2020 12:51:00 PM
Matthew Campbell
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Calculating cost to own when purchasing batteries

Estimate the cost of materials used when servicing the battery as recommended by the manufacturer. For comparison it is reasonable to use just $1.70 each time for distilled water, cleaning and neutralizing agents and ignore the other variable costs). Multiply this amount by the number of years the manufacturer says the battery will last in the application. Multiply the result by the number of times the manufacturer says the battery should be serviced per year to achieve the published life expectancy.Our experience shows most manufacturers will recommend you service flooded batteries at least once per month.

Two of the world's leading manufacturers and sellers of Flooded, GEL and AGM Deep Cycle batteries have stated: 

”Flooded batteries need water. More importantly, watering must be done at the right time and in the right amount or else the battery’s performance and longevity suffers. Water should always be added after fully charging the battery. Prior to charging, there should be enough water to cover the plates.”

“Batteries should be watered after charging unless plates are exposed before charging. If exposed, plates should be covered by approximately 1/8" of acid. Check acid level after charge. The acid level should be kept 1/4" below the bottom of the fill well in the cell cover. Water used to replenish batteries should be distilled or treated not to exceed 200 T.D.S. (total dissolved per million). Particular care should be taken to avoid metallic contamination (iron).”

“As batteries age, their maintenance requirements change. This means longer charging time and/or higher finish rate (higher amperage at the end of the charge). Usually older batteries need to be watered more often. And, their capacity decreases. Periodic battery testing is an important preventative maintenance procedure. Hydrometer readings of each sell (fully charged) gives an indication of balance and true charge level. Imbalance could mean the need for equalizing, is often a sign of improper charging or a bad cell. Voltage checks (open circuit, charged and discharged) can locate a bad battery or weak battery. Load testing will pick out a bad battery when other methods fail. A weak battery will cause premature failure of companion batteries”

According to the "world’s leading manufacturers" of flooded deep cycle batteries recommend that service is required – particularly as the battery ages – before and after everycharge/discharge cycle. In some cases they suggest that failing to do so will void the warranty. If you cycle the battery 2 times per week the battery will last approximately 3 years following the manufacturers recommended service procedures. (We attempt to use the manufacturers published life cycle data in the following comparisons).

This means your per battery service material costs will be at least $1.70 x 12 services per year x 3 years = $61.20; If you service as the manufacturers suggest it will be as much as $1.70 x 104 services per year x 3 years = $530.40. To achieve excellent 3 year life - cycled two times per week – flooded batteries need to be serviced at least once every 4 cycles or bi-monthly. $1.70 x 3 years x 26 services = $132.60 per battery. Every user of deep cycle batteries is familiar with dried out “rotten egg” smelling batteries, the result of not maintaining a proper service schedule over the life of the battery. In all of our comparisons we calculate service costs based on the flooded batteries being service after 6 to 8 cycles. Well below that recommended by the leading manufacturers.

In our opinion if you were to match a flooded battery against a Discover® 700 Series or EV Traction Dry Cell Series- of the same size and AH rating for use in the same application - you would find the following data to be a conservative representation of the comparable costs. Note that we have shown “cost per cycle” data for the Discover® battery at optimum, at drastically reduced and at 60% of the published life expectancy of a flooded battery. We present the results against a flooded battery that performs to its maximum as stated by its manufacturer.  We do this even though we show the flooded battery being serviced after 6 or 8 charge-discharge cycles and not after every charge/discharge cycle as the manufacturer required to achieve their published results.

Cost of Ownership

Figure 10 - Cost of Ownership

Discover® believes that – as a result of their design which requires less service, and assuming proper charging methods – Discover® batteries will out-value flooded batteries as it is more likely that the standards of service for the flooded batteries will not be met in the real world and as a result will not meet the manufacturers required levels to achieve maximum life. We make these reduced life expectancy comparisons in anticipation of positions that will be taken by Discover® competitors and other detractors that Discover® products will not deliver the same life cycles as a flooded battery.

Additionally, in the following comparisons, we do not take into consideration any of the other issues, inconveniences and/or costs associated with servicing, working with or having sensitive equipment around flooded batteries. These would include, but are not limited to:

  • damaged and/or special clothing
  • battery compartment repairs
  • air quality problems
  • workers compensation claims
  • occupational health issues
  • hazardous materials handling requirements
  • shipping restrictions and
  • damage to service areas from acid and corrosive by product spills

 Some of the most interesting and relevant results of the following study are:

  • The more competitive and demanding the channel (jobber/installer/large user/rental equip’t) the more compelling and feasible the switch to Discover® batteries becomes.
  • The larger the bank of batteries used, the more important costs associated with service becomes and the more compelling and feasible the switch to Discover® batteries becomes.

We think the results will surprise you and bring into focus why this is such an opportunity for Discover® users to greatly reduce their operational costs, and risks to their employees, communities and the environment that the use of flooded batteries currently presents. 

Topics: Battery 101

Additional Calculator Tool For Solar Installers

If you are a solar installer, we can help.

Discover Battery has produced a solar cost comparison calculator to help compare our LiFePO4 batteries to competitor batteries. When you fill out the calculator you will also be able to download a PDF of the results you can share with your customers.

Check out the calculator: CLICK HERE