Questions to ask when making a battery buying decision.

Oct. 28, 2024

Questions to ask when making a battery buying decision.

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Because of the growing number of performance rating schemes and/or ways to value your buying decision in the market today, it has become difficult to make a decision that doesn&#;t come with some form of buyer&#;s remorse at a later date. The following are some of the more obvious things to watch out for when buying:

Some companies rate their Reserve Capacities (minutes that the battery will deliver a discharge current) at 23 amps instead of the industry standard (BCI published) way of establishing Reserve Capacity at 25 amps.
Amp Hour (AH) ratings can be at 5-hour, 10-hour, 20-hour and even 100-hour rates, so make sure you compare the same rate.
Cranking Amps (the ability of the battery to deliver a higher starting current over a shorter period for engine starting) are given at different temperatures, so make sure that you compare the published &#;Cranking Amps&#; of each battery at the same temperature. CCA or Cold Cranking Amps at 0°F/-18°C is the industry standard rating. You may see ratings published at CA, MCA, MCCA and HCA. All reputable suppliers will publish the CCA.

Some companies have invented their own rating system by recognizing that the process of comparing deep-cycle batteries should be simplified. An American-based manufacturer of batteries invented a new labelling system incorporating the &#;Lifetime Energy Unit&#; (LEU). This was their attempt to help a buyer determine the lifetime performance and value of any given battery in the market. Simply stated, and in the words of the SANTA FE SPRINGS, CA. Manufacturer, &#;Lifetime Energy Units " signifies the kilowatt-hours of energy a battery delivers over its lifetime. The bigger the number, the total work the battery can perform. Before introducing LEUs, accurately determining battery performance and value required complex calculations. Engineers compute the true worth of a battery as the total energy it contains, measured in kilowatt-hours (KWH). To derive a number for KWH, they build a curve that profiles the relationship between runtime and the number of cycles. The area under the curve is the total energy the battery delivers over its lifetime. When amp-hours are multiplied by battery voltage, the result is the battery's capacity in watt-hours. The next step - comparing a battery's value - is also simplified. By dividing the LEU by the battery's price, the prospective purchaser obtains a value figure (energy units per dollar) that ensures an apples-to-apples comparison between competing products.&#;

Discover ultimately rejects this position. As with the variations in determining Reserve Capacity and Cranking Amps mentioned earlier, this is NOT a recognized Battery Council International (BCI) method for rating or comparing batteries as suggested by the manufacturer. The manufacturer leaves out the exact method of determining LEUs, for an exact comparison to be done, which was their stated purpose for establishing the rating. This creates a situation where two suppliers could use two sets of methodologies to determine their respective LEUs, making reasonable comparisons impossible. This implies that the LEU idea or concept is simply a marketing tool with no real scientific basis for engineers, as the manufacturer suggests.

LEUs &#; as a way of helping buyers make an informed decision &#; would work very well if the buyer was given some additional pieces of data (data that IS available from other manufacturers and that could be used to make meaningful comparisons):

The exact discharge control methods (test procedures) used in determining the battery's &#;Cycle Time&#; (what discharge rate and to what depth is the battery discharged?).
Whether or not the batteries can be pre-conditioned before running the procedure.
The resulting ampere hours of power discharged per cycle
The recharge control methods (test procedures) before the next discharge procedure.
The exact control methods used in determining the battery's &#;Life Cycles.&#;
The resulting ampere hours of power discharged over the life of the battery.

In addition to the problems listed above for making good performance comparisons amongst different batteries, using the LEU marketing tool to make a serious value comparison is equally flawed. The value comparison requires more detail. Some, but certainly not all, of the issues to be examined and required in determining value are:

Time and Supply costs associated with servicing the battery (as recommended by the manufacturer) to ensure it achieves its assumed life cycles.
Costs associated with Workers' Safety and Clothing needs (as recommended by the manufacturer).
The cost associated with Environmental Issues, Storage and Equipment Damage resulting from the emission of free hydrogen molecules during discharge and recharge.
Freight/time costs and/or restrictions related to shipping.

If these data were known, the buyer could then determine the true energy units per dollar or lifetime energy value as suggested by the manufacturer who introduced the LEU calculation.

What to consider when buying a deep-cycle battery

It is our opinion that to determine the actual best &#;bang for your buck&#; for batteries in cycling applications, you should gather the following information and perform the following calculations:

Information gathering before buying? Determine the amount of energy the battery will deliver in its life using test procedures recognized by worldwide manufacturers and published in the BCI technical manual. This information should be available from all manufacturers and should include the following:

Discharge current used (25Amps, 75Amps, 20-hour rate, etc.)
Discharge time (Cycle Life) to an effective 100% depth of discharge (1.75 volts per cell)
Discharge cycles (Life Cycles) achieved before the battery could not deliver at least 50% of its original rated capacity

NOTE: Different types of batteries use test procedures that allow different end-of-life criteria. For example, an electric vehicle or standard deep-cycle product would be considered at its end of life when it could not deliver 50% of its rated capacity. At the same time, a golf cart battery would not be determined to be at its end of life until it could produce at least 1.75 volts per cell during 40 minutes of discharge at 75 amperes.

Determine the number of times the battery will be serviced in its lifetime, as the manufacturer recommends. It is important to use the manufacturer's recommended service schedule. For time/cost analysis, we recommend you use an average of 10 minutes per service per battery.

Determine the average per hour/minute labour costs in your organization. This number varies by region and industry - should not include anything but direct labour costs. You can safely use a figure of $18.00 - $25.00 per hour ($.30 - $.42 per minute) ( dollars) without benefits etc. One transit authority stated that their direct labour cost associated with maintaining batteries in each transit bus was $180.00 per year; another stated it was as high as $550 per battery. We suggest using $22.00 as an average hourly cost ($.367 per minute).

Cost of service materials over the life of the battery, such as; distilled or specially treated water - using a per cell fluid usage by volume of 20% on an average cell volume of 2.35l/80oz and a 75% consumption efficiency or between $.02-$.04 per oz. Battery fluid volumes are as low as 5l/169oz and as high as 16l/540oz; cleaning and neutralizing agents at 1oz per battery or $.25 per battery per service; special clothing; repair and replacement of battery boxes and trays and more.

Cost Per Battery

Purchase price of the battery
Freight or handling charges (overland or can they be shipped through courier or air)

Calculating Cost to Own

Estimate the cost of materials used when servicing the battery as the manufacturer recommends. 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 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 that most manufacturers will recommend your service flooded batteries at least once a month.

Two of the &#;World's&#; leading manufacturers and sellers of Flooded, GEL and AGM Deep-cycle batteries state the following on their websites: &#;Flooded batteries need water. More importantly, watering must be done at the right time and in the right amount or the battery&#;s performance and longevity suffers. Water should always be added after fully charging the battery. Before charging, there should be enough water to cover the plates.&#; This would suggest that the world&#;s leading manufacturers of flooded deep-cycle batteries recommend that service is required, particularly as the battery ages, BEFORE and AFTER every charge/discharge cycle. In some cases, they suggest that failing to do so will void the warranty. If you cycle the battery two times per week, the battery will last approximately three years following the manufacturer's recommended service procedures. 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 serve as the manufacturers suggest, it will be as much as $1.70 x 104 services per year x 3 years = $530.40. Our experience shows that for a battery to last three years when being cycled two times per week, it needs to be serviced at least once every four 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 &#;rotten egg&#; smelling batteries, the result of NOT maintaining a proper service schedule over the battery's life.

NOTE: when asked, more than 80% of equipment managers could not produce or describe a &#;battery service schedule&#; - for equipment under their supervision that uses cycling batteries.

In our opinion, if you were to match a quality flooded battery against a Discover Semi Traction EV Dry Cell AGM or GEL battery of the same size and AH rating for use in the same application, you would find the total cost of ownership to be higher for the flooded battery option. Discover Semi Traction EV Dry Cell AGM or GEL batteries require less service, and as a result, with proper charging methods, Discover batteries will out-value flooded batteries. It is more likely that the standards of service for the flooded batteries will not be met in the real world. Therefore, it will not meet the manufacturer's required levels to achieve maximum life.

Additionally, when considering flooded versus Dry Cell AGM or GEL, one must also consider other 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
damage to service areas from acid and corrosive by-product spills

We feel the more competitive and demanding the channel (jobber/installer/large user/rental equipment), the more compelling and feasible the switch to Discover Semi Traction EV Dry Cell AGM or GEL batteries becomes. The larger the bank of batteries used, the more important costs associated with service and the more compelling and feasible the switch to Discover batteries becomes.

Factors influencing battery choice

Martin Walsh,senior application manager Motive and Reserve Power EMEA, EnerSys, looks at how to choose the best motive power source for electric warehouse and factory vehicles.

Many industrial applications depend on vehicles like forklifts, pallet trucks and personnel carriers to ensure quick, safe and efficient movement of stock and people. Increasingly, these vehicles are electrically powered and their potential depends heavily on the batteries and chargers they use for motive power. Hence, users have to consider key factors when they seek to purchase or upgrade vehicles&#; batteries. Also, electric vehicle OEMs should look into these factors to ensure that their latest offering includes the best available battery solution that will meet customers&#; needs. Key factors include consideration of lead-acid and lithium-ion (Li-ion) technologies and their variants, and Total Cost of Ownership (TCO).

Lead-acid battery technologies

A new type of lead-acid battery using technology known as Thin Plate Pure Lead (TPPL) offers OEMs and end users a practical and affordable alternative to both conventional lead-acid and Li-ion designs. TPPL resolves many of the lead-acid shortcomings, and allows users to achieve the productivity, economy and safety essential in today&#;s competitive environment.

Want more information on lead acid battery plant supplier? Feel free to contact us.

The following are four key types of lead-acid batteries:

&#; Flooded lead-acid (Lead-Antimony)

&#; Valve regulated lead-acid (VRLA) Gel type (Lead-Calcium)

&#; VRLA &#; Absorbed Glass Mat (AGM) (Lead-Calcium)

&#; Thin plate pure lead (TPPL) (Pure Lead &#; VRLA &#; AGM)

Flooded lead-acid batteries provide good lifecycle, but their inherent design invokes many challenges. Charging is less than ideal because they require complete charging periods of typically 8-12 hours and overcharge of 10-20% to generate acid mixing and minimise stratification. Additionally, regular water top-ups are necessary. Fast charging, though possible, requires special chargers, accessorized for battery and charging algorithms.

Commercially-available VRLA batteries of both Gel and AGM type offer improvements. However, they have a limited charge acceptance capability, so require an extended charging time of around 8 &#; 10 hours. Current Gel products do not respond efficiently to fast charging high current recharge programmes.

The advantages of TPPL

TPPL is an enhancement over the other lead-acid batteries based on two core concepts, thin plates and pure lead:

&#; Thin plates: TPPL positive and negative electrodes are only 1 mm thin, compared to 9 mm in typical conventional lead-acid batteries. This allows many more electrodes to be fitted in the same space, increasing battery capacity and boosting power density. As a result, space requirement for the same capacity as AGM is reduced by about 30%.

&#; Pure lead: AGM VRLA batteries use a lead calcium alloy for their positive and negative plates. TPPL uses high purity lead, together with very high purity sulphuric acid. The chemical behaviour of the batteries is significantly more stable, which offers advantages relating to charging characteristics and lifetime. Also, the grain structure of the pure lead makes the plates far less susceptible to corrosion.

Like the earlier VRLA products, TPPL batteries are sealed types, with minimum gas and no need for water top-ups. This design imparts very low internal impedance to the batteries and allows both a very high rate of discharge, and quick, efficient acceptance of charge. Operating in Partial State of Charge (PSoC) mode therefore becomes possible. This is known as opportunity charging, because operators can use occasions such as shift changes or lunch breaks to charge at high current for short periods. Weekend full recharge with a cell equalisation will bring the battery pack to full State of Charge (SoC).

The batteries can be charged at rates within the range 0.4C5 to 0.7C5, or two to four times the standard AGM and Gel charging rates. Fast charge algorithms for cyclic applications are available for rapid and safe charging. PSoC operations can take place without adverse memory effects on the batteries.

Fig.2 shows data from a food manufacturing facility where a 6-day / 3-shift application was carried out using a 48V-625 Ah battery pack. Charging duration is representative of the time available during a typical shift operation. During this regime the battery operated in PSoC mode. On the sixth day, the battery was given an extended charge, with a constant current equalization to bring the pack to full-state-of-charge in order for it ready for operation in the following week.

TPPL also offers improved energy density. Figure 3 shows the relative volumetric energy densities at cell level.

Energy consumption is reduced, as the batteries require lower overcharging, at typically 8 &#; 10% compared with 10 &#; 20% for flooded types. Up to 30% energy savings can be achieved by using TPPL batteries with suitable chargers.

Another advantage is available to users who plan to hold spare battery stock for quick replacement of spent units. Unlike conventional batteries that must be recharged every six to twelve weeks during storage, TPPL types can be stored for up to two years at 20°C when starting from a fully-charged condition. This reduces resources spent in monitoring the open circuit voltage of batteries in inventory and boost charging those that need it. Figure 4 quantifies battery performance during storage.

TPPL&#;S TCO reduction

TCO savings arise from both opportunities to streamline daily operations, and the improved battery technology. As motive power technologies support fast charging and PSoC operations, vehicles can remain actively productive for far longer without needing to stop for an extended charge period. As a result, multi-shift operation is possible, without requiring the space, capital costs and labour associated with stocking, maintaining and exchanging spare batteries. Furthermore, the costs and space needed for dedicated charging rooms, and truck routes to them, are eliminated as the TPPL batteries can be charged in situ.

Maintenance costs are further reduced, as time previously spent on frequent water topping up is saved. Energy costs also come down, as TPPL batteries require less overcharging than flooded cells. Once in use, the batteries provide a longer cycle lifetime than standard AGM and Gel types. Meanwhile, higher performance and better energy density allow for the specification of smaller, lower-cost batteries, while saving space within vehicles.

Li-ion: waiting to fulfil its potential?

Li-ion batteries&#; sensitivity to certain operating conditions and external factors mean they require electronic battery management systems, which contain the algorithms to operate the cells in a safe, controlled and optimized way, including shut down capability. Li-ion suppliers have claimed virtually zero maintenance, high power density and flexible charging as advantages over traditional lead-acid solutions &#; but these advantages are also found using TPPL. That said, Li-ion products do have an extremely high lifecycle, so they often outlast industrial trucks and can sometimes be re-used.

While lead-acid batteries are easily and virtually completely recyclable, disposing of Li-ion batteries presents a greater challenge. Nevertheless, major progress has occurred at a pilot plant level to enhance the recyclability of Li-ion and it is anticipated, in the next few years, that a more consistent and cost-effective method to recover important raw materials from the primary compounds may be established.

Conclusion

The advantages from TPPL are significant enough to transform materials handling in warehouses and factory areas. Motive power users and OEMs now have interesting choices. Lead-acid&#;s many decades&#; proven performance remains competitive through recent advances like TPPL, while Li-ion is an alternative that could become increasingly attractive as future developments become commercially available.