Deep Cycle vs Standard Battery

So,

I've had a recent debate with a friend about Deep Cycle Batteries vs Standard batteries.

Long story short, we have a Backhoe that we use infrequently. He swears that we should have a deep cycle battery in there because it will last longer due to the slight self discharge causing the battery to cycle more, I think it should have a standard battery to get the most amps while cranking.

I dont disagree totally with him, I just haven't read that or had the science explained. From my understanding deep cycle batteries are designed to be used for longer running periods, as in you cycle them to run something for a while, then recharge. I dont see how that could directly correlate to sitting battery life when compared to a standard battery.

Is anyone on here a battery expert and could shed some light on the debate? Thanks!

 

I'm not an "expert" but I have heard that deep cycle batteries are designed to be able to be nearly fully discharged and still accept a charge. This can be done many times. Starting batteries are not designed to do this and will often fail to charge if they are discharged too much.

 

I think you may both be right.
http://batteryuniversity.com/learn/article/lead_based_batteries

Starter and Deep-cycle Batteries
The starter battery is designed to crank an engine with a momentary high-power load lasting a second or so. For its size, the battery is able to deliver high current but it cannot be deep-cycled. Starter batteries are rated with Ah or RS (reserve capacity) to indicate energy storage capability, as well as CCA (cold cranking amps) to signify the current a battery can deliver at cold temperature. SAE J537 specifies 30 seconds of discharge at –18°C (0°F) at the rated CCA ampere without the battery voltage dropping below 7.2 volts. RC reflects the runtime in minutes at a steady discharge of 25. (SAE stands for Society of Automotive Engineers.) See also BU-902a: How to Measure CCA.

Starter batteries have a very low internal resistance that is achieved by adding extra plates for maximum surface area (Figure 1). The plates are thin and the lead is applied in a sponge-like form that has the appearance of fine foam, expanding the surface area further. Plate thickness, which is important for a deep-cycle battery is less important because the discharge is short and the battery is recharged while driving; the emphasis is on power rather than capacity.



Figure 1: Starter battery
The starter battery has many thin plates in parallel to achieve low resistance with high surface area. The starter battery does not allow deep cycling.
Courtesy of Cadex



Deep-cycle Battery
The deep-cycle battery is built to provide continuous power for wheelchairs, golf cars, forklifts and more. This battery is built for maximum capacity and a reasonably high cycle count. This is achieved by making the lead plates thick (Figure 2). Although the battery is designed for cycling, full discharges still induce stress and the cycle count relates to the depth-of-discharge (DoD). Deep-cycle batteries are marked in Ah or minutes of runtime. The capacity is typically rated as a 5-hour and 20-hour discharge.



Figure 2: Deep-cycle battery
The deep-cycle battery has thick plates for improved cycling abilities. The deep-cycle battery generally allows about 300 cycles.
Courtesy of Cadex

A starter battery cannot be swapped with a deep-cycle battery or vice versa. While an inventive senior may be tempted to install a starter battery instead of the more expensive deep-cycle on his wheelchair to save money, the starter battery would not last because the thin sponge-like plates would quickly dissolve with repeated deep cycling.

There are combination starter/deep-cycle batteries available for trucks, buses, public safety and military vehicles, but these units are big and heavy. As a simple guideline, the heavier the battery is, the more lead it contains, and the longer it will last.