Batteries
General
The battery of a forklift AGV from AGV Electronics is located above the drive unit and below the electrical control enclosure. The battery may be tractionary lead acid, gel or NiCd type. The location of the battery makes it very easy to access for maintenance. It is covered by a cover plate, which also holds it in position.
For other types of vehicles is the battery location depending on the AGV design. As a general rule is it positioned to be easy to access for maintenance. It is also important for the weight distribution in the vehicle.
A normal AGV has a 48 volt battery. The capacity depends of type of battery, AGV and operation. The battery may stand on a roller bed in an AGV where the battery is exchanged when discharged. This makes it easy to replace the battery by simply rolling it on and off the AGV.
Tractionary lead acid battery
In most AGV systems are normal truck batteries (tractionary) used. This type of lead acid battery is used for deep cycle discharge. It can operate 8-24 hours depending of size and operation. Up to 80% of its rated capacity can be used by the AGV. When discharged must it be recharged during 7-9 hours.
The battery needs to be filled with battery water normally once per week. This is done manually in each cell or through a central water filling system with one hose connection which is very reliable.
The high weight of a lead acid battery can be negative for an AGV as it will consume power only to transport its own battery, but it also functions as a stabilizing weight for a high lift fork lift.
| Positive | Negative |
| Deep cycle capability can use up to 80% of its capacity | Needs 7-9 hours for recharge |
| Low price | Needs water filling approximately once per week |
| High weight |
Tractionary gel battery
The gel battery is a lead battery with gel instead of acid inside. Up to 80% of its rated capacity can be used by the AGV. A positive feature is that it does not need any filling of water and is sealed. On the negative side is that it normally needs a longer time for recharge, typically 8-12 hours. The gel battery is also more expensive to buy compared to standard lead acid battery.
| Positive | Negative |
| Deep cycle capability, can use up to 80% of its capacity | High price |
| Needs no water filling which gives low maintenance cost | Needs 8-12 hours for recharge |
| High weight |
Nickel Cadmium battery
In a 48 volt battery system are 38 to 40 NiCd cells used. The NiCd battery in an AGV is normally used for up to 30-50% of its maximum capacity. The battery can be recharged with high current, up to 200 A, which gives short recharge time.
| Positive | Negative |
| Low weight | High price |
| Needs little water filling which gives low maintenance cost | Low capacity, needs recharge often |
| Quick recharge with high current |
Other types
Some other types are used for special application AGVs. Such batteries may be:
- Sealed-lead batteries that are available in 12V block batteries up to 70Ah and can be connected in parallel under controlled circumstances and are very useful in AGV applications. They have very low internal resistance and can be recharged with a high current in a short time. They are medium cost and can be used in a similar way as NiCd batteries, but has also deep cycle capability.
- Tractionary block batteries, which are medium cost smaller lead acid batteries with very good deep cycle capabilities.
- Gel block batteries, which are smaller low cost gel batteries with not so good deep cycle capabilities.
- Car start batteries, which are very low cost batteries, does not have deep cycle capabilities.