Batteries might look quite similar but there are quite a few things to think about before investing in a battery.
How do I know the capacity of a battery?
The capacity is stated in Ah (Ampere Hours) and for a traction battery most suppliers state the capacity according to the c5 standard, i.e. this is the capacity you can get using the battery constantly for 5h. Some state it according to the c6 standard which will give a higher rating for exactly the same battery, as an example a 500Ah [c5] battery has exactly the same capacity as a 520Ah [c6] battery. If we state the capacity according to the c20 standard, which is often the case for block batteries for e.g. golf carts the same battery would be rated around 600Ah. I.e. the heavier the use the less capacity you will be able to get from the battery.
What lifetime can I expect from a battery?
For a traction battery time it is not the most important factor and a well maintained good quality battery in a light use low temperature environment, and charged with a HF charger, can last for 10 years or even more. The most important factor determining the lifetime of a battery is the number of cycles it is designed for – cycles means the number of times you can use and then charge the battery. Some batteries are designed for as little as 700 cycles and some for 1,500 or more. The biggest difference between these batteries is the cell design and the amount of lead and other materials used. The fewer cycles a battery is designed for the cheaper the production cost – from a user perspective a 700 cycle battery should of course be less than half the price compared to a 1,500 cycle battery.
What is the difference between a soldered and a bolted connector?
Some battery brands use soldered connectors, probably because it’s cheaper in the production. The disadvantage you as a user get from the soldered connectors is that it’s expensive and time consuming to do repairs and even to change a cable. To do any repair the lead on top of the battery has to be melted with open fire which in combination with the gassing from the batteries creates an explosion risk. With a bolted connector it is a quick and easy job to do any repair and the cable connector is also flexible which means that it doesn’t crack should there be any movement between the cells.
What should I think about regarding the tray?
Regarding the tray you should think about three things; The thickness of the material used, the coating and the drainage. The thickness of the tray is both a safety and a longevity issue and a standard tray should be made from 4-6mm steel plates, sometimes with reinforcements to make sure that the tray is stable and doesn’t change its shape over time. The coating is very important from a longevity perspective. A thick epoxy powder coating also functions as insulation and protects the vehicles sensitive electronics for currency leaks. Some trays have a drainage hole in the bottom of the tray and while this might seem as a convenient way to get rid of any water in the tray, this uncontrolled draining will have battery acid leaking out into e.g. the hydraulics under the battery compartment but also onto the floor and thereby also the goods handled by the vehicle.