Question: I just got a 2000 BMW R1100RT and the previous owner told me the battery is 7 years old so I figure it's time to go.
I saw this video <https://www.youtube.com/watch?v=XEBjekqUV9c> and the guy points out that the battery sits right next to the engine and gel batteries deal with the heat better, and the current battery is a gel battery.
I have a regular lead acid battery I was going to use (spare backup I keep around) but now I'm wondering if it's a bad idea to use it, if it's going to be right next to the engine.
Any idea?

Answer: 
A typical lead acid battery require occasional maintenance. As the battery is recharged the acid outgasses. It essentially evaporates. This gas is corrosive and an explosion hazard if it concentrated in an enclosed container. Many motorcycles utilize a covered battery box. They may also use a drain hose to remove any acid fumes out of the battery and the battery box. A gel battery can offer lower maintenance and reduced outgassing. This is important if the battery is difficult to service or subject to high temperatures where the acid is likely to evaporate quicker. So the simple answer is yes it will work providing it is of the correct size (both physical size and amp rating). It may not last as long as a gel battery and may require more frequent service. Be aware that if the battery?box does not contain a vent tube you may see some corrosion in the battery box area.
To have this discussion, it is important to understand a few different lead acid battery types:

A **wet flooded cell** battery is a lead acid battery that, among other traits, makes use of case vents. This is one of the oldest battery technologies and is relatively high maintenance because the water in the battery will evaporate, requiring the owner to maintain the electrolyte level.

An **AGM** battery is a lead acid battery that has the electrolyte contained in a glass mat material. The acid absorbed in the glass mat containst just enough electrolyte to store energy, but not enough to have any freely flowing inside of the case. Because the AGM batteries do not have any freely flowing electrolyte and are maintenance free, they are often confused with gel batteries, though they are different from gel batteries in both technology and performance. The AGM lead acid battery is the most popular type of battery found in motorcycles.

A **gel** battery is a lead acid battery that uses a silica based gel to contain the electrolyte. Gel batteries are most popular in power supply applications such as a wheel chairs. Gel batteries have increased cycle life over other lead acid batteries but have the drawback of not being able to maintain high amounts of current in both charge and discharge. This drawback makes usage of gel batteries in automotive applications undesirable because both high discharge and recharge rates are required.

The issue you describe of problems related to a battery being near an engine have to do with wet flooded cell batteries where the water in the electrolyte evaporates more rapidly because of the heat. This is not an issue for any sealed lead acid battery, such as an AGM battery.

The only motorcycle manufacturer known to have used gel batteries is BMW, and generally only the OEM batteries from certain model years used gel technology. There is no modification required to replace a gel battery with an AGM battery, the AGM being the most popular type for sale for motorcycles.