With much of the nation under extreme heat conditions, high ambient temperatures can also affect your golf car batteries. Different battery chemistries react differently to hotter temperatures but, in general, excessive heat can damage batteries no matter what their chemistry. In general, extreme heat can shorten the life of any battery by as much as 60%, depending on how long they have been exposed.
Lithium Ion batteries are very rugged but they can go into thermal runaway when exposed to extremely hot temperatures. While the ambient temperature by itself won’t typically reach their safe limit of 140°F, those temperatures can be reached if the golf car is charged or stored outside in direct sun or in a garage, shed or other area that does not have proper ventilation or cooling.
Higher temperatures can also cause the Battery Management System (installed with most Lithium Ion batteries) to detect thermal runaway and disconnect the battery. Thermal runaway is an exothermic process that releases heat from the battery that in turn further increases the temperature in an uncontrolled manner. This can cause venting of flammable gases and potential fires and explosions with most lithium battery chemistries.
Flooded Lead Acid (FLA) batteries can also begin to deteriorate if exposed to constant elevated temperatures. Heat can increase the water loss rate due to increased electrolysis and also increase the self-discharge rate leading to increased charging and potential overcharging. If FLA batteries are overcharged at high temperature, they can go into a limited thermal runaway condition but, in this case, the batteries usually dry out and ‘fail safe’ without risk of fire or explosion. It is important to keep the flame arrestor vents in place and to maintain proper water levels in FLA batteries during charging particularly at elevated temperatures.
Absorbed Glass Mat (AGM) batteries must be charged with special chargers and/or charge algorithms that prevent overcharge at elevated temperatures. If severely overcharged, they can lose water that cannot be replaced as with FLA batteries. This will cause early failure but, as with FLA batteries, dry out will lead to a ‘fail safe’ condition without the risk of fire or explosion.
No matter what the battery chemistry, it’s a good idea to take precautions at elevated temperatures. All batteries should be charged and stored in a well-ventilated area, preferably one that is cooler than the outside ambient temperatures and not in direct sun. FLA batteries should have water levels checked more frequently at elevated temperatures. It’s essential to fill each battery cell with distilled water so that the electrolyte completely covers the plates but don’t completely fill the cells until after fully charging. After fully charging the batteries, fill the cells to ~1/4 inch below the fill rings. This will prevent overflow during operation.
When charged properly, AGM batteries can withstand applications in which regular maintenance is difficult or impossible even at elevated temperatures. If extreme temperatures are expected, chargers with temperature compensation should be used. Temperatures should be measured with a temperature probe located on the batteries and connected to the charger. Some chargers require the temperature compensation factor provided by the battery manufacturer to be entered into the charge control algorithm.
At high temperatures (as well as low temperature), specific gravity readings measured using a battery hydrometer for FLA batteries have to be corrected for temperature. Therefore, it is important to measure the electrolyte temperature when measuring specific gravity. If the temperature varies more than 5°F from 80°F, for every 10°F (5.6°C) above 80°F (26.7°C) you must add 0.004 SG to your hydrometer reading to get the proper state of charge of the battery.
Checking water levels and preventing overcharging will help keep your batteries in top shape during excessive heat conditions. Your batteries will also perform better and last longer, lowering your annual operating costs which can be a dramatic savings for individual golf car owners and especially for fleets. For more information on proper maintenance and checking the condition of your golf car’s batteries, visit www.usbattery.com.
