Everybody around here plans for winter. Almost nobody plans for summer, and heat does more damage to a battery pack than cold does. Cold slows a battery down temporarily. Heat ages it permanently.
What heat actually does
Every chemical reaction inside a battery speeds up as it warms. That includes the ones you want and the ones you do not. The published rule is that battery life halves for every 18 degrees Fahrenheit above about 77.
Our July afternoons average in the low to mid 80s, so the air alone does not get you there. The cart does. A dark body and a black seat sitting in direct sun run a long way above the air temperature around them, and it is the temperature of the pack that counts, not the number on the forecast.
Heat also drives water loss. A pack that needed checking monthly in May can need it every two or three weeks in the middle of August.
What to actually do
Park in the shade. The simplest and most effective thing on this list. A carport, a barn, a tree, anything. A cart baking in the open all afternoon is working against you before you even turn the key.
Check water more often in summer. Do not stick to a rigid monthly schedule through July and August. Look every couple of weeks. If the plates are getting close, you caught it in time.
Let it cool before charging. Charging generates its own heat. Putting a charger on a pack that is already hot from both sun and use stacks one on top of the other. Give it an hour if you can.
Watch for swelling. A case that looks bulged or distorted is a battery that has been cooked. That one is done and it will drag the rest of the pack down with it if you leave it in.
Tires and the rest of the cart
Heat raises tire pressure, so a tire set correctly in April can be over pressure in August. Check it. An over inflated tire wears in a strip down the middle and rides badly.
Dust is the other summer issue. Gravel roads and dry pastures put grit into brakes and bearings. A rinse and a look over the brakes partway through the season is worth doing.
Lithium in the heat
Lithium handles heat better than lead acid, and it does not lose water at all, which removes the whole watering problem. It still has limits, and a quality pack has a battery management system that will protect itself by cutting output if things get too hot.
That protection is a feature, not a fault. If a lithium cart feels like it is holding back on a very hot day, that is the BMS doing its job.
The short version
Shade, water, and do not charge a hot pack. Three habits, and they will add years to a set of batteries.
Questions about your pack? Call me. 406.270.9346.