The most common reason a school bus misses its morning run isn't the engine. It's a battery that couldn't turn it over at 5:45 on a cold morning. School buses are hard on batteries: short runs that never fully recharge them, long idles with the heaters, lights and radio running, and weeks parked over breaks. A little regular care saves a lot of jump starts.
Here's a practical school bus battery maintenance routine for the shop and the drivers.
What to do, and how often
| Check | How often | What to look for |
|---|---|---|
| Terminals and cables | Every PM service | Corrosion, loose clamps, frayed or chafed cables |
| Hold-downs and the battery box | Every PM service | Batteries held tight, box drained and clean |
| State of charge | Every PM service, and before winter | About 12.6 volts at rest on a fully charged 12-volt battery |
| Load or conductance test | Before winter, and when a bus starts slowly | Enough cranking power for the cold |
| The charging system | Before winter | The alternator charging at the right voltage, belts tight |
| Water level (if not sealed) | Every PM service | Plates covered; top up with distilled water |
Tip: Many buses have two or three batteries working together. Test them one by one, and replace them as a set: one weak battery drags the others down.
Getting through the cold
- Plug in block heaters on cold nights, so the engine turns over more easily.
- Test every battery before winter, not after the first no-start.
- Keep a charged spare and a jump pack in the shop.
- Cut idling with everything on: heaters, lights and radio running on a parked bus drain batteries.
Over breaks and summer
- Charge the batteries fully before a bus is parked for a long break.
- Turn off the battery disconnect, if the bus has one, to stop small drains from cameras and radios.
- Check and charge them again before the bus goes back on its route.
When to replace
Many heavy-duty batteries last about three to five years, less in hot climates or with frequent deep drains. Replace a battery that fails a load test, won't hold a charge, has a cracked or swollen case, or has started a bus slowly more than once. Write the install date on the battery so the next mechanic knows how old it is.
Good to know: Follow the bus and battery makers' manuals, and wear eye protection and gloves when working with batteries. Electric buses have high-voltage systems that only trained technicians should work on.
Doing it in FleetCommander
On a schedule. On Maintenance, New schedule for each bus with a Task name like Battery and charging system check, and Every (days) set to, say, 180, or tie it to your PM service with Every (miles). It shows Due soon, Due and Overdue, and Create work order turns it into a job. A seasonal check before winter fits here too. See the Maintenance guide.
Drivers and spares. Put Starts normally, no warning lights on the pre-trip template under Inspections › Templates, so a slow start is written up as a defect before it becomes a no-start. Keep spare batteries under Parts with a Minimum quantity, and Low stock is flagged before you run out. See the Parts guide.
Ava (Beta), the assistant in the app, answers Can I see the low stock parts? or Any maintenance overdue on Bus 104?. More on her page.
Related reading
Questions people ask
- How often should school bus batteries be checked?
- At every preventive maintenance service, with a load or conductance test before winter and whenever a bus starts slowly.
- How long does a school bus battery last?
- Often about three to five years, less in hot climates or with frequent deep drains. Replace one that fails a load test or won't hold a charge.
- Why do school bus batteries die in winter?
- Cold cuts a battery's cranking power while a cold engine needs more of it, and short runs with heaters and lights on don't recharge it fully.
- Should all the batteries on a bus be replaced together?
- Usually yes. Batteries working together should be the same type and age, since one weak battery drags the others down.