With the ongoing COVID-19 concerns, school bus fleet operations nationwide have been dealt some various challenges. Typically, school buses are not kept out of rotation for extended periods of time. However, with early school closures this year and the uncertainty of fall school procedures, buses will be kept in storage in some cases double the expected time, if not more. Annual summer maintenance procedures are checked off yearly; however, one issue that may affect your fleet is the electronics in a bus that continuously draw from the battery. This could potentially cause the voltage to drop below the required level to start the engine. Completing important maintenance on your fleet’s batteries now will ensure you have the necessary energy storage when operations resume.
Below are some helpful tips and procedures, from preparing for extended storage to getting your fleet back in service with optimal battery performance, provided by Deka Batteries.
Extended Storage Recommendations
WITH disconnect switch
1. Turn the battery disconnect switch to the “off” position if one is available and no further action required.
WITHOUT disconnect switch
1. Remove the Negative (-) terminal.
2. Remove the Positive (+) terminal.
3. Inspect terminals, posts and cables for any corrosion or damage. Clean or replace any dirty or damaged parts.
Resuming Service
When it is time to get your fleet back in service the following steps should be followed for optimal results.
1. Check the Voltage and CCAs on the battery. Should the Voltage test below 12.4V (flooded) or 12.6 (AGM) the batteries will need to be recharged and tested prior to use. (see “charging” below).
2. Inspect terminals, posts and cables for any corrosion or damage. Clean/replace any dirty or damaged parts.
3. Reconnect the Positive Terminal (+).
4. Reconnect the Negative Terminal (-).
5. If there is a disconnect switch, turn it to the “on” position.
6. The bus can now be started.
Testing
Testing batteries before installation for reconnection after extended storage will ensure you do not experience unexpected no-starts and downtime. Listed below are the two types of testing recommended by Deka Batteries.
1. Conductance Testing
Conductance Testing will measure internal resistance by sending a signal down into the battery. The result will show how many CCAs the battery currently has. This will also test voltage.
2. Load Testing
Load testing is the most reliable form of testing, as it will actually simulate putting a load on the battery.
For both conductance testing, and (especially) load testing it is important to use charging/testing post adaptors, never the stainless-steel stud.
*A note about posts: Never connect testing or charging clamps directly to the stainless-steel stud. Always use charging/testing adaptor posts to ensure lead-to-lead contact. If charging/testing adaptors are not available, the lead pad may be used if the connection is secure and safe.
- Stainless steel has a higher internal resistance than lead. This means it will be much more difficult for the energy coming from the charger to flow into the battery. At best, the battery may take a long time to charge, if at all. At worst, the electrical energy will build up at the stud and become thermal energy, causing the stud to melt (this can happen when testing with the load tester as well).
- When using a conductance tester, a false reading may be obtained if the testing clamps are connected directly to the stainless-steel stud. Remember, stainless steel has a higher internal resistance than lead, and conductance testers use internal resistance to determine the battery’s health.
Charging
Prior to charging, it is important to know if the batteries are Flooded or AGM, as they will charge at different rates. Follow the steps below for the best charging results:
1. Test the batteries to determine current voltage.
2. Use the chart below to determine what amount of time will be needed to charge the batteries at the desired rate.
- Example: A flooded battery at 11.8V will take 10.7 hours to charge at a rate of 10 amps.
- How to Identify: AGM lead acid batteries will say “AGM” or “Absorbed Glass Mat”, “sealed regulated valve”, “dry cell”, “non-spillable”, or “valve regulated” on the label. Look at the top of the battery. Liquid lead acid batteries have caps or removable tops unless they say “sealed” on the label.
3. Connect the Positive (+) charging clamp to the Positive post.
4. Connect the Negative (-) charging clamp to the Negative post.
5. Charge for desired amount of time and rate. Be sure to follow all safety precautions noted in your charger’s manual.
6. After the battery is done charging, let sit for 24-48 hours to allow the surface charge to soak into the battery. A load test will dissipated the surface charge if 24-48 hours is not available.
7. Retest the battery to ensure it meets the rating requirements.
Battery Shelf Life
Batteries are a consumable item, and will self-discharge over time. Should the voltage of a battery fall below 12.40V (flooded) or 12.60 (AGM) the battery will need to be recharged to 12.65 (flooded) or 12.80 (AGM).
- Disconnected, without any loads, it will typically take 3 months for these thresholds to be reached.
- Self-discharge is accelerated when the battery is installed in a unit, especially if not equipped with a disconnect switch, as the bus may have key-off loads drawing from the battery.
Take charge of your batteries now, and your fleet will be fully energized when it is called back in to action. During these uncertain times, Colorado/West Equipment, Inc. and Nebraska/Central Equipment, Inc. remain committed to customer satisfaction and passenger safety. Contact us today to discuss your passenger needs.