1. Batteries User Brianiac (2003), Batteries [photograph]. Retrieved from https://commons.wikimedia.org/wiki/File:Batteries.jpg

2. Clinical Use Primary:  Single use Alkaline, mercury, zinc air etc. Secondary:  Rechargeable Lead acid/gel cell Nickel Cadmium (Ni-Cd) Li-ion NiMH

3. All rechargeable batteries have a life span;  Typically # of charge cycles  The specification varies with technology  Heat & discharge cycles limit lifespan Common Problems:

4. Caring for Wet Lead Acid: Minimum cell voltage is 2V Hydrometer is the best test  1.23Kg/L density Rechargeable batteries lose capacity when stored-lead acid are no exception Trickle charge regularly when stored

5. Charging Rechargeables: Rule of thumb;  Non-current limiting charger-set voltage to nominal +20%  If an ammeter is not available-check repeatedly for excessive heat  Current limiting charger-set volts +20%, set current to max charge limit, check for excessive heat By Andrevruas (Own work) [CC BY 3.0 (http://creativecommons.org/licenses/by/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons

6. Rejuvenating Batteries: Procedure; Only if cell does not respond to normal charging! Never leave cells unattended!  Set current limiting supply to nominal +20%V  Set current limit to 20% of Ahr rating  Increase voltage until max current flows  Check cell heat-warm is acceptable, hot is not  Reduce voltage while current flow is maintained Note: This is a temporary repair, new batteries will be req'd.

7. Substituting Chargers: Important Specs;  Line voltage  O/P voltage  Max current o/p  Physical dimensions/mounting  Connector Some wall units are AC o/p  Bridge rectifier can change to DC Any customized charger should be permanently attached to the equipment it is used with

8. One can replace rechargeable cells for one use batteries if: - The equipment does NOT have an internal charger! If the charger delivers excessive charge, then the cells and device may be damaged Battery Substitution

9. You make a pack of 12, 600 mAh, 1.2 V, NiCd cells connected 4x3: –3 sets of 4 batteries in series 1.2 V x 4 = 4.8 V –3 sets in parallel 600 mAh x 3 = 1800 mAh You have created one, 4.8 V, 1800 mAh battery! Substitution Example

10. To charge your pack, use Trickle charge: 1800/100 = 18 mA for a few days Max charge: for NiCd=C=1800 mA (1.8 A)! Substitution Example

11. Check battery volts;  Nominal typically needs no adjustment Corrosion; clean if present Capacity testing; use equipment it supplies Check cables Check insulation Monitor voltage during charge from built in charger – fast rise typically Ok Minimum Testing:

12. Hydrometers are available in auto parts stores for acid batteries If the electrolyte level appears low or the acid level is too high, add distilled water Acid Batteries By Palagiri (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

13. Acid batteries - Hydrogen gas may build up if proper venting has failed: EXPLOSION 12.7 volt lead-acid battery can destroy a finger if a ring shorts the terminals Safety

14. Questions ?