====== Rechargeable Batteries in the Hacklab ======


===== Rules =====

  * Charging:
    * **DO NOT** leave charging batteries unattended.
    * **DO NOT** charge cells/batteries in parallel without balancing circuit
    * Multi-cell batteries must be charged using a proper balancing circuit.
    * Charging only in the battery charging area in G1. 
    * Single cells may be charged using simple constant current and constant voltage.
    * Battery charging must be contained within an appropriate fireproof battery charging bag.
      * Hacklab owns one such bag, kept in the battery charging area or the battery storage box. 
      * If you wish to provide your own safety bag, it must be approved by Hacklab. 
  * Storage:
    * Batteries must be stored safely in the designated storage box.
    * The terminals must be covered to prevent accidental shorting.


===== Reclaimed/Recovered Batteries =====

//todo: Safety reccomendations for recovered batteries such as the hoverboard 18650 packs.//

  * Safely dismantle and inspect
  * Check individual cell voltages
  * Look for parallel-wired cells
  * If internal balancer circuit is not trustworthy, replace with external balance connector

===== Risk assessment =====

This is **work in progress**, do not take it as gospel until completed. 

Overheating, fire and explosion risks for lithium batteries:

^ Risk ^ Mitigation ^
| Battery Fire | Charging will always occur in suitable fire/heatproof containers | 
| Over-charging | Charging will always be supervised. Users will apply appropriate voltage/current limits according to battery. |
| Individual cells may be overcharged when connected in series | Balancing circuit will always be used. |
| Batteries in parallel may not charge at the same rate, or unexpected current may flow between batteries. | Batteries will not be charged in parallel unless they are individually monitored. |
| Puncture damage | Batteries will be stored in their appliance or in a designated storage box to protect them.  The box will be in a visible location. Plastic "hard-shell" batteries will be preferred where there is a risk of puncture in-situ. |
| High current flows if terminals are shorted | Batteries will be stored with the terminals covered with a cap or electrical tape. |
| High energy density - general risk | Projects that use high capacity batteries will be fitted with isolator switches and fuses. |

===== Reference Material =====

The [[https://www.brca.org/more/eb/lithium-battery-safety-considerations|British Radio Car Association]] and [[http://www.bvrmc.uk/pdfs/lipo%20safety.pdf|British Model Flying Association]] both have very good writeups on battery safety and best practice. //BRCA also have good documentation on ESC and brushless motor use/safety.//

Tim Kerby suggested [[https://www.riscauthority.co.uk//index.cfm?originalUrl=utilities/download.html&fid=32025C47-9026-4ADB-BE9D84AA53E31014|this RISCAuthority writeup (PDF)]] as a basis for our Risk Assessment. 

[[http://www.hse.gov.uk/pubns/indg139.pdf|Using electric storage batteries safely (PDF)]], a publication from the HSE.