For the first technical meeting of 2021 Mark Gerber will speak on his part in designing the Apollo Guidance and Navigation System. Mark has many interesting antidotes he will share.

Mark originally gave this talk on September 2015 and it was really well attended. 

 

Date: 21 Jan 2021

Time: 07:00 PM to 09:00 PM MST

This will be a GoToWebinar event, our first ever.

Please register and after you register you will be able to add this event to your calendar. 

Just as new years are inevitable, so are the evolution of regulations. With the ubiquitous use of lithium secondary (a.k.a. “rechargeable”) batteries in portable electronics, and ongoing events that make the news due to lithium batteries catching fire, it is natural that regulatory standards were developed to help ensure the safety of devices using these cells.

IEC 62133-2:2017 is one such standard, and it deals specifically with safe operation of enclosed rechargeable lithium batteries in portable electronics in typical use cases, as well as “foreseeable misuse” such as shorting the battery terminals, and attempting to charge the battery when it is outside of the safe charging temperature range.

In order to increase product safety and reliability and meet current and possibly future regulatory safety requirements, Lithium Polymer battery charger systems should include all of the safety features associated with charge or use of liPO battery packs. Those include staying within the manufacturer datasheet specifications for maximum charge current, charging temperature range, maximum discharge current, maximum charge voltage, and minimum discharge voltage. Any safety features not already provided by the built-in PCM (Protection Circuit Module) embedded in the battery pack itself, should therefore be included in the device’s design. These may include battery bypass and management for lithium cells in series, for example.

A simple option for USB charged single cell LiPo battery packs is the Microchip® MCP73853. This fully autonomous USB powered CC/CV charger includes cell preconditioning, cell temperature monitoring, advanced safety timers, automatic charge termination, internal current sensing, reverse blocking protection and charge status and fault indication. Pack temperature is monitored via a thermistor (PTC or NTC) referenced to ground that is ideally embedded in the battery pack, or in direct contact with it.

With an eye towards including every available safety mechanism to reduce the risk of damage to batteries and the potential for a resulting fire, designers can keep up with and perhaps stay ahead of evolving regulations.