The Vorradler Electrolyte using the RoPD charging socket.

RoPD/EnergyBus charging port standard

December 6, 2013
3,696 Views

There are three big bicycle conventions each year. The Interbike at Las Vegas (Nevada) in September…Eurobike which is held at Friedrichshafen (Germany) in August… and Taipei International Cycle show, in Taiwan in March (to be fair, there are also significant shows in the Netherlands, called FietsVAK in March, and the the China International Bicycle and Motor Fair, held in Shanghai in May).

We were unable to make it to Eurobike this year, but Europe often leads the way when it comes to bicycle innovations. There are several countries where gasoline is about $8/gallon, so bicycles, and recently electric bikes, have been embraced with enthusiasm. My only reluctance to accept everything that Europe develops…is their low power limits. We feel there is nothing wrong with speed limits for powered bicycles on public streets. This is a safety issue. If you want a street bicycle that can go 35-MPH, you simply have to get an “S-Pedelec” license, and outfit the E-bike with the proper lights and other safety features (the “S” is for Schnell, which is German for FAST). In the US, similar “Moped” standards apply.

That being said…an interesting bit of news surfaced at the Eurobike 2013 convention. Several large manufacturers have decided to embrace a common charging plug standard, called “Rosenberger Power and Data” (RoPD). It is being promoted by the EnergyBus association, and I think it is a good thing. Unless a couple of other very large E-bike manufacturers stubbornly adopt a different standard, almost all E-bike companies are likely to fall into line over the next few years.

 

An RoPD plug and socket pair.

An RoPD plug and socket pair.

______________________________________________________

How did it start?

In 2002, the German postal service began experimenting with E-bikes to deliver mail on certain routes where E-bikes would be appropriate. They soon had over 6,000 pedelecs delivering mail, but when competing companies wanted to bid on future E-bike component supplies, Deutche Post realized that the different companies all used unique connectors and different charging protocols.

The driving vision for the new interface was based on the success of the automobile industry using the 1983 CAN system from Bosch (Controller Area Network), and also the success of the USB interface for the computer industry (Universal Serial Bus). Something was needed that would be backwards adaptable to existing systems, and also future expandable to allow likely developments for Light-Electric-Vehicles (LEV’s) .

These concerns were first presented at the 2004 LEV conference (in Taipei, Taiwan), and soon an international team of seven industry leaders began studying and discussing the potential issues to ensure a good first effort. In 2007 a protocol similar to CAN was adopted and soon after five more companies joined the association.

In 2011, the finished V1.0 standard was released, using the connector and communication protocol developed by Rosenberger. There are currently 58 members who have agreed to use the RoPD connectors and charger communication interface…including BMW, Bafang, Panasonic, and many other industry leaders. All new electric wheelchairs and mobility scooters in  Europe have switched over to the RoPD connector, along with battery-operated mobile medical equipment.

This Deutsche Post E-bike has a front geared hub that provides

This Deutsche Post E-bike has a front geared hub that provides 14-MPH (23 k/h), and the batteries are made to be swapped out quickly and easily. These bicycles were made by Sachsen Zweirad (Saxony Bicycle).

 

_________________________________________________________________________

How does it work?

The common RoPD connector standard is rated for 12V-48V, and a maximum of 40-Amperes of current.

The plug is polarised, so it cannot be plugged in backwards.

The plug and socket pairs employ water-resistant rubber boots. Although authentic RoPD connectors have shown robust moisture resistance, mounting the female socket facing downwards provides the best moisture protection during charging.

The system is for DC only, and there are two main power pin connections, with 4 smaller pins to transfer data.

The insertion depth is shallow, and the connectors are held together by a strong magnet. This protects the system from damage if the user pulls away without properly separating the connectors. The male contact-pins are spring-loaded to ensure good contact is maintained at all times.

The connectors will not energize the battery charging power until the data transfer connection verifies all the vital information. This feature also helps ensure a long contact life, since normal operations will not have any arc erosion problems.

If the battery pack has an embedded temperature sensor, the data pins allow a smart-charger to monitor the heat and adjust the charging amps to keep the battery within safe limits, while still charging as rapidly as possible.

Before charging can begin, a memory chip in the battery pack will use the data-pin connection to inform the smart-charger of the battery chemistry, the amount of Amp-hours (Ah) in the pack, and the cycle life record. If no identification chip is detected, the charger will request manual charging instruction inputs.

If the smart-charger senses a short on any of the connecting pins (due to moisture or any other reason), it will terminate charging immediately.

The Rosenberg RoPD charging socket on a Specialized Turbo Ebike

The RoPD charging socket on a Specialized Turbo Ebike.

_________________________________________________________

Written by Ron/Spinningmagnets, December 2013

 

Grew up in Los Angeles California, US Navy submarine mechanic from 1977-81/SanDiego. Hydraulic mechanic in the 1980's/Los Angeles. Heavy equipment operator in the 1990's/traveled to various locations. Dump truck driver in the 2000's/SW Utah. Currently a water plant operator since 2010/NW Kansas

  • Kent

    Please explain “If no identification chip is detected, the charger will request manual charging instruction inputs.”

    That’s a good question Kent. If you buy an RoPD connector set and solder them onto your existing battery, the charger will have no way of knowing if the battery is LiPo (which can be charged at a very high rate) or NiMH (which would need to be charged at a lower amp-rate per Ah of battery).

    Also, a 48V battery that has been discharged way too low (from sitting uncharged for a long winter) may “read” as a topped-off 36V battery, and a smart-charger would indicate that the 36V battery is full, and then refuse to charge it.

  • So, is this another “pay to play” standard where only the big companies can afford to buy the specifications and licences, or is it a “public” standard that everybody can use?
    From what I’ve read, it looks like the PHY interface is CAN bus, and the protocol is a version of the CIA battery protocol, can anyone confirm this? (or publish the bloody spec…)

    • EdB

      Surely a standard is a good thing? Inter-operability makes life cheaper and easier for everyone.
      Why ‘pay to play’? Page one of the energy bus assoc confirms it is an open standard.

      • I think they mean “open” as in non-proprietary – however that doesn’t necessarily imply “free and publicly available”. I’ll believe that it is really “open” when I can find a copy of the specification to download without having to pay thousands of dollars to join an “association” in order to get access…

  • Aleksandar Erski

    y need charger for this bike were to bay