Publications

Publications in the field on Lithium Batteries and their BMS (Battery Management System).

For senior managers of e-bike (system) & battery manufacturers/importers Battery Condition Test offers implementation of BMS to e-bike manufacturers or their suppliers. R & D costs are not charged when the manufacturer commits to recommend BCT’s battery analyzers to their (OEM’s) dealers, BCT considers the BMS suitable and the scale justifies this.
Quality Assurance at delivery Especially A-Brand E-Bike Manufacturers are concerned about their image with consumers. Research has shown that consumers who purchase an e-bike or scooter blame the manufacturer when the purchase does not live to their expectations.
When cells are produced, they are tested. But a small percentage has weakened when they are assembled into packs, usually months later. This may be caused by impurities in the electrolyte, resulting in shorts, which in turn cause an increase in the internal resistance.
In 2012 a seasoned Dutch electronic design team started to design a battery analyzer, specifically for e-bikes and after extensive consultation of the e-bike industry. After extensive alpha & beta testing in 2013 by many e-bike professionals and many valuable suggestions, the final release –aimed at e-bike dealers- was introduced in February 2014 and in fall 2014 follow-up models for S-Pedelecs and higher.
E-bike (system) manufacturers now have the option to offer their dealers an economical (volume pricing as low as € 195) battery tester with specifications, exactly fitting the requirements and with optional BMS interfacing, fine-tuned to your requirements. Custom cables and OEM branding will be available. Future upgrade to standard models is possible!
Warranty conditions for e-bike batteries always include the guaranteed capacity until the end of the warranty period. Often a maximum (full-equivalent or partial) charge/discharge cycles and more and more conditions to deny warranty in case of deep discharging and/or minimum charge intervals.
While Lithium Nickel Cobalt Aluminum (NCA) batteries are the main stream in e-bike batteries, other technologies may take over. Battery Management Systems (BMS) are often the Achilles heel of e-bike batteries.
When the state of health of a battery needs to be determined, most manufacturers rely on the readout of the BMS. Although most BMS’s provided a number, it does not say how reliable it is.

The BMS state of health (SOH) value

Most battery packs have a BMS that is based on a standard IC solution. Well known suppliers are O2micro and Texas Instruments. They have documented to algorithm used to calculate the State of Health. The chips computer the FullChargeCapacity (FCC) value if a discharge from full to empty has been done.
Electric Vehicle (EV) batteries can determine their capacity accurate enough to rely on for warranty purposes. EV’s have a built-in battery analyzer that also reads and interprets BMS data, which is vital for warranty evaluation. This article explains which limitations an E-bike BMS has, how to deal with this and how to -theoretically- resolve this.