Lee has discussed this in the past, it is likely in the archives. I see three main issues: - at lower voltage, the zener knee gets very soft so unless you use additional electronics to amplify, the zener itself does not work very well on a single cell as you already indicated, two cells might indeed be better since around 6V the zeners have the best characteristics but that introduces issues with imbalance between the two cells - Voltage differences while charging are very small with most types of Lithium. 3.2V at rest but 3.5V is over-charging a LiFePO4 cell whereas a flooded/AGM lead-acid battery can easily go from 12V to 15V and it does not hurt them to be sitting at 15V while balancing for an hour. - leakage and failure: while zeners are supposed to go "on" at a certain voltage, they will leak below that voltage so you are introducing extra "self-discharge" which can very per cell with the properties of the zener, so in a sense you are making the situation for Li-Ion worse. Also zeners can fail (shorted typically) and mechanically fail and the Lithium cells will not take well to being over-charged due to a failure
Cor van de Water Chief Scientist Proxim Wireless office +1 408 383 7626 Skype: cor_van_de_water XoIP +31 87 784 1130 private: cvandewater.info www.proxim.com This email message (including any attachments) contains confidential and proprietary information of Proxim Wireless Corporation. If you received this message in error, please delete it and notify the sender. Any unauthorized use, disclosure, distribution, or copying of any part of this message is prohibited. -----Original Message----- From: EV [mailto:[email protected]] On Behalf Of damon henry via EV Sent: Tuesday, June 23, 2015 10:37 AM To: EV List Subject: [EVDL] Lee Hart Zener Regulator for Calb cells Hi, I am wondering if anyone has adapted Lee Hart's Zener regulators for lithium cell use. I don't think the voltage of one cell is high enough to use this type of device on, but I think proper values can be found to regulate two cells in series. I would love to experiment with some of these and would like full bypass at 6.8 volts. I believe the 12 volt model can be tweaked by picking appropriate replacement Zener diodes, but I don't do a lot of this type of design, so I am not familiar with what is available or where to source the parts. Any help would be appreciated. thanks Damon Here is a link to Lee's design.http://www.sunrise-ev.com/LeesEVs.htm#zenerlamp -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20150623/2b159354/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA) _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
