Lee, It does not matter if the meter is powered from the aux battery or from the pack, it will draw something down to zero if the vehicle is parked too long with the meter running (idle) OR, if the meter is switched off, it will lose its current state of charge no matter from where it is powered either, so there is no benefit or drawback from using a non-isolated DC/DC converter to power the meter from the pack, other than that those converters are way cheaper and smaller than good isolated ones - the meter is at pack voltage potential anyway.
Of course the normal battery tender only attaches to the 12V aux battery, but it is just as easy to occasionally plug the EV in and charge the pack and the aux battery normally. 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 Lee Hart via EV Sent: Monday, July 27, 2015 3:56 PM To: Electric Vehicle Discussion List Subject: Re: [EVDL] 48V Energy Meter (Lead-Acid)... Cor van de Water via EV wrote: > Lee, Thanks for setting me straight that the backlight draws so much > power that it is better not to use a zener. The older E-meter/Link-10 had LED displays. They drew more current. The later LinkPro/LinkPro-Lite has an LCD display with LED backlight. These draw less, but the backlight is still a power hog and takes about 30ma at full brightness. The measurement electronics adds an additional 10-20ma depending on what it is doing at the moment. > An ordinary buck > converter can be OK if both the meter power and measurements are > connected only to the pack, since then no chassis connection exists. Sure; that's fine if you don't mind the continuous supply current. It's not a problem in an EV that's driven (and charged) regularly. The problem comes if you park the EV for months, and forget to disconnect the meter and don't have some kind of charger connected. > Do you know if the meter can be powered off when the car is not used > without losing its memory? Yes, they have an EEPROM that retains setup information. But it will reset the accumulated amphours to zero. -- Pollution is nothing but the resources we are not harvesting. We allow them to disperse because we've been ignorant of their value. -- R. Buckminster Fuller -- Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com _______________________________________________ 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)
