Hi Bill, I have to heartily agree that the dead accessory battery happens to everyone at one time or another (Murphy dictates how difficult the timing will be). I recall that we developed the habit of having at least one back up battery just for such a situation. We usually had a couple of the Hawker Genesis batteries on hand for replacements on Father Time's drag bikes, so it wasn't too inconvenient after the first time. -Tom True
On Sun, Jun 5, 2016 at 3:04 PM, Bill Dube via EV <[email protected]> wrote: > A dead 12 volt accessory battery has happened at one point or another to > everyone. > > We typically run a small DC-to-DC converter to keep the accessory battery > topped up, just to avoid the dreaded flat accessory battery. > You absolutely _must_ have a 12 volt accessory battery, but a DC-DC that > runs whenever the vehicle is "on" increases the reliability a great deal. > Small expense, but is good insurance against forgetting to charge the 12 > volt, which is easy to forget in the excitement of race day. (Ask me how I > know. :-) ) > > We use a Vicor DC-DC converter module (or more than one in parallel) like > this one: > http://www.ebay.com/itm/201199082834 > You might choose a different model, (like a VE-j72-CY) depending on your > main pack voltage and your wattage needs. You should get a 15 volt output > and trim it down to ~13.5 volts (read the data sheet). If you get one with > 12 volt output, it won't charge a 12 volt battery because it really puts > out exactly 12.0 volts. > > I don't know who originally said it but, "To finish first, one must first > finish." > > I'm guessing, but you probably used a portable "12 volt" battery charger > to recharge your Li-Ion "12 volt" accessory battery. That is likely what > ruined it. Almost without exception, the open circuit voltage of all > portable "12 volt battery chargers" is greater than 15 volts, (often as > high as 17 volts) which is a death sentence for a "12 volt" Li-Ion pack. > Always measure the open circuit voltage, with a voltmeter, on a battery > charger before you use it to charge a Li-Ion battery. Any power supply or > charger that put out over ~14.7 volts open circuit will toast a Li-Ion > accessory battery. Find one, like a laptop power supply, that puts out the > _correct_ voltage. > > Also, leaving a switch on overnight accidentally will drain the accessory > battery to zero, which will also result in the demise of a 12 volt Li_ion > accessory battery. Good to have an LED tail light or dash indicator light > that lets everyone know that the 12 volts is "on". > > Best of luck! > > Bill D. > > On 6/5/2016 1:20 PM, Casey Mynott via EV wrote: > >> Hey all! >> >> A historic day for the Shock and Awe racing team from Bothell Washington >> and >> the world of drag racing! >> >> After sitting in gridlock and sweltering heat on the #1 towards Mission >> Raceway, I arrived just as the track was doing lunch. All in all it was an >> amazing day with some serious excitement (a 9.589 second 152 MPH run) and >> a >> bit of a turn at the end of the day. During run #2 the 16 volt AGM (which >> was changed out for a faltering 16v lithium pack of headway cells) ran out >> just as the team was pulling up to the line. So, yesterday ended in a >> somber >> moment of reflection. A good reminder, racing is a tough sport, >> physically, >> mentally, emotionally, financially, all of the above! >> >> The team is at the track today hoping to get in another run, depending on >> how that goes possibly a second. >> >> For now, enjoy the video! :) >> >> >> https://www.youtube.com/watch?v=L53JTDnmj_w >> >> >> Cheers! >> >> Casey >> >> -- >> View this message in context: >> http://electric-vehicle-discussion-list.413529.n4.nabble.com/Shock-and-Awe-Historic-run-9-589-Seconds-152-MPH-tp4682360.html >> Sent from the Electric Vehicle Discussion List mailing list archive at >> Nabble.com. >> _______________________________________________ >> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub >> http://lists.evdl.org/listinfo.cgi/ev-evdl.org >> Read EVAngel's EV News at http://evdl.org/evln/ >> Please discuss EV drag racing at 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 > Read EVAngel's EV News at http://evdl.org/evln/ > Please discuss EV drag racing at NEDRA ( > http://groups.yahoo.com/group/NEDRA) > > -- Remember, it is not that the glass is half empty, in reality, the glass is merely twice the size that it needs to be! -TNT'82 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20160605/81e90a4d/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Read EVAngel's EV News at http://evdl.org/evln/ Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
