Lee, In another forum I posted the following info about the Powerware: I have an EV with a 120V pack and therefor I am looking at a 3kVA unit from Eaton (Powerware) which can also be found under a dozen or so re-branded names (I have seen IBM, NCR, Avaya, ...) They have several different lines of UPS and the battery voltage varies from IIRC 24V, 48V, 120V. Then there is LTI which has mostly 120V and 360V and some 480VDC although I believe they also have small units at 24V and 48V. There are plenty UPS brands that have 12V though those are never the high power units and there are many more crappy 12V inverters and UPS'es than high quality ones. One thing to check if you use a UPS is if it will start without prior AC present. I did check the Powerware and that requires that you press the "on" button for 5 seconds to force it to start from battery alone. Since Powerware allows to parallel a large number of batteries to extend run times to many hours, it is implicit that it can also deliver the rated power for a long time. BTW, the 5 seconds "on" button trick worked on many UPS'es from APC and the like (often re-branded as Compaq or others) Crappy inverters/UPS'es have so small batteries that they cannot supply power for more than about 5 minutes and that is what they are sized for in terms of cooling as well... Cor.
Cor van de Water Chief Scientist Proxim Wireless Corporation http://www.proxim.com Email: [email protected] Private: http://www.cvandewater.com Skype: cor_van_de_water XoIP: +31877841130 Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203 -----Original Message----- From: [email protected] on behalf of Lee Hart Sent: Tue 2/12/2013 7:54 AM To: Electric Vehicle Discussion List Subject: Re: [EVDL] EVs as power source On 2/11/2013 1:41 AM, Cor van de Water wrote: > the input side of a UPS would make for a backup charger, in fact > it might charge faster than the charger I have in my EV today. Maybe yes; maybe no. I've played with a few UPS (Sola, APC, SL Waber). The ones I looked at would have some significant shortcomings if you tried to use them as a battery charger, or as an inverter with your EV's battery pack. The Sola could not start generating AC unless there was already AC on its input. It used the AC from the AC line, or from its own inverter output, to power its logic section. Without AC, the inverter could not start. It depended on the AC to "precharge" the power supply, so when it went away, there was enough power to start the inverter. The SL Waber had a "hot" non-isolated charger for its battery pack. I destroyed one by thinking I could use it to charge a battery that had its negative side grounded! It also would not start inverting without a source of AC just prior to the inverter switching on. All of them had really miserable chargers. They delivered a very low charging current (like 1 amp max), and it was a constant-voltage "float" charger, fixed at 13.8v max. All of them also had very poor heatsinking, intended only to run at full power for maybe 5-10 minutes (only as long as the batteries would normally last). But these are all smaller "consumer" UPS. The big commercial units are (hopefully) better designed and more versatile. Before I bought a UPS to use as a charger or isolated inverter, I'd want to hear from someone who has tried that particular make/model (like Cor did on the 3kv Powerware 9125). -- The most dangerous enemy of a better solution is an existing one that is just good enough. -- Eric S. Raymond -- Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.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)
