Jan, The OP requested charging his boat's 48V pack from his 48V solar bank, so I doubt that the EMW charger or other standard 110-240V AC supplies/ chargers will work on 48V DC. For charging from a road-going EV as input, that may be possible though it is always a challenge to discover the limitations of the setup before they cause failure and that can be in a catastrophic way - think about an input stage that has 4 diodes that rectify the AC input, but now all current only goes through 2 diodes so they may overheat and fail, which is designed to be handled by the fuse blowing up, but the fuse is only designed to work on AC, so it creates an conductive arc instead and the current continues to flow.... Usually things don't fail this badly but you need to be aware of what can happen so you can assess the risk of a failure and see if you accept the consequence of that.
Regards, Cor van de Water Chief Scientist Proxim Wireless Corporation http://www.proxim.com Email: [email protected] Private: http://www.cvandewater.info Skype: cor_van_de_water Tel: +1 408 383 7626 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Jan Steinman Sent: Monday, April 21, 2014 10:44 AM To: [email protected] Subject: Re: [EVDL] Charging your EV pack from other batteries? Electric Motor Werks actually says you can do this with their charger (http://emotorwerks.com/tech/electronics): "Both non-PFC and PFC units can be used to charge your battery from a DC source. This feature can be used to charge one EV from another, to use the charger with a separate rectifier (e.g., for 3-phase operation), charger your EV from your solar array / stationary battery, etc. Non-PFC units can be used with DC input above the voltage of the battery being charged (up to ~400 VDC) PFC units can be used with any DC source ~100-400VDC." Anyone have experience with EMW chargers? I'm considering one, because my current (hah!) charging method is to charge five batteries at a time with a 40V/40A lab power supply. That means five days for a full charge of my 24 batteries. :-( Jan > Note that MANY switching power supplies can be run from DC. This means the best way to charge from another EV MAY be through your charger. > > If your charger has a "universal" AC input, such as "110 VAC to 240 VAC," then chances are that the first thing the line sees is a bridge rectifier, which changes AC into DC. The rectifier will "commutate" your DC in the proper direction, so you don't even need to worry about polarity. Most modern chargers are over 95% efficient. > > So, the BEST way to assure you get the proper charge for your batteries from another EV might be to connect your AC charger to the other EV's battery pack -- assuming it doesn't go over the peak voltage that the AC line would supply to it. (Generally, 240 * 1.414, or about 340 VDC.) > > You probably cannot do this with a charger that has a voltage selection switch that lets it operate on either 120 VAC or 240 VAC. That implies that there may be transformer or other AC-specific component in there. And the charging current available may be reduced by 50%, since only half the input bridge rectifier is being used. > > (If you think you may be doing this often, and have the proper skills and documentation, you might bypass the input bridge entirely to get back the full charging current capability.) > > Kids, don't try this at home! Unless you're skilled at electronics and have a schematic, the next step would be to contact your charger's manufacturer to see if they think this is a good idea! (And for liability reasons, they likely won't. See if you can talk to one of their engineers, not a sales droid. And see if you can wrangle schematics out of them.) > :::: Given an infinite source of energy, population growth still produces an inescapable problem. The problem of the acquisition of energy is replaced by the problem of its dissipation. -- Garrett Hardin :::: Jan Steinman, EcoReality Co-op :::: _______________________________________________ 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)
