The datasheet for this module can be accessed from this page: http://www.digikey.com/product-search/en?KeyWords=jw150a1 (the other module that shares the same PCB that it is mounted on is the JW150C1, the same 150W but 15V output instead of 5V) The output from the JW150A1 can be trimmed from 3V to 5.5V So from a nominal 48V battery bank, you can create a charging voltage of between 51 to 53.5V which should allow charging your boat batteries quickly to at least 80% from a half-empty solar pack.
The module has both a "trim" input as well as a remote on/off so it is relatively straightforward to create a max output voltage limit as well as a power down when the output voltage goes over the max you want to provide. Since you are charging sealed lead-acid batteries, I expect that you like to keep the charging voltage below 14.2V per battery and in case it does (if you are plugging in your boat during a sunny day and the solar bank is also charged to its max voltage) then you'd want the DC/DC converter to drop out, which might still allow leakage from the solar bank to the boat, but never at a higher voltage than the solar bank and since they are the same batteries and configuration (4 series) this should not be a problem in this case. But if you never leave your boat plugged in and just want to charge for a couple hours, then run the boat, the simplest solution is to set the DC/DC converter for a fixed (boost) output voltage and just run it all the time while charging your boat. Note that this converter has current limit and it is allowed to run it in current limit mode continuously which makes it a charger with a I-U type profile. (Current limit until max voltage, then voltage limit) The current limit is typically around 120% (36A). The modules I have come with a small heatsink attached, but you may need to add a larger heatsink or blower to remove excess heat when running it in current limit mode, since the efficiency can drop to about 83% at current limit, which means around 35 Watts may need to be dissipated during full-bore charging, if the unit overheats it will throttle itself back but the internal electronics will not be too happy at that temp. If you want to run a controlled output voltage then it will be needed to add a little circuit to trim the output based on the voltage measurement, but when you just need it to provide a fixed voltage the circuit is as simple as a resistor attached to the trim pin. If I am not mistaken, I have offered these converters on a board in the past with 2 converters (1 for 5V and 1 for 15V, so both a JW150A1 and a JW150C1 on a PCB with some external components to regulate the 48V inrush and filter noise) for $25 plus shipping. Here are the datasheets for the two converters: http://www.digikey.com/product-search/en?KeyWords=jw150a1 http://www.digikey.com/product-search/en?KeyWords=jw150c1 Let me know if you have any questions. 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 Lee Hart Sent: Tuesday, April 22, 2014 2:18 PM To: Electric Vehicle Discussion List Subject: Re: [EVDL] Charging your EV pack from other batteries? Dan Baker wrote: > Thank you everyone for the replies so far- as hoped lots of fantastic info! > So it sounds like Cor's idea and Marco's drawing are my best bet. So I > guess my only other question would be around this charging scheme is would > I need to regulate the charge control once the EV pack reaches full charge > (i.e. prevent overcharging)? Would I have to implement a timer? > Cor, please yes send me info and pricing on your brick DC/DC module. Cor's solution is a good one. The DC/DC can boost the voltage so the destination pack can reach "full" even if the source pack isn't full. You will need to decide what charging algorithm you want to use. Then provide hardware to do it. The simplest algorithm is just a constant voltage charger. You would wire the control input of the DC/DC to hold the *total* voltage applied to the destination battery at something like 2.25v/cell (13.5v per 12v battery; 54v for a 48v pack). That will work, but could take a day or more to reach full charge. Or, you can set the DC/DC's output to charge as fast as it can, until the destination battery reaches something like 2.5v (15v per 12v battery, or 60v for a 48v pack). Then hold the battery at this voltage until a) the current falls under 2% of its amphour capacity, or b) the current stops falling, or c) some period of time has elapsed (1/2 to 4 hours). This would take a lot more effort to set up, but would also reach full charge much faster. -- Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius, and a lot of courage, to move in the opposite direction. -- Albert Einstein -- Lee Hart's EV projects are at 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)
