I tested the Power Supply thing and was not happy with the results. I bought a MEANWELL SP-480-48 48V 10A supply for $90 off of Ebay. It's been quite a while since I tested it, but I think I was not happy with the current limiting and was afraid that I would always be running it too close to it's max. I believe there are simple add on circuits you can use to overcome this, but the Chinese chargers I went with were in the same relative price range (a little less expensive) and were turnkey.
Damon ________________________________ From: EV <[email protected]> on behalf of Cor van de Water via EV <[email protected]> Sent: Tuesday, January 30, 2018 3:36 PM To: Electric Vehicle Discussion List Cc: Cor van de Water Subject: Re: [EVDL] Leaf module charging recommendations Fred, So your meter indicates 3.54V as 3.56 or 3.57 which is less than 1% error. For Lithium the nominal voltage is not when pretty much dead as Lead, but closer to the halfway point. Since your pack is pretty low in charge, below 20% I am guessing, the total pack voltage is well below the nominal voltage, which is 12 x 3.8 = 45.6V Max charge voltage of each cell is 4.2 but I would suggest to keep it under 4.1 if you are not required to get the absolute max out of the pack at all costs. If you are doing a race for max distance then go ahead and aim for 4.2 or higher, but in daily operation if you want longevity, then I suggest you charge to 4.1V. You will need a (simple) BMS to tell you when a cell goes over 4.2V or under 3.0V and preferably does some low-current balancing for you, for example the Leaf BMS has 10mA balance current and runs 24/7. You definitely want to get a signal from the BMS when any cell is hitting its limit so you can either drop a contactor (to stop charging or driving) or at minimum get a very noticeable warning that something is going out of spec, so you can respond to it (especially while driving, since during charging you are likely asleep). 12 x 4.1V is 49.2V which is a convenient voltage that most 48V power supplies can easily be trimmed up to using the trimpot on the supply. I have very many 48V power supplies, so let me know if you like to talk about getting one. In fact, last week I disassembled an Enginer unit, which is a 48V Lithium battery pack for a Prius with a charger and a DC/DC converter to the Prius's Hybrid packs ~200V, 5kW. I do not trust the BMS that came with it as most batteries were toast, but you are welcome to experiment with it if you like. Success, Cor. -----Original Message----- From: EV [mailto:[email protected]] On Behalf Of fred via EV Sent: Tuesday, January 30, 2018 3:15 PM To: via EV Cc: fred Subject: [EVDL] Leaf module charging recommendations Thanks to Jerry Dycus for selling me a great looking clean Volt battery module. My still-working Radio Shack (top of the line) digital multimeter tells me all the cells are within 0.01 at 3.56 or 3.57 volts. I've found this useful bit of data: Number of cells 36 Construction 12 in-series x 3 in parallel Length 9.5" Width 9.5" Height 10.5 Weight 45 lbs Output terminal M6 nut Amp Hour 47 Total Voltage 48vdc CELL SPECIFICATIONS Cell type Laminate type Cathode material LiMn2O4 with LiNiO2 Anode material Graphite Rated capacity (0.3C) 17 Ah Average voltage 3.8 VDC Maximum Voltage 4.2VDC Minimum Voltage 3.0VDC I measured 42.5vdc across each 12 cell block and the math says it should be 42.72vdc, which is close enough for my meter. It's not 48vdc and from an earlier discussion I expected that to be the case. When it comes to charging this battery, I would like to ensure to get the right stuff. My experience with other lithium based batteries is that the nominal voltage of the charger is referenced to the battery and in all cases, the battery voltage is higher than the nominal voltage "listed." That is to say, a 36v battery charges to 42vdc and rarely drops to the 36v reference figure in regular use. The charger, of course, pushes electrons into the battery at those higher levels. In the case of the Volt battery, I believe I would not want to use an off-the-shelf charger rated for a 48v battery. My search results have all been ending in devices with excessive top-end termination. I would like to have an off-the-shelf solution, however, if such a charger exists. My current collection of chargers are plug-in and go type, in that they have appropriate profiles for charging to a specific level and tapering off as appropriate for the pack. As an additional consideration, this battery does not need to be charged in an hour or even two or three. I'm amenable to a configuration that requires a ten hour or longer charge period, especially if cost is lower. I welcome corrections to my train of thought, even to the point of derailment as appropriate. I'm hoping for an off-the-shelf solution that works out-of-the-box or works with appropriate adjustments on the panel or equivalent. -------------- next part -------------- An HTML attachment was scrubbed... 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