Hi Jay, Indeed an 8' piece of cable 10 AWG copper has close to 0.01 Ohms of resistance. The Leaf modules have about 3 mOhm internal resistance so 0.006 for the series pair but you have 3 series pairs in parallel, so 0.002 Ohms in your case. Now for the internal resistance of the golf cart batteries.... I once had a 120V (20 GC batteries) truck that I remember the pack sagging quite hefty under full load, which was only 300-500 Amps. So, I am guesstimating that the internal resistance of a well-used Golf Cart battery might be as high as close to 0.1 Ohms.
So, my expectation of connecting your Leaf modules to the two GC batteries with the 10 AWG wire is that the Leaf modules will hardly sag, just go down with being discharged over time, the wire will not drop more than a few tens of volts and thus the GC batteries will be pushed close to 16V with the current probably somewhere in the 20 - 40 Amp range. The GC batteries will be fizzing and bubbling gas from being over-charged, but that is all. Try it and you will find out, this is just my expectation. Cor. -----Original Message----- From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of Jay Summet via EV Sent: Friday, September 08, 2017 6:11 PM To: Electric Vehicle Discussion List Cc: Jay Summet Subject: [EVDL] Dump charging from 16.4 volt Nissan Leaf modules to 12 v Lead Acid battery? I have a set of two (older) 6v golf cart batteries wired in series for a 12.5-14.5 volt system. The capacity of this system (measured after an inverter) is around 0.6 kWh, or around 30% of a "new" set of golf cart batteries. I also have a block of 6 Nissan leaf modules, 3 parallel 2 series, or 180 AH @ 16.4 volts fully charged. If I were to connect the charged Leaf modules (16.4 volts) to the discharged lead acid system (around 12.5 volts) with an 8' 10Ga jumper cable, what would happen? Obviously, the 180 AH of Nissan Leaf modules would be happy to provide more amps than either the jumper cables or golf cart batteries can handle. Since there is a 4 volt difference between the different battery banks, a 0.1 ohm wire resistance would give 40 amps, but a 0.01 ohm wire resistance would give 400 amps. (10 Ga wire is good for 30 amps, and could probably handle 40 amps, especially as the amps would go down over time as the voltages equalized...) I'm most interested in knowing if the lead acid batteries will draw more or less amps than the jumper cables can handle. (e.g. how resistance in the Lead Acid batteries interacts with the rest of the system). I figure somebody out there has some practical experience with transferring energy from one battery chemistry to another? Jay _______________________________________________ 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)
