Dump charging from 16.4 volt Nissan Leaf modules to 12 v Lead Acid battery?

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Dump charging from 16.4 volt Nissan Leaf modules to 12 v Lead Acid battery?

Electric Vehicle Discussion List mailing list
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
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Re: Dump charging from 16.4 volt Nissan Leaf modules to 12 v Lead Acid battery?

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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:[hidden email]] 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
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Re: Dump charging from 16.4 volt Nissan Leaf modules to 12 v Lead Acid battery?

Electric Vehicle Discussion List mailing list

> 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.

Or maybe the insulation on my jumper cables will start to melt and smoke
will shoot out of little holes.....[had that happen one time....] I
guess it all depends upon the internal resistance of those golf cart
batteries....

> The GC batteries will be fizzing and bubbling gas from being
> over-charged, but that is all.

(I'd probably disconnect them once they reached 14.5-15 volts...this
isn't something I'd leave unattended....)

>
> Try it and you will find out, this is just my expectation.
> Cor.

The other option is that I have a 500 watt 12 volt power supply, so I
may just use that to "top up" the lead acid batteries from full pack
voltage.

Jay
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84 volt converter dc to dc

Electric Vehicle Discussion List mailing list
 My scooters dc to dc is getting warm I what to run more led lighting do I
looking for a extra power probally  20-30 watts. And yes I'm reducing my
incandece load .

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