Found this as I was digging in the Bedini SG group..... Might hold an answer about matching the impedence with the target set of batteries.....

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Hi Monsieur and ALL,

if your batt's only last 1 hr, then you are pulling them down WAY WAY TOO FAST

<snip>

John has stressed this to me, that the SG is a 1 to 1 charger, what
you put in, you get out, no OU..... But when you charge 4 or 5 batts
from one batt that is a matched set, you get 4-5 charges for the price
of 1, so long as you follow the batt rules..............!!!!!

1. Never discharge a batt or bank, faster than C20, anything less is ok up to a point,
and on these small batts C24 rate is more like it.....
Roamer has posted how to figure the C20 rate calculations elsewhere on
the SG fourm.........

2. never go below 12.00V on the small batts, starter batts and marine
deep cycles, and 10.5V on the true deep cycles golf cart, solar Batts,
etc....

3. because of the currentless radiant spikes charging the batts, they
will start to last longer at that C24 rate, and charge up faster every
time, once they have been through a few cycles and
conditioned..............

4. Your coil or coils should match your matched set of batts..... if
your C24 rate is .4 amp, than you can't pull a very big coil or only one
coil, if the C24 is more like .8 amp than you can pull a larger wire
coil at .8 amp, or 2 smaller wire .4 A coils that at their higher rpm
might only pull .6 amp between them, if you have a big marine deep
cycle batts it's C24 at some thing like 1.2 amp than you can pull a
really big wire coil like Roamer talks about, or you can pull 2 .6
amp coils or 3 or 4 smaller amp coils
sweet spot = highest rpm / lowest current draw point of a coil or
coils, right before more resistance will make extra pulses......
bigger wire coil = higher rpm, more current,--- more smaller coils =
higher rpm at less current draw for each coil because of the higher rpm,
but more total current than just one coil
and all this depends on your rotor number of magnets etc as far as what
the sweet spot rpm and amprage is gona be for a given coil size or
number of coils running at that sweet spot rpm

you want to charge as many batts as possable, from one rotor all the
time, if you are not charging 4 batts from one batt even if you have to
let the trickle charger make up the diffrence for a while, than ya aint
getting it..........

pay for 1 charge, get your first charge back, and 3 charges for free,
or pay for 2 and get 6 for free at a higher rpm...........

if you got it running so that you are getting the first one back and 3
for free, every time you discharge 1 of the 5, then as John says you
should be jumping up and down........

OK as John says, one more time, how much current comming from the
drive Batt, vs how much current is going to the charging batt, is not
what we are looking for here, when tuned to the sweet spot, the
charging current will ALWAYS be FAR LESS THAN the Current Driving the
Coil...!!!!!!! SO, what is charging the batts.....? the CURRENT
LESS Radiaint Voltage Spikes.... so forget about the in/out current
ratio thing and LOOPING as that is not where the magic happens,
it's really all about the batterys, and NOT about the motor.........

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If I am reading this correctly, then the coil we have should match the c-20 rating..... small coils for small batteries, and larger coil / wire for the big batteries.

So.... since I am drawing 2 amps to charge my golf cart batteries, I might need the heavy duty speaker coils to match.......

So... am I to have a resistance of 2 amps if my c-20 rate is 2 amps in my coils?