I can't tell you about the Leaf packs, but when I built my electric lawn
tractor, I wound up with a used Volt pack from HybridAutoCenter

Specifically the 48v/47ah Volt pack -

It was $430 plus freight, which brought the price to around $500.

I also bought a low end BMS from them for $150, and $165 for a 10amp charger.

The BMS does balancing and prevents overcharge, but the operator (me) is
on the hook to not over-discharge the batteries.  I just watch the

12s pack of Volt modules.

Mine has no coolant, but was still bolted together.

The charger shuts off at 50V.  I stop cutting operations at 42V.  When
mowing and it drops below 42V, shut the mower deck off and the battery
voltage recovers to ~44V and there's plenty left to drive around and
return home.

(I also use it to plow snow in the winter - the electric tractor has never
failed to start, even at -20F)

I'm use the Motoenergy motor.  I estimate a 100amp draw average while
mowing - my 2kwh pack gets me 20 minutes of grass cutting, give or take. 
That's enough to cut the front yard or the back yard at a decent pace, or
both if I do it all in 5th gear. :D

Charger takes several hours - I think 8 or so - to restore the battery. 
It is short enough that I can mow first thing in the morning and do it
again in the late afternoon - but also long enough that I can cut the
front yard one evening and not feel guilty about letting it charge
overnight and resuming the next day.

The motor is a permanent magnet, rated at "48v" and does just fine.

I keep toying with getting a second 2kwh pack and paralleling them.  The
current pack sits up front, between the grille and motor.  I have room for
a second pack between the motor and steering column, still under the hood
- and also, I think, room under the seat where the starter battery used to
be, above the pulley and main drivebelt for the transaxle.

My biggest issue with the 12S Volt pack - I had hoped to run lead, with
multiple taps at 12, 18, and 24V available so I could use the tractor as a
power supply for my DC spool-gun welder.  Drive to the location.  Hook the
welder to the supply, weld, drive back.  Unfortunately, 48V is not only
"too much" but beyond the spool-gun's limits as well.  (18V is probably
the right voltage for general field welding).

Perhaps I could tap off the series-connecting "foil" connections on the
top of the battery back, but I haven't been that ambitious.

I used a 48-->12Vdc converter to run the head lights, and provide a power
port for field-operation of the amateur radios - but haven't found an
inexpensive 48->18 solution that supplies enough current for the welder.

I'll live with it. :)

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