I'm probably the last person in the state with a cordless mower, but I
like it because of the low noise and lack gas, fumes, lots of parts
that can break etc. I've always been able to do our entire 1/4 acre
lot on one charge, provided the grass is dry, but I admit it tends to
bog down near the end, and more so recently. (It's kinda heavy too.)
Bought it in '97 --a Toro Carefree 24(v).
I have just barely survival knowledge things electric so I'm seeking
If I could get a 20% longer run time I'd be happy. I took off the lid
of the mower. There are 2 12V batteries wired in series driving a 24V
motor. There's a empty slot for one more 12V battery. The label on
the batteries read: "Yuasa sealed rechargable lead-acid battery ylm
18-12 12v 17.2Ah voltage regulation 14.4-15.0V initial current 4.3A
I thought I would buy and install an extra 12V battery of similar
amp/hours and form factor. (Found one at gotbatteries.com.) I'll wire
the new one in parallel with the original two (keeping those wired in
I can't find much out about the internal charger (You plug this mower
into a 120V socket to recharge.), but the charger is still going to
see one 24V battery anyway, right?
Do you think my idea will work or am I missing something?
PS. I called Toro (who no longer makes cordless mowers) and they
"didn't recommend" my idea, but I believe they're just being legally
careful. Also I'm gonna strap 15 lbs of barbell plates to the mower
to test if I can tolerate
the extra weight!
I think that your idea will not work. Simply put, the batteries you have now
are set up to behave like 24 volts. If you wire a 12 volt battery in
parallel, it's going to try to dump the higher voltage (24V) into the single
odd battery, and fry the second battery.
I'm guessing that the replacement battery was quite pricey.
Now, if you wanted you could get two garden tractor batteries at Walmart,
and wire them in the same as the other ones (plus and minus and all that).
They likely aren't the same size, though.
I had a battery booster pack from BJ's Wholesale club (for jumping car
batteries) and the light got left on during the winter, and froze the
battery. I got a garden tractor battery and moved all the wires and such
from the jump pack. Oughta work. Right?
Only other difference, the garden tractor batteries are starting batteries,
not deep cycle. I'd suggest either two new Yuasa batteries (simple
replacement of the two you have) or mow the lawn in two days. Those sealed
cells do get weak after a couple seasons. Brand new ones may well have the
extra 20% you desire.
you have 2 12 volt batteries wired in series to make a 24 volt battery??
if that is correct then adding a 12 volt battery parrallel i gonna give
you something like this... 24 volts + 12 volts = 36 volts divid by 2
gives you 18 volts.. so you gonna loose power and not get 24 volts to
the motor... why not just replace the two old batteries at a higher
amp. hour rating and that should make it work longer... make sure the
wheels turn freely and the blade is not full of cord/string around the
shaft, that will show it down... a mower bought in 97 might just be on
its last leg... any rechargable item i ever bought did not last very
Just on the remote chance this isn't a troll... If you connect a single
12v battery in parallel with a 24v battery (of which the two you now
have is the equivalent), you will probably get an explosion, spewing
battery acid and battery parts for a fair distance, blinding you and
causing acid burns and lacerations to your upper body and face. What
happens is that excessive current will flow through the three batteries,
now in series, with one wired backwards, causing the electrolyte to
boil, creating enough pressure to rupture the case of one or more of the
batteries. You might get away with paralleling another set of two
batteries, or one 24v battery, but there are precautions to be followed
to equalize the charge state between the two sets of batteries. It is
generally not recommended to operate a new set and an old set of
batteries in parallel, anyhow. All in all, leave the thing alone.
email@example.com (wahzoo) wrote in message
As others have pointed out, the third battery will not work as you
need to keep the battery stack at 24V, something you cannot do with 3
12V batteries. 6 years is a very long service life for a lead acid
battery (when was the last time a car battery lasted you 6 years?).
Replacing only one will only help a little as both batteries have aged
equally. Safest bet is to go with the exact replacement. Next
safest, get a suitable replacement of the same Amp-Hour rating, so
much the better if that lawn tractor at walmart fits the bill. If you
decide to go with a higher amp hour rating battery, the charger may
give you problems.
Sorry, adding a third battery couldn't possibly work the way
you want to wire it unless it was a 24 volt battery. Before
you go looking for a 24 volt battery (and get stuck with
having to determine if your charger will still work),
however, I have some other suggestions.
Batteries will "behave" better if they don't get too warm -
so perhaps a few 10 minute breaks while cutting will stretch
the duty cycle a tad.
Another possible help might stem from the fact that some
oxidation (was it oxidation, sulphation, or some other
reversible chemical consequence, darned if I remember off
the top of my head!) occurs with fast chargers - so if the
charger that comes with the mower has an charge rate
incompatible with getting the most from the batteries over
time, a slow charge a time or three <s> per season might
return some capacity.
To check this out, I would obtain a 12 volt slow charger
(couple hundred milli-amps maximum charge rate) and use it
for about 14 - 20 hours on each battery, ONE at a time.
Testing is strictly a "proof's in the pudding" situation...
Oh, the more work the motor has to accomplish, the more
quickly the batteries get run down - so let me also suggest
keeping the blade sharp and well balanced.
How dumb. I wrote it bass ackwards. I meant that I'd wire the two
original 12v batteries PARALLEL and then 3rd new 12v battery in SERIES
with those, giving 24v.
So would that work? What's wrong with it if it doesn't?
Well, now, if you wire the old + to the other old battery +, and wire the
old battery - to the other old battery -, and then wire a combined - to the
new battery + and then wire the old battery + to the machine, adn the new
battery - to the machine.... now we're talking.
Say your old batteries are about half dead, then side by side they would
just about equal one new battery.
I think you're on to something.....
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