5 Cell Lipo to start my old Sears lawn tractor

[Ypedal]

Not sure what the repercussions of doing this are.. but so far it works.

My old Sears lawn tractor's battery is shot, the belts are worn beyond imagination and with the clutch fully pressed the belts still drag making it difficult to start, put a meter on it and it peaks at over 200 amps on 12v ( with an A123 4S 2P M1 cell pack ) it would turn over slowly and not fire up..

with a 5 cell Lipo however, she turns over !!.. I quickly pull the wire as soon as it starts but what nasty things can i expect from this ?.. the 12v charging side of the tractor feeding a 20v lipo ?

 

[amberwolf]

Perhaps melting the starter?

Damaging ignition relay(s)?

Anything that has to handle the startup current has to handle the amps you're drawing, so if it's not made for the current it's drawing under present conditions, it could suffer over time.

Also mechanically, if there's that much torque required just to get it started becuase fo the wear/etc., stuff not intended to take that torque will wear faster or potentially break/shear.

Engine (not starter) will also run hotter if it has to put out that much more torque all the time becuase of that loading, and use more fuel, etc.

 

[Ypedal]

Well, all that is pretty much acceptable right now, the motor belches smoke when it first starts ten runs clean once warm but the entire thing is on it's last legs, i'm just trying to stretch every last bit from it without spending anything on it lol.. when the motor eventually does die, i'd like to make it electric !.. i have an Agni95r motor on hand already.

 

[amberwolf]

Probably belching smoke from oil leaking thru the cylinder rings until it warms up enough that they fit more tightly.

 

[MrDude_1]

A 4cell lipo (16v) will start just about any 12v car, motorcycle, boat, tractor, etc.. motor.
Once started, they will "charge" to 13.2-14.5 volts give or take a few points... so they never "charge" a lipo at all... the voltage potential is never higher than the battery.

assuming your tractor is like every other one I have worked on, the 20v 5cell will work just fine to start it. Just remove it afterwards..... but dont do any long cranking on it. In otherwords, if it doesn't start because of some engine problem, dont hold the key down and crank it for 10 seconds to fire it over... the motor or the solenoid will overheat.

 

[Ypedal]

Ok, that's what i was worried about, so the 18~20v lipo will not mess with the ICE's 12v charging system, just won't take any charge from it.. ( and that's perfect, it only takes about 3 seconds turning over to fire up, even in this cold weather )

 

[Ypedal]

don't really care about the lipo.. i got lots of scraps to pick from