Permanent Magnet DC motor ?s

Caver Dave

Caver Dave

Just holdin' it down here in BFV
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Mar 10, 2005
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Figured someone on here may work in the DC power industry or have some knowledge on the subject...

Anyways, today I grabbed an old GE permanent magnet DC motor (off an old LawnBoy Cordless electric mower), in hopes of using it to power a small gear pump (SBC oil pump).

I'm unable to cross reference the motor (model# 5BPA34NAA44) to get the specs, but suspect it's 36VDC (my pappy believes it had "3 motorcycle type batteries").

Can I run this off 12VDC? If so, what are the cons (reduced life, less torque, decreased speed)?
 
Less power, less torque, and depending on the load, a lot of heat.

When I replace the brushes on the hydrulic drive motors on the electric lifts I use my battery jump box to run the motor while I dress the commutator, the motor runs but at a much slower speed and much less power. it drained the heck out of my jump box, but it's easier to do it this way on a bench than when the motor is in place in the machine and running on 24/36/48 volts.
 
Thanks Kevin... I tried to bump it over via my booster box (dead :mad: ) & it spun VERY slowly... like 60rpm. Also tried with a 1/2 size lawnmower battery (also near dead :mad: ) with NO rotation.

I'll try to spin it with my fully charged Redtop in a bit and see what happens, though it does appear I'll need at least 24V just to make any power. Might be back to the drawing board time! :rolleyes:
 
What about using a step-up transformer, or some similar device to get you up to 36v? will that add too much heat/trouble to be worth it?
 
Dave - what the hell are you building now ? A transformer could be cheep if you scrounge one. BUT may be hard to find one to exactly match your needs.

Possibly you could find a different motor maybe a starter motor ? fan blower motor ? wiper motor ? something thats already 12v ?
 
Transformers and DC are mutually exclusive by the laws of physics. Anything in the DC voltage boost genre will be much expensive if it's expected to carry a dynamic inductive load and work for more than a very, very short period. There were some military DC boost units on one of the surplus sites recently, but they were 24-28 volts and they're BIG, so probably not much use.
 
yager said:
Dave - what the hell are you building now ?
Click to expand...

Was hoping it'd power a geared oil pump (now leaning towards Mopar since they're tapped) to use for grease collection... perfect for collecting when grease is more like crisco!

12V starters aren't designed for continuous ops and I'd just as soon not have to pump in 30 second cycles! :D

That's what I figured Bruce... either too huge or expensive to deal with.
 
Thought I'd revive this for a followup...

Having multiple batteries to juice this POS enough to pump was gonna be a PITA. Ended up with a cheap 1/2" drill spinning a SBF(ord) oil pump because of the 5/16" hex drive (a weak point for SBF builders, not an issue for pumpers :flipoff2:)

Next wild @$$ scheme is using the 36V DC motor as a generator in a wind generator setup... :lol:
 
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