[josmeijer]

The horesepower we use for electric motors here in Europe is rather straightforeward.

it´s 1,36 horespower roughly in a kw.
all other horsepowers (EPK, IPK etc) are long forgotten, though they might be used by vague merchants to whip up the power (just like speaker-watts)

But type-plates are reliable enough to stick to the */1,36 to use in your calculations.

 

[josmeijer]

no worries, you won´t wreck any motor if you test it on a lower voltage as it is designed for, if it is able to run freely.

 

[josmeijer]

But can you find a single phase AC motor with anywhere near the peak power required for an on-road EV?

single phase AC motors are no option.
They have near-to-none starting couple while using up to 30 times nominal amperage until at their top-speed.
You should use triphase motors that are dumped 100 a day by industry so can be found on any scrapyard is all (k) wattages and speeds.
Next thing is to convert DC to triphase AC.

Inverter motor controllers (also industry standard, and easily obtained on ebay etc at reasonable prices) can be fed by DC
simply multiply the input voltage with 2 sqrt (roughly 1,4) and you have the required voltage.
So 110 v AC gives 162 DC volts.

Inverter motor controllers come in single-phase in / three-phase out that are rather popular.
They exist in up to 3 kw /220-240 volt in and >500 kw in threephase.

For more power you have to get three phase in/out types. These can be DC powered too, by paralleling the phases.
(first stage of any inverter controller rectifies the AC so phase is no issue, but you should check wit the manufacturer if this can be done without triggering some safety)

Yet the drawback is the high battery voltage but, as our soccer-idol Johan Cruyff says: "every disadvantage has it´s advantage" : you save many kilo´s of copper wiring and you might get a nice deal on small standard AGM batteries.

Finally,if you want to dig into it, most inverter controllers can do DC braking wich can be used to convert braking energy into battery power (instead of useless heat on your brakes).

But I must honestly say that all I state here remains theory for me.
I have lots of plans but all reside on paper until now.

 

[josmeijer]

It is not impossible that those firms find it more profitable to replace the motor with a new Chinese or salvaged motor.
Yet, in my opinion the best place to get it (and where I got mine) is from a firm that sells and maintains forklift trucks.
They usually take in the old when they sell a new one and the majority of these is wrecked.
I asked them to look out for one and I paid their time to disassemble it.

 

[josmeijer]

A1 and A2 are the rotor connections and S1 and S2 are the (serial) field connections.
So if you connect A1 to the battery and S1 to A2, it should run one way if you connect S2 to the other battery pole, and the other way with S2-A2 interconnected and S1 on the battery.
If that trick doesn't work, I fear there is some massive short cirquit in the field winding or in the wiring.

 

[josmeijer]

Re: Finding a motor on a (cheap)budget

CW- S1 to battery; S2 to A2; A1 to other battery terminal.
CCW- S1 to battery; S2 to A1; A2 to other battery terminal.

if I´m not mistaking I said the same, , though phrased a little differently .

But after some close reading (wich I didn´t do the first time) I found that you changed the polarity of the battery and left the field alone.
So there is probably nothing wrong with the motor.
What you should do, is changing the polarity of the field, (swap S1 and S2) en never mind the polarity of the power source to change direction.

 

[josmeijer]

Forklifts:

The battery is the most expensive part, often over $5k.
(....)

A busted electric forklift is often dirt cheap after you subtract the resale value of the battery. The batteries are often over 2000lb, mostly lead. Scrap batteries are 30 cents US a pound, so over $600, and the lift can be had for $500. What's the catch? A forklift weighs 4500+ lbs. You must pick it up in person.

You should get them in Holland, I pay 1,8k€ (roughly 1,4k$) for a 24v set of 700AH tubular batteries (and real good ones, I bought them in 2000 and they still have approx. 90% of their initial storage capacity by daily use).
So for a 48v forklift that would make 2,8k.

Batteries are seldom really dead. If you buy the forklift with batteries that need replacement you stilll would get a couple of miles out of them after thoroughly loading (and refilling with distilled water) so if you can get it anywhere in the neighbourhood you could still drive it to your garage if you´re lucky.
Nevertheless I would still recommend paying the firm that scraps the thing to unmount the motor at a reasonable price so you are not left with 4100 tons of scrap, and they can still sell it for roughly the same price so everybody happy.
I don´t now how regulations are in the US but here lead-acid batteries are virtually worthless, as nowadays they only accept empty ones that are cleaned from any trace of sulphuric acid and you have to dispose of that acid in a legal way so any profit on the lead is eveporated on advance.