1/2 HP ECM motor charging 12v battery at over 12v?

[FUEL]

Alright, so my uncle gave me a 12v battery (motomaster 520AMPS at 32F, 70min reserve) not i know that this battery is more then like toast but i thought i could use it to run a few tests. now when i got it it read 5V and 0.02amps. now when i hook it up to the ECM and run my drill it first went up to almost 80V, now as you leave it the volts start to drop, like now, after running it on and off a bit it seems to peek at about 30v, it's seems as it charges the volts from the ECM drops. what i want to know is, is this happening cause it's a dead battery or would the volts still go so high even with a new battery? cause when i hook up a 12V cordless drill battery it peeks at around 15.5v to 16v when it's fully charged

[ghurd]

The battery is toast.

It will not happen with a good battery.
It take a high charging amp to AH capacity ratio to get a good (new or functional) battery up to 16V.  16V is too much.

The bad battery is sulfated.  That means lots of crud on the plates.  The amps can not get through the crud as easy as they should, so the charging voltage can increase past anything normal.  The crud has a high resistance, so the ECM is sort of operating almost open circuit.
The high voltage broke through some of the crud, making a place where some amps can get through (effectively lowering the battery resistance).  That's why the peak voltage now is 30V.

Do not take the 12V drill battery past about 14.5V, or it will be damaged too.
G-

[FUEL]

Thanks, i was sure it was doing that cause the battery is done, just didn't understand how it all happen, thanks for the explanation. it was easy to get it to go from 5V to 9V but to get it to charge any more seems to be hard, i just wanted to see how much load the battery would put on the ECM, to get an idea if the blades i made will turn it.

the 12V drill battery is 5 years old and didn't hold a charge before i striped it apart and wired it up to the ecm, it seems to hold a charge a bit better now, seems to stay around 12V to 13V, discharges very quickly though, it was on it's was out the door when i thought i could use it for some tests, i don't imagine i'll use it for anything else

[ghurd]

Semi-loaded and 80V sounds like the ECM is still wired in the factory configuration?
That will put cut in at about ~110RPM depending on the version, and limit the peak output current to just a couple/few amps.

At the least, need to wire IRP.  Meaning snip the Star point, and run 6 wires out to 3 bridges.
The cut in will still be pretty darn low, probably stalling carved wood blades.  Maybe not so bad with PVC.
The peak output will be better in IRP than Star.  Maybe plateauing around 4.6A realistically with simple IRP.
G-

[FUEL]

Hmm, i will have to look into that some more, as it stands i get a max output of 2.7amps and i don't know at what rpm it's cutting in but i can reach 12V turning the shaft by hand/fingers. i made a few PVC sets of blades like many how-to's on the net, i made a 4 blade set out of 8" pvc pipe, each blade was 62" dia  and 4.5" wide and the widest, also made a 2 blade all in one out of 12" pvc, 46" dia and 4.5" wide. i only set it up on the top of a ladder, just pointed into the wind, no pivot, about 20FT off the ground in a residential area, with no load i would get around 30V with the 4 blades and would get around 50V or so with the 2 blade. so for now i'm going to try it with the 2 blade set up, was thinking of adding to more blades to it but shorter yet not sure what it would do and have had the time to set it up and test in the wind again

[ghurd]

the 2.7A is because of the extra coil resistance in Star.
IRP will make almost (not quite) twice the power.
46" dia PVC in simple IRP is plenty.  62" is too big.

Did you see this?
It is past simple IRP, but the idea is the same.
http://s701.photobucket.com/albums/ww20/ghurd1/ECM%20Conversion/

G-