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Discussion Starter · #21 ·
Well the tranny should take a while to pump up after it's stopped but Mizlplix eventually ran a external pump and a T&C flat track converterless kit. If it was a powerglide you'll wear the low bands out, I won't claim to be qualified on anything modern.

I run an alternator, back when I converted, dc-dc boxes were too low power and unreliable and I'm too lazy to redo, besides that's where the ac gets driven from. Figure 2hp at idle about the same as the power steering so 3-5hp don't sound all that wasteful even if it's 3kw.

Only thing I can think of is run it like a chevy small block and keep it in gear until 4,000 then shift up if you have the battery headroom to go that high. That should put you at 2500 max power but cooler. I have a 5 speed, so any time I'm below 2500, it goes down a gear even on the freeway. Kostov told me they tested them to 6000, mine has been to 5500 once (oops)
The external pump is an idea. Wouldn't take much for that.
 

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1. I have some concerns about this. Don't want to burn anything else up!

2. There's pros and cons to this. Being I don't have regen, the alt gives me regen, or at least free power to run the AC and fan while coasting. I also have a DC-DC I removed but installed it again temporarily a while back. Didn't make much difference.

3. I've studied motors and worked with them for decades in plants but I don't understand this in a DC motor, AC absolutely.

4. It is timed like it came from the factory. And to change that is not something I'm interested in at the moment. That may happen later but it's a PIB to work in that area.
1. Electric motors are not designed to idle, and idling at a low RPM there is not much airflow to keep the motor cool. = It's going to start getting hot even before you start putting a load on it. DC Motors are huge heatsinks that will absorb the heat but don't like getting rid of it. Once you get "behind the curve" then thermal runaway is inevitable.

2. Yes, the pro is that your truck drives. The con is that it isn't very efficient and you need to spend a bunch more money than you originally calculated on more batteries. If that's fine, then great. If you want to make your truck more efficient, then it's not great.

3. More voltage = less current for the same power. Less current = less heat, less wasted energy. More voltage = more RPM with less current, more speed with less current.

4. The timing is probably why it feels sluggish compared to your 9" motor. If you advanced the timing it will drive better. If you don't want it to drive better, don't adjust it. That simple.
 

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Discussion Starter · #23 · (Edited)
1. Electric motors are not designed to idle, and idling at a low RPM there is not much airflow to keep the motor cool. = It's going to start getting hot even before you start putting a load on it. DC Motors are huge heatsinks that will absorb the heat but don't like getting rid of it. Once you get "behind the curve" then thermal runaway is inevitable.

2. Yes, the pro is that your truck drives. The con is that it isn't very efficient and you need to spend a bunch more money than you originally calculated on more batteries. If that's fine, then great. If you want to make your truck more efficient, then it's not great.

3. More voltage = less current for the same power. Less current = less heat, less wasted energy. More voltage = more RPM with less current, more speed with less current.

4. The timing is probably why it feels sluggish compared to your 9" motor. If you advanced the timing it will drive better. If you don't want it to drive better, don't adjust it. That simple.
As an electrician of 40 years working with motors, I just don't see in a DC motor that "more voltage = less current". With an AC motor, lower supply voltage leads to higher current BECAUSE at lower voltage the armature is slower. More current is allowed because lower speed = lower back EMF but it's designed to run at X rpm. As more current speeds the armature rotation, the back EMF increases reducing current. The back EMF will almost = input voltage at it's design speed where current becomes steady due to the voltage and EMF almost being equal. In my mind it doesn't matter if the voltage is 10 or 100 so long as it can push the current to reach the rotation speed desired. I'm not so stubborn as to think I can't be missing something however. If I truly need more voltage, I need to understand why to justify spending the money. However a DC motor doesn't run at a fixed design speed, it's a totally different animal.

Also you know that the pack voltage isn't the same as the motor voltage due to the controller right? That said, if the pack is 160V and the controller is putting out 50, 80 or 100 volts to the motor and easily pumps more amps than the motor is rated, why do I need more pack voltage? That's the quandary I'm in now. Hopefully you or someone can clue me in.
 

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Discussion Starter · #24 ·
Just to be clear, I don't have an acceleration problem. It's more than I need in most cases. I did however see a substantial increase in torque when I added two golf cart 12V batteries in series with the pack. However since they died quickly I didn't finish my testing. They are being replaced in a few days so I may try it again with the new batteries and note any change in power use and heat.
 

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Discussion Starter · #25 · (Edited)
Yup still here every once in a blue moon. Hate the google educated bunch that comment but haven't built anything.

Reconfiguring it to parallel field seemed to help it and haven't noticed a reduction in performance.

Ooooh I like that concept, except that it might increase current significantly.

1. "Interpoles are counter wound coils that reduce back emf which leads to zorching the commutation at voltages above 150v" Did you mean "BELOW" 150v?
Nope above 150 the carbon in the brush gaps conducts or the air gap becomes inadequate and you get uncontrolled flashover. Two things: arcs erode the comm, and huge braking effect as the powered poles no longer align.
2. Can you explain why the voltage needs to go up? I could add some but I'd have to reconfigure the battery box and charger.

Doesn't need to go up, but the motor charts show as you increase voltage you conquer back emf , current requirements go down, possibly more battery capacity.........
3. Anything else that you can suggest other than a motor swap?

On a kostov, just go in there and disconnect the interpoles and make sure it it's neutrally timed, since they all seem to be retarded from the factory. Kennybobby did a how to maybe 10 years ago, but it's a common industrial maintenance.

If I need to boost the voltage, I certainly can. However the (200AH cells) Calb pack I run has lost some capacity, has about 15K miles on it. Not sure how much but a recent replacement battery voltage holds steady while the others have dropped a bit and it throws my balance meter out somewhere around 150AH of use. Where I once got about 90-100 miles on a charge, yesterday I ran it about 45 miles and the voltage was dropping fairly fast, down to 148V at 149AH depleted. So it would def help my range to go higher pack V.

Ok the timing. Maybe that's it. I'll have a look and go to neutral if that's where I need to go. I generally run the rpm low like a gasser would normally run thus the blower install. An recommendation on the timing with the rpm I use in mind?

Thanks a ton! Hope I can figure it out and that helps.
 

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Discussion Starter · #26 ·
One more note. Went to the Kostov site and ended up leaving a message about this. They say with interpoles the timing is different than standard motors and they are FACTORY SET at the right place. Moving them can result in motor destruction. Well IDK how they're supposed to be so I asked them. Don't want MORE issues!
 

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You want at least 2500 rpm when making power. I will keep on sayng that.
Retarding timing increases the high voltage tolerance so they do that. 4 degrees. They didn't admit the retard back 5 years ago until you asked what it was while replacing the brush plate.

Didn't know they were still in business, as I know they were purchased outright by some company in a neighbor place. I do know they weren't supplying parts last year when I needed brushes and definitely didnt answer the phone, fax, email.
 

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Discussion Starter · #28 ·
You want at least 2500 rpm when making power. I will keep on sayng that.
Retarding timing increases the high voltage tolerance so they do that. 4 degrees. They didn't admit the retard back 5 years ago until you asked what it was while replacing the brush plate.

Didn't know they were still in business, as I know they were purchased outright by some company in a neighbor place. I do know they weren't supplying parts last year when I needed brushes and definitely didnt answer the phone, fax, email.
I hear ya. However on their site it says the timing is retarded for interpole motors and set at the factory for that and that moving it risks damage to the motor. Didn't give any details or say how far it could move before damage would be likely. In that light I don't want to change it but if someone could explain it in a logical manner how moving it back to Zero wouldn't pose an unacceptable risk, I'll yank it and crank it!
Thanks btw!
 
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