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poor perfomance!!

3225 Views 16 Replies 7 Participants Last post by  vpoppv, 
lou-ace
2010-12-03

A little disappointed today.( 1994 mazda b2300 chasis, amd4001 9” motor, curtis 1231c controller) I attempted the 20 mile barrier with the EV and almost didn’t make it back. Now it is cold 38-40 F. and windy I went 10 miles out and beat a 30-60 mile head wind on the return leg ( at 50mi/hr on a state highway), when I noticed a significant drop in voltage ( from 100-110) to 85-90 volts and had no more acceleration power. The last 5 miles to home was up some small hills where I could further appreciate decreasing current as lower voltage and no more than 300 amps, about 1 mile from home, up a small hill, I was slowing down loosing the remaining power I had, and I stopped at a pull of and shut her down. Luckily my wife was at home and I called her and had her bring the other truck and a tow cable. When she arrived I decided to have her just drive in front of me while I attempted to finish the last leg home up a small hill, about 10 minutes had elapsed. So I followed her up the last small hill back to the ranch, the EV now seemed to have all of it’s original power and I drove it home on it’s own power with plenty of acceleration @100+ voltage and plenty of amps. I immediately read all cells ( #20-6volt) and they read between 6.04- 6.08 with the majority @ 6.06, after 1 hour Eq. the pack read 121.3 volts. I don’t quite know how to interpret these values. But I was really hoping for a 30 mile range so that I could use the truck for a work vehicle ( I have a 28 mile commute to work with a charging station available there). The variables that I’m considering are #1 these are new batteries, and this is their 3rd cycle hopefully they will “ break in” a little bit, #2 it is cold and according to the chart (http://www.batteryfaq.org/ ) I was just under 50% SOC hopefully, when it is warmer these cells will give it up better, #3 I’ll have to try this again when I’m not driving against a hurricane. I may also try removing the air induction coil that I put on the motor ( go to EVamarica for this article) after the runs I’ve done this is the only thing, other than the motor, that gets a little warm with a hard run, my coil is 15ft of 1-0 copper between the windings. All connections and battery terminals have remained cool to the touch, I don’t think I have a connection issue. If anyone out there has any suggestions I’m all ears.
I guess the question that really comes to mind is; is this the kind of performance that I can expect with this setup? Or is it unrealistically low? Is there anything that I should be doing ( checking each batt. Closely, checking the drive for drag?), to increase range? Thanks again. Ps attached is an article from EV America for the induction coil.

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G
Sorry to say but lead will not get you very far at freeway speeds. I learned my lesson too with my electric Ghia. 96 volts worth of 6 volt batteries only got me about 20 to 25 miles at speeds of 45 to 65 mph. It just would not do any better. You could do better if you could add another pack to your system. In effect doubling the usable AH of your batteries. But then you must deal with serious weight. Most who get 40 or so miles from lead are doing under 45 mph. I just don't want a large golf cart. I want to be able to drive a decent distance at a decent speed too. Lithium is the only true way to go. Lessons have been learned. They are expensive up front but really do go the distance. It makes electric truly viable. I, like many before me had lofty goals and expectations but soon learned the truth. Many have given up on electrics because of this very thing. For short distances lead is great and viable but for longer distances nothing is really any better except maybe NiMH or NiCAD or NiFE. Those are also very expensive and heavy like lead. They are better than lead but not better than lithium. I think your right on the money on speeds and distance with your pack.

Suggestions: Put a good heat sink on your controller. Use good batteries. Change your low voltage cut off to a lower value if you can. Keep the rpms up but not too high. Find a good medium setting for the RPM and AMPS used. Monitor the Controller AMPS and Battery AMPS. Find your sweet spot and try to stay with that as much as possible. In stop and go traffic coast as much as you can. Brake as little as you have to.


Pete :)

http://greenev.zapto.org/electricvw
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Duncan
Hi lou-ace

(1) Get shot of that induction coil - all its doing is wasting energy!

(2) Loss of power and getting it back sounds more like a controller overheating issue to me
how good is your controller heat-sink?

You are marginal for achieving your aim -
go over the vehicle looking for dragging brakes and the like

Have you made any of the easy improvements to the aero?
Like blocking off the grill?
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D
Hi
I do not think your battereis are fully charge I have 12 volts battereis and have to charge them to 16 volts for a full charge. Try useing a hydometer it needs to read at the very top of the green also it will take about 50 DOD to get the batteries to there full proformance. Hang in there it will work. http://www.youtube.com/profile?user=htcracing#grid/uploads
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dtbaker
cold lead really takes a hit... probably -30% in range below 40F I'd estimate from mine. Especially with extended heavy draw from highway speeds. Floodies will have major voltage sag below 50%DOD combined with 'Pukers' effect.
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lou-ace
WOW! geat input guys!!!!

GODDTI, there is
a heat sink on the controller this is just a flat plate of aluminum pasted to the controller, I have a fan on top of the curtis 1231c and after all of the runs the controller feels slightly warm to touch on the bottom the top is cool, I don't know if I can change the low voltage cuttof on the controller, my sweet spot seems to be at 45 mph I can pull about 105v and 200 amps ( does this mean I,m pulling 21 kw vs. kwA? or is it the difference between my startig voltage 126v vs 105v <26v X200a = 5.2kwt>)?

Duncan, Yesss! I'm probably just 5 miles short of my goal! I'll
loose the induction coil easy enough. yes I've closed off the grill, I think I'll also loose the tail gate ( will use a cargo net gate).
the front end needs an alignment. I'll also hoist and rotate each wheel checking for drag. What do you think about 40-50 wt oil in the rear end? I've put 40 wt. synthetic in the tranny.

DRAGSTER;
I'm using the zivan 230v charger, but will do some hygrometry to certify charge!

thanks the encouragement guys, I'm really happy with the short performance of the rig and will continue to use the floodies as a grocery getter, for their life, that coupled with the optimizing that I'll do I'm already looking forward to switching to another storage medium in a couple of years. almost wish I'd waited a little longer and done lipo's now!!
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lou-ace
WOW! geat input guys!!!!

GODDTI, there is
a heat sink on the controller this is just a flat plate of aluminum pasted to the controller, I have a fan on top of the curtis 1231c and after all of the runs the controller feels slightly warm to touch on the bottom the top is cool, I don't know if I can change the low voltage cuttof on the controller, my sweet spot seems to be at 45 mph I can pull about 105v and 200 amps ( does this mean I,m pulling 21 kw vs. kwA? or is it the difference between my startig voltage 126v vs 105v <26v X200a = 5.2kwt>)?

Duncan, Yesss! I'm probably just 5 miles short of my goal! I'll
loose the induction coil easy enough. yes I've closed off the grill, I think I'll also loose the tail gate ( will use a cargo net gate).
the front end needs an alignment. I'll also hoist and rotate each wheel checking for drag. What do you think about 40-50 wt oil in the rear end? I've put 40 wt. synthetic in the tranny.

DRAGSTER;
I'm using the zivan 230v charger, but will do some hygrometry to certify charge!

thanks the encouragement guys, I'm really happy with the short performance of the rig and will continue to use the floodies as a grocery getter, for their life, that coupled with the optimizing that I'll do I'm already looking forward to switching to another storage medium in a couple of years. almost wish I'd waited a little longer and done lipo's now!!
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G
You need a good deep finned heat sink on the back of that puppy with a good fan that pushes some air. That factory flat plate was not designed to take care of all the required cooling. You MUST have a sink on the back of that. With this knowledge I am sure you are getting into thermal cut back. At least you know that is working. Get the heat out. Your controller will like you much better. You will like the bit extra it gives and you will like the longer life before you need to replace it too. Do not skimp in the area of controller and motor cooling.

Pete :)
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H
Not having an EV right now, I refrain from posting much.

However, I DO know, that pickups have terrible aerodynamics. My Son had a GMC S15. We were in home remodeling, and used it for hauling tools and supplies. One thing, being in the Upholstering type business, was to install a Tonneau Cover. We bought the correct Fibreglas stays and brackets, and made up our own cover. At 65+ MPH, the wind passing over the Cab, would slam those strips down, and make that Vinyl cover loose and floppy. First time, scared the crap out of us.

If you have light weight plastic sheet, and some lightweight strips, and want to experiment, this would be something to try. Will keep ice and snow out of the bed, if nothing else. That Coroplast stuff might be cheap enough to try ?? Run it from the top of the cab to the top of the tailgate. Even a camper CAP would be better than open bed. Maybe a used one ??

We had a Full size Chevy Pickup with a hardtop bed cover. It would get slightly better mileage than BIL's near identical pickup.

Those Cargo webs will still catch a LOT of air, and have no effect on the spillover of air over the cab.

Just some maybe useful info from where I sit. Yeah, Mythbusters says it's all bunk. I know better.
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G
A truck was designed for an open bed. It was never designed for a cover. Not even a camper. If you fill your bed with items then it would be fine to cover it to keep it in during travel. If empty, it's best left open with gate up.

Pete :)
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H
Can't agree, Pete. From things we have done, in the past, that turbulent air will put drag on the bed, needing a bit more power to maintain speed.

Just watch a Nascar Truck Race, and see what happens when they damage that bed cover.
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G
We are talking street car/trucks, not NASCAR are we. Trucks were not designed for NASCAR either so it's natural to modify to squeeze that tiny extra bit from the vehicle. I'd bet you can't even measure the differences at normal driving speeds. The poor performance is not coming from no bed cover.
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Duncan
Hi Guys

Lou said

Now it is cold 38-40 F. and windy I went 10 miles out and beat a 30-60 mile head wind on the return leg ( at 50mi/hr on a state highway),

That is a 90+ mph air speed - at that air speed things like the truck bed cover start to make a difference - I know mythbusters said that it made no odds but I think that was at 60 mph

Overall I think Lou is marginal on his aim but by fixing some small things;
Drag, controller cooling, aero
He should be able to meet his range needs

If he is too marginal in a bad headwind - how about scrounging/making an air speed indicator and keeping to a maximum of 70mph?? air speed?
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H
You win, Pete. I have NO personal spreadsheet stuff from the past 40 years.

Maybe the OP can just go to ecomodder.com and search for all the results that HAVE been documented.
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G
Not trying to win anything. All things considered I think he did quite well. Controller cooling and battery warming will yield more than a truck bed cover. Tire pressure is another as well. It's a truck. Not an Indy car. Not a NASCAR either. Most mods for the street don't yield much. Some but not much. If you want aerodynamic get an aerodynamic vehicle. Otherwise it is a decent performing truck. Even cooling the controller wont yield much performance but it could help gain a little distance which is what I think he wants anyway. Any vehicle will have trouble with a stiff headwind.

Pete :)
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A
Harold in CR said:
Can't agree, Pete. From things we have done, in the past, that turbulent air will put drag on the bed, needing a bit more power to maintain speed.

Just watch a Nascar Truck Race, and see what happens when they damage that bed cover.
Click to expand...
As shown on Mythbusters, with the bed open and the gate up, there is a "bubble" of slow-moving air formed in the bed, that carries the fast-moving air from the top of the cab over the bed and gate smoothly. With a cover in place, or the gate down, the air goes over the top of the cab and comes down hard on the bed of the pickup, causing much more drag and resistance.
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vpoppv
I'd put my efforts into battery warming. That will get you the extra distance you need IMO. My batteries have been rock steady at a 12.42v for the lowest one for months, but the second the temp dropped to around 30-40 degrees, my lowest is down to a frightening 12.02v at the end of my commute. Simply insulating the batteries will help.
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