[exchaoordo]

I've got a 72v system using 9 8-v Eveready golf cart batteries and an Alltrax controller and a D&D motor on a 1971 Beetle -- basically a Wilderness EV setup that I bought almost finished.
I'm finding a maximum range of 10 miles in mixed driving, which seems low. Since I don't know the car or the batteries or the motor I want to know if I'm way off and what to do about it. I understand that the batteries may not take a full charge if they are new, but I had it up to 76.9 volts today; I also understand that the motor brushes need to run for a while, but I don't know how long or how much difference this would make. I don't have any idea how many hours are on the motor, but not many I'd guess.
Other than that I wonder about tire pressure, transmission losses, etc. It seems to shift fine and the tires are about 32 psi (more than the Beetle wants). Any advice for this new EV owner is much appreciated. I've been doing a good job with the volt and amp meter on the system -- many thanks for the replies to my last thread. I can even now connect my computer to the controller and get a mountain of data, not much of which means anything to me offhand, but it did tell me that the throttle is going to 100%. Should I worry or will this improve do you think?

 

[GerhardRP]

I can even now connect my computer to the controller and get a mountain of data, not much of which means anything to me offhand, but it did tell me that the throttle is going to 100%. Should I worry or will this improve do you think?

Send me a mountain of data and I will try to say something. Ahead of anything, sticky brakes is a place to start for poor range.. Is anything warm after a drive? your in a PM.email
Gerhard

 

[alvin]

http://www.diyelectriccar.com/forums/showthread.php?t=11709
If you go to this link and work the range formula backwards for your battery type and amp hour rating you should be able to determine if that is normal or if something else is wrong.

 

[GerhardRP]

I've got a 72v system using 9 8-v Eveready golf cart batteries and an Alltrax controller and a D&D motor on a 1971 Beetle -- basically a Wilderness EV setup that I bought almost finished.
I'm finding a maximum range of 10 miles in mixed driving, which seems low. Since I don't know the car or the batteries or the motor I want to know if I'm way off and what to do about it. I understand that the batteries may not take a full charge if they are new, but I had it up to 76.9 volts today; I also understand that the motor brushes need to run for a while, but I don't know how long or how much difference this would make. I don't have any idea how many hours are on the motor, but not many I'd guess.
Other than that I wonder about tire pressure, transmission losses, etc. It seems to shift fine and the tires are about 32 psi (more than the Beetle wants). Any advice for this new EV owner is much appreciated. I've been doing a good job with the volt and amp meter on the system -- many thanks for the replies to my last thread. I can even now connect my computer to the controller and get a mountain of data, not much of which means anything to me offhand, but it did tell me that the throttle is going to 100%. Should I worry or will this improve do you think?

Hi Dan,
I got your data dump.
My first guess is that the Peukert effect is robbing your amp-hes.
Do you have specs on the batteries re: amp-hrs [or model number or physical size.]
Gerhard

 

[Russco]

I've got a 72v system using 9 8-v Eveready golf cart batteries and an Alltrax controller and a D&D motor on a 1971 Beetle -- basically a Wilderness EV setup that I bought almost finished.
I'm finding a maximum range of 10 miles in mixed driving, which seems low. Since I don't know the car or the batteries or the motor I want to know if I'm way off and what to do about it. I understand that the batteries may not take a full charge if they are new, but I had it up to 76.9 volts today; I also understand that the motor brushes need to run for a while, but I don't know how long or how much difference this would make. I don't have any idea how many hours are on the motor, but not many I'd guess.
Other than that I wonder about tire pressure, transmission losses, etc. It seems to shift fine and the tires are about 32 psi (more than the Beetle wants). Any advice for this new EV owner is much appreciated. I've been doing a good job with the volt and amp meter on the system -- many thanks for the replies to my last thread. I can even now connect my computer to the controller and get a mountain of data, not much of which means anything to me offhand, but it did tell me that the throttle is going to 100%. Should I worry or will this improve do you think?

Yep, I've got a 71 super Bug also. You can read about it at Russco EV:

http://russcoev.com

The Wilderness Kits are basically the cheapest components available. And you get what you pay for, both in performance and life span.

Let's start with the system voltage. Seventy-two volts is very low for an on road EV. Lower voltage = low top speed, about 45 MPH. Low top speed = driving in third or fourth gear, which increases the motor current, equating to an even lower top speed. The D and D motors are an odd ball underated motor that tends to overheat and is waaaay too small for the VW.

The 8 volt batteries are not recommended for they have only 6/8 the current of a 6 volt golf cart battery capacity and when coupled with the low volttage system, lead to a great sag under load and short lifespan.

In my experience, the motor should be over 100 pounds, the batteries at least an 84 volt system of real name brand 220 AH golf cart batteries. Anything less leads to an unexceptable wimpy EV conversion.

Been there, done it all in 30 years of conversions.

 

[DIYguy]

I've got a 72v system using 9 8-v Eveready golf cart batteries and an Alltrax controller and a D&D motor on a 1971 Beetle -- basically a Wilderness EV setup that I bought almost finished.
I'm finding a maximum range of 10 miles in mixed driving, which seems low.

Without running the numbers... I'd say it sounds about the right range for what you have.....

 

[GerhardRP]

Hi Dan,
I got your data dump.
My first guess is that the Peukert effect is robbing your amp-hes.
Do you have specs on the batteries re: amp-hrs [or model number or physical size.]
Gerhard

Hi,
In your email, you asked if a data set at full range would be useful...YES. Also, if you could let the car rest for at least 6 hours afterwards and measure the pack voltage for DOD, that would be great.
BTW, your battery power useage comes to 170 W-hr per mile and 141 to the motor.
Gerhard

 

[vpoppv]

My car has a much smaller motor than yours, and some very, very used batteries, but when I start off in the morning I'm at 78.2 volts. And that is not right off the chargers, that's at least 12 hours after charging is done. I'm using 12v batteries though. My guess is you should have a higher voltage reading than me even though you are running 8v batteries. Have you taken any voltage readings of each battery? That's where I'd start anyway.....

 

[jockepocke]

My car has a much smaller motor than yours, and some very, very used batteries, but when I start off in the morning I'm at 78.2 volts. And that is not right off the chargers, that's at least 12 hours after charging is done. I'm using 12v batteries though. My guess is you should have a higher voltage reading than me even though you are running 8v batteries. Have you taken any voltage readings of each battery? That's where I'd start anyway.....

I had a similar problem, getting about 7 km of range instead of calculated at least 25 km. Some measuring revealed bad batteries, and I am having them replaced by warranty!

Measure you cells after driving, if some are significantly lower in voltage, look out! I drove with a voltmeter connected to one of the worst cells, and it plunged from almost fully charged to negative volts as I hit the accelerator!

 

[CRW]

I've got a 72v system using 9 8-v Eveready golf cart batteries and an Alltrax controller and a D&D motor on a 1971 Beetle -- basically a Wilderness EV setup that I bought almost finished.
I'm finding a maximum range of 10 miles in mixed driving, which seems low. Since I don't know the car or the batteries or the motor I want to know if I'm way off and what to do about it. I understand that the batteries may not take a full charge if they are new, but I had it up to 76.9 volts today; I also understand that the motor brushes need to run for a while, but I don't know how long or how much difference this would make. I don't have any idea how many hours are on the motor, but not many I'd guess.
Other than that I wonder about tire pressure, transmission losses, etc. It seems to shift fine and the tires are about 32 psi (more than the Beetle wants). Any advice for this new EV owner is much appreciated. I've been doing a good job with the volt and amp meter on the system -- many thanks for the replies to my last thread. I can even now connect my computer to the controller and get a mountain of data, not much of which means anything to me offhand, but it did tell me that the throttle is going to 100%. Should I worry or will this improve do you think?

Hello - Sounds like you might have a soft battery or two. You can measure the voltage across each battery and see if one or more is drooping under load. Ideally they should not dip more that 2 volts. (I have run some into the ground.) See if you have a battery that drops voltage much quicker than the rest. That is the weak link that will bring down the pack. Beware. He can be a bad influence. You don't want to see what happens when batteries go bad. - crw

 

[GerhardRP]

Hi Dan,
I got your data dump.
My first guess is that the Peukert effect is robbing your amp-hes.
Do you have specs on the batteries re: amp-hrs [or model number or physical size.]
Gerhard

Found this EVDL post with the battery info.
http://www.diyelectriccar.com/forums/showthread.php/evdl-official-energizer-battery-specs-11150.html
Using the numbers here, the Peukert exponent works out to 1.28.
With the current shown in your data dump to calculate capacity used accounting for the Peukert effect, you should be at 82% capacity after your 5 mile drive. The battery voltage agrees with that. [looks like a 100 degree day.]
If you drive to 50% DOD, your range should be 14.5 miles.
If you push to 70%, range could be 20 miles.
Gerhard

 

[exchaoordo]

Thanks to everyone for the replies and especially Gerhard for running the numbers for me. I need to find time to do all the math and learn about Peukert. So it sounds like my best boost in range will come from improving the batteries. I guess I'll wait till these die. thanks to for the battery info, I had the same frustrations trying to find specs.
-dan

Found this EVDL post with the battery info.
http://www.diyelectriccar.com/forums/showthread.php/evdl-official-energizer-battery-specs-11150.html
Using the numbers here, the Peukert exponent works out to 1.28.
With the current shown in your data dump to calculate capacity used accounting for the Peukert effect, you should be at 82% capacity after your 5 mile drive. The battery voltage agrees with that. [looks like a 100 degree day.]
If you drive to 50% DOD, your range should be 14.5 miles.
If you push to 70%, range could be 20 miles.
Gerhard

 

[bagghist]

Hello - Sounds like you might have a soft battery or two. You can measure the voltage across each battery and see if one or more is drooping under load. Ideally they should not dip more that 2 volts. (I have run some into the ground.) See if you have a battery that drops voltage much quicker than the rest. That is the weak link that will bring down the pack. Beware. He can be a bad influence. You don't want to see what happens when batteries go bad. - crw

CRW, I have a similar issue with my 72-V (6x12v) system. Can you clarify -- when you say 2 volt dip under load, do you mean compared to pre-load baseline or compared to the other batteries?

 

[jockepocke]

CRW, I have a similar issue with my 72-V (6x12v) system. Can you clarify -- when you say 2 volt dip under load, do you mean compared to pre-load baseline or compared to the other batteries?

compared to baseline... All the batteries should ideally show the same voltage (or at least not differ more than a few tenths of volts) under load, everything else says you have an unbalanced pack or poor cell(s).

 

[bagghist]

compared to baseline... All the batteries should ideally show the same voltage (or at least not differ more than a few tenths of volts) under load, everything else says you have an unbalanced pack or poor cell(s).

I actually had them all professionally checked; the fluids were fine and they all load-tested "good" (sorry, no hard numbers on that). But I see replicable differences when I drive up a hill steep; on is always about 0.5 or so volts lower than the others. It has a slightly lower final charge (maybe by 0.2 volts if that), and seems to have a slightly lower charging voltage. Lo and behold it's also the one battery that has evidence of boil-over. But are those differences large enough to be important? You're saying a 2-volt sag while while driving up a hill is when it's bad, if I understood correctly.

My battery guy suspects that the Zivan was undercharging. Not consistent with the boil-over I guess, but consistent based on his observations of my 72-V Zivan charger versus his 12-volt shop charger. This Zivan had a chip swapped in it by the former owner, but nobody knows why. He thought maybe the initial chip may give a deeper charge. I talked to Zivan and they're sending me yet another chip.

 

[jockepocke]

I actually had them all professionally checked; the fluids were fine and they all load-tested "good" (sorry, no hard numbers on that). But I see replicable differences when I drive up a hill steep; on is always about 0.5 or so volts lower than the others. It has a slightly lower final charge (maybe by 0.2 volts if that), and seems to have a slightly lower charging voltage. Lo and behold it's also the one battery that has evidence of boil-over. But are those differences large enough to be important? You're saying a 2-volt sag while while driving up a hill is when it's bad, if I understood correctly.

My battery guy suspects that the Zivan was undercharging. Not consistent with the boil-over I guess, but consistent based on his observations of my 72-V Zivan charger versus his 12-volt shop charger. This Zivan had a chip swapped in it by the former owner, but nobody knows why. He thought maybe the initial chip may give a deeper charge. I talked to Zivan and they're sending me yet another chip.

I understand! I have a theory that the load test does not stress the batteries as much as you do when driving (a car uses A LOT of energy, for me sometimes 300 A, and any difference in internal resistance will be much more significant than for eg 30 A, so it is possible you have a bad cell, but measuring with low currents may not show anything wrong. 0,5 volts difference is quite a bit, you should probably keep an eye on that!

I cannot say if 2 volt sag is bad or ok, it depends on the steepness of the hill, speed etc, and lead acid does sag a lot under hard load (due to internal resistance). But having a voltage sag means your batteries are eating some of your energy, so ideally you should aim to drive with as little sag as possible.

I have som problems with unbalanced lead acid pack, and I bough 10 small small cheap 3 step charges, one for each battery, to use for balancing the pack.

 

[bagghist]

I understand! I have a theory that the load test does not stress the batteries as much as you do when driving (a car uses A LOT of energy, for me sometimes 300 A, and any difference in internal resistance will be much more significant than for eg 30 A, so it is possible you have a bad cell, but measuring with low currents may not show anything wrong. 0,5 volts difference is quite a bit, you should probably keep an eye on that!

I cannot say if 2 volt sag is bad or ok, it depends on the steepness of the hill, speed etc, and lead acid does sag a lot under hard load (due to internal resistance). But having a voltage sag means your batteries are eating some of your energy, so ideally you should aim to drive with as little sag as possible.

I have som problems with unbalanced lead acid pack, and I bough 10 small small cheap 3 step charges, one for each battery, to use for balancing the pack.

Ok, to clarify, the V diff across 12-volt batteries at rest is ~0.2. The V sags (at maximum load while driving) are large, maybe up to 3 V, with one or two batteries sagging up to a half volt more than the others.

As an aside, I'm intrigued... how you charged your ten batteries with individual chargers. Did you need to take them out of series with each other (or is that irrelevant)? Did you need to always hook up ten pairs of connectors?

 

[GerhardRP]

Lo and behold it's also the one battery that has evidence of boil-over.

Perhaps the boiled over cell liquid was replenished with distilled water. Maybe the addition of a little battery acid would help.
Gerhard

 

[bagghist]

Perhaps the boiled over cell liquid was replenished with distilled water. Maybe the addition of a little battery acid would help.
Gerhard

Sensible idea. Except that the spill over must have been minimal and mostly cosmetic, because the fluid level and electrolytes were both fine.

 

[jockepocke]

Ok, to clarify, the V diff across 12-volt batteries at rest is ~0.2. The V sags (at maximum load while driving) are large, maybe up to 3 V, with one or two batteries sagging up to a half volt more than the others.

As an aside, I'm intrigued... how you charged your ten batteries with individual chargers. Did you need to take them out of series with each other (or is that irrelevant)? Did you need to always hook up ten pairs of connectors?

Ok, a half volt may be ok, but watch out if there are some batteries that are always the low ones, and keep an eye on them, and your voltage sag seems normal as well!

The batteries stay in series! And I do not think there will be a problem charging with the main charger at the same time as the small ones are on (but have not tried yet, batteries are away for warranty replacement).