# Batteries affecting range?



## Sunking (Aug 10, 2009)

So what is your watt-hour per mile calculation? 

I have assumed you de-rated the T145 AH capacity for the 1 or 2 hour discharge rate to 180 AH right?


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## Jordysport (Mar 22, 2009)

Sunking said:


> So what is your watt-hour per mile calculation?
> 
> I have assumed you de-rated the T145 AH capacity for the 1 or 2 hour discharge rate to 180 AH right?


that would be my first thoughts that the 60% of lead acid wasn't taken into account, 160-180ah.


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## CPLTECH (Sep 14, 2007)

I will share my experiences since I have a similar setup as yours: 94 S10, same motor/controller/120V, batteries are the US Battery version of the T145 (Heavy aren’t they?). Have traveled some 7K & batteries are still doing “well”.
Last year I attended a night school that was 14 miles away (28 trip total, some days a tad more). Did 55-60 on the interstate and climbed some grades at 45-50 to avoid toasting the motor for long periods of time. During cold weather that affected battery performance, I would take the 35MPH back roads home. Just as with ICE, highway mileage is better than a lot of stop & go. My E Link 10 meter would switch to red (indicating battery level had just dropped to 60%DOD but not yet to the 80%DOD) just a mile or 2 before home. The AH usage of the meter registered 90-100AH & took ~18KWH to replenish. This meter gives both readouts, since the Peukert Effect plays havoc with the batteries. You are doing the right thing to be gentle for max mileage. Although 30 is the about the most I’ve gone, I feel it will take me another 5 or 10 with ease. 
If I stay with LA, I want to go to 144V to get a little better “zip & zowie”. Motors ”love” the upper voltage range for efficiency. If I choose 8V units, it will reduce the weight by 200# and hope to have about similar range. 

1st - up to 20MPH
2nd - up to 40
3rd - above 40


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## Sunking (Aug 10, 2009)

By my calculations it sounds about right. The T-145's have about 180 Ah capacity at the 2 hour discharge rate, 160 @ 1-hour. That gives you a storage capacity of 21 to 23 Kwh. However only 50% of that is available to you from a full charge unless you want to replace batteries every year. So that leaves you with let's say 11 Kwh to work with. At 30 miles works out to around to 366 wh/mile. 

So that is why it is important to know what the wh/mile should be, so you can tell what is going on.


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## el ohmbre (May 28, 2009)

Thanks for the replies. So it seems my range may be reasonable based on your responses. (Although I don't think I could get anywhere near 30 miles at 60 mph.) I guess my expectations may have been off.

Honestly, this is a bit embarrassing but I never did the calcuations before I started. I tried but didn't know where to get some of the inputs so I relied on others and used more or less a standard combination of parts.

Is there a way to calculate what the wh/mile should be?

Tom 
www.elohmbre.com


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## Sunking (Aug 10, 2009)

el ohmbre said:


> Honestly, this is a bit embarrassing but I never did the calcuations before I started.


Well that was a major oversight on your part. I don't mean that to be critical, but there is no way to even guess without running the calculations.

I am an electrical engineer and don't have the calculations at hand to share with you. But I am certain someone will and help you out.

FWIW the benchmark is 200 wh/mile. Telsa Roadster is around 150 wh/mile


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## el ohmbre (May 28, 2009)

Yes, I'm not offended. I knew I was taking a chance going ahead without fully understanding the engineering behind it.

I used the EV Calculator website and one engineer ran a spreadsheet for me but I don't fully understand either of them.

The spreadsheet contains a section labeled CURRENT REQUIRED (AMPS) for various speeds, can this be converted into watt-hours/mile?

Or do I need to research a watt-hours/mile calculation?

Thanks,
Tom


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## tj4fa (May 25, 2008)

I can't help noticing your shift points of 20-40mph in second gear and 3rd gear above that.

It may be apples to oranges going by my 91 Ford Ranger and not researching the transmission/rear end gear ratios between the Ranger and S-10, but driving by the amp meter, my truck uses around the same amount of amps at 45-50mph in second gear as it uses at 30-35mph. 

I also always use first gear to get going before shifting into second.

(I read amps with the gauge shunted right before the motor - it seems the motor's "happy zone" is pulling around 125-150 amps with my 144V system - same motor and controller as yours).

I seldom consider using third gear unless on rare occasions I want to go >60 mph.

Perhaps you can check to see if your truck is more efficient at a higher motor rpm for a given (gear) speed possibly extending your range a bit?

Of course the old addage "more lead=more range" may apply...


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## CPLTECH (Sep 14, 2007)

What is my wh/mile?
Using that regular 28 mile trip as the example, the on-board meter would say ~425.
However, after losses to fully recharge batteries, the figure jumps to ~625.
Way back when I posted this scenario, someone agreed that ~1.5 times is normal.

For my short local runs, the electrical cost per mile runs 8 cents per mile.


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## tj4fa (May 25, 2008)

I used to have a friend from another forum that hosted a spreadsheet calculator I built using formulas I found on the wiki and posted here but it seems it's no longer on his server.

Here is a snapshot of what was given (18KW to recharge for 28 miles).

I kept the KWh rate at 07 cents so what you pay will affect your numbers a bit.

If you pm me your e-mail, I can e-mail you the spreadsheet calculator.


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## el ohmbre (May 28, 2009)

Regarding shift points.
I've also notice that I pull about the same amps at 25 mph as I do at 40-45 mph in 2nd gear (just under 200). If I shift to 3rd gear it jumps to 300 amps. This is anytime there is load. Generally I try to keep a very light touch and give it just enough juice to maintain speed and I can get the amp draw down to nearer to 100.

Regarding watt-hours
I don't have one of those E link 10 guages. I looked for one during construction and saw they were discontinued. I checked again today and see there is an e link 20 now which I assume is the successor.

I'll do some research to see if I can learn how to calculate my watt-hours / mile. As I mentioned, I'm a bit embarrassed I completed the project and don't understand some of the most basic calculations.

Tom
www.elohmbre.com


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## el ohmbre (May 28, 2009)

Oh, one more thing. I tried to use a Kill A Watt to measure the kwh used to charge. I charge on a 110v 20 amp circuit. The Kill A Watt started beeping when the current draw passed 15 amps. It kept beeping as the amps stabilized at 22.6.

I was afraid I was goint to hurt the Kill A Watt so I removed it and noticed it said 15 Amp on the back.

In any case, I'm not sure how I can draw 22.6 amps on a 20 amp circuit. 
But if it draws this much through the entire charging cycle do I figure the kwh by multiplying 22.6 amps x 8 hours x 120 volts then dividing by 1,000 to get kwh of 21.7?

It might be a bad assumption that I draw 22.6 amps during the entire charging cycle. But is this the way the math would be done?

-Tom


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## Jordysport (Mar 22, 2009)

hi, this is what setup i use









I got it from somewhere off the net then i modified it slighly with Range for lithium and range for lead acid, and also alows you to work out your accelaration based on your peak power. if anyone wants it just pm me and i will email it to you.


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## PatricioIN (Jun 13, 2008)

this may be obvious already, but pay close attention to your ammeter. You want to use whichever gear uses the least amps at a certain speed. My EV uses ~70 amps in 2nd gear to keep a steady 40mph on level ground - just as an example. If I'm in third gear at 40, I use slightly more amps. It just takes a little while to learn your car.

Also, some hypermiling tricks are good too! Google hypermiling and take some of those ideas into your EV. I would guess you'd have better range with 20 trojans. I have 15 170ah 8v for 120v total and get better range. Granted, my car is lighter and more aerodynamic, but I would think that would be offset by the fact that you have more batteries. All the conversions I've seen seem to agree.. max range with 6v, less with 8v, even less with 12v.


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## 86Honda (Apr 15, 2009)

My former pack of 8 x 12V FLA were just problems. Never got more than 30 miles, usually closer to 20. Winter range was downright anemic and nearly useless. 
Shift points are 25/30, 45/50 and about 65 (almost never use 3rd, and 4th only highway, which I try to avoid). As mentioned before, running at higher RPMs near the shift point will mean lower amperage.
Now, with LiFePO batteries, 40 miles are possible, depending on speed. And the pack weighs over 1000 lbs. less.


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## el ohmbre (May 28, 2009)

The comment about watching the ammeter might be the key.

I see closer to 200 amps in 2nd gear to maintain 40 mph and it jumps to 300 amps if I try 3rd gear.

I can reduce the draw a bit with a very light foot but the speed will usually not hold for long. 

I wonder if there is something that is causing a overly high amp draw?

Tom
www.elohmbre.com


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## PatricioIN (Jun 13, 2008)

if you're truly pulling 200amps to maintain 40mph on level ground, then something is wrong somewhere.. that's WAY too much power for that speed.


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## tj4fa (May 25, 2008)

200Amps sounds high for 40mph.

A couple quick thoughts:

-Add more air in your tires
-Maybe adjust the Curtis 1231C controller's current/acceleration adjust pots Page 24-25 of the Curtis manual.
-Are you getting the full throw on your PB-6 potbox lever?
-I'm not a big fan of those universal post battery terminals (but that's me). Maybe check to see if they are tight and if any cables are getting hot indicating a poor connection?

http://www.evsource.com/datasheets/curtis/Curtis_manual.pdf


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## el ohmbre (May 28, 2009)

Oh, by the way, my ammeter is connected to a shunt located between the controller and the motor. I'm told it reads higher in the this location than when located between the battery pack and controller. Could that explain the difference?

Tom


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## tj4fa (May 25, 2008)

el ohmbre said:


> Oh, by the way, my ammeter is connected to a shunt located between the controller and the motor. I'm told it reads higher in the this location than when located between the battery pack and controller. Could that explain the difference?
> 
> Tom


I have my ammeter shunt located like yours. At 45 mph, I pull around 100-150A depending on grade (slight decline-slight incline). A more severe incline would require 200A.

I'll have to see if I can find some kind of inclinometer so I can really see the different grades and the amp pull along the way back and forth to work.


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## 86Honda (Apr 15, 2009)

At 45 mph I am at the top of second gear and usually pull about 100 amps. My ammeter shunt is also between the controller and motor. But in 3rd gear it almost never pulls less than 200 amps.


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