# Range Question



## Duncan (Dec 8, 2008)

Hi
You are looking at a 130v - 100Ah pack - 13Kwhrs - 10.4Kwhrs at 80%
At 300whrs/mile = 34 miles
Sounds a bit marginal for a 35 miles each way commute
Also 300whrs/mile - what speeds are you going to be driving at?
If you are at highway speed you may be eating more power, my car (with terrible aerodynamics) uses twice the whrs/mile at 60mph it does at 30mph


----------



## twright (Aug 20, 2013)

I have several route choices to get to work. I will not take the interstate because this car has a top speed of about 60 mph. This means i'll take the surface streets and go about 45mph. There are about 15 stoplights on this route, but no hills.


----------



## elevatorguy (Jul 26, 2007)

Welcome to the forum, I agree with Duncan, could be marginal. I don't know much about your controller, but could you add some batteries to increase the voltage? That may be less expensive than going to higher AH batteries.
If you are on the edge of range, problems could occur if you have to run the heat, have cold batteries, headwinds, etc.


----------



## Caps18 (Jun 8, 2008)

With the LiFePO4 batteries, you might have a higher top speed and would be able to take the interstate. You might want to drive 60 mph anyways for a little better efficiency, but it would be worth testing if stopping and accelerating would use more power vs a constant high speed. And your time might be worth something too.

I would look at how heavy the vehicle is in pounds and then divide that by 10 to get the Wh/mile value. See if there is anything else that can be removed to save some weight. Is is possible to add a few more batteries as a cushion and to have them not discharge quite as much each trip? Take a look at how many cycles you would get out of them at 80% discharge compared to 70% discharge and figure out how many years it would take you to reach that amount.


----------



## tomofreno (Mar 3, 2009)

Figure around 25% - 30% range reduction in coldest temperatures in winter due to cabin heating, stiffer drive train and cold batteries (if unheated) if your heater is around 3kW. It would be less than that driving on the highway, but the proportion is larger at lower speeds where not as much power is used to move the vehicle, and you will also be sitting at those stoplights with the heater running.


----------



## dtbaker (Jan 5, 2008)

twright said:


> I have recently purchased a 2000 Ford Escort ZX-2...
> (The vehicle has a Warp 9 and an Open Revolt controler.)
> ... planning on buying 40 Lithium Iron Phosphate batteries of 100 aH for this vehicle
> 
> I want to be able to drive it to work 35 miles, recharge during the day and drive it home.



35 miles is going to be close with 130v x 100ah, but probably doable IF the batteries are not dead cold in am. i.e. if you store/charge in a garage or have battery box heaters built in. REMEMBER you should not charge if pack core temp is below freezing!

charging may be an issue... depending on charger available. working 8 hours, how many kWhr can you get back on board? do you have only 110vAC level 1, or access to 220v?


----------



## twright (Aug 20, 2013)

I have access to Level 1 110 vac inside the parking garage. This is the most convenient option.

Two blocks away is a Level 2 charger. I'm hoping to not have use this option.

I was planning on buying a 2000 watt charger. Is that enough?


----------



## twright (Aug 20, 2013)

Here's the real basis for my question:

I have been doing some energy measurements from the onboard volt and amp meters.

At 50 mph, I am using 180 amps at 110 volts. This gives me 396wh/mile. If I buy 40 100 aH lithium cells, that calculates like this:

100 aH X 128 Volts= 12,800 kw/hours

12800 \ 396 = 32 miles !

I won't make it! Is there something wrong with my calculation? Are my wh/mile numbers reasonable?

I was doing the test in 3rd gear and that gives me about 3400 rpm. Is that my best option?

Thanks for your help.


----------



## Frank (Dec 6, 2008)

Should be okay... If you recover 1kWh every hour for 9 hours you can pretty much fully recharge when at work. 115 volts * 10A = 1150 watts. A standard receptacle cannot supply 2000 watts. Make sure your charger can limit current draw so you don't pop the breaker at the parking garage!


----------



## dtbaker (Jan 5, 2008)

twright said:


> I have access to Level 1 110 vac inside the parking garage. This is the most convenient option.
> 
> Two blocks away is a Level 2 charger. I'm hoping to not have use this option.
> 
> I was planning on buying a 2000 watt charger. Is that enough?


standard 15amp breaker 110vAC house circuit really should only pull 1500 watts.... even then the extension cord can get pretty warm. at that rate you can figure how many hours it would take to replace the kWhr consumed, plus 5% or so for charger efficiency loss.

so, a 2000 watt charger doesn't really do you any better unless you get on a level 2 (220vac) circuit

in your case a regular 35 miles is going to be cutting it close, and hammer your batteries pretty hard which *may* reduce the total cycles you get out of them. they will last longer and you'll be more relaxed if you up your design to 120v x 130ah to have a little extra capacity.


----------



## Frank (Dec 6, 2008)

I thought it was 35 miles *round trip*. TWRight: is it 35 miles one-way?


----------



## ken will (Dec 19, 2009)

twright said:


> I want to be able to drive it to work 35 miles, recharge during the day and drive it home.
> Will this combination give me the 35 miles round trip?


Is it 35 miles to work, or 35 miles round trip?


----------



## twright (Aug 20, 2013)

It is 35 miles each way.

Does anybody have an opinion about the current and voltage readings that i took with the current lead acid batteries?


----------



## major (Apr 4, 2008)

twright said:


> Here's the real basis for my question:
> 
> I have been doing some energy measurements from the onboard volt and amp meters.
> 
> ...


Looks like you did the math correctly and the numbers sound reasonable. But beware, using nominal figures for energy in the battery can prove optimistic. At a 2C discharge you may not get the full rated Ah. And the voltage may be a bit lower. And you should not plan to run to 100% DoD. With a headwind or as the battery ages, you'll come up short. Typically guys try to base on 80% max DoD.


----------



## twright (Aug 20, 2013)

It sounds like I need more battery and less wh/mile.

I will check the alignment of the car. Anything else I can do to make it better? The tires are already at 42 psi.


----------



## dtbaker (Jan 5, 2008)

twright said:


> It sounds like I need more battery and less wh/mile.
> 
> I will check the alignment of the car. Anything else I can do to make it better? The tires are already at 42 psi.



belly pan, rear wheel skirts, and tailpan to prevent 'clamshell' turbulence under rear help a lot at highway speeds. check your brakepads to make sure they are free to move off the rotor.


----------



## twright (Aug 20, 2013)

How much improvement can I expect with aerodynamic mods? 5%?


----------



## Frank (Dec 6, 2008)

% improvement depends on a lot and is hard to guess at. You can also slow down a few mph which will help most, use synthetic fluids in tranny, rear end, etc. Losing weight by switching batteries will also help. If you can squeeze more battery in though that would be the best solution. Lack of hills makes this even more attractive.


----------



## dtbaker (Jan 5, 2008)

twright said:


> How much improvement can I expect with aerodynamic mods? 5%?


yeah, in that ballpark. depends on speeds, stops/starts, hills, etc. I would not want to cut a daily commute calculation that close to depend on aero mods. A partial bellypan is a good idea regardless just to keep water/snow/debris off the motor. If you seal up the middle, don't forget to give the airflow from the motor bay somewhere to go!

a 'cool' mod is to consider removing side mirrors and going with video, but it may not be completely legal in most states. you start getting into spending several hundred dollars for tiny improvements.

another mod you could consider is going to Xenon headlights, which would cut your consumption a little, but thats pretty small compared to the heat needed for winter driving (1500-3000 watts).

you'll be WAY better off investing in higher capacity batteries to give you a better cushion on range. The extra weight will affect your stop/starts negatively, but pay off for the extended highway miles. If you can keep your average DOD less than 70% your batteries *should* last a lot longer.

all this being said, you should take a close look at your commute and consider whether an AC system might yield enough benefit from regen braking to be worth the extra expense. The ballpark results from a couple people here that have gone AC is that they see about 10%-15% greater range with same size battery pack in 'average' suburban driving with *some* stops/starts.


----------



## twright (Aug 20, 2013)

I have an update with some additional data:

The car is a little bit heavier than I expected. It weighs 3340 lbs.

I also discovered that one of the brakes was dragging and that the alignment was horribly off. 

After correcting these items, the new energy consumption figure is: 

170 amps X 109 Volts = 371 Watt Hour/Mile

That's pretty close to the estimate of 10 lbs/ watt hour/per mile rule of thumb.


----------



## dtbaker (Jan 5, 2008)

twright said:


> I have an update with some additional data:
> 
> The car is a little bit heavier than I expected. It weighs 3340 lbs.
> 
> ...


the weight becomes a factor only during accelleration.... at steady state it doesn't really matter. I have found it best to find a 'fairly flat' couple mile stretch of road where I can maintain a set speed with little chance of anyone pulling in front of me.... zero ah, bring the car up to speed in the same manner each time, and take a couple runs out and back for a couple data points. I think you need a 3 to 5 mile stretch of road to take the minor variability out and get a good picture of steady state consumption.

The other figure that is interesting is finding your average consumption 'at the wall' over say 100 miles of average use around town. You can do this by putting a 'kill-a-watt' meter at your outlet and keeping a cumulative total of kWhr you put in over 100+ miles of use. This takes into account all losses in charging, etc and gives you a fairly safe estimate of miles remaining given your ah consumption during the day.

btw, I am curious what you found most effective to reduce brake drag. what did you DO to reduce drag?


----------



## twright (Aug 20, 2013)

It wasn't really the shoes dragging. One of the rear brakes drums was rubbing on the backing plate. I just bent the backing plate away from the drum.

It rolls much more freely now.

BTW, doesn't your "off the wall" meter not take into account any inefficiencies of the charger?


----------



## dtbaker (Jan 5, 2008)

twright said:


> It wasn't really the shoes dragging. One of the rear brakes drums was rubbing on the backing plate. I just bent the backing plate away from the drum.
> 
> It rolls much more freely now.



oohhhh..... I had front disc brake dragging once. turned out that the 'ears' on the pads were too tight in the caliper slots and didn't allow the pads to get pushed back off the rotor very well.... just a little drag generates a fair amount of heat! indicating wasted watts of course. I filed down the ears a little, and it seemed to help as the calipers seemed to remain cooler after driving around, and the wheel spun freer when up on a jack.


----------



## dtbaker (Jan 5, 2008)

twright said:


> BTW, doesn't your "off the wall" meter not take into account any inefficiencies of the charger?



mmmmm, the point of using the kWhr meter at the outlet to track the TOTAL cumulative power you put in, is that it DOES track all the power including the 'losses' in the charge cycles. So, this is a good picture of the operational cost INCLUDING charger loss.... making it a conservative number to estimate range remaining as you are driving around.

One thing to be careful of is I have had two kill-a-watt meters basically melt from heat kicked out from extended 12 amp draw when using an extension cord that had a clear end and a little neon light showing it was live. The clear ended extension cords are bad news for extended high-amp use, and I would suggest using only the NON-lit ones rated for 15-20 amps if you are charging from 110v outlets.


----------



## Frank (Dec 6, 2008)

Right... don't try to use a 16 ga. cord for EV charging! Always make sure your equipment is UL listed for your loads.


----------



## dtbaker (Jan 5, 2008)

Frank said:


> Right... don't try to use a 16 ga. cord for EV charging! Always make sure your equipment is UL listed for your loads.


the cords I had trouble with were 12ga, rated for 15amp, but had the clear ends with the built-in neon 'live' light. I chopped that sucker off and put on a plain end.... no more heat buildup.

I'd suggest using 10ga if you can find it, or make one yourself minimum length from outlet to usual vehicle location, with 20 amp rated plug ends.


----------



## Frank (Dec 6, 2008)

Well that's certainly interesting... Thanks for sharing this experience.


----------



## dtbaker (Jan 5, 2008)

Frank said:


> Well that's certainly interesting... Thanks for sharing this experience.



we got a little off topic there, but when talking about range.... losses in the charge cycle are often overlooked as far as total consumption 'at the wall'. you can't do anything about your charger (some are more efficient than others), but you can reduce 'line loss' to heat by using a big fat extension cord that doesn't heat up! Also by having the cord as short as possible.

The neon clear plug ends just scare me, so I thought I'd mention it. I've had them blacken and soften the plastic on an outlet, and melt a kill-a-watt meter. At first I thought it was the kill-a-watt meter not handling the 8 hours of 12 amps, but it turned out to be the neon plug end.


----------



## Inframan (Jan 30, 2011)

So where did you get the calculation of 371 watthours/mile? Seems really high for a ford escort.


----------



## twright (Aug 20, 2013)

I have an onboard ammeter and volt meter. I just got some steady state readings at 50 mph that I could easily compare. I know it doesn't take into account acceleration and deceleration, but it is an easy number to get for comparison.


----------



## twright (Aug 20, 2013)

I have some additional data. I installed a JLD 404 and measured the amp X hours over a 11.1 mile route.( This route is about half highway and half 40 mph stop and go sections) 

I used 32.9 amp x hours during this route. If I use 110 volts average during this trip, it comes out to 326 watt hours/mile. This it almost exactly the same as the calculated estimate of 10% of the vehicle weight (3340 lbs)!

I'm planning on removing the lead acid batteries and installing Lithium ones in their place. I will lose at least 500 lbs by doing this. 

Does anybody know if I will really decrease my wh/mile by 3340/ (3340-500) = 18% just because of my weight reduction?

I really want to drive to work with this vehicle (35 miles), but I know its going to be close.


----------



## dougingraham (Jul 26, 2011)

I believe you are right and it is going to be close. I suspect on warm days you will make it and on cold ones you wont. And so that the batteries will last a long time you want to try to limit the depth of discharge to 70 or 80%. If you can add a few more cells I would. Is a cell count of 40 the most the Open Revolt controller allows? If so then replace it with a controller that allows higher voltage or use 120AH (or more) cells instead.

You will be amazed at how much better the car drives after you make the battery swap.


----------



## kennybobby (Aug 10, 2012)

*Weight is your enemy...*

A vehicle of 3340 lbs with .33 Cd, area = 24.2 sf, Crr of 0.015, needs 10kw just to hold 50mph according to the ecomodder calculator (200 Whr/mile). At 2840 lbs the online calc indicates aero and rolling load of 9310 W at 50mph (186 Whr/mile), only about a 7% reduction in load due to just the weight loss. 

You reported using 19.8kw before and 18.5kw after fixing the brake dragging (~370 Whr/mile). And with the JLD you measured a lower consumption of 326 Wh/mile, so a 12.8 kWh pack would give you 39 miles range at that average speed and weight. Using the 10% rule of thumb at the lower weight, 284 Whr/mile, gives a theoretical range of 45 miles. On paper a 35 mile trip would use up 77% of the pack.


----------



## dougingraham (Jul 26, 2011)

*Re: Weight is your enemy...*



kennybobby said:


> Using the 10% rule of thumb at the lower weight, 284 Whr/mile, gives a theoretical range of 45 miles. On paper a 35 mile trip would use up 77% of the pack.


This is exactly what I was estimating. The problem occurs when there is a 20mph headwind in the rain when it is cold and the car is being heated from the traction pack. All that 23% estimated excess is used up in this circumstance.

The other thing that needs to be considered is that range does go down as the batteries age. It is a good idea to plan so that in 8 years you can still make it even though you have lost 20% of your battery capacity.


----------



## major (Apr 4, 2008)

*Avoid range anxiety*



dougingraham said:


> This is exactly what I was estimating. The problem occurs when there is a 20mph headwind in the rain when it is cold and the car is being heated from the traction pack. All that 23% estimated excess is used up in this circumstance.
> 
> The other thing that needs to be considered is that range does go down as the batteries age. It is a good idea to plan so that in 8 years you can still make it even though you have lost 20% of your battery capacity.


I agree with this logic. twirght should devote some of that potential weight reduction to increase his battery. He'll be better off with like 18 kWh or more. I know it will cost more, but I think it will prove to be worth it in the long run. Less range anxiety and greater usefulness or utility will mean a lot


----------



## twright (Aug 20, 2013)

It sounds like I need a few more cells. However, I am worried about my controller and battery charger.

The controller is an Open Revolt and it says that the max is 144 volts. Does that mean 144/3.2 = 45 cells? Does anybody know if this controller will handle that many cells?

The battery charger says the max is 120 VAC. Will this thing handle 45 (or more) cells?


----------



## major (Apr 4, 2008)

You don't have to go up in voltage to increase energy (Wh).


----------



## twright (Aug 20, 2013)

Unfortunately, I do:

I have on order 40 100Ah cells. They have already been shipped and will probably arrive right after Christmas.

I don't think I can cancel them now.


----------



## dougingraham (Jul 26, 2011)

twright said:


> The controller is an Open Revolt and it says that the max is 144 volts. Does that mean 144/3.2 = 45 cells? Does anybody know if this controller will handle that many cells?


This would seem to be a question that would be easy to find the answer to. The only thing I found was 144 volts nominal. To me this means 45 cells but who knows what they mean by this. I will look a little more and see if I can find out. The idea probably comes from twelve lead acid batteries each having a nominal 12 volts. In this case the control would see an off the charger value of 172.8 volts (14.4*12) and that would mean perhaps 48 cells. (172.8/3.6).



twright said:


> The battery charger says the max is 120 VAC. Will this thing handle 45 (or more) cells?


120VAC is the input rating. What is the output rating? Is this a Lithium charger? If you are using 40 cells you would need to set the CV voltage to at least 136 volts (40*3.4 volts) and at most 144 volts (40*3.6). If you cant set the point where the charger switches to constant voltage mode to somewhere in there you will need a different charger. A lead acid charger will not have the correct profile for lithium cells and will do a less than excellent job at it.


----------



## Duncan (Dec 8, 2008)

Re - OpenRevolt

The parts used are 200v max - 
So Paul recommends 144v to give a fair bit of safety room,
I use 44 cells,


----------



## twright (Aug 20, 2013)

I wasn't very clear about the charger question:

The charger I was referring to was NOT the main pack charger: It will handle a cell increase.

The charger I was asking about is the one that I have in the vehicle that charges the 12 lead acid battery. (This is in place instead of a more common DC-DC converter.)

This 12 volt charger is a "Smart" charger that keeps the 12 volts charged. It is connected to the main battery pac. The directions for this charger say: Max 120VAC. I'm sure this means to not plug it in to 240 VAC, but I don't know how high of a DC current I can use.


----------



## dougingraham (Jul 26, 2011)

twright said:


> IThis 12 volt charger is a "Smart" charger that keeps the 12 volts charged. It is connected to the main battery pac. The directions for this charger say: Max 120VAC. I'm sure this means to not plug it in to 240 VAC, but I don't know how high of a DC current I can use.


If it worked on DC before then most likely it can stand at least 170 VDC input which is the peak DC voltage after rectification. (120VAC * SQRT(2))

It might handle considerably more than this but 170 volts would mean at least 47 cells taken to 3.60 volts each so you should be good.

As always when re-purposing something there could be unexpected considerations but this seems a relatively safe bet since the charger in question has already been used on DC.


----------



## twright (Aug 20, 2013)

I have a recent update. Thanks to everyone that contributed because: It Works!

I have been regularly driving my vehicle 34 miles to work. With 40 100 AH cells, I had a range of about 45 miles at 100% Depth of Discharge (DOD).

The car had enough range and enough speed to drive on the highway and make it to work. However, I wanted more margin, so I installed 4 more batteries (for 44 total 100 amp hour cells).

I now have a range of about 50 miles. I have had the car to 75 mph, and it will go faster than that, but I don't need to.

The Open Revolt controller is working fine at 140 volts.
The heater is working fine at 140 volts.
The 12 volt battery charger is working fine at 140 volts.
It takes me about 7 hours to charge from a 110 outlet after the 34 miles.

It's all working great and saving me $8-9 a day in gasoline expenses.

Thanks for everyone's help.


----------



## elevatorguy (Jul 26, 2007)

Good to hear! Glad you got it sorted out and it is working well.


----------



## Caps18 (Jun 8, 2008)

Very cool. Did you weigh your car at some point?


----------



## twright (Aug 20, 2013)

I haven't weighed the finished product. I only weighed the lead acid version. It weighed 3340 lbs.

I removed 1000 lbs of batteries and replaced them with 330 lbs of lithium iron phosphate batteries.

So, it should weigh about 2700 lbs.

I need to get an accurate weight, but that's close.


----------

