# formula for lithium battery pack



## Ziggythewiz (May 16, 2010)

The usual rule of thumb is 1 wH/m/10 lbs, so with your new weight you should be able to get 40 miles with 100AH cells.

Do you know your current wH/m? From the description, I figure you're running to 80% DOD to get that 30 miles, which gives nearly 400 wH/m. Is this a truck running at highway speeds?


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## dragonsgate (May 19, 2012)

I do not think I am drawing my lead acid batteries down 80%. I usually pull out of the garage at 151 volts on the meter and at 30 miles showing on the trip odometer the voltage is usually 144 sometimes as low as 140. At any rate a hundred amp hours is what I unsurely came to with my elementary math. Thanks for the watt hours to pounds rule.


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## Ziggythewiz (May 16, 2010)

I say 80% because that's around where performance will drop significantly. On a 144V nominal system, 144V would be nearly dead (8.0V ea). You can probably only get around 100 AH out of those at a 1 hr rate, so if you use 80 I'd call that 80% DOD.

If you're planning lithium, you'll need an AH counter. I'd get one ASAP so you can get some measurements with your lead, and see just how much it takes to get around. I use a JLD404, and got another on the way


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## GerhardRP (Nov 17, 2009)

Can you describe your driving style; how long does your 30 mile trip take?
You are in Houston, that means flat terrain and temperatures of 90-100 F, I'd guess.
Gerhard



dragonsgate said:


> My car weighs 2,760 pounds. It has an advanced dc 9” with a 500 amp Curtis controller at 144 volts nom. The batteries are Trojan T-875 eight volts rated 170 amp at twenty hours. I can get 30 miles on a charge before there is a noticeable drop in performance. I am trying to figure what amp hr rate lithium battery pack at 144 volts would give me at least 40 miles comfortably. The lithium’s would shave a good 400 pounds of the vehicle weight so that should be factored in. Is there some kind of formula?


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## dragonsgate (May 19, 2012)

I live in the Ozarks Mountains of North West Arkansas. There are quite a few steep hills here. I do not try to hyper mile although over the years I have learned to use the down hill side to my advantage. I make a 10 mile round trip run to the post office just about everyday. I drive balls to the walls until I hit town and then get behind some touron creeping up hill with their foot on the brake through town drop my packages and then book it on back home. I usually charge every other day on that routine. I try to do most of my shopping locally in my small community of 2,000. I hardly ever go more than 19 miles round trip. Sometimes we go to Wally World about 12 miles away. That is a fun ride cause I get to open her up and hit 70 or better for a few miles some of which is up hill. There is a two mile grade on that stretch I would hazard to say that at least half of it is pretty close to 6%. Going down is fun and coming back if I am lucky and do not run up on some slowpoke I have pulled that hill at over 60mph in third gear. 60 is good as the roads here are also twisty. I could go on but just suffice it to say I drive as fast as legally possible or what I think I can get away with. My dream/goal like most of the unfortunate souls that are still running on lead is to change over to Lithium. I would love to get the highest amp hour pack possible but the reality of the pocketbook has a nasty way off screwing things up so the next best thing is to figure the smallest possible pack while maintaining the range I have learned to live with.


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## Ziggythewiz (May 16, 2010)

What kind of car, motor, and controller are you running?


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## dragonsgate (May 19, 2012)

Ziggythewiz said:


> What kind of car, motor, and controller are you running?


My car weighs 2,760 pounds. It has an advanced dc 9” with a 500 amp Curtis controller at 144 volts nom. The batteries are Trojan T-875 eight volts rated 170 amp at twenty hours. I can get 30 miles on a charge before there is a noticeable drop in performance. I am trying to figure what amp hr rate lithium battery pack at 144 volts would give me at least 40 miles comfortably. The lithium’s would shave a good 400 pounds of the vehicle weight so that should be factored in. Is there some kind of formula? It is the yellow Fiat X19 0n page 4 of the garage.
Your previous answer of 100 amp hour was what I was figuring.
​


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## Carl55 (Jun 9, 2012)

Just curious, got photos of those batteries in the car.


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## Ziggythewiz (May 16, 2010)

dragonsgate said:


> It is the yellow Fiat X19 0n page 4 of the garage.
> Your previous answer of 100 amp hour was what I was figuring.


Ok, yeah, that should do nicely. I can't afford to go full lithium for a while, but I think I can swing a full booster pack in the next month or so


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## EVfun (Mar 14, 2010)

dragonsgate said:


> I live in the Ozarks Mountains of North West Arkansas. There are quite a few steep hills here.


Hey, I used to spend time each summer back there as a child. It was great. Very different attitudes than western Washington. I used to hunt for mineral samples and interesting fossils while hiking all over the woods. There was all the catfish you could eat waiting to be pulled from Bull Shoals Lake.


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## dragonsgate (May 19, 2012)

Carl, I am curious why you need photos of the batts. They are Trojan T-875 eight volts. I will take some pictures tomorrow and post them. EVfun, my parents lived on Bull Shoals Lake in Diamond City. You can still experience culture shock in parts of Arkansas. We moved here from SoCAL 25 years ago. I have spent some time up in Washington. I did two art shows a year there for about ten years and have done some Jeeping there. I have gone full circle in the fact that I was born back here and moved to California with my parents in 1956 and am now back here. I live out side the Historic town of Eureka Springs. It has a very eclectic population. By the last census 700 of the 2,000 residents claim to be artists. I live outside the city limits so I don’t count. I think of it as a land locked island because the closest big city is about 50 miles away. I manage with a 30 mile range fairly well around here. 40 miles would be nice for a little extra margarine. The next step up in range would have to be 150 miles to get me to the big city and back. I go to Fayetteville every once in a while. We go and get art supplies or I have an appointment at the VA. By the trip odometer in my Dodge it is usually 150 miles there do errands and back. I don’t think I could get enough batteries of any kind in my rig to go that far much less afford them.


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## octagondd (Jan 27, 2010)

If you go with the 100AH cells I would think about the new CALB CA grey cells. They are supposed to have a bit better power rating and less sag under heavy load. You will need that going up the hills. EVTV has them, but not sure how many left. His price comes with the bolts and braided connector straps. Also, get the AH counter like someone suggested above.

The CALB SE 130s would probably be a good cell size for you to give a bit of leeway on your distance, but I believe they are discontinued.


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## dragonsgate (May 19, 2012)

For what it is worth here are some pictures of the batteries. I threw in a pic of the controller too. Hope it gives an idea of what to do or not. Octagondd, I am aware of the grey’s. They do sound good. I still have to the end of the year before I will be able to make any solid choice. For now it is just I’m gonna and I wonna.


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## GizmoEV (Nov 28, 2009)

As someone else suggested I would get an Ah counter ASAP. That will easily give you all you need to determine what size LiFePO4 pack to get. In addition to the JLD404 that EVTV sells you might consider the CycleAnalyst from ebikes.ca. It runs directly off of the battery pack and has a plethora of features. It does not, however, have a pukert's exponent entry so it won't be very good at determining your lead acid SOC because as the current draw increases the meter doesn't account for the decrease in useable capacity. For Lithium batteries, however, the effect is very minimal so it doesn't matter. What you really want is your average consumption rate and the CA will calculate that for you if you hook up the speedometer function.


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## Carl55 (Jun 9, 2012)

Thanks for the photos. I am considering that model of car for my build. I could not imagine how you got all those batteries in. I found your car in the garage and was really curios. Also found one with 12v sla and one with lithium. With that panel removed you could put a lot of lithium in there, wallet willing. Again thanks for your time.

Carl


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## dragonsgate (May 19, 2012)

The X19 is kind of neat and they are a sturdy car and handle the 1134 pounds of lead but 18 lead batteries are a challenge to fit in. I did some radical things to get those batteries in there. I have driven and worked on Fiats for over 30 years so kind of know what I am doing. Unless you are doing lithium right off or you are planning on lower voltage than 144 I suggest a bigger car. I do not know about the Fiero but I think it is a little bigger and was designed by the same guy so they look similar. There are some Fiero’s on this sight so you might look at them. My first pack was 12 volt Excide deep cycles. I think they were 27 series or something like that. The car was about 300 pounds lighter and I could bark the tires. Even driving as easy as I could 20 miles just about flattened the batteries consequently they did not last long. What panel are you speaking of removing? One other thing about the X19. Parts are a bitch and expensive and getting worse.


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## Carl55 (Jun 9, 2012)

In the photos you posted it looks like a panel was removed. It looks like it was between the headlights in the front where the nine batteries are in formation. I have a similar situation. It is about 15 mi to work. To go to Walmart it is about 54 mi. To go to the city it is a little over 100 mi. I am sure I will have to start with lead then move up.

Carl


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## dragonsgate (May 19, 2012)

There was a box that housed the radiator. I inverted the box to accommodate batteries. Twelve 12 volt batteries took up more volume than the eighteen 8 volts I am running now. Notice how far in front of the shock towers the batteries are. With 12 volts there was an extra row. The car handled like crap with that extra weight hanging why out there. When I went 8’s I had an empty space so I bobbed 10 inches of the front of the car shaving some weight off the front plus I don’t scrape every time I pull into a parking lot. The perforated angle iron you see in front just reinforces the fiberglass front end. The structural frame work is down below right in front of the batteries. Depending on the lithium pack I get (if ever) there will be even less battery forward of the front wheels. The if ever is because I just read in ev news that lithium prices are going up about 17%. The reason I started this thread was to get some conformation on my seat of the pants estimate of the smallest lithium pack I could use and maintain what little range I have now. 100 amph was pretty much agreed on here and I had my financial partner on the ropes. I was just about to explain to her how cool 160 amph would be for a few thou more. Now I have to tell her that a bare minimum pack is going to cost a few hundred more. I hope it is going to only be a few hundred.


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## Carl55 (Jun 9, 2012)

Thank you for going out of your way and taking time for me. At $135 a cell that would be $22.95 price increase. That stinks. From everything I have read you should get 40+ miles from 100 amp hrs. Good Luck 

Carl


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## Ziggythewiz (May 16, 2010)

Just because lithium is going up doesn't mean our cells will. As production keeps ramping up the economies of scale should bring ours down at least as fast as material costs might rise. It doesn't take a lot of lithium to make a lithium cell.

The prices I've seen for CALBs hasn't gone up lately even with the newer cells.


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## dragonsgate (May 19, 2012)

Ziggythewiz said:


> Just because lithium is going up doesn't mean our cells will. As production keeps ramping up the economies of scale should bring ours down at least as fast as material costs might rise. It doesn't take a lot of lithium to make a lithium cell.
> 
> The prices I've seen for CALBs hasn't gone up lately even with the newer cells.


I agree but I like to fret. Life is unfair that way. Most of the stuff I have worried about never happened.


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## octagondd (Jan 27, 2010)

I put the numbers in the ev calculator at evconvert.com and came out with about 30 miles at 60mph in 3rd gear down to 80%DOD. It has an 82 Fiat in the default cars, so I used that. I also put in an incline of 6 to see how many batt-amps would be drawn on your hill run - [email protected] I don't know if his incline number is equal to grade or not. I sort of assume it is. How many batt-amps are you pulling when going up that hill at 60mph? 

There are a lot of other variables on the calculator like wind, rolling resistance, gear ratios, tire size, etc, but I just used what came up as default. I have a feeling this estimate is a little low based on what others have said they thought you could get, but I guess getting that amp hour meter and measuring your current rig would be the best way to tell how much lithium you will need.

The cost for the 100AH CA cells with straps and hardware with shipping would be about $7000.


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