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Discussion Starter · #1 ·
I currently have a 144 v (12, 12v) lead acid deep cells in my ev. What is the recommeded configuration of a replacement LiFePo4 bank. Also, I believe the lead acid capaity are based on 20 hour discharges (Are the LiFePo4 capacities base on 20 hour or 1 hour).
Are there Lithium packs that can be connected in series that provide equiviant capacity. Or do packs require parrallel connection? I look at ev assembly and they have a 32volt 20ah pack?
 

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The most strait forward reconversion would be to use 45 to 48 cells, either Thunder Sky or CALB, with an amp hour rating that is at least 60% of the 20 hour capacity rating of your current lead batteries. That should allow almost all the rest of the parts currently in your EV to remain the same (except the charging system) and get you the same or slightly more range.

If you can install higher amp hour cells you can get more range. You should install a pack large enough that the peak amps will not be greater than 3 to 5 times the cells amp hour capacity. This may be a consideration in choosing cell capacity larger than needed to meet your range goals.
 

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Discussion Starter · #4 ·
Can I use 200 watt hours per mile.

Range of about 40 miles round trip.

8000 kwatthours required at 144 volts (my current system)= 56 Ah

Considering losses should I buy a 70-100 ah battery?
 

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Sounds about right. I'd suggest using 45 cells, in either the 90 or 100 amp hour size. A little extra range isn't a problem, coming up a little short is.
 

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Sounds about right. I'd suggest using 45 cells, in either the 90 or 100 amp hour size. A little extra range isn't a problem, coming up a little short is.
i agree with EV FUN.
have you found any good battery supplier?
besides battery bank,you have to use a good charger and BMS too.
 

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If you want your investment to last, I think you should size the Ah of your cells based on the recommended discharge rate of the cell maker.

Calb recommends .3C. That keeps heat from building up. Heat eats capacity. If you create heat due to undersized cells, you have to cool them as well or risk them overheating and getting damaged. OTOH if you can't afford that or don't have room for them I guess you'll just have to purchase what you can.

I wanted a 100 mile range as I use mine for work traveling to jobs out of town, most less than 40 miles. A bonus of sizing for that is that my truck will cruise frequently at less than .3C current draw. I used 200Ah cells, 50 of them for a resting voltage about 160V. Higher voltage will reduce the current draw also for a given wh load.

My cells at recommended .3C discharge is 67A. Only on acceleration or hills will I exceed that and only for 30 seconds max. For the $$$$$$ that I spent on them, I want them to last a looong time and I have expectations they will.

Also the heat build up from high C discharge causes the electrolyte to vaporize which causes the case to swell. That has been reported a lot on here as well.

One more point, you'll lose weight and wh/mile so whatever your amp draw is now it will drop in my case an estimated 30% due to 25% weight savings and lower internal resistance. I'm also reducing non battery weight about 5% so if I'm lucky maybe a 40% reduction in ah!

Just don't skimp on the Ah if you aren't limited in some way so that you keep your amps down below .3C. Make those boys last!
 

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So... I'm new to the whole idea of powering a car with electricity and where to buy the supplies, so please bear with me.

chaz_fwb Was suggesting basically the same solution I had "calculated" (in quotes since I'm not quite sure I was calculating correctly) for my EV MGB idea (1 bank of 48 3.2V 110Ah batteries). But then what ElectriCar said makes sense too (48 3.2V 200Ah batteries)... What can anyone say to sway my thinking one direction or the other?

The place I'm looking at for prices is batteryspace. Again, I'm new here, so I hope it's not against any rules that I'm posting a couple direct links (please correct me quickly if it is not okay).

LiFePO4 Prismatic Module: 3.2V 200 Ah, 10C Rate (640 wh), CE Listed (60.0)

http://www.batteryspace.com/LiFePO4-Prismatic-Module-3.2V-200-Ah-10C-Rate-640-wh-CE-Listed.aspx

48 x $304.00 = $14,592



LiFePO4 Prismatic Module: 3.2V 110 Ah, 12C Rate (352wh), CE Listed (33.0)

http://www.batteryspace.com/LiFePO4-Prismatic-Module-3.2V-110-Ah-12C-Rate-352wh-CE-Listed.aspx

48 x $166.25 = $7980.00




Thoughts??
 

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So... I'm new to the whole idea of powering a car with electricity and where to buy the supplies, so please bear with me.

chaz_fwb Was suggesting basically the same solution I had "calculated" (in quotes since I'm not quite sure I was calculating correctly) for my EV MGB idea (1 bank of 48 3.2V 110Ah batteries). But then what ElectriCar said makes sense too (48 3.2V 200Ah batteries)... What can anyone say to sway my thinking one direction or the other?

The place I'm looking at for prices is batteryspace. Again, I'm new here, so I hope it's not against any rules that I'm posting a couple direct links (please correct me quickly if it is not okay).

LiFePO4 Prismatic Module: 3.2V 200 Ah, 10C Rate (640 wh), CE Listed (60.0)

http://www.batteryspace.com/LiFePO4-Prismatic-Module-3.2V-200-Ah-10C-Rate-640-wh-CE-Listed.aspx

48 x $304.00 = $14,592



LiFePO4 Prismatic Module: 3.2V 110 Ah, 12C Rate (352wh), CE Listed (33.0)

http://www.batteryspace.com/LiFePO4-Prismatic-Module-3.2V-110-Ah-12C-Rate-352wh-CE-Listed.aspx

48 x $166.25 = $7980.00




Thoughts??
First thought.... that is too much money for LiFePo4. Shop elsewhere.
Second thought.... don't believe the 10C 12C stuff. It's more about not wanting to do than being able to do it...for a short time... very short time.
Third thought.... what is the weight/type of vehicle? What is the controller, what is the motor? Trans? Driving expectations?

These guys are all right... but it makes sense to fit your design with the right battery to achieve what they are saying. To do that, we need more info.
 

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So... I'm new to the whole idea of powering a car with electricity and where to buy the supplies, so please bear with me.

chaz_fwb Was suggesting basically the same solution I had "calculated" (in quotes since I'm not quite sure I was calculating correctly) for my EV MGB idea (1 bank of 48 3.2V 110Ah batteries). But then what ElectriCar said makes sense too (48 3.2V 200Ah batteries)... What can anyone say to sway my thinking one direction or the other?

The place I'm looking at for prices is batteryspace. Again, I'm new here, so I hope it's not against any rules that I'm posting a couple direct links (please correct me quickly if it is not okay).

LiFePO4 Prismatic Module: 3.2V 200 Ah, 10C Rate (640 wh), CE Listed (60.0)

http://www.batteryspace.com/LiFePO4-Prismatic-Module-3.2V-200-Ah-10C-Rate-640-wh-CE-Listed.aspx

48 x $304.00 = $14,592



LiFePO4 Prismatic Module: 3.2V 110 Ah, 12C Rate (352wh), CE Listed (33.0)

http://www.batteryspace.com/LiFePO4-Prismatic-Module-3.2V-110-Ah-12C-Rate-352wh-CE-Listed.aspx

48 x $166.25 = $7980.00




Thoughts??
There are links on the right hand side of the browser window that has links to the sites sponsors. Many of them sell lithium batteries and there are others besides that if you're willing to do some searching. Those batteries in your link seem way over priced.
 

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You should be able to get Calb batteries, the consensus #1 battery out there for about $1.23/ah so a Calb 200A would be about $248 with hardware plus tax. You may get them cheaper. DIY guy got them for a really good deal. Shipping from California to South Carolina for my 51 cells was about $450 so that added about $9 each.

Again, try to buy something that will operate normally at 0.3C or less if you want to maximize life. Running a higher voltage will reduce operating current draw for a given speed which again is better for your batteries AND will give you more top end speed and possibly more torque.
 

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So... I'm new to the whole idea of powering a car with electricity and ...48 x $304.00 = $14,592


48 x $166.25 = $7980.00


Thoughts??
I bought mine from here

http://elitepowersolutions.com/products/product_info.php?cPath=16&products_id=43

They cost $199 for 260 AH Thundersky's. They also include ALL HARDWARE!!! Some places charge extra. Lots extra!

Plus they may have enough in stock here in the US, that you may get them in a week like I did.

Best BMS I found was the MiniBMS advertised on this site.
 

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I bought mine from here

http://elitepowersolutions.com/products/product_info.php?cPath=16&products_id=43

They cost $199 for 160 AH Thundersky's. They also include ALL HARDWARE!!! Some places charge extra. Lots extra!

Plus they may have enough in stock here in the US, that you may get them in a week like I did.

Best BMS I found was the MiniBMS advertised on this site.
I was hoping someone would post a different supplier:) I had tried a couple links on the right, but had no real success. One, in particular, only seemed to list part numbers and prices for camera batteries. Now, I'm sure they are actually the same thing, but without some sort of real description attached to the part number, I remained ignorant:)
 

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First thought.... that is too much money for LiFePo4. Shop elsewhere.
Second thought.... don't believe the 10C 12C stuff. It's more about not wanting to do than being able to do it...for a short time... very short time.
Third thought.... what is the weight/type of vehicle? What is the controller, what is the motor? Trans? Driving expectations?

These guys are all right... but it makes sense to fit your design with the right battery to achieve what they are saying. To do that, we need more info.
Thank you for your thoughts! I'm on the verge of hijacking chaz_fwb's thread... So I'll throw my specs in another post.

I think the real question here is: Is there a good rule of thumb in going from a 144 v (12, 12v) lead acid deep cell setup to a LiFePO4 setup? I think I'm seeing recommendations for between 144V and 160V (more is a bit better for current draw, operating temperature and torque). In chaz_fwb's configuration, what "real-world" benefits could be realized by going from a 100Ah battery to a (hypothetically) a 200Ah battery? Would the battery pack literally take you twice the distance?
 

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Thank you for your thoughts! I'm on the verge of hijacking chaz_fwb's thread... So I'll throw my specs in another post.
Then maybe u should start one, cause u keep asking questions without giving the info...;)
I think the real question here is: Is there a good rule of thumb in going from a 144 v (12, 12v) lead acid deep cell setup to a LiFePO4 setup? I think I'm seeing recommendations for between 144V and 160V (more is a bit better for current draw, operating temperature and torque). In chaz_fwb's configuration, what "real-world" benefits could be realized by going from a 100Ah battery to a (hypothetically) a 200Ah battery? Would the battery pack literally take you twice the distance?
Re: rule of thumb....Not really, until you determine what you have and what you want. What are your existing components rated for? Can your controller limit motor voltage? Yes, doubling the ah's will double your range...practically speaking.
 
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