# Battery Options



## ginfaxi082 (Jan 13, 2012)

I recently obtained an old model VW Beetle, and I'm considering converting it to an EV. But I'm not sure if it would be possible to get the range I require.

First, my daily commute is a rather long one (about 25 miles one-way). And I live in the country and drive alot of rural roads on my daily commute, so I don't think I would benefit much from regen braking. Therefore, I'm leaning towards purchasing a 120v DC kit because it's the least expensive way to attain realistic highway/rural road speed.

But, as I mentioned earlier, my daily commute is somewhat of a long one, so I would need a 60 mile range at a minimum. I don't think that 20 T-105s would give me the range/speed combination that I require and I think lithium ion is my only realistic option.

However, I am not at all familiar with lithium batteries. So my question is: how many of what type of batteries should I use to get the range I require? I'm not a millionaire, but I am willing to put a little money into this project if it means I get to dispense with the hassles associated with ICE engines (gas, oil, coolant, belts, hoses, etc.).

Thanks!


----------



## cruisin (Jun 3, 2009)

ginfaxi082 said:


> I recently obtained an old model VW Beetle, and I'm considering converting it to an EV. But I'm not sure if it would be possible to get the range I require.
> 
> First, my daily commute is a rather long one (about 25 miles one-way). And I live in the country and drive alot of rural roads on my daily commute, so I don't think I would benefit much from regen braking. Therefore, I'm leaning towards purchasing a 120v DC kit because it's the least expensive way to attain realistic highway/rural road speed.
> 
> ...


I have a 1970 VW conversion using the AC-50 with 36 CALB 180ah batteries. range is about 100mi depending whether I am alone or have others in the car with me. Range is better with my AC system than it was with the previous DC system, even without using regeneration. If you would PM me, I could help you in your decision making process of what would suit your purpose. I have included some pictures of both the DC and AC system as well batteries for you to see what can be done to a VW.


----------



## ginfaxi082 (Jan 13, 2012)

That's way cool! What kind of speed can you get out of the AC-50? Do you have any issues attaining highway speed?


----------



## cruisin (Jun 3, 2009)

ginfaxi082 said:


> That's way cool! What kind of speed can you get out of the AC-50? Do you have any issues attaining highway speed?


No issues, it will go about 85mph in 3rd gear. It uses no clutch and shifter and reverse gear have all been removed. Uses 3rd gear only, just like a production EV. 4000rpm at 65mph, but AC motor will go way over 8000rpm
unlike DC limited to about 4000rpm.


----------



## Martinsmith (Jan 13, 2012)

The battery universe is further divided along the lines of battery construction. Currently, there are three common lead-acid battery technologies: Flooded, Gel, and AGM.
Basically, an AGM can do anything a Gel-cell can, only better. However, since they are also sealed, charging has to be controlled carefully or they too can be ruined in short order.


----------



## ginfaxi082 (Jan 13, 2012)

Martinsmith said:


> The battery universe is further divided along the lines of battery construction. Currently, there are three common lead-acid battery technologies: Flooded, Gel, and AGM.
> Basically, an AGM can do anything a Gel-cell can, only better. However, since they are also sealed, charging has to be controlled carefully or they too can be ruined in short order.


Thanks for the info! Are there any lead-acid batteries that will give me the speed/range I require?




crusin said:


> I have a 1970 VW conversion using the AC-50 with 36 CALB 180ah batteries.


I know that ah generally refers to how long a battery will last, and I found a source online that offers the Thundersky 160ah lithium batteries at a good price (about $80 less per battery than the CALB 180s). How would using 160ah batteries instead of 180ah batteries affect performance/range?

P.S. Sorry about all the nub questions, and I sincerely appreciate all the feedback!!!


----------



## mora (Nov 11, 2009)

Lead acid: more weight, less range for same Ah. Cheap at first but if you calculate how long those will last you'll decide to go for lithium instead.

Lithium: less weight, cost to get a set is higher than with lead acids but will outlast any lead acid pack if handled properly. More range and better performance.

One 160Ah Thundersky/Winston cell weighs 5,6kg or around 12 lbs. You'll need 37-38 cells to get your desired 120V pack. Whole pack would weight about 456lbs. Based on assumption that 36 180Ah cells will get you 100 miles you'll consume a bit more than 200 Wh/mile. Let's say you do 240 Wh/mile. 37 160Ah cells would give you 18,9 kWh of battery capacity. If you use only 80% of it you are babying your batteries. That'll give your batteries long life. That'll leave you about 15 kWh of usable capacity. If you consume 240 Wh/mile you'll get 62 mile range. And you still have that 20% leftover if you really need to push it further (78 miles total). Highway speed will reduce your range a bit no matter which battery you choose.


----------



## ginfaxi082 (Jan 13, 2012)

mora said:


> Lead acid: more weight, less range for same Ah. Cheap at first but if you calculate how long those will last you'll decide to go for lithium instead.
> 
> Lithium: less weight, cost to get a set is higher than with lead acids but will outlast any lead acid pack if handled properly. More range and better performance.
> 
> One 160Ah Thundersky/Winston cell weighs 5,6kg or around 12 lbs. You'll need 37-38 cells to get your desired 120V pack. Whole pack would weight about 456lbs. Based on assumption that 36 180Ah cells will get you 100 miles you'll consume a bit more than 200 Wh/mile. Let's say you do 240 Wh/mile. 37 160Ah cells would give you 18,9 kWh of battery capacity. If you use only 80% of it you are babying your batteries. That'll give your batteries long life. That'll leave you about 15 kWh of usable capacity. If you consume 240 Wh/mile you'll get 62 mile range. And you still have that 20% leftover if you really need to push it further (78 miles total). Highway speed will reduce your range a bit no matter which battery you choose.


Wow, thanks Mora! Is there a formula you use to calculate that?

My daily commute is exactly 52.8 miles. Only about 10 of it is highway, but a good bit of it is rural roads, and Alabama ******** do not like to drive slow! So based on your calculations, I may want a system that provides a bit more range than the 37 160ah battery pack. Would that mean more batteries, or the same amount of 180 or 200 ah batteries?


----------



## Yabert (Feb 7, 2010)

Hey Gin

To calculated range:

-36 cells 180Ah: 36x3.2v = 115.2v x 180ah = 20736 wh (20.7 Kwh)
-40 cells 160Ah: 40x3.2v = 128x x 160Ah = 20480 wh (20.5 Kwh)

20500 wh / 240 wh per mile = 85 miles

But you should use 80% capacity so that give a range of 68 miles

*All this is theorical and base on 240 wh per mile consumption.*

Oh! And what about charge at work and build smaller pack?


----------



## skooler (Mar 26, 2011)

Right,
I noticed the math in the post above.

I thought it'd be a good idea for me to not read / ignore it and work it out as well. then we can see if the figure is the same  (make sense?)

I would guess a bug would use 240-300WH per mile.

lets call it 30 miles each way (to be safe) so 60 miles total.

60*240wh is 14.4KWH then *1.2 (cant run them flat!) - 17.280KWH
60*300wh is 18KWH, *1.2 = 21.6KWH

So for 17.280KWH you would need 90 * 60AH cells, 54 * 100AH cells 

For 21.6KW you would need 112 * 60AH cells, 67 * 100AH cells or 34 * 200AH cells

Using the 60AH cells will give you a higher voltage which gives higher RPM. or you can double them up in parrelel to give you more flexibility with where to locate them.

As an example, a Sinopoly 60AH cell (below) weighs 1.9KG so 180 - 220KG of batteries. not sure about CALB, HiPower etc.

http://sinopoly.todayir.com/attachment/201110101354083_en.pdf

How does that compare (still havent looked!) 

Cheers,

Mike


----------



## dladd (Jun 1, 2011)

Don't even think about lead. Go with Lithium.

Think in terms of energy. If you assume 250Wh/mi (that's pretty efficient) you will need 250Wh/mi x 60mi = 15,000Wh or 15kWh. I'd knock off another 15% for cold weather and heater usage, so 15kWh x 1.15 = 17.25kWh. Thats actual usable energy, and since you don't want to take a battery below 80%, your battery pack size would need to be 17.25kWh x 1.2 = 20.7kwh. 

You can then allocate that however you want. 32 200ah cells, 64 100ah cells, craploads of Headway cells, etc.

The AC-50 Cruisin is talking about above is the only good low cost AC option (has regen) and can use up to 36 cells, I believe. DC will let you go with higher voltages, but may not be quite as efficient.

check out http://www.corbinstreehouse.com/blog/plug-bug/ for a very detailed log of a bug build with quite a bit of performance data.


----------



## mora (Nov 11, 2009)

I believe a bug won't consume 300 Wh/mile unless going 65 mph. My Golf (rabbit) wants 175A at 90V to maintain 60 mph speed (about 100 km/h). That's about 250 Wh/mile. It is also heavier and might have a bit worse aero than any bug so bug will likely consume less in any case. If going slower than 40 mph it consumes less than 200 Wh/mile. These readings are not measured "from the wall".

But yes, you should add some more reserve capacity if you are going for electric heater/AC.


----------



## ginfaxi082 (Jan 13, 2012)

Ok. I'm sold on lithium!

What is the best / least expensive source for lithium batteries?


----------



## skooler (Mar 26, 2011)

ginfaxi082 said:


> Ok. I'm sold on lithium!
> 
> What is the best / least expensive source for lithium batteries?


It depends a lot on where you are based. (?)

Cheers,

Mike


----------



## ginfaxi082 (Jan 13, 2012)

skooler said:


> It depends a lot on where you are based. (?)
> 
> Cheers,
> 
> Mike


Podunk, Alabama, if that helps...


----------



## ginfaxi082 (Jan 13, 2012)

skooler said:


> For 21.6KW you would need 112 * 60AH cells, 67 * 100AH cells or 34 * 200AH cells


All the lithium batteries I saw online were 3.2v and various ah. So if I used 112 60ah cells, that would equate to 358.4v, right? But the AC-50 is rated at 72-108v. So couldn't that high of a voltage damage that system?


----------



## cruisin (Jun 3, 2009)

ginfaxi082 said:


> All the lithium batteries I saw online were 3.2v and various ah. So if I used 112 60ah cells, that would equate to 358.4v, right? But the AC-50 is rated at 72-108v. So couldn't that high of a voltage damage that system?


As a dealer for the AC-50 and CALB batteries I can lead you in the right direction if you PM me. Using the AC-50 the maximum voltage that the controller wants to see is 130v. 36 CALB cells will give you the voltage you are looking for. Some have used 38 cells and dont use regen until their voltage drops. The controller will protect itself from excessive voltage. I have converted many VW and Porsche cars since 2002, so I belive I can provide you with the information you are looking for. Here is my car.


----------



## skooler (Mar 26, 2011)

ginfaxi082 said:


> All the lithium batteries I saw online were 3.2v and various ah. So if I used 112 60ah cells, that would equate to 358.4v, right? But the AC-50 is rated at 72-108v. So couldn't that high of a voltage damage that system?


Yes, if they are all in series.

You could parellel the cells or go for fewer, larger AH cells. using the smaller cells gives you more flexibility on where to position them.

I only mentioned the 60AH cells as the new Sinopoly 60AH cell specs, size and weight are brilliant. I am starting to hear excellent reviews of them, I just wish that my order would hurry up!

It all depends on weather you want to go for an AC or DC setup. 

Cheers,

Mike


----------



## ginfaxi082 (Jan 13, 2012)

So if you wire batteries in parallel, their current combines but not the voltage?


----------



## skooler (Mar 26, 2011)

ginfaxi082 said:


> So if you wire batteries in parallel, their current combines but not the voltage?


Thats correct.

Parellel combines current and series combines voltage. The important thing is to keep everything in balance.

As an example, If you went down the AC route, you could go for 3 parellel strings of 36 cells (36S3P) (115.2V nominal)

For DC you could go for 2 strings of 56 cells (56S2P) for the added advantage of higher voltage. (179.2V nominal)

It's not something that you will see done much, as I said before, it gives you the added flexibility with placement. I wouldnt normally recommend it but the new Sinopoly 60AH cells make it a lighter/ more flexiblesolution. The downside is that its more cabling!

Just an idea  Otherwise a single string of 36 cells (as cruisin suggested) will work just as well.

As for the best/least expensive source,

CALB, HiPower and Sinopoly are the obvious contenders for prismatic cells.

CALB seem to make good quality cells although they are a bit larger and heavier thean the newer sinopoly (formerly ThunderSky) cells, which are only just starting to be used.

Cruisin is a supplier for CALB cells, I can supply Sinopoly Cells. The links on the right hand side of the forum are worth a look.

You are probably looking at $1.10 - $1.40 per AH per cell.

Cheers,

Mike


----------

