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Need Help, Going to buy Headway's fo the Big 13 Pulling tractor

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Need Help, Going to buy Headway's for the Big 13 Pulling tractor

PLEASE!
Looking for help and advice.

Well, the money's put aside and we are ready to buy 104 Headway 38120P batteries to power the 13 inch motor in the pulling tractor.:D

I'm looking for the best value since I'm retired. The $2000.00 or so is a big chunk for me so I have to get the best value I can.

The 72 volts we tried last season just didn't do it (of course the bad gearing choice I made didn't help:eek:).

100 batteries for the tractor and 4 spares. (the 4 will probably be used as a 12 volt control battery)

We plan to go with 50S 2P to start off this year and next year we will be adding 50 more batteries as we prove out the systems and home made controller until we reach a total of 200.

Looking for advice from people who sell and/or who have bought Headway batteries.

I can wait a while since pulling won't start until May of next year. I'll also be building a Simon/Jack charger and we are looking at various balancers.
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Discussion Starter · #4 ·
I bought 540 for my build. I got them directly from Loraine. Everything totally above board. I had them sent directly to my house by air. The cost (including shipping, taxes and brokerage which Loraine took care of) was less than anything I have seen for sale domestically. I could have saved $2 per cell if I wanted to wait a few months if I had them sent by boat. You can always email her and ask. She usually answers quickly.
galeson,

Thanks for the information.

The idea of saving up to $2.00 a cell for the slow boat from China shipping might mean a few extra cells. Since we are on the ragged edge of requirements, that may make the difference. To be honest I thought that the total cost from China and the cost from US suppliers was pretty equivalent.

I'll search up Lorrain's email and get with her for a quote.
Did you get link plates and the snap together pack pieces from her as well?

Have you decided on a BMS?

Jim
 

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Discussion Starter · #5 ·
Only 2P ? These are 10AH cells, right? How much battery current are you expecting to pull , pun intended... ?

2P sounds a little low, make sure you don't kill your investment prematurely.
dimitri.

You are right, we are right on the edge of minimum requirements. But thanks for the concern.

The batteries should give 20C, thats 200 amps per string. Pulls generally last about 15 seconds in the class we are aiming for. The first 1/4 of the pull is lightly loaded we also are planning on the controller to limit the current. so we are hoping to get through by being careful.

We have also discussed going with 33S 3P but that may drop the voltage too much to allow us to build enough momentum to keep the draw down for the last part of the pull.

Every thing is a trade off.

I also figured with the big tax increases next year to pay for all of the Obamanations plus no cost of living increase for social security AGAIN, I better get in now before the government takes it all.

Jim
 

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Discussion Starter · #9 ·
Re: Need Help, Going to buy Headway's for the Big 13 Pulling tractor

Just curious -- I thought folks added weight for tractor pulls? Might this be the rare case where the weight of lead acids could be a virtue? Just curious why the trouble and expense of lightweight, high power lithiums. Are you trying to get below a certain weight for a class?
David,

The class weight I am trying to match is 1350 lbs. with driver. The ICE tractors in that weight class are allowed up to 1500 cc engines.

Right now we have about 160 lbs slack for batteries with my partner in it (I'm too heavy to drive it) the eventual 200 cell battery we want will weigh just about that. There are size limits, length and width as well, we just physically can't fit enough lead into it, never mind weight.
 

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Discussion Starter · #10 ·
The 38120P cells are 8Ah. Back on April 9 Mike Willman posted his testing of the P cells. He got up to 60C, but he heated up the cells considerably. Who knows how long they will last with this kind of abuse.
I bought the snap together pack pieces and link plates from Lorraine also. They were about 1/3 the price.
galeson,

We saw that too. I know that the 38120 P are 8 ah, I just used the 10 ah figure David used to simplify the reply.

We plan on air cooling for sure and even discussed CO2 expansion or Ice Pack cooling. We are going to limit ourselves to 20C for starters. I'll be contacting Lorrain tonight as well as any US distributors as I find them.

Have you used the snap together pieces yet. Are the pretty strong. Pulling tractors don't have suspension and the tracks can be rough, never mind the slam down from wheelies. Do you think they could stand the abuse?

Again thanks for your comments.
Jim
 

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Discussion Starter · #11 · (Edited)
Power is power, so 33S 3P will put the same stress on cells as 50S 2P , since decrease in voltge means proportional increase in current. The only way to address it is to add more cells, either 50S 3P or 33S 4P.
We are thinking that 50S 2P to start off is the way to go because we want the higher voltage. The first 1/4 to 1/3 of the pull is where you build speed for momentium. By going with the higher voltage you get more speed before the transfer load starts increasing drag. Same power gets you further because you can store more inertia in the lightly loaded portion of the pull

I have no hands on experience with stressing Headway cells to their limits, but I would check with someone who does. I think CroDriver has HeadWay pack in his BMW racer and he is likely giving it run for its money.

I would not just assume the cells can handle 20C just because the spreadsheet says so. Heat management and busbar connections become a concern when running at max C rates as well.
There have been a few high load tests run that I have been reviewing and it looks like 20 C for 15 or so seconds is possible as long as you rest, cool and recharge between Runs. Since we rarely hook more then twice a day, with sufficient recharge/balance time in between. We only do 15 or so pulls a year we so hope we can get through the first year with a 100 cell battery.

We will see.

We will be contacting CroDriver as well as anyone else we can think of who are using the Headways.

Please keep your thoughts coming, they are helping. If enough of you convince me I really need to go to 150 batteries to start off instead of 100, I'll try to squeeze my 401K for more resources.

Jim
 

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Discussion Starter · #23 ·
Re: Need Help, Going to buy Headway's for the Big 13 Pulling tractor

Hi Jimdear2,

I've been gathering data on various batteries for use in EVs and you might want to take a look at what I found. Go to the the list of batteries on the following page and sort by 'Watts (max)/pound.' The best batteries will appear at the top of the list. You can click on a battery to do some pack calculations...

http://www.zuglet.com/batteries/batteryList.php

The HeadWay batteries certainly offer the benefit of the screw terminals -- but, the maximum power density (per pound) is considerably (50%) better on the A123 and Panasonic Lithium batteries. You will have to put more batteries in parallel -- but, it might be worth looking into.
Zuglet,

That is quite a nice bit of work there. I'll be looking through it for a bit.

I know the A123s are more power per pound but the difficulty in getting them, working with them and the cost per unit all put them on a second choice list for me in this application. Since we will be stressing the pack we will want to be able to disassemble and repair/replace without major work.

This chart should be made available to more of the people on the DIY site. I recommend that you place it in it's own thread.

Jim
 

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Discussion Starter · #28 · (Edited)
Hi Jim

How many Amp can delivred our controler?
Yabert,

The controller is still under developement. My partner (an EE) in this madness, has bought a bunch of 600 volt 400 amp IGBTs and is slowly collecting the necessary stuff to do an at least 1000 amp 300+ volt controller using the Paul and Sabrina board.

Otherwise I keep looking at the other high end big voltage big current controllers. We will see how he does.

I use Headway 38120S 10Ah on my suzuki DRZ coupled at a 700A controller. In my 26S 3P configuration the voltage drop at 2.3v per cell at 600A (20C) in the first second (1-2 sec.) of acceleration. After my small motor isn't capable to pull higher Amps.

If you use 1000A controller the 2P configuration will be not enought!!!
Depending of your gear ratio you probably need more Amps (torque) and less voltage (speed).

So, for a bit more money, a configuration 30S 4P could give to your 13" motor a good power for 15s. But you will be over the battery spec!!
Use headway at 30C discharge probably reduce a lot his life....
But it's probably a good test for not to much money....

Good luck!
I have decided, after all of the advise I have recieved, to purchase 155 38120P 8 ah cells for their high C rating with decent capacity.

We will use them in either a 50S 3P or a 36S 4P configuration. with the extras as spares. We need fairly high rpm from the motor to keep the wheels spinning but still need grunt when the weight transfer box starts loading the pan, with the 36S and 4P configuration we are looking at 800 amps at 90 volts. Assuming the cells maintain at least 2.5 volts when under max C. we may change to a 50S 3P pack if we don't have enough wheel speed or need al of the power at the end of the pull.

The actual power curve should look something like 110 to 115 volts with maybe 300 amps for the first few seconds (5 to 7) then slowly rising to peak at at as much as 800 amps at 90 volts for the last 2 or 3 seconds. Total time span 13 to 18 seconds. eventually we want to get to a 50S 4P pack. Total gearing could vary from about 4 to 1 up to 20 to 1 depending on the sprocket selection.

There are so many variables it may take years to get it right. With tractor pulling you generally get one try to get it right. All of the tuning is done in your head. No practice or tuning runs. Thats part of what makes it fun

So you have pretty much confirmed that I am on the right track. THANKS:D.

Also want to tell you how very impressed I am with the quality of craftmanship on your bike. With a little tweeking and optimizing of the overall bike design as a true electric I believe it would compare favorably with any comercial product out there.

Be well,
Jim
 

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Discussion Starter · #29 ·
Re: Need Help, Going to buy Headway's for the Big 13 Pulling tractor

There is a thread on ES about pulling a starter motor for 6 minutes, I believe, on a Honda Civic.

Also, pulling a starter motor on a High tech Ford v-8 engine, for less time. batteries took the load, still take a charge and still have not blown up.

They come in different voltage packs, lighter in weight, and the guys that are into serious battery tech, are becoming very enthused.
Harold,

They do look enticing but they are just a bit too leading edge for my pocketbook. I'm going to go with something a bit more mainstream to start out. There are just too many variables involved without throwing in something else new.

Maybe when we get ready to hit the sand drag tracks where you need BIG power for 3 or 4 seconds, I'll look again.

Thanks for your input, hope a few others follow up because this looks interesting.

Jim
 

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Discussion Starter · #32 ·
Jack,

Thanks for the info, I was getting just a little antsy about what the voltage sag would be at a full 25C. It looks like a 2.4 volt per cell or so from your data. I can't tell how long you were able to hold that load.

I guess we will try a 38S/4P layout to start. thats about 130 volts nominal at 3.45 vpc. If we can keep the sag to 2.5 volts that's still going to leave us about 95 volts.

I've went ahead and bought an Open Revolt kit that I plan to eventually run on my Cub Cadet, I might just try it out for starters on the Big 13. Darin, my partner in this thing, has a bunch of BIG IGBTs and capacitors and is planning on a 300+ volt and 1000+ amp controller to use for when we finally can afford and get the total 50S/4 or 5P pack built. The big pack is for sand drags.

We will probably be running some very similar tests to the ones you did on our batteries. Mostly we will be seeing if they will individually come up to 3.5 volts and then sustain, say a 175 amp load while maintaining +2.5/2.6 volts for 15 seconds. We have some big electric bus Brake resistors we will be using as a fixed load. Then we want to see what the resting voltage will be. From there I'll bottom balance them to a common voltage, and build each series layer and do a charge to 3.45 volts per cell and see how thay balance out then do a load and again see how they balance out.

The idea is to look for cells that don't maintain standards. Manzanita Micro only gives us a 2 week warranty on DOA so I have to get them checked fast.

How does that test program sound? Any suggestions for anything else I should look for?

Jim
 
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