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

5315 Views 31 Replies 12 Participants Last post by  Jimdear2
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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Jim i thought i'd post some of my headway testing data here if you don't mind ? did'nt really want to go starting another thread. Cell pac used is a 4s2p pack of 8ah p cells. Some charges and discharges had already been carried out on this pack prior to today. I also used them to test a few chargers i purchased. Sadly these chargers aim for 3.65v per cell which , without a bms, causes overvoltage.

The first graph shows a 1C (16A) constant current discharge followed by 5A and 2.5A discharges to get as much energy out of the pack as possible.

Next i used a 12v 65w car headlight bulb to try a very rough bottom balance. I got all the cells to 2.85v +/- a few mV. They were then placed on a 10A constant current constant voltage charge to 13.8v total (3.45v/cell) until current dropped below 0.8A.

I next used my much battered "solar" battery tester to load em up to 400amps to check if the cells kept in line under severe discharge events. They did. As usual , the old battery tester started pouring smoke so i had to abandon that phase. The voltage dip on cell 4 was caused by a loose wire on the cellog.

Finally i recharged at 10A to a cv point of 13.75v. To my amazement the delta v of the pack diminished to as little as 2mV at times and i think leveled out to 14mV at cv point.

I have the data files in text format if anyone wants to veryify the fine print. Cellog interval was set at 2 secs which i admit may have been a bit coarse.

My "gut" tells me the start of the charge knee is somewhere between 3.45 and 3.5v per cell. I could also quite plainly see capacity differences in the cells today. cells 1 and 4 were lower than 2 and 3 as the former hit the charge and discharge knees much earlier.
 

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