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[picasso]

These guys are dirt cheap and I get stuff from them all the time. A device like these might work good. https://www.surpluscenter.com/sort.asp?UID=2009120617092492&catname=misc&keyword=XTTT


What also might work is to put a big piano hinge on the side. And when you need to open it take out the long pin for the hinge. It will be real fun trying to line it up and compress it back.

[guity]

Tried to order 2 60 AH batteries at EV Components for $66 apiece, but they didn't have any in stock, and the next supply doesn't come in until February.   But the EVComponents people were really nice.  They steered me to Jungle Motors in San Juan Capistrano, CA.  Jungle Motors sold me the batteries, to be shipped today, for $83 apiece.  Also bought a cable from Monoprice, (the best damn place to buy computer cables in the universe) that has a male serial interface on one end and a USB interface on the other.  The serial interface will plug into the Alltrax controller and the USB will plug into a computer.  Unfortunately I have no laptop so will have to disconnect and lug entire desktop down to garage when time comes to set controller.

I was trying to tell the Jungle Motors guy that I also needed to order one of those metal bars that appears to be copper but is covered with rubber-looking insulation in the middle and is used to connect each cell together serially.  But the guy said they are called "battery straps" and one comes standard with each battery.

And then for grins I purchased some ratchet straps for $20.  I'm thinking that if they can be placed in the right way where there is space for them to fit with all the other parts of the bike, they could close those hack-sawed metal cases back up...maybe not, I'll see.

[guity]

Does anybody sell cheap gizmo's to drain battery voltage, or does each individual have to solder together a bunch of wires and resistors to make one, or hook the battery up to wife's hair dryer?

[guity]

Plan A

1) Put cinder blocks underneath the bike to raise the rear wheel off the ground -- should be easy with no batteries currently in the bike

2) Arrange the battery cases containing the 22 surviving batteries next to the bike and hook all the wires up between the packs and between the packs and the bike

3) Run the bike with the rear wheel raised off the ground until the 22 batteries are drained down to 2.8 volts each

4) Charge the 2 new batteries to 2.8 volts and try to cram them into the open spots in the cases, hook them up and then try to cram the bulging hack-sawed cases into the bike and get everything hooked together

5) charge the 24-battery bike to 24 times 3.75 = 90 volts

6) Turn on the bike and see if anything explodes

Possible variation: keep the battery cases outside the bike, continuing to run the raised rear wheel for a couple of cycles even after the new batteries are in place, so that all batteries can be easily monitored to verify their voltages aren't wildly different...

[guity]

Plan A is a total flop. I was going to drain the batteries of voltage by running the motor at full speed while the bike was suspended in the air. Then I was going to join the 2 new batteries in at the same low voltage (2.8 volts apiece) and charge all 24 of the batteries up and then run them all down again once or twice to make sure they all kept the same voltage.

But when the rear wheel runs without traction at full speed, it only draws about 10 amps. So I would probably take hours and drive my neighbors crazy before I ran the batteries down to 2.8 volts apiece. So I guess I am going for plan B: charge the 22 batteries up to around 3.7 or 3.8 volts apiece, and charge the 2 new batteries individually up to the same amount, and then try to put everything back together again.

But with Plan B I will be stuck with having to take the battery cases out every time I want to check the individual voltages on the batteries, which is fairly hellacious...

[guity]

It looks like one of my two replacement batteries is bad. At first I thought it was my $11 little Tenergy lifepo single cell battery charger, because I put the battery on it (or maybe I put the charger on the battery) all night and the battery only got up to about 3.5 volts. That was the first time I had used the charger so I assumed it wasn't any good, or at least it was so slow that it was useless.

But now I am using it with the other batteries and it works pretty good - charges them up to 3.75 volts and then stops automatically, and since they are already up in that voltage area anyway, it doesn't take very long. I guess I will just run the bike with the rear wheel suspended to take all the batteries below that 3.75 ceiling and then use the Tenergy to take each battery back up to 3.75 individually. Then replace the replacement battery, and maybe the bike will be good to go...

[guity]

The charge output of this little Tenergy lifepo charger is specified to be 2 amps (and a pre-charge current of .5 amp, and cut-off current of .2 amp).

I used the regular charger to charge everything to the top -- it looked like this:

3.9----------3.8----------3.75
3.8----------3.9----------3.9
3.9----------3.8----------3.7

3.7----------3.8----------3.7
3.9----------3.7----------3.8
3.8----------3.9----------3.9

3.55---------3.9
3.7----------3.9
3.9----------3.8

(the 3.55 is the (apparently) bad replacement battery).

After the general charging, I ran the bike with the rear wheel raised to take the pack down a few volts so that every cell would be less than 3.75 volts. Now I am going through each cell individually and using the Tenergy charger to bring each one up to 3.75 volts (though 3.75 volts doesn't look much different than 3.8 volts on my multimeter).

[guity]

It took a long time to go over 23 batteries with the single cell charger, but the numbers smoothed out a little bit:

3.7--------3.7-------3.8
3.7--------3.7-------3.64
3.64------3.68------3.64

3.64------3.64------3.68
3.68------3.64------3.64
3.64------3.64------3.64

3.55------3.7
3.64------3.64
3.7--------3.64


The 3.8 in the top right corner of of the first 9-cell pack is because the measurement was taken immediately after that last battery was taken off the Tenergy charger. All the rest of them settled down to 3.64 -- 3.7 after a few minutes, so I assume that top right corner cell has settled down as well by now.

I'll leave the Tenergy charger on the 3.55 cell all night and see if anything good happens...

[guity]

The Tenergy still isn't done charging the "bad" 3.55 volt battery, after 11 hours.  However, the voltage of the battery has climbed to 3.7, so the battery isn't really "stuck" at 3.55.  If the "bad" battery turns out tobe good then maybe I can run the Tenergy charger over the batteries again to see if I can get cell voltages closer together.  Then perhaps I can run the motor (and perhaps just leave the headlight on all day) to run the charge down a ways to see if the batteries are staying even...

[guity]

Now 4 main tasks left --

1) get the battery voltages as equal as possible
2) run 25 wires from the positive terminals (and the last negative terminal) of the batteries that are long enough to reach to the space under the gas tank, thereby allowing the batteries to be checked for voltage and charged or drained as necessary without having to remove the godawful trays
3) schlep the computer downstairs and set it up next to the bike and connect to the controller
4) try to remember how to re-assemble the bike

[picasso]

You can build a board of light bulbs for large multi cell loads and for single cell a low volt light is always fun like an old 6volt car spot light. It will be dim but is a nice glowing load so you know its on. I've also seen guys use toasters for a load, basic toasters. the endless-spear forum should have a good number of options. Please report back what you find. I've never looked into that yet. The cells I deal with are in a pack and I have a tester to drain them out and cycle. I have a ton of cells around in many states of charge. Sorry didnt keep up was away for a bit. 

For the cells taps you can run them into a small pelican case case to keep water and metal away from them. For now you can use stuff like this http://www.radioshack.com/family/index.jsp?categoryId=2032289 and just stuff it in a box

Also it might not be a good idea to run the motor with no load for extended times. Id ask Electric moto about that one with your motor.

And if you want a good deal on a laptop I will give you one at a price you will love. I have a few OQO computers around. Its about as small as you can get.

[guity]

Picasso, that radio shack link you provided looks like a total lifesaver.  I just purchased a small wooden board for 2 bucks, and I was going to drill somewhere around 75-100 small holes in it to make narrow slits for disconnects to fit through.  Then I was going to drill 50 or angular half-holes perpendicular to the slits so that the disconnects could be rotated and snugly fit into the half-holes.  If this device keeps all the wires arranged and safe from shorting, it will be a huge plus for me...

THANKS!

[guity]

Went ahead and bought a couple 12-slot Euro terminal strips for $5.89 apiece.  These should work perfectly for monitoring because multimeter probes can be fit into them easily.  It might take some modification to get them to work with my single cell charger (and my newly home-made single-cell battery drainer) because each uses alligator clips which might have a hard time fitting inside the plastic openings and attaching to the cylindrical metal conductors inside.  But wow, what a find!  They already paid for themselves from the refund I got by returning a large package of connectors I had bought to be individually crimped onto each wire...

[EVmc]

 the wife's hair dryer didn't work ?
buy a battery load tester
can not use on cells in series (over 12volt)
but you can discharge a single cell
or whole pack wired in parallel 3.2 volt  pack
can adjust from 1 amp draw to 50 amps
need a small fan on charge tester to cool it, 4'" fan is best
I usually only pull 30 amps from a 60Ah cell or pack
Odd thing about one I use is if you turn amperage knob to off
it will still pull amps.  had to turn father to left, felt like knob was unscrewing but wasn't
before you use, check it on a car battery
make sure when knob turned down pulling no amps
as if it is will get sparks not good , just have to get used to it
and you have to be monitoring voltage drop don't let go past 2.7 volts
no reason to go near 2.5 volt. I guess you got that already.
  500 Amp Carbon Pile Load Tester   $69.99
will need 80mm, 120 volt fan to cool
the one I used only pulls 70A most from 60 AH thundersky
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=91129


Power supply 3.5v @10A and 5v @32A 420 18078-PS
www.Mpja.com

All electronics has lots of stuff at low prices
Are you charging and discharging One cell at a time?
oh I see you charge 72v charger then finish off with tenergy charger
good luck

[guity]

Thanks for the tip Evmc.

That battery load tester is tempting.  I'll see how much time I end up spending on voltage levels, and if it is significant I will go for that kind of tool upgrade.  For now I should gain a helpful tool with my cheap-o BMS because now (hopefully) I can put the bike back together and still be able to work on the voltage, therefore being able to drain the pack by riding.  I've gotten a lot of readings on the batteries between 3.3 and 3.9 volts, but I really want to see what they look like from 2.8 to 3.3 volts.