Headway Pack Builders thread

Okay, I charged the bad cell up with other cells in parrelel. Now it is back holding 3.4 volts. The pack is now reading 79.5 volts from terminals and 76.9 volts through BMS. Is This normal? I cant get the charger to turn on through the BMS but the pack is under the chargers output voltage.
 
you need to start documenting, pictures will help. when you say BMS reads one thing and terminals another, we don't know what you are referring to.

did you build this pack yourself with the 72V BMS from headway?

when you state that the pack will not charge because of a bad cell, that is not possible unless the cell is already reached 3.9V and the high voltage cutoff line is active.

so you should be able to charge the low cell while it is in the BMS. you should not have to remove a cell to charge it.

first, make a list, measure each cell voltage by putting your voltmeter right on the terminal of each cell, one after the other from the low end which is #1 to the top, #24.

if any of the cells is reading 3.9V, that could be the reason the BMS has stopped the charging. if you have individual cells reading that high and others that are down under 3.5V then you should use a small power resistor, something like 5W, 5ohm?, to discharge the high cells by shorting the individual high cells with the power resistor, so that the BMS will turn back on and allow the other cells to charge up. do this after you measure the cells individually.

if you built the pack yourself, then the next thing is to go back and double check all the wiring of the sense wires for opens or spots on the sense wire plug where you might have damaged the wire/pin junction, or bent the pin in the sense wire plug. do that after trying to balance the pack.

if you can get it to start charging again, then measure the voltage on the lowest cells and see if they climb at all while charging, and if the BMS shuts down again from the high cells, continue bleeding charge off of them until you can get all the cells up over 3.5V while it is charging. that is 84V which is much higher than it appears your charger has been able to do so far.

measure first. BOL, dm
 
I went to the Menards home buildings supply store today looking for someway to secure my Headway batteries. I walked around the different departments - plumbing, electrical, etc trying to find something that would fit around the cell snug. I found two things - one was
1 1/2 inch black irrigation piping but I didn't want to get a big role of it. The other was a cheap foam paint roller. I cut it into about 1 1/4 inch slices . Next I will see if I can find some kind of adhesive to glue them together. It seems like this will keep the cells apart while still letting them get a bit of air between them. I am only making a 16 cell 48 volt pack so it will be small.
What do you think ?
 

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Hmm, while I'm sure that will protect individual cells, I'm not sure it's a good idea for a pack creation. Firstly the foam will compress and not provide much protection, but more importantly because it's soft it will put all the pressure on the cell connectors. I'm not sure the screw ends can take that much force, and I wouldn't like to have any force on them. I would rather see rigid ways of holding the cells in place with flexible cell connectors. Copper weave works well. If you removed the foam, and hot glue'd the plastic pipe together you'd be doing better. Then you could pad the entire pack to prevent impact damage.
 
Bikelectric: I'm always amazed by the ingenuity of people out here 8) , which is what led me to my final solution. If you haven't already seen this thread, it covers some other approaches that you may want to consider:

http://endless-sphere.com/forums/viewtopic.php?f=14&t=13233
 
I scraped some of the foam off and used hot glue - seems to hold together tight. I think I scrape most of the foam off of a couple new rollers, then glue them together, and then cut the slices - probably won't need them to be so wide.

The reason I started this is because I was trying to tape the cells together and it wasn't very easy and also kind of crooked. The headway pack I got from the Joshua group buy was put together with strips of paper or cardboard between the cells, hot glued, and uses the terminal connector straps for some of the strength I think. That pack has bounced around in my pack all summer and so far no problems. So this frame I am making should be much stronger than that.
 

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I just ordered my headway pack Friday with hopes of it arriving later this week.

I order direct from Ecitypower.com:

36x 38120S
50 Battery holders and cell connectors
Charger 48v 10a
16s BMS 100a cont. 200a peak

~$1000 with shipping

Seems like everyone is having trouble getting the proper cell holders together and cell connectors. Ecitypower has cell holders and connectors, and they were cheap! Maybe they will not be quite as inexpensive if they are ordered directly with no batteries but still might be worth a try. I will post an update as soon as they are received.

38120_Holder.jpg


38120-Connector.jpg
 
I think the issue with the headway cell hoders was that they were too tight and used to crack on the positive side. Hopefully they've fixed that issue by now. There's a thread somewhere about it. What one person did was to trim the heat shrink off the positive end of the cell.

I spoke to victoria a while back, they say they have new holders that fit the 40160 cells, so hopefully they've reworked the whole batch.
 
I saw how the Headway cells can be put end to end in series using a small stud. Last night I had the idea of doing this and slipping them inside a 1 1/2 inch piece of PVC pipe which could then be hose clamped along the inside frame of the bike. Of course all of them for a 48 volt pack wouldn't fit so it would be in sections with a flexible connector in between. I would use the pieces of cut up paint roller to cushion and stabilize the cells inside the PVC pipe.
I haven't measured up my bike frame to see if this would work or not - I come up with 84 inches long or about 7 feet for 16 cells.

I wonder though if heating of the batteries would be an issue - not sure how warm they get discharging under load . I also know the BMS balancing wires would have to snake through the PVC and not sure if there is a length limit to them.

Just an idea I came up with to put the batteries in the center area of the frame to balance their weight out and keep them out of the way.
 

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Just received my cells today from Ecitypower. So far everything looks great and measures great. I am going to put everyone of my 36 cells on the CBA to test it out. Heres what I got:

img0495w.jpg
 
Lol lame they sure do, guess I'll have to cut the shrink wrap too
 
Well after what seems like forever :roll: I finally completed and installed my 8s2p pack for my Goped electric scooter. :mrgreen:

When I decided that I wanted to take this project on a year ago, I could barely remember Ohm's law and few basics about series/parallel circuits. :? Thanks to this forum and all of the wonderful ideas and input from everyone here, I can finally claim success... I have come a long way and could not have done so without all of your help.

So Thank You everyone. 8)

View attachment IMG_0939.JPG
View attachment IMG_0970.JPG
 
if your battery holder is continuous underneath, you can squirt a little foam under the cells and let it expand underneath and on their sides to keep them secure.

wrap the cells and wire in saran wrap first so the foam doesn't adhere to the cells so you can dig them out later, a little expanding foam goes a long way so find places in the house (or car in my case) where you can use the rest of the can at the same time since they are one time use things.

now you learned ohms law, next is following kirchoff's rules.

nice, show a picture of where your display ended up on the handlebar. i have a scooter to fix now too. very nice.
 
I just got my bits direct from Headway today. Plastic mounts are now yellow, but still a nice fit on the minus end and a bit too tight on the plus end. They do go in if you shove... I'll post some pics when I've done some assembling.
 
Oh yes, and one thing I forgot to ask: where do people get 50A+ resettable fuses from? All the ones I can find are much lower power than that. Even the standard-size automotive ones which are widely available in handy inline fittings don't go that high - you need the maxi ones. Can one put several polyfuses in parallel and expect it to work? My controller is nominal 48A, actually pelaks at 52 according to my watts-up. So I guess I need at least a 50A fuse, preferably 60+. Ideally I'd put in one per battery section, for wiring protection (I'll have 4, to fit where the old lead-acids went).
 
dnmun said:
if your battery holder is continuous underneath, you can squirt a little foam under the cells and let it expand underneath and on their sides to keep them secure.

wrap the cells and wire in saran wrap first so the foam doesn't adhere to the cells so you can dig them out later, a little expanding foam goes a long way so find places in the house (or car in my case) where you can use the rest of the can at the same time since they are one time use things.

now you learned ohms law, next is following kirchoff's rules.

nice, show a picture of where your display ended up on the handlebar. i have a scooter to fix now too. very nice.
Click to expand...

Thanks for the suggestion dnmun, but as luck would have it, the pack(s) fit so perfectly, that the rubbery ends on the cells make excellent contact/presuure with the battery pan, frame, the wooden deck and wooden deck spacer such that there is no movement at all when the deck is bolted down over it all. Pure serendipity :mrgreen: I will put a small foam slab on the ends, as I see that is the only remaing possibility for movement (forward and aft). So I think unless I detect that my assumption here is wrong, I'll leave it be and preserve the air flow around the cells.

I have taken some test drives, and I have to say the difference from my SLAs is quite remarkable. I have a new high output motor for this scooter that now can finally have its current demands adequately satiated. :twisted: what a hoot :D

Don't have the CellLog display mounted up on the bars yet, but that is likely to change so I can better hear the alarm, and at least see the bar graph portion while riding. This project is far from completion, but at least I am up and running. It's like a perpetual science fair project :lol: .

Does anyone know off hand know if Goodrum's 8s BMS has one dimension that is 3" or less? If it does, I may actually be able to fit it in there between the deck spacer center rung and the cells. There is about 3/4" clearance under the rung. I better start plowing through his sticky to see if i can find out :roll: .
 
Scoot,

Nice battery pack. I am new to this, but very interested in a Headway pack, perhaps similar to the one you constructed. As the cells fit tightly in your battery box, I am guessing that each 4 cell group sits flat on the bottom of the battery box. If so, what is the inside width of the battery box and what is the height of the 4 cell group in the battery box? Are the copper connecting bars custom or off-of-the-shelf commercial items? Thanks

Rich
 
richmpdx said:
Scoot,

Nice battery pack. I am new to this, but very interested in a Headway pack, perhaps similar to the one you constructed. As the cells fit tightly in your battery box, I am guessing that each 4 cell group sits flat on the bottom of the battery box. If so, what is the inside width of the battery box and what is the height of the 4 cell group in the battery box? Are the copper connecting bars custom or off-of-the-shelf commercial items? Thanks

Rich
Click to expand...

Thanx Rich... the 4 SLAs that used to be there are B&B HR9-12. They measure 2.5 x 3.75 x 6 inches each and lay down sideways in the pan. they fit flush on the topside with that wooden deck spacer shown in the previous pic #3. the pan itself flares outwards another 1/4" on the top which is just enough to fit the headways in there.

IMG_0576.JPG

They copper straps were hand made from plumbing straps from Home Depot... only place I could find the solid copper versions. This was my factory :shock:

What kind of EV are you anticipating a retro on?

View attachment IMG_0979.JPG
 
scoot said:
They copper straps were hand made from plumbing straps from Home Depot... only place I could find the solid copper versions. This was my factory :shock:
]
Click to expand...

Were those 1/2 inch copper straps or 3/8 ? I found 3/8 pure copper straps at a local home store but everything else was copper plated steel. I will check Home Depot though I thought I had looked there once before.

What did you use as studs between the cells that you have end to end in series ?
( looking at your photo of parts now I think I see some metric set screws but they don't look very long)

--Larry
 
bikeelectric said:
scoot said:
They copper straps were hand made from plumbing straps from Home Depot... only place I could find the solid copper versions. This was my factory :shock:
]
Click to expand...

Were those 1/2 inch copper straps or 3/8 ? I found 3/8 pure copper straps at a local home store but everything else was copper plated steel. I will check Home Depot though I thought I had looked there once before.

What did you use as studs between the cells that you have end to end in series ?
( looking at your photo of parts now I think I see some metric set screws but they don't look very long)

--Larry
Click to expand...
The set screws were m6 x 12 mm long. I'll probably try to find some 14 mm long on my next pack. I set them in to the negative end of the cell which bottoms out securely at about 6mm. The red end is much deeper, but I think bottoming out on that end may damage the cell... but not sure about that.

I know some who have chosen to use brass rod, but I was not concerned myself with their conductivity. I'm just relying on the cell to cell contact for that (or strap to cell as it were).

Pretty sure the sraps were 1/2" but I'll verify when I get home tonight. I do recall that they are about 0.8 mm thick. BTW drilling copper is a PITA. My handy paper hole punch worked wonderfully.

Also, I need to compare the hole spacing (40mm pitch) on these prefab ones with mine... if they match mine close enough, I think I'll save myself a whole lot of trouble next time. besides they look really quailty/beefy and inexpensive ta' boot :)
http://www.kennedyalternativeenergy.com/accessories.html
 
scoot said:
The set screws were m6 x 12 mm long. I'll probably try to find some 14 mm long on my next pack. I set them in to the negative end of the cell which bottoms out securely at about 6mm. The red end is much deeper, but I think bottoming out on that end may damage the cell... but not sure about that.
Click to expand...

I couldn't find any set screws so I made some myself with some long m6 bolts and a hacksaw. Then I rounded the edges with a dremel. Mine were probably about 14-15mm long. And yes, I was also suspect about going too deep into the + side so made very sure I went into the negative first.
 
I buy 12mm ss set screws on Amazon; i tried making themyself too, way too labor intensive when you need 100s of them.

-JD
 
scoot said:
bikeelectric said:
scoot said:
They copper straps were hand made from plumbing straps from Home Depot... only place I could find the solid copper versions. This was my factory :shock:
]
Click to expand...

Were those 1/2 inch copper straps or 3/8 ? I found 3/8 pure copper straps at a local home store but everything else was copper plated steel. I will check Home Depot though I thought I had looked there once before.

What did you use as studs between the cells that you have end to end in series ?
( looking at your photo of parts now I think I see some metric set screws but they don't look very long)

--Larry
Click to expand...
The set screws were m6 x 12 mm long. I'll probably try to find some 14 mm long on my next pack. I set them in to the negative end of the cell which bottoms out securely at about 6mm. The red end is much deeper, but I think bottoming out on that end may damage the cell... but not sure about that.

I know some who have chosen to use brass rod, but I was not concerned myself with their conductivity. I'm just relying on the cell to cell contact for that (or strap to cell as it were).

Pretty sure the sraps were 1/2" but I'll verify when I get home tonight. I do recall that they are about 0.8 mm thick. BTW drilling copper is a PITA. My handy paper hole punch worked wonderfully.

Also, I need to compare the hole spacing (40mm pitch) on these prefab ones with mine... if they match mine close enough, I think I'll save myself a whole lot of trouble next time. besides they look really quailty/beefy and inexpensive ta' boot :)
http://www.kennedyalternativeenergy.com/accessories.html
Click to expand...

FOLLOW UP:

The home depot straps are 1/2" wide Larry, and the hole pitch on my hand made straps is consistently 39 mm which ensures snug cell to cell contact on the heat-shrinked surfaces. I think I'll try the pre-made 40 mm pitch ones next time and nibble on the holes a bit if need be. they are twice as thick and silver plated too 8)
 
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