Headway Group Purchase

[mi7d1]

As I was quoted it is true that I said I was disappointed in the wrapping. An yet on the survey I said

3 for the battery themselves. Sure the wrapping around the packs was a surprise but would I have know or cared if they were in a case.

Which is it a 3=meh... or disappointed which might be closer to a 2 on the survey. I'll say it doesn't matter too much to me. It's what is inside the wrapping that is important the rest is just paper and tape. My e-assist will not run on paper and tape. The batteries and BMS matters and I was very pleased when Dennis and I opened up the one pack. It was beautiful inside and I am very happy at this time. I try not to judge a book by it's cover nor a battery pack by it's wrapping but I'm not always sucessful. My whole e-assist installation on my velo has been a custom job. I purchased the Headway pack knowing ahead of time that these too might need to be reworked to fit my needs.

 

[dnmun]

one other thing i noticed on bill's pack. the BMS is designed for 12S. so the 36V BMS has been redesigned since kurt got his pack.as i remember from looking at kurt's BMS, his had 16 channels available, but only 12 channels were populated. also there are a total of 10 output FETs, but still the 3207. i now realize the pcb on bill's pack has another 4 FETs on the other side of that heat sink block, so output resistance should be about 1/2 milliohm. also on kurt's BMS the wires appear to be 12AWG or maybe 10 and single wire, but on bill's they were either 16 or maybe 18G,but 4 wires total to carry the rated 60A max.

http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=7117

 

[Kurt]

Small correction,
My BMS has two power wires for - & + for a total of 4 power wires.

This might be a silly Question .
What do the 10 output fets actually do?
what is there function on the BMS?

Kurt.

 

[dnmun]

kurt, all the current from the battery goes through those FETs. if the current exceeds the 3C rating (60A) or if the total pack voltage drops below 30V (2.5V/cell) then the FETs are turned off and the current flowing from the battery stops. the other parts are there to allow the individual cells to balance during the charge cycle. by using so many FETs in parallel, the resistance to current flowing through them is low and the power lost in the BMS is minimized. for .5milliohm, the power lost at 35A would be only about 18mW, which is why they don't warm up at all.

i think the 48V packs likely still use your type BMS, but they may have redesigned the 16S BMS pcb too.

 

[Jozzer]

So is there no individual cell monitoring for LVC? It only measures the total pack voltage?

 

[dnmun]

jozzer, i don't know about that. i think it was kurt, but maybe somebody else, mentioned that his BMS was cutting out when it got down to 30V, but i have not analyzed the circuit to determine if there is individual cell level monitoring, hopefully someone can figure it out. maybe victoria can find out for us, or someone else knows.

 

[Lessss]

Victoria (Headway)

Please see if the wire attachment method to the battery can be changed.

We have seen that with power tool packs the battery closest to the lead wire is the first to fail. Since Headway is assembling the batteries in clusters of 4 they have the ability to center the connection wire equidistant from the 4 battery screws. Currently the wire is closer to two cells of the four. I suspect these two will be the first to fail.
I have photoshopped a picture of how I would like to see the wire attached. I would also like to see a protective plastic edge added to the metal square so the side of the square can't rub and eventually cut(or short) the wire. Preferably covering the entire square plate but just around the edges or even just the wire side edge will do.

 

[dnmun]

lesss, not sure if this will allay your anxiety, but the white sheath you see is an anti chafing sleeve around the outside of the balancing wire, which is itself insulated and the sleeve is actually glued onto the top of the solder spot so it won't 'walk away' from the wire (you can see the white adhesive at the end). there is no stress on or interference where it goes over the edge of the plate, so i doubt if that will end up getting shorted. i actually think the anti chafing sleeve is a little overkill. also they use only red wire for the balancing wires, whereas with kurt's i noticed that the wires were different colors following the resistor color coding BBROYGBVGW. i did see one screw which was not torqued all the way down onto the lockwasher, almost a full thread short of the others, but still tight, not sure if it was crossthreaded since i didn't try to tighten it, not my battery, but i suspect just not totally tightened to max torque at assembly.

 

[Lessss]

Ah cool. Still like to see the attachemnt point in the center though.

 

[John Grant]

Good Morning All

-Thanks everyone for the change in direction of this thread; now we are getting some where.

Grant

 

[Kurt]

I think it will be interesting to know what the output voltage of the chargers they sent is. The one 36v at 3 amp they gave me is working fine but the output voltage is only 42.5 volts. This seamed a little low compared to other 36v lifepo4 chargers.

I am not sure if the headway cell run at a lower voltage at full charge I remember some one commenting on this in the past.

When I first charged mine the charger got to 42v then cycled on and off for about 5 mins I presume this was it balancing. I kept it on charge for about 12hrs and the pack got to 42.3v . After this initial charge I haven't seen it do any balancing at all in over 30 charges.

Kurt.

 

[Lessss]

Well a 12 V SLA usually reads about 14V.4 off the charger so 42.3 isn't that far from 43.2(3*14.4) so it sounds ok to me.

 

[Doctorbass]

Great news here, The Blue Headway i tested seems to be the winner from now with high rate discharge compare to the Wh delivered!

It have the most Wh over all 3 cells and seems to have the best form factor for heat dissipation and energy density :wink:

Eventhough the temperature and Voltage drop was the highest.

http://endless-sphere.com/forums/viewtopic.php?f=14&t=8926&start=15

Doc

 

[dnmun]

thanks for info about cell level LVC. can you confirm that the pack level cutoff is 30V for the 12S packs, 40V for the 16S packs?

 

[julesa]

Victoria (Headway)

Please see if the wire attachment method to the battery can be changed.

We have seen that with power tool packs the battery closest to the lead wire is the first to fail. Since Headway is assembling the batteries in clusters of 4 they have the ability to center the connection wire equidistant from the 4 battery screws. Currently the wire is closer to two cells of the four. I suspect these two will be the first to fail.
I have photoshopped a picture of how I would like to see the wire attached. I would also like to see a protective plastic edge added to the metal square so the side of the square can't rub and eventually cut(or short) the wire. Preferably covering the entire square plate but just around the edges or even just the wire side edge will do.

The batteries aren't in clusters of four, they're in clusters of 2 -- you're seeing the positive end of one cluster connected to the negative end of the next cluster. The metal square itself carries most of the current. The wire lead soldered to the metal square just goes to the BMS, doesn't carry any significant current, and placement would be very unlikely to influence cell life.

It would be nice if all wires were protected from being cut by the sharp edge of the metal, and the main current leads on the start and end of the series chain should be placed equidistant between the two cell terminals on each end.

Victoria,
Thank you for being so responsive. I find it very encouraging to see a supplier with good product and good communication. I am looking forward to seeing your 15Ah cells!
-Jules

 

[Lessss]

julesa
Ah I didn't catch that.
If it's just the bms wire then yeah my suggestion is not necessary.

 

[dnmun]

the sense wires have an anti chafing sleeve, attached at the end where it is soldered to the 2P plate. it isn't really clear why the end pair of the konions fail on such a consistent basis but that is what doc and gary confirmed, but it may be something specific to the tool packs.

i think these guys are already ahead of us, from the design of the BMS anyway. lotta overkill. huge heat sink and low impedance FETs, anti chaffing sleeves on every wire full length, polyfuse to blow if the pack overheats, did not see any of that on the other BMS i have looked at. and they even have designed a new board specifically for the 12S packs, when kurt got his pack last year they were using a 16S pcb and only used 12 channels. everything indicates they are moving up, not static. new cells is good too.

 

[Ypedal]

Hey.. an opinion from the forum, and/or info from Victoria maybe, the BMS in this picture from one of the group members i'm helping out..

4 wires bundled into one group on the negative side, all hook up to the same spot on the BMS, can one of these 4 be used for the charger and the other 3 for discharge ? Or is there another reason for this method of assembly ?

2 wires on the + side, one for charge, one for discharge.!~?

edit : I expected the Charging Negative would have been on it's own on the BMS, seperate from discharge.. ??

 

[JoeG]

I would like to get some feedback from the group buy people, or anyone with headway battery experience.

I recently purchased a 48V 20Ah battery directly from Headway, It only took 2 weeks to get the pack and Victoria was great answering all my questions. When I first received my battery I noticed that a few of the battery terminal screws were loose. I tightened them as tight as I could and after each of my 4 test rides a few loosen. They have lock washers, but they don't seem to keep the screws tight. I'm concerned because soon I plan to build custom cases and once they are enclosed , I won't be able to get to the screws easily.

Has anyone else had this problem? Found a solution?
Would it be alright to loctite the screws from an electrical stand point?
Any feedback would be appreciated

Thanks,
Joe

 

[Ypedal]

The cells need to be secured to each other.. i've used hot glue with pretty good success for this .. a long bead of glue between each cell body from end to end usually does the trick ! :wink:

If the cells wiggle around and spin , one side will loosen, then it moves more, etc.....stick'em

 

[Ypedal]

8)

 

[JoeG]

Thanks for the reply Ypedal. I like your website by the way.
The pack does have a thin fillet of what looks like hot glue between the cells, but it isn't any where near the size of yours. When I take the pack apart I'm going to have to try to determine if the cells are loose and causing the screw issue.
Joe

 

[dnmun]

the pack that bill and i opened also had a screw which was not totally tightened as much as the others, but still snugged up. i told victoria about it, the cells had never moved, it was just never tightened as much as the other 47.

gaston, i think you charge it by connecting directly to the output wires, just like a nicad or SLA. just add power poles to the ends. not sure how it shuts down the charging current though, when the pack reaches max charge. i noticed the 4 little wires too. seem like they are each about 16AWG at most, maybe 18, so 60A really is the max.

 

[voicecoils]

gaston, i think you charge it by connecting directly to the output wires, just like a nicad or SLA. just add power poles to the ends. not sure how it shuts down the charging current though, when the pack reaches max charge. i noticed the 4 little wires too. seem like they are each about 16AWG at most, maybe 18, so 60A really is the max.

yes, charge and discharge through the same + and - leads. I've put two Anderson PP45's on on each. For the positive that's one on each red wire. For the negative it was one connector for a pair of black wires each. Those PP45's can then be combined into a single PP75 should high current discharge be needed.

 

[mi7d1]

yes, charge and discharge through the same + and - leads. I've put two Anderson PP45's on on each. For the positive that's one on each red wire. For the negative it was one connector for a pair of black wires each. Those PP45's can then be combined into a single PP75 should high current discharge be needed.

I wired mine the same way. One pair of Anderson/Sermos connectors going to the controller and the second pair for charging or using a dc/dc converter.

I'm only using a 20A controller but I never though of connecting the two pair into a PP75. Thanks for mentioning it.