Headway 38120S 24S EVassemble BigHit 2 Crystalyte HS3540

Hello all,
I want to present you my project and my disappointment about the Headway batterys.
I started to build this bike in objective to cycle to my job, 32km go and back. (project started in summer 2013) and your forum has been a big library, thanks! (easy to read, a lot of subject)

Base is a Specialized big hit 2 and I opted for Crystalyte solution 45A controller, computer, and HS3540 motor.

For battery, I mounted 24S with 38120S Headway(10Ah, 50A discharge) and BMS adequate (60A ~80V)
I bought 24 38120S headway/BMS/Charger in Ev-Assemble.


First run! great!!!! 69 km:h, fast, enjoy, really happy, big smile. :lol: (July)


But, when I wanted to charge juste after the run, nothing, one element was dead (0.07v for one).
After discussions with Michael from ev-assemble (where I bought the batterys/BMS/Charger 6A)
he sent me one element and I payed one more with shipment fee... ok

One month passed to wait, I received the element and all was good after assembly.
I started to cycle to my work.


I took my bike twice a week to go to work.
Perfect, some accessories for the night and bagages.
All was perfect, easy to use, plug and it charged.


But, with the cold weather, autonomy was bad, no worries, I could cycle 16km to work and I charged it for the return.

And this week, not cold, i wanted to charge it, nothing... bad.
The charge did'nt started. (one element?) no worries, I had one element in spare.
But when I wanted to change one, it proved to be that it was 2 elements who were dead!
I can't repair it!

And with my ohmeter, I can check some disparities for each element...
I'm not really happy with this brand, I may have already done 100 cycles of charge/discharge and it's not good.
despite BMS and quality assembly...
It seems that the quality of batteries is really perfectible. I assume that some more will pass out in even less time if I change one more time.

I have not written yet to Michael from Ev-assemble at this time, but I'm little bit disappointed.
I lost the price of battery system (~650€)

Can I assume that when you first built the pack, you checked to make sure the bms was charging and balancing all the cells to begin with. By that I mean you checked the charge on the individual cells and they all were at ~3.5-3.6V. It's also what I thought was a well known fact that the headway cells were considerably over rated in C rates. Their cycle life is based on a 1C discharge rate. A 10ah 20s 20C rc lipo pack can be had for ~$250. That should be enough to make 40km@35kph easily. Pulling <4C they should last 300-700 cycles or more if you don't over discharge them.

After having changed the first new cell, and charged the entire battery, I checked the voltage for each element and I had good tension. (Just to make sure of the effective work of the BMS)
I tested them individually a couple of time before intensive use.
The BMS seems to work good.

I'm disappointed because i exposed my project to Michael.
I simply based this concept on datasheet... (seems serious as I can see on their brochures)
http://www.evassemble.com/index.php?main_page=product_info&cPath=2&products_id=19
http://www.chinaheadway.com/en/productsh.asp?id=187
I cycled usually at 35KM/h and I could read ~12A contunous discharge...
But, in acceleration, I could read 35-45A during 5-10 second max...
All seemed ok for me.

If i use an RC LiPo pack, what is the best way to have the same easy to use system (plug and play)?
What kind of BMS can I take? And charger?

Thanks for your interest.

As I recall from other threads, the RED coloured "Bleeding Balancing" BMSes from EVAssemble are not a good choice - don't balance well?. The GREEN BMSes, used on the BMSBattery http://www.bmsbattery.com/bmspcm/323-17s26s-24a-max-discharge-current-bms.html seem to work much better. I've had very good luck with the 16S version, on several packs of Headways, and even on a Ping pack, where I replaced my old Ping bms with the green one. Not sure about 24S version. Consider trying the green ones.

Hello Leproto!



I have been using Headway 40152S 15Ah Cells for about 4000 miles of cycling. I have used them for 1.5 years and they have never failed. In that time I have had various other components fail, (connectors, chargers, throttles, break-levers) but never the batteries.
My Headways have been "Plug and Play All The Way." My Headways have been very robust. I think that you should check the operation of the BMS to see how it is charging and discharging your batteries.

Charge your battery pack and check all the cells. Write the voltages on paper for reference. Then go for a medium length ride to partially discharge your batteries. Check the voltages again and write down the voltages. Finally, charge your pack again and while it is charging, check the voltages of each battery at 30 minute intervals to see which batteries are charging and which are lagging.

Keep copious notes and post them here. Unless you got some really bad Headways, B stock, it shouldn't be the Headways.

In regards to C ratings of Headways, they are a bit over rated. 10 C may be possible in a laboratory, but 2 C is more real world. That is my personal experience.

Some people like RC lipo. It is inexpensive and has high C ratings, but it is generally not "Plug and Play." If you want to use RC lipo then you must use caution with charging and handling them. With proper handling and attentiveness using RC lipo is fine, but if you get sloppy with them then they could burn your house down.

http://endless-sphere.com/w/index.php/Chargers_LiPo#Avoiding_a_LiPo_fire_or_explosion

leproto said:

If i use an RC LiPo pack, what is the best way to have the same easy to use system (plug and play)?
What kind of BMS can I take? And charger?

Click to expand...

Like any other battery system you can do what you want to with it. Personally I don't like bms's, so I run mine bare and charge with am rc charger. If you want to install a bms though you can and then charge just like you do with the headway pack. But I'd never walk far away from a charging lipo pack just in case there was a problem, I've never run into a problem in the 3 years I've been using them, but there could be a first time. You would need a new bms. The one you have for lfp won't work with lco because of voltage differences. Your current charger would probably still work if you could adjust the voltage down to 84V for a 20s lco pack.

OK!
Thanks a lot for your responses.

As I Read, I will stop immediatly this carnage. (I have no time to test individually all the batterys, and to take risk to damage more.. )
I will take one green BMS and change all batterys who were suspected to be bad (I will charge all cells separatly with a RC Charger and see).
And go for news adventures..

So, I will send this link of this thread to EV-Assemble (Michael and Irene) and to headway contact.
Just to stop to sell this piece of s* BMS...

PS: i have updated my profile.

Assuming that's Toulouse, France and not one of the other Toulouse places, please add France to your profile location.

I too have been using the 38120S Headway in 16s and have no problems at all.
I recently posted my build here http://endless-sphere.com/forums/viewtopic.php?f=6&t=56343
I have done about 36 cycles and 700 km. My BMS is from em3ev.com.
The cells are always within .01v of each other. They seem very stable, and i am still getting same performance from when new.
I am running 16s at 48v so I only have about 36A max peak. never been over 40A.
For a safe battery that can be screwed together , and plug and play with BMS, I think their weight is worth it.

So yeah, either you got bad batch, or bad BMS.
Also make sure the screw terminals on the batteries are tight, they can come loose and then unbalance. I had it had a couple time at first but no probs once you are aware of it.

Thanks for helping, it works fine with this new BMS. Now, it remains to finish the body. (no time before ...)

Almost perfect, but it's enough.

leproto said:

Almost perfect, but it's enough.

Click to expand...

Nice Build Leproto,

Can you tell me where you got your Rear rack from and Mud guard as i have been looking for something like that for my Bighit.

Sorry for the delay.
Here and here
With some arrangements.

leproto said:

Sorry for the delay.
Here and here
With some arrangements.

Click to expand...

Thanks for that, I took your idea and with a couple of mods got my rack to fit well on my Bighit.

Looking good!

My bike is really perfect!
Nothing to do apart charging batteries and inflating tires sometime.
I don't know why this solution is not used by more people. It's an investment in start, but almost nothing after.
It is the same time in motor bike by higway than by the city with ebike.