I am one of those people who have trash talked Chinese vendors such as EV-Assemble, BMSBattery, and various eBay sellers based on what i have seen from the reports of users on ES.
Strangely enough; i was selected to be a reviewer of an ev-assemble 12ah 36v headways pack, and recieved one in the mail, courtesy of Michael at EV-Assemble, in exchange for a review.
I have to admit, i was curious about the battery packs EV-Assemble was selling though. There is definitely a niche between
RC lipo and ping packs that needs to be filled in the electric bike world. Considering the low cost of these packs, it is hard
to write this option off without further investigating.
Disclaimer; i am not affiliated with any vendors or ebike companies, period.
I do however, like providing reviews for the sake of helping people on ES make an educated decision on what to buy.
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OK, so the package arrived today. The first thing i noticed is that this is the first Chinese vendor i have dealt with to actually admit that there is a lithium battery inside, with a big sticker with flames on it.
The battery and charger were packed fairly well considering that they were being shipped via air and not sea. There was an additional layer of thin rubber around the battery too.
The charger i recieved ( 4A, kingpower, 36v ) was packed with 2 extra sets of 45a anderson connectors. I thought this was a nice touch, for a charger that retails at what, $35?
It is a light and compact charger; i think i will actually order another one as an opportunity lipo charger for my main bike.
There was no manual pertaining to the battery itself.
Another picture of the kingpower charger.
Inside the kingpower charger - yes; i took it apart before even powering it up. This is how we do things on ES
There are 3 potentiometers on this charger, but look at this VR3... looks like it is for voltage regulation. It seems like this charger is adjustable, this is a big plus because it could potentially work as a lead acid or RC lipo charger.
OK, so the battery pack has two sets of wires coming out of it. I think there is a potential problem here in the design though. The charger wire has black shrinkwrap around it instead of blue. This could easily lead to the user accidentally connecting the charger into the wrong place. I think this can be improved, with blue shrink wrap on the charger.
On the scale, the battery came in at about 12 pounds. Remember, headways are not the lightest batteries. They are in fact in the lower end of the whr/kg scale for lithium batteries, around 100whr/kg. On the upside, they are one of the more higher output lifepo4 chemistries, being rated at 5C constant discharge.
Well, the first thing i did was disassemble the pack. Under a layer of thick shrinkwrap was a box made out of 6 sheets of a material that EV-Assemble calls 'FR4'. EV-Assemble also says that the shrinkwrap is fireproof. I noticed that the tape around this box was 3M tape.
One concern is that the battery pack seemed to shift around inside this case. it is a minor annoyance; a tighter fit would be preferred.
OK; so let's talk about the pack construction now that we have freed this pack from it's cage.
Notice the BMS on top.. with no protection. This could be a problem down the road.
It would be a good idea to at least label the outside box as to prevent the user from sitting the battery down so that 10 pounds of cells aren't sitting on top of it. It is just one of those things that could happen if the user is not aware of this.
Other than that, the pack looks well-protected against vibration, shock, and drops. So all annoyances aside, this pack seems well built.
It looks like ev-assemble used the stock headway cell blocks and interconnectors.
This is a good thing, and professional a build as any other headway pack.
The balance leads to the BMS are interconnected by wrapping the wire around the cell connector. I am not a fan of these types of connections, but the duct tape should prevent the kind of vibrations that would knock these loose. This is adequate. All the cell screws were tightened down properly.
The power output leads were mechanically crimped. This is probably better than a soldered connection since they can take vibration better this way.
Pack voltage as shipped was 40.3v.
Initially, the cells had differing voltages. This is before any kind of balance charging, however.
We are also at 1 cycle here, and these cells have not been broken in just yet.
After putting this battery on the charger, The BMS did it's work in very short time. 2 cell LEDs lit up on the BMS and then went dark within 2 minutes. I assume this means that the cells are all balanced, since there was no manual provided with this battery.
The charger started whirring as soon as it was plugged in. The fan wasn't too loud, and did stop spinning when the charge was over.
Without the box, this pack came in at about 11 pounds.
It looks like a triangle mount of this pack could be difficult. It fit within my cranks however, leaving a few MM of space. Mind you, my cranks are not bowed out at all. With a wider bottom bracket, or cranks that bow out a little, it would not be too hard to mid-mount a 36v or 48v 12ah version of this battery.
The battery fit very snugly into a topeak MTX rear bag.
With the battery charged to 41.90v ( after resting for about 15 minutes after charging ), i figured it's time to take this battery out for a spin!
So in true ES fashion, i immediately pointed the bike up the steepest hill possible in order to draw peak amps. I hit my amp limiter quickly running a MAC motor up a 0.5 mile 7% grade. Then proceeded to ride around town for ~30 minutes.
OK; so let's talk about performance; that's what you really wanted to know about, right?
This is definitely not 20C RC lipo or 20C A123 we are talking about. I got a 4-4.5v drop with a 3C ( 36 amps on a 12AH pack ) load. The C rating of these cells does coincide somewhat with my RC lipo; i do get 1.25v of voltage drop on 10AH of 10s/36v RC lipo. These headway cells do have 1/4th of the discharge C rate of the RC lipo and A123, so they have 4x the voltage drop.
Coming from lipo, this was a bit of a downer. I think if you are purchasing a headway pack, you do need to overspec it a little. Running it at 2C-2.5C constant would be best for performance and cell life.
If you were to run lower amps, or a 16ah pack instead of a 12ah, the performance would be rather good.
The upside here is that these cells will handle loads that ping packs would choke on.
On ev-assemble's website, they mention that this pack is rated at 36 amps ( 3C ), but capable of 50 amps max discharge (~4.1C).
I believe these are realistic C numbers for the headway cells. I have seen other resellers claim 5C rated, 10C continuous; that seems dishonest. I respect EV-Assemble for conservatively rating these cells. The manufacturer of the cells do claim 5C/10C, but going off these tests, that seems overblown.
To further drive the point home, after an average 2C load for ~30 minutes in 87f/31c outside temperature riding, inside the topeak bag, these cells got quite hot. The temperature was between warm and burning your hand. Mind you, if i ran 20C lipo at 10C constant in the same conditions, it would be hot as well.
So the reality check is that these cells need to be ran below their rated limit for long life and minimum voltage sag.
I do not believe these cells will perform well or last long at 5C or above.
After draining 10.5ah from the pack, the cells were amazingly well balanced. I could not drain further due to my LVC. I will follow up on this review later for a more thorough test of the cell capacity.
Overall conclusion:
+ There are a few minor nags with the construction of the pack, however the quality of workmanship was pretty good, and better than expected at this price point.
+ EV-Assemble is honest about the C/amp rating of the headway cells on their site, and that is very respectable.
+ The headway cells are a good upgrade from SLA or lower output lithium, but do not stack up to the more powerful stuff, however they are a very safe and cost conscious choice, especially at the asking price.
+ The kingpower charger seems pretty decent. The adjustable voltage is a big plus.
I give the EV-Assemble pack a an 8 out of 10 rating. A manual and some minor changes to construction would bring this pack up to a 9 or 10.
I give the headway cells a 7 out of 10.
+ The positives here are that these cells are cheap, have a higher than average discharge rating, and long cycle life. A pack of these will do what a ping pack cannot do. These are ideal for applications where weight and size requirements are relaxed.
+ The negatives are the size and weight of the cells. These headway packs are large for the watt-hours you get. I would also not consider these cells 10C constant capable per the manufacturer's specifications. Given air cooling, you could most likely reliably run these cells at 3C constant, but i would not push them up to 5C other than the occasional burst of amps.
Strangely enough; i was selected to be a reviewer of an ev-assemble 12ah 36v headways pack, and recieved one in the mail, courtesy of Michael at EV-Assemble, in exchange for a review.
I have to admit, i was curious about the battery packs EV-Assemble was selling though. There is definitely a niche between
RC lipo and ping packs that needs to be filled in the electric bike world. Considering the low cost of these packs, it is hard
to write this option off without further investigating.
Disclaimer; i am not affiliated with any vendors or ebike companies, period.
I do however, like providing reviews for the sake of helping people on ES make an educated decision on what to buy.
-------
OK, so the package arrived today. The first thing i noticed is that this is the first Chinese vendor i have dealt with to actually admit that there is a lithium battery inside, with a big sticker with flames on it.
The battery and charger were packed fairly well considering that they were being shipped via air and not sea. There was an additional layer of thin rubber around the battery too.
The charger i recieved ( 4A, kingpower, 36v ) was packed with 2 extra sets of 45a anderson connectors. I thought this was a nice touch, for a charger that retails at what, $35?
It is a light and compact charger; i think i will actually order another one as an opportunity lipo charger for my main bike.
There was no manual pertaining to the battery itself.
Another picture of the kingpower charger.
Inside the kingpower charger - yes; i took it apart before even powering it up. This is how we do things on ES
There are 3 potentiometers on this charger, but look at this VR3... looks like it is for voltage regulation. It seems like this charger is adjustable, this is a big plus because it could potentially work as a lead acid or RC lipo charger.
OK, so the battery pack has two sets of wires coming out of it. I think there is a potential problem here in the design though. The charger wire has black shrinkwrap around it instead of blue. This could easily lead to the user accidentally connecting the charger into the wrong place. I think this can be improved, with blue shrink wrap on the charger.
On the scale, the battery came in at about 12 pounds. Remember, headways are not the lightest batteries. They are in fact in the lower end of the whr/kg scale for lithium batteries, around 100whr/kg. On the upside, they are one of the more higher output lifepo4 chemistries, being rated at 5C constant discharge.
Well, the first thing i did was disassemble the pack. Under a layer of thick shrinkwrap was a box made out of 6 sheets of a material that EV-Assemble calls 'FR4'. EV-Assemble also says that the shrinkwrap is fireproof. I noticed that the tape around this box was 3M tape.
One concern is that the battery pack seemed to shift around inside this case. it is a minor annoyance; a tighter fit would be preferred.
OK; so let's talk about the pack construction now that we have freed this pack from it's cage.
Notice the BMS on top.. with no protection. This could be a problem down the road.
It would be a good idea to at least label the outside box as to prevent the user from sitting the battery down so that 10 pounds of cells aren't sitting on top of it. It is just one of those things that could happen if the user is not aware of this.
Other than that, the pack looks well-protected against vibration, shock, and drops. So all annoyances aside, this pack seems well built.
It looks like ev-assemble used the stock headway cell blocks and interconnectors.
This is a good thing, and professional a build as any other headway pack.
The balance leads to the BMS are interconnected by wrapping the wire around the cell connector. I am not a fan of these types of connections, but the duct tape should prevent the kind of vibrations that would knock these loose. This is adequate. All the cell screws were tightened down properly.
The power output leads were mechanically crimped. This is probably better than a soldered connection since they can take vibration better this way.
Pack voltage as shipped was 40.3v.
Initially, the cells had differing voltages. This is before any kind of balance charging, however.
We are also at 1 cycle here, and these cells have not been broken in just yet.
After putting this battery on the charger, The BMS did it's work in very short time. 2 cell LEDs lit up on the BMS and then went dark within 2 minutes. I assume this means that the cells are all balanced, since there was no manual provided with this battery.
The charger started whirring as soon as it was plugged in. The fan wasn't too loud, and did stop spinning when the charge was over.
Without the box, this pack came in at about 11 pounds.
It looks like a triangle mount of this pack could be difficult. It fit within my cranks however, leaving a few MM of space. Mind you, my cranks are not bowed out at all. With a wider bottom bracket, or cranks that bow out a little, it would not be too hard to mid-mount a 36v or 48v 12ah version of this battery.
The battery fit very snugly into a topeak MTX rear bag.
With the battery charged to 41.90v ( after resting for about 15 minutes after charging ), i figured it's time to take this battery out for a spin!
So in true ES fashion, i immediately pointed the bike up the steepest hill possible in order to draw peak amps. I hit my amp limiter quickly running a MAC motor up a 0.5 mile 7% grade. Then proceeded to ride around town for ~30 minutes.
OK; so let's talk about performance; that's what you really wanted to know about, right?
This is definitely not 20C RC lipo or 20C A123 we are talking about. I got a 4-4.5v drop with a 3C ( 36 amps on a 12AH pack ) load. The C rating of these cells does coincide somewhat with my RC lipo; i do get 1.25v of voltage drop on 10AH of 10s/36v RC lipo. These headway cells do have 1/4th of the discharge C rate of the RC lipo and A123, so they have 4x the voltage drop.
Coming from lipo, this was a bit of a downer. I think if you are purchasing a headway pack, you do need to overspec it a little. Running it at 2C-2.5C constant would be best for performance and cell life.
If you were to run lower amps, or a 16ah pack instead of a 12ah, the performance would be rather good.
The upside here is that these cells will handle loads that ping packs would choke on.
On ev-assemble's website, they mention that this pack is rated at 36 amps ( 3C ), but capable of 50 amps max discharge (~4.1C).
I believe these are realistic C numbers for the headway cells. I have seen other resellers claim 5C rated, 10C continuous; that seems dishonest. I respect EV-Assemble for conservatively rating these cells. The manufacturer of the cells do claim 5C/10C, but going off these tests, that seems overblown.
To further drive the point home, after an average 2C load for ~30 minutes in 87f/31c outside temperature riding, inside the topeak bag, these cells got quite hot. The temperature was between warm and burning your hand. Mind you, if i ran 20C lipo at 10C constant in the same conditions, it would be hot as well.
So the reality check is that these cells need to be ran below their rated limit for long life and minimum voltage sag.
I do not believe these cells will perform well or last long at 5C or above.
After draining 10.5ah from the pack, the cells were amazingly well balanced. I could not drain further due to my LVC. I will follow up on this review later for a more thorough test of the cell capacity.
Overall conclusion:
+ There are a few minor nags with the construction of the pack, however the quality of workmanship was pretty good, and better than expected at this price point.
+ EV-Assemble is honest about the C/amp rating of the headway cells on their site, and that is very respectable.
+ The headway cells are a good upgrade from SLA or lower output lithium, but do not stack up to the more powerful stuff, however they are a very safe and cost conscious choice, especially at the asking price.
+ The kingpower charger seems pretty decent. The adjustable voltage is a big plus.
I give the EV-Assemble pack a an 8 out of 10 rating. A manual and some minor changes to construction would bring this pack up to a 9 or 10.
I give the headway cells a 7 out of 10.
+ The positives here are that these cells are cheap, have a higher than average discharge rating, and long cycle life. A pack of these will do what a ping pack cannot do. These are ideal for applications where weight and size requirements are relaxed.
+ The negatives are the size and weight of the cells. These headway packs are large for the watt-hours you get. I would also not consider these cells 10C constant capable per the manufacturer's specifications. Given air cooling, you could most likely reliably run these cells at 3C constant, but i would not push them up to 5C other than the occasional burst of amps.
