Z1/X2 E22 frame battery

[JRA]

Figured I would consolidate here information about the stock 840wh battery and the quest for an even better version for use as a second battery at the least.

The M620 I have decided is a wh muncher no matter how you slice it. Sure you can waddle along on Mode 1 for miles and get as good a range as most other bikes outside of the SL versions out there but these bikes are more XL and the potential power output to be able to tool along at a good rate of grin inducing speed is too hard to pass up!

The end result for me at least is the quest for a second battery to use for longer than the >25 mile rides I typically do around my place. Also I am not 100% convinced that the stock battery is all that it can be based on my other battery use over the years on lesser watt motors. A top priority is that the battery fit seamlessly into the stock mount and luckily it appears that the case used is a fairly common sort and available. Luckily the same format is used in both the Z1 and X2 as well as other DengFu origin frames which in the end will make it easier for the manufacturer.

In communicating with the overseas sales person at the manufacturer that I picked up on when looking for the right case style on AliExpress I feel it is possible to achieve a better battery. But the problem is that due to the case size being fixed as it is and the fact that the stock battery fills it up with little extra space that how to do so is at this point is still unanswered but now that the Lunar New Year is over we are back in contact and working on the solution.

I took the discharge end cap screws out and slid out the battery to get the data from the BMS to send over as well as whatever I could see of the cells. As I suspected the BMS is a 30A but my contact replied that is actually is more like a 27.5A and said that a 40A BMS would help but also be larger in size so fitment might be an issue? We will see as it is a critical part of the equation. Especially for those that have upgraded higher potential watt ouput controllers or even stock M620's run at over 1000w.

A noticeable problem I am having is motor performance below 46V which seems to drop off the edge of a cliff. Lower voltage is always going to put out lower power but in the past I have never noticed such a significant power loss that far, 5V, from the LVC? I did switch to 21700 cell batteries 3 years ago so that may be the difference because I did notice an improvement in lower voltage performance of my 18650 ones at the time. To that end along with trying to improve the 48V battery and the fact that there is the ready ability through the display to also use a 52V battery as it works out it may be possible to stuff a 15ah 21700 cell, 780wh, pack in the stock case. A bit less capacity but perhaps another level of performance?

Regardless none of this is going to happen overnight but I am going to keep the hammer down on the project and hopefully have a sample of each battery here within a month. From there testing will take place and if they work better then an avenue will open up for others to be able to get on board also if they want? I am not looking to become a battery dealer and just doing this to satisfy my personal needs so I only see this as a link to a manufacturer direct sale. Shipping is expensive per battery direct but the headache of a group buy and sending them out from a location here in the states is nothing I want to deal with. As of yet no pricing has been determined but one of their stock batteries is under $500 shipped so they should be around that figure. Certainly much better than the $1400 my Levo riding buddy was complaining about the other day for their 700wh model!

 

[JRA]

Mr. Hicks, while I appreciate your input as far as how your Frey bike goes it does have a different battery style than the title of this post suggests. In fact I think there is another post on here that addresses the Reention/Dorado type batteries and the fact that they have different ones including at least one that features 21700 cells?

Not trying to be a snob here but so many threads get convoluted by folks talking cross purposes and even though their info is sound in regards to the general conversation it can cause confusion to those that are looking for information specific to their system. Of which there are a pretty large number of relating to this post.

 

[greeno]

I hear you about wanting to up the existing battery's performance on your rides. Having the battery below the downtime presents it's own limitations as far as going bigger and still utilizing the same internal connection point.
That was the #1 priority when I purchased my bike a while back. Having a platform to expand the original battery profile and still trying to make it look like it was built that way, for the most part. So by utilizing the inside of the main triangle was a big deal for me.
Pretty sure the battery enclosure is utilizing 100% of the available space inside so your limited by that unless you modify that specific shape and still be able to fit it in the same spot. Depending on the space inside the 21700 batteries are about 3/16" longer side to side so if you got the room your good.
Not sure going to the 21700 size will really gain you much advantage.

Just an example in size spacing: ( top to bottom rough )

18650 batteries are 18.75mm x 65.25mm in size.
So your existing pack which is 48v / 17.5ahr which would be 13 x 5 = 65 batteries x 18.75mm is 1217.75mm of space existing inside the enclosure.
A 21700 48v / 20ahr pack would be 13 x 4 = 52 batteries x 20.25mm which would give you 1053mm. So depth wise your good as well.

Now another factor is the 9.8a continuous discharge rating on the Samsung 50E which means using at least a .2mm x .7mm nickel jumpers to carry the 30a max if needed.
More batteries is always better when connecting series to series groups, keeping the heat down is key. More heat loss means less power available.

Sounds like your already pretty knowledgable on the whole process and you probably already know all this stuff but having a larger battery is HUGE in my book.

Me and a buddy went for a ride last Tuesday and ran into three other E-bike riders that parked at the same spot as we did and so we combined the group and rode for the most part together. They peeled off early to head back on the fire road to preserve battery to make sure they got back to their truck. My friend and me did another loop to the south and then climbed back to the top and ran the more challenging downhill section back to the truck. Got back to the truck and we did 26.6 miles and my battery was at 54.2v. Those guys showed up a little later and they were almost empty and one guy said his was shutting off and then restating it the last 2 miles or so. They did 17.7 miles total.
Were running our smaller 52v 24ahr batterys in place of the 34ahr we use for the longer rides.
Having range is the whole show for me.
Good luck and post up how your project turns out. Innovation is good that's how things get better.

 

[JRA]

Thanks for the input @greeno. I am by no means well versed on battery tech but do know enough to ask questions and follow the advice of those that are, like yourself. Cause lets face it the die is cast as far as you suggest on just how much will stuff into the case. BMS size, physical and A wise is also a consideration. Working with my "contact" is the usual back and forth just trying to get on the same page due to the language barrier.

Those triangle packs you are using sure do set the bar high for ah's on board. Your bikes must weigh 70lbs! I am also looking at getting a lower ah battery that weighs less but still will give me a decent daily range. Then in combo with the stock pack I will get up in that range for longer days in the saddle I have planned. Which will be primarily riding logging roads long distances. At speed.

Nowhere to carry on the bike though so will have to be a back pack but they make a few that will work for that purpose to choose from.

 

[greeno]

My bike with the "smaller" 24ahr battery pack weighs in at 59.96lbs as shown on my hy-tech scale set-up.

The 34ahr battery add's another 6lbs to that.

I thought about using 21700 a while back but the cost comparison didn't pencil out for me. I see alot of packs that are using the same Samsung 35E but there rated at 8a continuous. I have had great luck using Sanyo/Panasonic GA cells and they can put out 10a continuous for about the same cost. Probably made 20+ packs or more and have yet to have a cell go bad. The older BMS's I was using became problematic but after switching to a different brand they have been bulletproof.
Small mods to the bike and battery connect areas sometimes need to be done.