XM-3000 LiFePO4 upgrade
Current Motor Company received their first inventory shipment of batteries on Friday (as opposed to the smaller R&D orders). So, I "liberated" 20 of the 40Ah cells to see how easy it would be to upgrade my XM-3000 from SLA to LiFe.
The answer is - very easy. Packaging the 20 cells in five "4-packs" they are almost a drop in replacement for the pre-existing Greensaver batteries. They're ever so slightly wider (maybe 1/4 inch or less?) - and that's with the two end plates on. So it's a snug fit - but that's no bad thing. The 4-pack is also thinner - so there's some space that could be filled with a simple spacer. The cells are taller so I will need to cut away some of the under-seat tub - haven't done that yet. The bolt size on the LiFe is bigger than on the GS so I also had to put new lugs on the cables.
I don't have the specs on me but the bike is now significantly lighter - which helps with accel. Top speed is the same - 41mph actual (46mph indicated). Range is also better (not sure what the 1C Ah rate on the GS's were - but certainly not 40Ah). I plan on adding the CuMoCo BMS to this set up. I'll report back when I do.
If CuMoCo were to sell DIY upgrade kits for 5 x SLA to 20 x 40Ah LiFe with a per-cell BMS would folks be interested in purchasing these? Cost would likely be in the $1750 to $2000 range (that's my best guess at the moment).
I'm absolutely interested--especially as my GS batteries are starting to show signs of old age. Here's what I would desire in a DIY upgrade package:
* Cost closer to $1500 if possible (can these be safely shipped at a reasonable cost?)
* Complete package, maybe including spacers, lugs and extra wire?
* Step-by-step instructions
* Photos of each step, showing battery placement, etc.
* Some sort of warranty on batteries and BMS
* Advice on how to recycle the old batts?
This sounds like an exciting project, especially if the bike will weigh less! Thanks John!
Consider threaded inserts and then smaller bolts in the (2, 4, 6, or 8?) cell "posts" where existing smaller-hole connections are used.
Also, there might be enough metal around the hole on the existing lug to just drill out the hole?
I posted this in the battery section of this forum but I will place it here also....this offer on EBay is considerably cheaper than what you are talking about in the above posts....Mikie
A couple cents worth of observation on that pack. It's a 72b 40ah pack from Hi-Power, no BMS, but with a "balancing charger". The beginning price on the auction is $999 and there is a reserve price which hasn't been disclosed. Therefore the beginning price is not the price, the reserve price is the price. It's not fair to John's suggested price to compare it with a non-price on an ebay auction.
In questions he quoted $10,000 for a pack using 200 ah cells.
He finally disclosed the reserve price:- $2499
Wow-- nice catch man, you caught him and called him out! John is still my main man, I just need business to turn around and in a major large way before I can upgrade. Mikie
Before I can upgrade, I obviously need to get the old Greensaver SLA's out. I need some tips here--I know they're stuck in with industrial double-sided tape. I tug and tug, but can't get them to budge, especially the rear-most one in the lower tray, which needs to come out first. Any hints?
Hi -- I had trouble getting mine out too, but it was a long time ago. If you can get a scissors jack to spread apart the housing some that would help you get ahold. Another way would be to take some wire and screw it into the + &- posts, making a kind of lifting loop then you would really be able to get some leverage to take it out. Good Luck....Mikie
Lifting loop of wire + to - posts ... CAUTION do NOT short the battery ... DANGEROUS.
Also, pulling on the terminal posts MIGHT rip them right out of the battery top, destroying the cell, hazardous, and DANGEROUS.
Have you removed all the hardware and wires from all of the cell posts?
And, have you duct-taped (cloth type, double layer) over each post to help avoid dangerous accidental contact?
ARE these cells only held down by the tape?
Is there a solvent (again DANGEROUS) that will loosen the tape?
Maybe a little solvent, carefully used in a well-ventilated space, would be effective?
Are the cells banded into packs of maybe 3?
Or, are they individually placed?
If banded, can one "hook" onto the band on either side. On the TS 3-cell packs in the 5000Li, the compression bands have lifting "straps" (heavy string) installed, but the string-connection is a bit weak.
Does the "grip" of the tape weaken when it gets hotter?
Are the cells wedged into the battery box?
When replacing the battery, will you be able to re-use the same battery box?
Is there a drain hole at the bottom edge of the battery box?
How does the manufacturer recommend removing the cells?
Gary--you are absolutely right sorry for being so stupid! But you can use a non conductive rope or even duct tape squished up is very strong. Spray a little WD-40 along side of the outside of the battery packs and then try the rope or tape, it will come out and you can move forward with your mod. Best....Mikie
Thanks, guys, for the ideas...As you know, the battery tray is pretty tight, and doesn't have any openings in the bottom...I might be able to pry the sides open a bit, however. Another idea is to take a wire coat hanger and make a small prong on the end...if I could snake this down the sides of the battery, I might be able to get the prong underneath to help pull it up...
Woo Hoo, got the Greensavers out! Sprayed plenty of wd-40 down the sides between the batteries and the metal tray, and let it sit overnight...seems to have loosened the tape's grip sufficiently that I could rock the batteries out. Thanks for the advice, everyone!
Joe-- glad to help, and enjoy the lithium batteries I know you will be happy....Mikie
For anti corrosion try ACF-50 that stuff is incredible. I have tried every anti corrosion formula out there and that stuff is amazing and doesn't leave a waxy residue like some of the other higher quality stuff.
A few things I've learned form my experience with Thundersky LiFePO4's so far. This is all, of course, "anecdotal" so take it for what it is worth.
When new, the cells have free liquid electrolyte that can be heard sloshing around when shaken. This free liquid electrolyte goes away after the first one or two charge/discharge cycles. I have since learned that this is due to a portion of the organic solvent electrolyte breaking down electrolytically during the first few charge cycles and forming a "solid electrolyte interphase" on the anodes. This interphase then prevents the remaining electrolyte from breaking down.
The above has two important implications:
1. The proper formation of this electrolyte interphase is important for good cell life and keeping the internal resistance low. This may be the purpose for the Thundersky-recommended procedure (page 31 of the manual) of initially "conditioning" each cell, by charging it at 1/3C, discharging it at 1/3C (to a minimum of 2.5 V but I'd stay higher), then recharging at 1/3C. Unfortunately, due to the confusing bad English in the manual, many people miss or mis-interpret this recommendation and think it is referring to kind of optimum procedure for regular use.
2. The cells should be mounted upright, for at least the first few charge cycles, (in my opinion, all the time) or some of the anode and cathode material may not be submerged in the electrolyte, inhibiting proper interphase formation.
My experience with my two scooter conversions so far supports conditioning the cells. The first set of cells were bought unconditioned and simply charged with my available .2C charger - then discharged (at much faster than 1/3C) during first use of the scooter with the new pack. The second set of cells were conditioned using the Thundersky procedure before I bought them. With about the same number of cycles and about 3500 to 4000 km on each pack, the unconditioned pack shows about 5% more warm-weather internal resistance, worse in cold temperatures, and I even had to replace a couple cells that started refusing to balance with the rest of the pack. The conditioned pack has been performing flawlessly.
Hope this helps with the current motor scooter project.
PS - Should you have any spares, what would you sell just bare cells for? Thanks.
John, do you think you'll be able to do a round of conditioning of the batteries on the bikes you are building? Getting a slow discharge doesn't seem too difficult (though it'll be annoying to leave the bike parked with the headlights on for a week once it's delivered), but the slow charge would seem to require using something other than the standard charger, which most customers won't have.
Mike - yes, we will be conditioning the batteries before installing them.
Make sure you mention that on your website.
"We run all batteries through a controlled charge/discharge/charge cycle to detect factory defects and provide initial conditioning." (or something like that)