Rebuilding Wavecrest Tidalforce hub battery

[DCMotorworks]

Picked up an M-750 tidalforce w/ a weak battery this weekend so I'll be looking at options for refurbishing the hub pack. I am planning on sticking with the NiMH chemistry. I've been reading up on the project here on ES, at the Google Tidalforce Forum and of course Ambrose's EBikeRider blog (ty Ambrose great stuff there) but there is a lot of information to sift through.

If any one who has done this has some insight, info or links to threads your input would be greatly appreciated.

DC

 

[miro13car]

E+ uses GP Golden Peak cells in its hub battery.
But seriously NMH cells are archaic choice with all those Lithium possibility.
TF is very easy to run on any 36V battery.
I ride my TF for over 5 years on Lithium.
You should concentrate on low mounting Lithium pack on your frame if you want to maintain low Center of Gravity.
This is how it can be done

 

[DCMotorworks]

woah. That curved battery pack is flipping awesome! ty for your response. I figure I will eventually make a lipo pack for the "B" battery after splicing a jumper between the poles in the dash control board (as outlined here: https://sites.google.com/site/continuousforce/home/tidalforce/everything-tidalforce ) but at the moment i was just thinking of rebuilding the existing pack w/ 30 Ni-MH 11AH 3c cells. I am looking for plug and play and the whole thing is set up for it. I still need to pull the battery pack apart and take some measurements, but honestly, rebuilding the pack w/ Ni-MH looks like it will cost about $100 - $150 for 30 11AH 3C cells. or maybe I can just fit 10AH cells in there. or maybe due to space restictions I can ONLY use the original (SAFT - ty Amberwolf) 9.5 AH cells at like $20 per cell?? Hoping that is not the case. if this was a "take it to the limit" project I would be all about "how many Lipos can I fit booya". But I have too many other projects atm. Kinda seems like Lifepo4 would be a big hassle in terms of retro-fit vs performance and (given my lack of experience w/ lipo) putting Lipo in a hub case that is not easily assessable just seems dumb. I mean, it would be cool and all to be able to do a "dude, check out my girlfriend's bike on fire on Youtube" post, but really, if Lipo is not practical and I compare the performance of Ni-MH chemistry to Lifepo4 chemistry, I am thinking Ni-MH is not so bad. People seemed to love these bikes like 8 years ago when they were new. so, a few hours of work soldering (I was thinking I could get tabbed cells and solder them in series rather than spot welding) and $150 to make it 1.5 AH better than new again?

Please, talk me out of my plan.

DC

 

[amberwolf]

I hope you have a known good source for your "11Ah" cells. If you're looking at Ebay or Tenergy or the like, don't expect the cells to actually deliver anything remotely close to what they promise, especially at the loads expected in an ebike.

There's not many good NiMH cells around, especially for our purposes. I can only remember SAFT brand at the moment, there are a couple of others that escape me.


If you look around ES, there are a couple of threads showing rebuilds (or attempts, at least) with pictures, of TF battery hubs.

 

[dogman dan]

Buy a regular wheel, and a good A123 battery pack from Emissions Free. Or just go to RC lipo now.

 

[deardancer3]

As the others said, it is really hard these days to get good Nimh cells that will deliver oveer 20 amps peak with no significant sag.
I used to repair Nimh packs and built maybe a dozen in previous years before the lower Lithium xxx costs.

you will spend more time studying, researching and testing than actually buildiing.

And I for one am not crazy about having anymore weight in the rotating wheel than absolutely needed.

please consider going A123 or similar (maybe Headway?) in an external pack. (bionx now predicts over 5 year life with their new Lith packs with good care)

my two watts worth

 

[miro13car]

b

 

[miro13car]

You cannot simply disconnect old cells connect new ones and TF
Is ready to go.
TF was ahead of it's times when it was designed and it is still very sophisticated e bike
the most smooth in riding out there because it uses 7 phase motor,sinus PWM motor control .


LEVT is service company forTF which can rebuild your hub battery.
They have software for TF.

 

[DCMotorworks]

Ah. ok. great info. thanks all. Especially the warning about having to re-flash the BMS. And about not being able to actually get 30 amps out of the 3c cells I was looking at on line. Batteryspace sells 50 amp NiMH cells at about $10 each plus shipping. they might be up to the task but at that price I would have to be nuts to not follow Dogman's advice and just go w/ a better chemistry. The initial point was to keep the bike stock. I was reasoning that if the cheaper cells didn't work out I would just use them in flashlights and boom boxes or w/e so the purchase wouldn't have been a total waste. Ambrose has informed me that there are numerous sensors and thermistors integral to the pack/BMS that would most likely be damaged during removal. He recons it to be possible yet very challenging.

on the positive side of things, I pulled off the battery/hub cover and was able to test individual cell voltage. surprisingly all the cells had between 1.3 and 1.35 volts. I really expected to find some totally or very nearly dead cells in there. maybe this pack is not as bad as I initially thought. I'll cycle it a few more times and see what I have here.

DC

 

[DCMotorworks]

The BMS seems to be keeping the pack from fully charging. after a few cycles all 5 state of charge led's on the dash were lit (comapred to 3 a few day ago) but pack voltage was reading 39v after a very brief ride of 5 min or so. disconnecting the data cable and the battery output connector seems to allow for a deeper charge. or maybe the temp sensors in the BMS were just shutting down the charger prematurely and cycling the pack is slowly improving its capacity. I opened the case again and removed the pack and most cells are now reading 1.41v to 1.42 w/ a few outliers in the 1.43v range and one low cell at 1.398v.

just got back from a 6 mile ride. performance was still lack-luster but a bit better. feels a lot like a 36v 350w geared hub I had a few years ago. the soc dash lights went from 5 to 4 this time compared to 5 to 2 last time I rode the same route. not too convinced that the soc lights are accurately showing me anything though tbh. I think I read in a TF thread that they show how many AH the BMS has recorded being supplied by the charger rather than actual pack voltage or something like that. sounds weird but seeing how everything else on this bike is proprietary and overly complicated I can believe it

DC

 

[DCMotorworks]

8 mile ride. battery is charging up to 41.8v now. sags badly to 37.5 after the 1st mile or so of the ride but maintains its anemic performance for a full 8 miles. problem is I don't have a 36v pack to put on this bike just to get a baseline of it's potential performance. I guess my next step is to just wire up 36v of sla, if only to run it around the block and see what it does. If only to run it around the block - thought that bared repeating. or I could pull apart a 16s 10ah headway pack and run it on 12s sans bms just to try it out on a strong 36v battery. Still slightly annoyed to learn that "one does not simply replace NiMH cells in a Tidalforce" (ya, I wanted to make a meme for that but no).

I have downloaded some circlepack software to figure out how feasible rebuilding the front hub battery w/ A123 cells will be. still doing the math. I'd have to fabricate a cell holding clam shell apparatus to hold the new size cells which also included space for the bms but If I am going to put any real work into this I really want to keep the battery in the front wheel case. ya I know; just hanging a pack from the frame or w/e would be way easier, but that is just not how I roll.

I like the clean tough look of these bikes - one of the reasons I bought it. when I rolled it into the house for the 1st time even my GF (who would normally say "WTF! you bought another E-Bike?)" said "woah, that looks bad-ass. can I ride it?". even a random woman in front of the grocery store felt compelled to comment on how cool it looked. so ya, chicks dig the look of this bike. I am going to rebuild the front pack.

DC

 

[momo]

i installed A123's inside the front hub a few years ago. has been working very well. let me tell you, it's a big project.
32 cells in total for 8s 4p. 9.2ahr is the maximum a123 you can fit. Lvc is another issue you should monitor closely. If they only made donut shaped lithium cells capacity
inside the hub could be as high as 20-30ahr. At this point in time im ready to upgrade to 10s and 10ahr of lipo. Stay away from Nimh ancient technology you will regret it.
once you go lithium you don't go back.

 

[DCMotorworks]

wow, nice, thanks for the info Momo. 32 cells seemed easy to fit (space restriction-wise I mean, not work involved). I was still calculating to see if I could somehow shoehorn 40 in there but w/ a bms it has so far appeared to be highly unlikely.

how did you construct a frame to hold the A123 cells? do you have an internal bms?

and ya, I have all but written off the idea of using NiMh. like maybe if I could get 30 SAFT cells for free I would try it.

and and ya, the more I research it Lipo is looking like a very viable option now but still, my 1st foray into Lipo probably shouldn't be locked in a hard to access enclosure. or maybe it absolutely should. or... maybe not.

so, I would be bulk charging the say 2X 5s 8000mah w/ a 36v lipo charger and I'd have the balance leads routed out so I could check individual cell voltage w/ a cell-log? and occasionally have to balance charge when necessary?.

waitwhat? I swore this would not turn into a "imanoob how do I use Lipo" thread. I mean I planned on finishing reading everything I could on the subject and starting that thread soon, but not for this project per se.

well anyways, the evolution of this project has gone from NiMH (Survey says NO) to A123 (Maybe) to Lipo (??). assuming I could securely/safely enclose 10s X AH lipo in a TF hub, what would you do to make it as close as possible to safe plug and play? Is it possible?'

DC

 

[deerfencer]

I've been riding a TF S750X for about 6 years with lipoly packs after ditching the front battery hub and I can tell you the difference in performance between the Saft NIMH and the newer HobbyKing lipos is night and day. You saw how bad the sag is on NIMH; how about 1.2V sag on a HK-sourced 37V 24Ah lipoly 30C pack? I now see 1300-1500W max continuous WOT off a fresh charge, and 1100-1300W for the rest of the hour. See my posts @ Google TF group for more info.

L Hayes

 

[miro13car]

DCmotorworks,
I understand how front hub battery can have appeal to you.
I would also love to mount my LiFePo cells inside that shell.
DO NOT give up , you can eventualluy mount BMS outside the hub?

 

[DCMotorworks]

BMS outside the hub would kind of defeat the purpose. I am back to the initial plan of possibly replacing the NIMH cells in the front and also putting together a LiPo pack to run as the "B" Battery. I figure I will just order a few each of some different brands of NiMH D cells and torture test them to see if any can hold up to the challenge before purchasing the 30 I will need for the re-build. interestingly, I found some Flashlight forums that have a wealth of graphs and info on NiMH cells with some posters reporting being able to reliably pull 3c out of fairly inexpensive 1000mah D's

I also saw on another TF thread that the statement concerning the BMS losing it's programming was refuted. still awaiting confirmation of this but if none is forthcoming I will probably try it just out of curiosity at this point. *Edit. this has been strongly refuted now.*

admittingly I already have 2 48v Lifpo4 commuters, a 72v bike near completion and a full suspension mid-drive that I continue to tinker on so this TF is really just something to play around with anyway atm.

DC

ps. ya, flashlight forums. same passion but instead of oil-cooling your hub to sustain 5Kw up hill they are modding their lights w/ heatsinks and whatnot to sustain X million candle power for X hundred seconds or w/e. who knew?

 

[deerfencer]

Good luck. The TF system is way sophisticated and many like you have tried and failed to rebuild the A pack. With all due respect it's a fool's errand IMO.

lh

 

[DCMotorworks]

thanks Deerfencer. I have been reading many of your posts on the TF forums lately and miro13car has recently linked this:

http://groups.google.com/group/tidalforce/browse_thread/thread/357976a0f2e1a45b/5aee1bdcca16dec0?lnk=gst&q=reprogramming%2Bbattery+#5aee1bdcca16dec0

which is pertinent to the topic.

DC

 

[miro13car]

Refuted what?
It is not important what is lost, without reprogramming BMS electronics after cells replaced you cannot use TF !!!

 

[oatnet]

Refuted what?
It is not important what is lost, without reprogramming BMS electronics after cells replaced you cannot use TF !!!

Incorrect. Without "reprogramming," you merely have a State-Of-Charge indicator that is out-of-sync until the next time you go under 32v (I think that was the voltage point).

The problem - besides saggy NiMh chemistry - is finding replacement cells. I tested a wide range of NiMh for this purpose, they mostly gave half their rated capacity for 50 cycles before failing. When I could find saft cells, they cost way more than the LEVT upgrade.

DC, have you considered adding a "booster battery" in series with your existing pack? You can squeeze in (2) series LiFeP04 cells and stay under the 47.5 voltage cutuff. This will give you a few WH for more range, and with the higher voltage you will get more watts into the motor, making it feel less anemic. For about a year I ran a Tidalforce IO Cruiser with A/B batteries and a 20ah booster pack from 10ah headway cells.

-JD

 

[jay2rocket]

i installed A123's inside the front hub a few years ago. has been working very well. let me tell you, it's a big project.
32 cells in total for 8s 4p. 9.2ahr is the maximum a123 you can fit. Lvc is another issue you should monitor closely. If they only made donut shaped lithium cells capacity
inside the hub could be as high as 20-30ahr. At this point in time im ready to upgrade to 10s and 10ahr of lipo. Stay away from Nimh ancient technology you will regret it.
once you go lithium you don't go back.

Hi - am working my way through the threads...when you setup the A123s in the hub what did you do as far as the BMS board and control - did you use as is, reporgram, modify, or replace it?