BMS-Free, info for the curious on bypassing the BM-mess

[Emoto]

Yeh need 2x7dpst or 1x14dpst older style audio might do, would have to be careful lot of magic smoke and sound and light show if wasn't break b4 make or solder iron bridges.
Though there's electronic matrix switches that might do the deed if your that savvy, over my head for sure :?
But Im happy bout my little naked set up for now.
Still no temp sensors that's a heck of a long thread to look through

OK, Show us the setup when youve finished it

Dadanadada my Speedict's rocked up, s%@#t its tinsy.
Thought there was nought in the box.
I'm pretty certain those temp sensors transmit data, now.
Thanks for your help there Moto.So ill order some.

Can you elaborate on the temp sensor transmit data, ?
No worries iv'e learned a lot on the sphere, any time i can help it's Carma .
Iv'e just ordered a smart phone

Arlo great review, the charge timer shutdown, is a good function, [you could charge just short of target voltage say 3.4 cell, and then finish charge supervised if you want, no malfunctioning " bms mess" ]
I know its not as fast as some bulk chargers but no swapping from bulk to balance charger is more appealing for me. just hope they are built well and reliable

 

[Arlo1]

When I bulk charge I just use the cheep lipo alarms and when the first cell hits 4.22 and the alarm beeps I check all of them to see how well its ballanced then I rid it and only balance every few months. SO now I will have 2 of these chargers set up to charge more ofter so the balance will be better and because the ballance is better and no cells should go over 4.2v it will help my pac last longer.

 

[megacycle]

OK, Show us the setup when youve finished it

Nothing flash hope :lol: just better vacpacking.

I'm pretty certain those temp sensors transmit data, now.
Thanks for your help there Moto.

Can you elaborate on the temp sensor transmit data, ?
No worries iv'e learned a lot on the sphere, any time i can help it's Carma .
Iv'e just ordered a smart phone

Which phone are you getting Be careful Im having issues as they are only up to about ice cream at 2.4 my galaxy note won't connect and I even tried a sonic still no good think its the beta firmware Im buggered, even my son whose a wizz can't do it. .
Maybe the software will catch up soon with the latest controller theyre making.

The sensor should be this one http://www.maxim-ic.com/datasheet/index.mvp/id/2812
1 wire data trans. HK won't can't sell me anymore they come with powerlog.
I'm assuming the other temp sensing inputs on it are digital I/O ill double check.

Arlo great review.
Seconded

con

Apologies for the quotation mark mocking up Im using my phone and has issues with the ES site.

 

[Emoto]

Which phone are you getting Be careful Im having issues as they are only up to about ice cream at 2.4 my galaxy note won't connect and I even tried a sonic still no good think its the beta firmware Im buggered, even my son whose a wizz can't do it. .
Maybe the software will catch up soon with the latest controller theyre making.

The sensor should be this one http://www.maxim-ic.com/datasheet/index.mvp/id/2812
1 wire data trans. HK won't can't sell me anymore they come with powerlog.
I'm assuming the other temp sensing inputs on it are digital I/O ill double check.

Arlo great review.
Seconded

con

Apologies for the quotation mark mocking up Im using my phone and has issues with the ES site.

So just double checking the sensor is for speedict ?
Hk does a temp sensor separately in a plastic housing for battery temp monitoring, you can dismantle it for the sensor.
ive ordered a sony xperia with 2.1 or 2.3 "gingerbread $198 AUS delivered / interesting os naming.
On the speedict I requested to danny, as a option for hub motors using the hall sensing from the controler for speed, he said it is possible via software, but have to schedule it . hope he gets more requests to motivate him, i think you should contact him on your compatibility issue.

Arlow : if you have a cell-log to check the charger accuracy that would be good enough, cunning way of using the unused charge ports of both chargers for the remaining 4s pack
I bet the next version is 8s, only thing to watch is the balance wire temp/resistance

 

[CanadianWinters]

No doubt it's been said many times before in many threads, but if you opt to go BMS free, which is cool, it comes with risks and you should try to make life easier for yourself by having on board:

A Cycle Analyst or some equivalent means to tell you at the very least your pack voltage
Balance taps which are easily accessible from the pack, and

And in the tool shed:
An RC charger easily programmed for different chemistries which can balance at least 6 cells at once, should they be low.
A multimeter, and knowledge of how to use it

BMS's, especially ones which allow active balancing are really handy for LiFePO4 cells, but to my knowledge they are more difficult to find for LiCo. EIG stocks a system for their cells, and I don't doubt it's pretty good. I just plug the Cell_Man bike in when I get home and the odd low cell gets topped up nicely but trimming the high cells down.

I Agree with all of the above.

I am running BMS-Free but I need to control the batteries in a way or another. I even build a "Computer" with similar functions to the Cycle Analyst:



unfortunately I burnt some components of the board yesterday (danm!) and I have to buy a new one.

Btw, I think bms-free can be ok for low voltage & low power systems, like my bicycle (36v 30A controller), for more powerful system things can get more complicated.

 

[megacycle]

So just double checking the sensor is for speedict ?
Hk does a temp sensor separately in a plastic housing for battery temp monitoring, you can dismantle it for the sensor.

Which one is that buddy? I wouldn't be surprised if they did have a compatible sensor and got lost in they're own catalogue.
Yeh apologies for the confusion the temp sensor is for the powerlog, for running on the bike with the cellogs monitoring the bikes parameters. I have 2 builds kinda overlapping and just sifting, sourcing and evaluating bits for both and they will be quite different from each other., if have a failure too in one kit not short of a ride too

ive ordered a sony xperia with 2.1 or 2.3 "gingerbread $198 AUS delivered / interesting os naming.

Hopefully your new phone's O/S apple pie and custard works ok with Speedict.
Maybe I just got a faulty one.

On the speedict I requested to danny, as a option for hub motors using the hall sensing from the controler for speed, he said it is possible via software, but have to schedule it . hope he gets more requests to motivate him, i think you should contact him on your compatibility issue.

Danny's asked me to send it back ive mentioned it looks like a connectivity issue but he said just send it, would expect he knows best there.
Personaly Im not worrying about the speed feedback that way I would just look at your phones gps speed would be much more accurate too would expect.

 

[Emoto]

Another member also posted about the hall / speed support but danny didnt respond to him

Hopefully your new phone's O/S apple pie and custard

speedict Question if your using gps for speed you have to be online reciving data yeah
Those temp sensor's you linked look the goods nice range ect
Just had a look for the temp sensor, your right it is lost in hk, but if you get stuck/ or anyone else requests it ill go on a mission / its a common sensor.

 

[megacycle]

speedict Question if your using gps for speed you have to be online reciving data yeah.
No not normally it will just work like a car gps, but yeh if your data is enabled and for maps etc going too you would have data usage happening, usually in the phone you can just disable mobile data while your away from your wifi.

Those temp sensor's you linked look the goods nice range ect
Just had a look for the temp sensor, your right it is lost in hk, but if you get stuck/ or anyone else requests it ill go on a mission / its a common sensor.

Good for now buddy ill get the 1st sensor with the powerlog and go from there TA.

Messed up on the quotes again

 

[Tommy L]

Wow, I gave an opinion again.....now I'm in for it. O'well, as long as the ES police are going to be knocking on my door later today I may as well admit everything. 3 of my 5 ebikes have or have had Currie Ezip motors on them at one time or another. Boy, am I glad to get that off my chest! :wink:

Bob

Bob! I was reading thru this thread and read your post........lmao!
Confession time...... I have a Bionx But I run it with a LiFePO4 Pack I made myself as the Bionx one failed.

I also have a 9C2810 running on a Lyen 4115 18FET at 132v nom jamming up to 4Kw into that 9C

and finally .... I too am BMS less But I need to monitor each cell to see If I have duds so I can keep the pack in good order.
A LVC alarm on all cells whether it be visual or by buzzer is cool.

Tommy L sends.... \\m// Rocking Onward and Learning everyday! \\m//

 

[dumbass]

Wow, I gave an opinion again.....now I'm in for it. O'well, as long as the ES police are going to be knocking on my door later today I may as well admit everything. 3 of my 5 ebikes have or have had Currie Ezip motors on them at one time or another. Boy, am I glad to get that off my chest! :wink:

Bob

Bob! I was reading thru this thread and read your post........lmao!
Confession time...... I have a Bionx But I run it with a LiFePO4 Pack I made myself as the Bionx one failed.

I also have a 9C2810 running on a Lyen 4115 18FET at 132v nom jamming up to 4Kw into that 9C

and finally .... I too am BMS less But I need to monitor each cell to see If I have duds so I can keep the pack in good order.
A LVC alarm on all cells whether it be visual or by buzzer is cool.

Tommy L sends.... \\m// Rocking Onward and Learning everyday! \\m//

Just a few weeks ago my CellLogs saved 2 of my my packs. I hadn't relized that 1 cell in each pack wasn't getting fully charged. I went out for a 30 mile trail ride and for the first time one of m alarms went off. As if that wasn't a big enough surprise the other followed shortly behind it. Same cell #3 in both packs. Without the CellLogs and buzzers I would have never know I had low cells and run them to death. Weater running lifepo4 or lipo I think CellLogs and a buzzer are cheap reliable insurance.

Bob

 

[dnmun]

but a BMS is not cheap reliable insurance? like duh!

 

[Tommy L]

but a BMS is not cheap reliable insurance? like duh!

Does a BMS have LVC for just the whole pack, or does the LVC work at the Cell level?


Tommy L sends.... \\m//

 

[arkmundi]

Going without a bms will always result in battery damage. I like to think in terms of electronic bms, OR human bms. Human bms generally still makes use of some kind of an electronic tool, at a minimum, a voltmeter. Or a wattmeter, or a cycleanalyst, or low voltage warning devices.

dogman!! you're the man - always good to read your sage advice to us newbies. You said it better than I ever could. I'm still on my first e-cycle and battery build. As of the moment, 21-Aug-12, I'm almost done, but have yet to take my first trip. Close, and as excited as this old brain gets these days, like a teenager about to get laid for the first time. Anyway, I've decided to take the incremental improvement path, that starts out without a BMS, doing the "human bms" thing, because knowing watt's going on is part of the fun! Figured I could always get a BMS latter should the manual approach prove too tedious.

 

[arkmundi]

LiFePO4 - medium energy density, potentially the safest current LiPo chemistry, 3.3V nominal, 3.65V to 3.7V maximum, no lower than 2.7V on deep discharge

Thanks for the refresher on battery chemistries. I'd like to add that there are two versions of LiFePO4 - the open market version because its just chemistry, and the A123 patented nanophosphate version. Its the latter that I and a lot of folks on this forum use. So when talking about the pros & cons of various BMS approaches, I for one would like to see discussion specific to this, and in particular the A123 AMP20 prismatic pouch cells. These are hefty 20ah cells. I don't know enough about the charge/discharge characteristics of these cells over time and many cycles to venture any opinion on how to best protect them from damage.

 

[docnjoj]

I'm using 3.60 for charge max and 3.0 for cutoff with my kfong LVC switch. Will be testing this weekend but our route goes about 20 miles so we will see. I expect 13-14 AH from the 36 volt 20 AH nominal agniusm packs of 2x6S under my seat for balance on my trike.20 AH A123 cells of course.
otherDoc

 

[arkmundi]

Afaik this is quite accurate with alarm http://www.hobbyking.com/hobbyking/store/__18987__On_Board_Lipoly_Low_Voltage_Alarm_2s_4s_.html limited to 4s
there is also a 8s hardcase version i dont know about accuracy.

Thanks for the clue! Newbie question on these: for an A123 AMP20 cell in a 12S configuration, where Agniusm's build kit has balance leads to all the cells: the cells are rated 3.3 volts and the alarm happens below 3.3 volts. I don't know what happens as amp-hours are consumed. Does voltage drop in a corresponding manner, progressively? These are 20ah cells and battery. What's the voltage supposed to be as this cycles from 20ah to 15ah to 10ah to 5ah? Is voltage supposed to remain constant at 3.3-3.4 volts? What's the low voltage danager point?

 

[dnmun]

2V

 

[Arlo1]

3v Try not to go below 3v because the capacity is gone and the smallest load will cause the battery votage to dip from 3 to below 2v !

 

[arkmundi]

Just a few weeks ago my CellLogs saved 2 of my my packs. I hadn't relized that 1 cell in each pack wasn't getting fully charged. I went out for a 30 mile trail ride and for the first time one of m alarms went off. As if that wasn't a big enough surprise the other followed shortly behind it. Same cell #3 in both packs. Without the CellLogs and buzzers I would have never know I had low cells and run them to death. Weater running lifepo4 or lipo I think CellLogs and a buzzer are cheap reliable insurance. Bob

Thanks for the advice. Guess I'll have to spend more, like a home-owners insurance policy. Every see that movie "The Money Pit".

 

[999zip999]

At 3.2v LVC on a bike battery is good as below 3.2v the battery starts to go flat fast on the draw of a bikes needs. Plus I'm running without a BMS and can get 17.99ah out of my pack. Why test the battery limits ?

 

[dnmun]

it is not testing the battery limits.

the lifepo4 cell will discharge down to 2.1V before it has used all the capacity. this is the normal test of storage capacity, from 3.65V down to 2.1V.

everybody does it all the time with a normal BMS but now people think that you have to use lifepo4 with the same limitations as lipo. they are not the same.

 

[dumbass]

it is not testing the battery limits.

the lifepo4 cell will discharge down to 2.1V before it has used all the capacity. this is the normal test of storage capacity, from 3.65V down to 2.1V.

everybody does it all the time with a normal BMS but now people think that you have to use lifepo4 with the same limitations as lipo. they are not the same.

Speaking of lifpo4 cells I think the LVC verys depending on the brand of cells you have. It could be as low as 2.0v and I think I've seen some that recommended as high as 2.7v. The issue is to know where the knee of your brand cell is and cut off just before it as your max discharge. Personally I prefer to stay well above it that point.

Bob

 

[dnmun]

LVC is a value set by the BMS. it has nothing to do with the manufacturer. any and all lifepo4 operate in a voltage range between 2.1-3.65V.

lipo is different. it will be damaged if the cell voltage drops below 2.7V.

 

[dumbass]

LVC is a value set by the BMS. it has nothing to do with the manufacturer. any and all lifepo4 operate in a voltage range between 2.1-3.65V.

lipo is different. it will be damaged if the cell voltage drops below 2.7V.

Except as mentioned by several in this thread they are not running with a conventional BMS. And if I remember correctly many BMS have adjustable low and high voltage cutoffs.

While all lifepo4 cell may be capable of opperating in the 2.1 to 3.65v it is not always the recommended range by the manufacture. GBS and ThunderSky for examply recommend 2.8v and the normal cutoff point.

Bob

 

[dnmun]

i know of no commercially available BMS that have adjustable HVC or LVC. i have analyzed about 8 different BMSs and none of them use 2.8V as the LVC. every one uses 2.1V for the LVC.