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

[thedarlington]

this info is out there and spread out all over, so here's a dedicated "BMS free zone"thread specifically for this, when starting out BMS can easily be the biggest pain to understand, most don't even have a brand and each have obscure specs making them hard to compare, and then many very easily fail, often the most frequent failure point to a non working ebike. Its easily the shadiest part to ebikes with little details and then trying to compare them... so instead here's a thread to those of us who preffer a more purist simpler solution, yes you do need to watch #'s a bit more closely but it's also more rewarding to know exactly whats going on with your ebike, sorta like manual vs automatic.

rule of thumb>>> [#Series * Voltage] & [#Parallel * mil AMP hours] = total Battery Volt & mAmphrs ... LIFEPO4 @ 3.3v, & LIPO @ 3.7v

some options for you are:

LIPO - - simple and robust batteries, small and lightweight battery packs which are not as delicate voltagewise as lifepo4, many cheap low voltage alarms ($1) set to go, but more expensive and dont last as long, works out to about double lifepo4 cost? (citation needed) manual balancing (is it needed for lipo?)

CELL LOG Method - - for LIFEPO4 & LIPO designed to watch many connected batteries at the same time, can add a low voltage alarm, connect individual cells by series of 8, manual balancing (or main charge and then manual balance w/ battery medic overnight?)

INDIVIDUAL voltage alarms and low voltage monitors LVMs, these are cheap on ebay ($1-2) but mostly for 3.7v lipo's, so cheap for a visible digital readout, and come with buzzer already, if i could find some for lifepo4 id be in BMS free heaven, also need manual balance (battery medic?), or perhaps mod them down to 3.3v, the digital readout will work, its only the alarm part that needs modding

feel free to add your own info or correct my stuff

[dnmun]

gobbledeegook.

nothing hard to understand about a BMS at all. not sure why it is so difficult for you.

but it is hard to understand what you are talking about.

if you are cheap and don't wanna pay for one, that is one thing, but is it fair to imply it is safe for other people to risk their equipment to failure because they think you have some special insight?

you need to emphasize that you do not understand how a BMS works and not tell people they can use their lifepo4 packs without one without any risk to the pack.

[thedarlington]

i think the real issue is you're assuming alot of things some and putting words in my mouth which can come off as pretty rude, you never wanna put the ass in assume much less in an aggressive manner, the title was pretty clear on what this thread is about so why get mad when it obviously wasn't your thing, i clearly stated wanting the control and gave the manual vs auto example, i hear most of those guys in racing still shift with manual controls as well automatics been around for what 100 years? so for some of us being in control is our thing, why get mad? many on the forum already avoid the BMS, and have a much better understanding of that if you want to discuss the issue but as i said, my thread didn't start this trend its been around for a pretty long while here, some reasons for it:

1 BMS boards fail all the time and almost no one keeps extras so this can mess you up for weeks,

2 its not as easy to compare BMS systems, sure more $$$ better quality are you looking to sponsor me that $300 board and call it a day?

3 i understand what a BMS is, you buy it usually preinstalled already... and they protect and balance your battery dude, whats so hard to get about that? the problem arises when someone doesn't wanna buy a made kit and wants to build one because not all specs are given evenly and then matching the ones you want with reviews is a scavenger game since they're so unique, that some of us would preffer to ride with cell logs while deciding

4 if BMS's are so great why did gary, fetcher, and everyone else who bought their boards decide to go thru years of trial and error making many prototypes and then making and soldering each and every connection on their own boards for something thats so great and already available? theres a couple 100+ page threads on those alone that spanned a couple years

5 many of the guys on lipo have been BMS free for a while already so if you wanna start calling people cheap you could start over there

6 i got a BMS in each of my batteries and have for quite a while now so being cheap was never the final point take that up with the lipo guys if you want to, but if anything both methods can be combined, this is only for discussing non 'auto' BMS methods

and sure also cuz ppl are cheap, im sure many here have a vetrix or zero but signed up for the thrill that only a rusty 18mph huffy can give you

[dogman]

Well that got off to a bad start. Perhaps more usefull to others woud be a list of links to good threads that do explain how to go without bms, and others that explain what a bms is. Here is one from just yeserday, that has an as always excellent BMS explanation from Jeremy.

viewtopic.php?f=14&t=41513

Going without a bms will always result in battery damage. I like to think in terms of electronic bms, OR human bms.

Electronic bms might be as simple as an LVC on the controller, and a charger that stops before the cells overcharge. Or it can be a fully functioning cell level monitored low voltage cutoff, balancer, and amp limiter.

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.

A great many of us run a bms, then do the human bms thing as a backup. Like running with a signalab bms on a pingbattery, but also having a cycleanalyst.

Most RC lipo (lico) users actually do make use of a bms of some kind. Their RC chargers have the HVC and balancing functions included. So all they need on the bike is voltage monitoring or low voltage cutoff.

[circuit]

A good start would be for all novice users to use a BMS and live their life easy.
BMS-less system for a user who has no _good_ knowledge of what he is doing is a recipe for guaranteed failure. Dead cells, dead electronics, burnt-down house... Pick either one or all of them. I'm doing customer support and believe me, you don't want to go that road.
If you feel like you are the one to go blind without bms, it's your risk. But don't stick it to others.
I think the less info the better.

[dogman]

Couldn't agree less with that comment about limiting the info. I guess my post count says that if nothing else. This forum alwasy has and always will be about sharing the info. Letting others know what did and what didn't work in our latest experiments.

But I do agree, the majority of people in the world should stick to a reliable battery with a bms, BUT learn to monitor if the bms is working or not. Ping + Cycleanalyst basicly.

Noobs should not dive straight into RC lipo unless they are not noobs, that is, they have experience with them with RC toys. However this is ES, and some of the noobs have degrees in electronics or engineering. Those kind of genius folks can easily figure out how to handle a few RC toy batteries. Other degrees, maybe not. My wife had to show PHD chemists how to fix the gas chromatograph many many times. The janitor had unplugged it from the wall to mop.

[dumbass]

I don't know why but everytime someone refers to going without a BMS on ES someone goes crazy. And to frequently feel a need to abuse the thread's writter. Ane with good reason...after all how dare they have an opinion. While thedarlington thread title may have implied going without a BMS anyone with any amount of knowledge understands that's not what he is recommending. He is simply rehashing what has been talked about many times. Alternitives to a full blown BMS. As dogman clarified there are many veriations to the term "BMS". To include manual monitoring. To me this is the true fact that is not being understood. And it's totally personal as to how you as an individual want to monitor and control your packs. So weather you go totally manual or a full blown electronic system go for it ...it's your business. The real issue is that you DO use some methiod that works for you.

My first season I treated my lifepo4 pack like they were lead packs. Plug in a charger and come back after the charger turned off (next morning) and I had no BMS of any kind. Like many others I thought everything was cool because when I did a manual check all the cells were balanced. Da! What I didn't relize was they will almost always be in close balance when at rest. I was lucky and did no major damage. I now have 4 - 24v 20ah packs and still do not use what most would consider a BMS. In stead I use cellLog8s to monitor and control both high and low voltage. It works for me and I consider it as or more reliable as many so called profesional BMSs. But lets remember a CellLog could easily fail too.

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!

Bob

[Jeremy Harris]

this info is out there and spread out all over, so here's a dedicated "BMS free zone"thread specifically for this, when starting out BMS can easily be the biggest pain to understand, most don't even have a brand and each have obscure specs making them hard to compare, and then many very easily fail, often the most frequent failure point to a non working ebike. Its easily the shadiest part to ebikes with little details and then trying to compare them... so instead here's a thread to those of us who preffer a more purist simpler solution, yes you do need to watch #'s a bit more closely but it's also more rewarding to know exactly whats going on with your ebike, sorta like manual vs automatic.

rule of thumb>>> [#Series * Voltage] & [#Parallel * mil AMP hours] = total Battery Volt & mAmphrs ... LIFEPO4 @ 3.3v, & LIPO @ 3.7v

Which chemistry do you mean when you say "LiPo"? LiFePO4 is LiPo, so is LiCoO2, so is LiMnO2, so is LiMnCoO2, so is LiNiMnO2, in fact ALL lithium ion cells are lithium polymer................

some options for you are:

LIPO - - simple and robust batteries, small and lightweight battery packs which are not as delicate voltagewise as lifepo4, many cheap low voltage alarms ($1) set to go, but more expensive and dont last as long, works out to about double lifepo4 cost? (citation needed) manual balancing (is it needed for lipo?)

Dangerous assumption here, as every LiPo chemistry is different, and LiFePO4 is just one of the many LiPo chemistries. When determining voltage characteristics, safety etc then you need to be specific about the cell chemistry.

Here is a brief run down on the various types of LiPo cells and the relevant voltages, etc:

LiCoO2 - Commonly used for RC type LiPo packs, 3.7V nominal, 4.2V maximum, no lower than 3V on deep discharge (preferably no lower than 3.5 to 3.6V for best life).
LiMnO4 - Not that common, nominal voltage 4V, maximum about 4.5V, low energy density when compared to LiCoO2
LiNiO2 - high energy density, nominal voltage 3.5V, maximum about 4V, no lower than 3V on deep discharge
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
LiCo1/3Ni1/3Mn1/3O2 - higher energy density than LiCoO2, 3.6V nominal, maximum about 4V, no lower than about 3V on deep discharge
LiNiMnO2 - very high energy density, not yet commonly available, 4.2V nominal, maximum and minimum not known

[amberwolf]

Here is a brief run down on the various types of LiPo cells and the relevant voltages, etc:

LiCoO2 - Commonly used for RC type LiPo packs, 3.7V nominal, 4.2V maximum, no lower than 3V on deep discharge (preferably no lower than 3.5 to 3.6V for best life).
LiMnO4 - Not that common, nominal voltage 4V, maximum about 4.5V, low energy density when compared to LiCoO2
LiNiO2 - high energy density, nominal voltage 3.5V, maximum about 4V, no lower than 3V on deep discharge
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
LiCo1/3Ni1/3Mn1/3O2 - higher energy density than LiCoO2, 3.6V nominal, maximum about 4V, no lower than about 3V on deep discharge
LiNiMnO2 - very high energy density, not yet commonly available, 4.2V nominal, maximum and minimum not known

I wikied this list here:
http://www.endless-sphere.com/w/index.p ... LiPo#Types
but I would like to add this note to the last one, if you are referring to "NMC" types:
"(actually is known from datasheets such as EIG's: http://www.eigbattery.com/eng/product/C020.pdf : 3.65V nominal, min recommended 3.0V, absolute min 2.5V, max charge 4.15V.)"

[thedarlington]

good points i dont run lipo but its pretty much the go to term that everyone knows those hobbyking packs by usually zippys, and i agree BMS is good but sometimes you do need another solution like when a BMS goes out, or when you're in between BMS's while buying or waiting for one, but both ways compliment themselves anyway its always good to know about a 2nd alternative method

check out this cool improved celllog on ebay, $3 cheaper than hk and free ship, so $7-9 cheaper? here's whats awesome, display #s look twice as big (bigger lcd + bigger font), and most importantly it already comes with 2 PROGRAMMABLE LOW VOLTAGE ALARMS (w led?) , vs HK logs which you buy separately and figure out how to put it (+solder to a jst?), i couldn't find any benefits to the HK log vs this one
http://www.ebay.com/itm/130708314415?ss ... 1439.l2649
also this guy shows how to hack the backlight resistor dropping from 30mA to 10mA http://www.youtube.com/watch?v=t4gtmzkYD1E
it looks like hyena approves of this model as well, if he posted it here i missed it so here's the vid http://www.youtube.com/watch?v=4cM8P6eIQ_I

i also found a cheaper and ALREADY BOOSTED??? Battery Medic balancer, in 50 100 & 150 watt versions for balance and discharge, correct me but i think this is what GGoodrum's booster boards did for an extra $15 when they where for sale, cheapest 50w is again $7-9 cheaper than HK? boosted one is easy $20-25 cheaper and available since its a 2 in 1 IF it does what gary's used to do
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0068386284

cheapest 8s plug i found
http://www.ebay.com/itm/130673356442?ss ... 2118wt_922

let me know what you guys think about these, i really liked the bigger #'s on the BVM loggers, that was my main complaint on the HK logs

i already bought a couple of those and maybe doing the resistor hack

i considered also making a newbie BMS thread yesterday, thats why i made this only for BMS free methods but then i got caught up looking up LVM's, i dont know enough about BMS's to add to that one, just know i got a smartec brand which is supposed to be good, but the fact that ppl still post threads like the one dogman linked shows the BMS is still a black box to many (again why i made this thread), i myself am clueless on whats good vs what isnt, or what a good price for each unique BMS is, most BMS boards aren't even branded, so if you're sold a fake good luck figuring that out, which again, proves the importance of a BMS free method,

i know i've seen a couple threads here where someone's lost their battery pack bc of a faulty BMS, and a couple more where their BMS failed, why trust a BMS blindly? i feel much safer with a live voltage readout and alarm than some failure prone board which idk whats going on or if its working until its too late,i side with fetcher and gary on this, i dont like the current BMS's out there and they seem like a ripoff for how failure prone they are so yes im biased, but im sure if you ask members what part they're most weary/ unsure of, there will be much less confidence in the BMS than other components, save maybe flimsy connectors

[jonescg]

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.

[Jeremy Harris]

good points i dont run lipo

So, you're running on what? Lead acid? Nickel Metal Hydride? Nickel Cadmium?

My guess is that you ARE running on LiPo, most probably LiFePO4.

Given that there are so many different LiPo chemistries around now, we need to be clear about what we're discussing here. The first commonly available LiPo cells were LiCoO2, so there was no need to be specific, using the term LiPo could only really mean LiCoO2. Things are very different now, so we need to be more specific, it is confusing, and potentially dangerous, to not understand the different types of LiPo cells around.

For example, charging a LiFePO4 LiPo cell to a voltage that would be safe for a LiCoO2 Lipo cell would probably damage it, as would discharging a LiCoO2 LiPo cell to a voltage that would be safe for a LiFePO4 LiPo cell. Using the term "LiPo" without any further qualifier is unsafe.

[Jeremy Harris]

I wikied this list here:
http://www.endless-sphere.com/w/index.p ... LiPo#Types
but I would like to add this note to the last one, if you are referring to "NMC" types:
"(actually is known from datasheets such as EIG's: http://www.eigbattery.com/eng/product/C020.pdf : 3.65V nominal, min recommended 3.0V, absolute min 2.5V, max charge 4.15V.)"

Thanks for doing this and digging out the extra info on NMC, AW. I was pushed for time when posting that and couldn't quickly find those numbers when I looked.

The last one on that list is the newer chemistry than the EIG NMC cells, with a higher energy density and nominal voltage (~0.9 kWh/kg and 4.2 V respectively). I can't seem to find out much about them in terms of practical stuff, but AFAIK they aren't yet readily available to us.

[etriker]

I think checking the data sheet on the cells you are going to use is the best way to know the voltages.

These are called High Power Lithium Ion ANR26650M1.

http://visforvoltage.org/sites/default/ ... 1specs.pdf

Most all quality cells have one.

[thedarlington]

thanks jeremy yea life, for some reason the chemistries mentioned here have always been life or lifepo4, SLA, Nimh, and then the notorious lipo aka hobby king packs, so these are LicoO2 then? i dont follow them so close just picked that term up from common use here, i think Rc retailers like HK are to blame for spreading bad info, i like HK but they should emphasize tech specs over buzzwords and marketing, sometimes its hard to even compare features/functions of their stuff bc most are not listed, no regrets goin with the better ebay copies, and btw ill be using either ethernet, VGA ,or IDE, to hook these things up

[Jeremy Harris]

thanks jeremy yea life, for some reason the chemistries mentioned here have always been life or lifepo4, SLA, Nimh, and then the notorious lipo aka hobby king packs, so these are LicoO2 then? i dont follow them so close just picked that term up from common use here, i think Rc retailers like HK are to blame for spreading bad info, i like HK but they should emphasize tech specs over buzzwords and marketing, sometimes its hard to even compare features/functions of their stuff bc most are not listed, no regrets goin with the better ebay copies, and btw ill be using either ethernet, VGA ,or IDE, to hook these things up

No really bad info, just that for a long time the only commonly available LiPo cells were LiCoO2, other chemistries didn't come along until after LiCoO2 had become well established, at least in the RC hobby sector. Inevitably, the RC folk just referred to the LiCoO2 cells they were using as LiPo, as it was an easier term to use.

Then other LiPo cells came out, using different chemistries and having different voltages and characteristics, creating the need to be more specific when discussing cell type. This still doesn't really affect the RC folk, who are the biggest hobby user group of this stuff by a long way, as they still mainly use LiCoO2 LiPo, with only a few of them using LiFePO4 LiPo. It does affect us though, as there are ebike batteries around that use a variety of different LiPo chemistry cells.

[etriker]

Little or no info about voltages on Hobby King ?

http://www.hobbyking.com/hobbyking/stor ... ouse_.html

Stuff like this you better look places other than the seller info or data sheet to find the voltages.

Bad info for sure.

And don't get me going on the wire size they use or the way the cells are connected or why the cells that die first are the ones that do not have nano 5000 printed on them.

[thedarlington]

yep most stuff goes like this http://www.hobbyking.com/hobbyking/stor ... tors_.html
or http://www.hobbyking.com/hobbyking/stor ... duct=18987
the 2nd one's actually wrong bc these things DONT work for lifepo4 since you can't set the alarm and it can't sense what chem you put, figured this out after customer support didnt get theres diff. voltages, imagine finding out after their $10 shipping and 3 week wait (if stocked), a specialized store like HK should be able to clear all that stuff out before shipping yet i actually found better info from resellers like ebay and DX, i ended up hunting down info for what diff. meters do in the comments section of all places

[thedarlington]

checking back in again, it appears that this super cheap smart universal ebay charger (18650, aa, aaa, 9v etc) can recognize and fill up lifepo4 just fine, its not super fast but for this price you can just buy 16, and use thru balance connectors, i simply hookup each cell +/- terminal without disconnecting the series, i wondered if it was possible but it seems like it is without a problem

heres my charger it can detect anywhere from 1.5v to 9v (that i know of) so 3.65 is right at home and i verified http://www.ebay.com/itm/1-x-AAA-AA-1865 ... 3f16d00902

[thedarlington]

i am now using ethernet rj-45 connectors instead of the balance plugs, easy to find, way cheaper setup since theyre so commercial and especially for longer lengths and easier install with crimps
so right now net cables are (-) and balancers are (+), 1-8s and 9-16s ... plan on adding net cables for all (+) terminals later, these smart chargers are great, not only do they do lifepo4 but i can simply charge them individually at the same rates that i would with a larger more expensive charger, so if a charger goes bad its only a $3 hit vs $60 and they are guaranteed balanced since theyre all getting topped off individually not having to share 1 charger current, once its more organized and cleaner i think this is a better way to charge and balance my cells than blindly relying on a BMS and charger

oh yea by the way, for those of you who swear by the BMS, it wasn't until i was installing the ethernet, that i actually found my BMS was connected wrong to 8 cells, half the pack! it wasnt too bad but still how do you mess that one up? all headways are black on the bottom its not that hard to know which side's which, only 2 cells where seriously unbalanced, so now im sold on opening up my pack, monitoring each cell individually and charging each guaranteeing balance than blindly trusting my BMS

[docnjoj]

Now that is a clever idea. Nice work.
otherDoc

[999zip999]

Are those single strand sense wires ?

[docnjoj]

Are those single strand sense wires ?

"Stranded vs. Solid wire
Almost all patch cables that are made have stranded wire. Stranded wire is normally specified for use in patch cables due to its superior flexibility. There has been some talk recently, in the technical sector of the structured wiring community, regarding the possible use of solid conductors for patch cables. The reason for the spotlight on solid wire is that it is supposedly more stable, under a variety of conditions. Please note that we now offer custom Solid copper category 5E patch cables in Plenum insulation in lengths of up to 295 feet. These cables are suitable for use in air handling (Plenum) ceilings and environments."

otherDoc with the quote from Lanshack

[thedarlington]

i dont understand the question of single strand wires, i think no? there are 8 wires inside the fat net cable, all insulated and of very good copper quality (pretty stiff so you know its good, but regular stranded not 1 single solid copper), they are highly rated for data, don't loose their tiny internet signals for 150 feet, (vs USB ~8feet), theyre twisted by solid/stripe pairs (oranges, greens, browns, blues)... these are all (-), and doing (+) soon,

say you need 3 feet, you cut once and instantly 8 cables of same length, with a nice sleeve to keep the mess in order, and you pay for only one 3 foot cable, not 24 feet (8x3) at retail price (they reason you bought a whole lot more and charge that way, just look at how long it is all over the floor! actually yea think about how long 24 ft of cable looks, even rolled up it looks long) even at the cheapest gauge (say this gauge) its still waaay cheaper to buy in cat5 bc its sold as 1 cable, which you then split to 8, thats how retail works, connectors are crazy cheap, you can buy 100 via ebay vs one 8 pin jst for $3 on ebay THATS AN INSANE DIFFERENCE!!! ebay also sells crimps for like $3 so for the price of 2 balancers, u get the whole cable making lab, i also buy my cable at flea markets, no one wants it!!! so i got like 3 100' rolls for $2 each, look in used stores, but i do not recommend the ebay ones, theyre very thin, its also pretty cheap in bulk rolls from home improvement stores (and i think better quality real stiff home wiring stuff)

so for my setup here, its net1 cable for left 8s bank, net2 for right 9-16s bank, and the cells are in series flipping polarity so all striped on top, all solids on bottom, to keep standard cat5 plug order, ill wire the (+) the same way since its so easy, cheap, and hold better than splicing the balancer leads, these are to charge each cell independently via cheapie $3 smart chargers, since i found i can charge w/o having to disconnect the series, i'll add coupler/splitters out1 for charging out2 to handlebars for the cell log live monitoring via net cable strapped onto bike, linked one below



http://www.ebay.com/itm/New-3-Way-RJ45- ... 257323686f

[thedarlington]

got this pic from megacycle, pretty handy and much cheaper than an 8s balancer connector for your cell logs, using IDE