Bottom balancing?

[SunKing]

I have not seen experimental results to challenge the basic premise of this and similar results. Unless there is some refutation of this, I do not see how you can come to any meaningful conclusions if your basic assumptions are inverse of the findings.

I do not doubt the data you presented, and have seen this data before. Issue is it does not apply because it is AC circuit Impedance. It is not DC Resistance. The AC Impedance will be DC Resistance + Inductance/Capacitance Reactance which is fine if you want to know what the impedance is at a specific AC frequency and SOC level. What the test data does not show is DC Resistance vs SOC and is incomplete as it shows no data down to 0% SOC and Beyond 0 to 2.5 vpc range where resistance goes down. Your paper only goes down to 20% SOC . Where is the Rest of the Story?

The article you presented supports my statement Ri is essentially flat and to operate LFP between 20/80%

Actually I see now your New SunKing intro thread that gives us some info about your background, that's good, now I have some idea - and a ham to boot! Sweet! It does appear however that your professional experience extends to the use of LFP batteries as an end user

I am a PE and worked in Electric Utility and Telecom for about 35 years. In that tenure power generation, battery plants, generators, power distribution. an dlast 10 years quite a bit of Solar battery systems. As a hobby built or you could say converted 3 golf carts into something else like a 60 mph thrill ride. My battery experience is 35 year Pb, NiCd, and LFP. I am also a RC Plane Pilot kid at heart and we use LiPo fo rmotors, and LFP for control.

 

[dnmun]

there is nothing to indicate that the internal resistance is flat. you need to go look at the transconductance for lithium cells and the mass transport equation is entirely dependent on the number of available ions to transport charge and the number of ions available is dependent on the SOC. go read . go learn.

 

[wb9k]

In the low power world of consumer electronics which live at room temp, your assertions about impedance are mostly true. However, when you get into extended discharge pulses, especially at lower temperatures, they are not. A big part of the problem here is "consumer electronics myopia", something that effects even really educated guys outside the automotive sector who are not used to considering the extreme conditions that, sooner or later, are inevitably present in a car.

Attached are power capability and DCR curves for the A123 Amp 20 under a range of conditions. Note that these are for discharge only, charge numbers are different which complicates things further. Note also that there is considerable drift in the characteristics with temperature. Temperature gradients within a pack bring yet another opportunity to slowly introduce imbalance to a pack.

You could get away without the convenience of automatic balancing, but you MUST have cell-level voltage monitoring to enable robust detection of problems and, if necessary, immobilize the car until a problem is corrected.

 

[SunKing]

FWIW, the discussions over on DIY EC are usually in the context of a car using large-format LFP cells like CALB, Sinopoly, etc.. You don't have to dig very far on that board to see Sunking saying that people like me are in on a conspiracy by cell makers to sell you BMS's you don't actually need.

Quit putting words in my mouth. You have no clue what my capabilities and experiences are. All you know is your so called authority is being challenged and you do not like it.

There is absolutely no chance any company or business would ever even remotely think of ever up selling a customer or product they do not necessarily need or want? No company would ever dare think about that. Wake up my friend and go to a Fast Food Restaurant. Maybe even buy a car and buy that extended warranty. How about a Bong, booze, cigarettes, or Whacky Tobacky? How about a Pet Rock while you are at it?

I use to be a [text deleted by moderator] Engineer like yourself. I use to be in the Thou Shall Use a BMS Club, let me design one for you. You know that Smart Arse Engineer that cannot be taught anything and closed minded.. Heck I even have MSEE and PE after my Jerk of a name with 35 years experience working with batteries and power. I use to think just like your [text deleted by moderator] does today. As a [text deleted by moderator] like yourself I use to think there was an engineered solution to everything. Heck even have an Orion Jr in my current EV. I just do not use it as BMS and wish I had not wasted my money on it as a simple Cell Monitor would tell me what needs be done.

Simple Fact is BMS are for Morons, Lazy, and commercial products. They are not required. For people who know nothing other than stick the key in the ignition and drive off. Bottom Balance of LFP cells does two simple thing no BMS cannot possible do or compete with. Passively eliminates the risk of Over Discharge, and cost NOTHING to implement putting your Smart our Smart Arse's out of work.

I never said you should not use a BMS. All I said is you do not need a BMS if you know what you are doing. Here is how I work and have more protection than any BMS alone can provide.

1. Bottom Balanced my 16S 100 AH GBS 48 volt battery 8 months ago to 2.5 vpc. Still in Balance today and I will re balance when and if it becomes unbalanced.

2 Set my Motor Controller LVD to 47 volts which is well above 2.5 vpc at 40 volts pack voltage.

3. Have Orion Jr monitor cell levels and send a Disconnect Signal to Motor Controller is any one single cell reaches 2.5 volts or less for more than 15 seconds. I also use it to send a Signal to the Charger to turn off Charger as soon as any cell reaches 3.6 volts which is always cell #4 which is the weakest at 102 AH.

To charge I use an old Telecom 48 volt 50 amp battery rectifier. All Telecom Battery Rectifiers are industrial Grade CC/CV units. I charge at C/2 until one cell reaches about 3.6 volts. It is always cell 4 the weakest cell, and after experimenting a bit with Cut Off Voltages in my case 3.6 volts is the point so when rested is roughly 80 to 90% SOC. All other cells are just slightly lower or equal voltages.

So I have 3 lines of defense on the Discharge Side. First line of Defense as designed is a very Conservative Automated LVD setting in my Motor Controller to trip off when Pack Voltage reaches 48 volts or roughly 20% remaining capacity. Second Line of Defense is a Battery Monitor that will operate th eLVD in th eMotor Controller is any one cell sees 2.5 volts or less for more than 15 seconds.

Third line of defense is completely Passive and Cost NOTHING and all that is really needed. I Bottom Balanced the batteries. If by some chance 1st and 2nd line of Automated Defense fails, once pack voltage reaches 40 volts or 2.5 vpc, th system just comes to a HALT. No damage other than calling the Wife telling here to bring the truck and Tow Bar.

See I use to be a [text deleted by moderator] like yourself. Then I grew and wised up with age. That is why I am retired at 57, and living in paradise playing all day long doing whatever I want.

 

[dnmun]

your discussions make it absolutely clear how incompetent you are. amazing that you called yourself a battery expert and were on these battery research councils.

 

[wb9k]

Simple Fact is BMS are for Morons and Lazy people.

Which meets the description of probably 99% of car drivers. Your system is a non-starter in the real world.

 

[wb9k]

Oh, you can find this quote:

Originally Posted by evlithium View Post
a BMS is necessary for the CALB battery pack.

Sunking: Nonsense.No BMS is needed. That is what salesman and manufactures want you to believe.

http://www.diyelectriccar.com/forums/showthread.php/causes-lifepo4-venting-and-0vi-149146p2.html

 

[wb9k]

when people say they are professionals it makes me sick. what profession?

do you know any physical chemistry. have you ever had to do advanced chemistry homework or studied any materials science?

what profession? you said you are on some consulting board with respect to battery technology, so what board and what did you do?

for you to not understand what W9 has explained to you just proves to me you are faking your "professional" credentials.

Professionals are far from infallible. I spend the bulk of my work time finding and helping to correct the errors and oversights of a whole bunch of professionals. I don't have any reason to believe SK is faking his credentials....they're just not as comprehensive as he believes they are.

 

[kd8cgo]

The simple fact is SunKing, you're preaching to the choir. Many hobby-level project here don't use a BMS, especially when they are using LiPo. It's a convenience feature for people that saves time and effort. The people who don't use a BMS, use a balancing charger to set up their pack 99% of the time, which does the same top-balancing procedure - and then bulk charge for the remainder of the time. Automation is for literally everyone who does not wish to waste there own time on manual pack or cell-by-cell balancing and monitoring - no matter the level of motivation or intelligence of the user - I can find no correlation here. Unless you get some thrill out of performing menial tasks out of some Zen-Bhuddist-like devotion to the banal, I see no reason to push your method. I can imagine manual balancing might be a good occupation for an actual moron however, so perhaps you could hire some people to perform this task who cannot perform higher-skilled functions. Otherwise, normal people usually like to participate in more creative thought, rather than mind-numbing, boring, unnecessary Rube Goldberg Olympics like manual pack balancing.

You appear to push low SOC balancing for the main purpose of preventing cell reversal. This is not a problem if you don't design a system that allows for it to happen, or tells the user hey guess what, your battery is dying!!. Or you simply know how much energy is in your battery - any idiot can figure out the energy budget for a round trip with decent accuracy, why is there such a concern about running a cell dead? We even have tools to automate that for us, we're so lazy here on ES. I'd suggest that maybe we should start having a co-pilot log shunt voltages and plot them on graph paper over time, and report to the driver the current Amp-Hours left in the battery after of course hand calculating it (no calculators! LAZY BASTARDS!), does that sound like a similar good idea for smart non-lazy people to do!?

 

[dmwahl]

Simple Fact is BMS are for Morons and Lazy people.

A BMS broadens the group of people benefiting from lithium battery technologies. Sure, you can monitor each cell periodically, manually top/bottom balance, etc and it will likely work out for you, but it's not even remotely feasible for a mass produced consumer product. Forums like this and DIYEC are not representative of the general public. The average person wants to get in their car, turn the key, and have no thoughts about what goes on under the hood.

 

[wb9k]

Perhaps it would be good to clarify what is meant by "BMS". To me, it's a Battery Management System that does a whole host of things via any number of means. Balancing is usually one of them, but it doesn't have to be. Things like LVC and HVC are also part of a total "management system". So when SK says "no BMS is required" yet describes his system, which as I've said to me IS a BMS of sorts, I'm confused by that. It seems self-contradictory. People think I'm being a jerk sometimes when I seek to clarify terminology in very specific ways, but when we don't do that, threads like this can be the result because people are talking about different things without even realizing it.

What other definitions of "BMS" are being used in this conversation?

 

[kd8cgo]

It's a good point, could be battery monitoring system and/or battery management system. My 18650 packs handle LVC/HVC and balancing functions, which is about all you can ask for besides potentially data logging for trend analysis, which I'd love to have if troubleshooting were ever required - a lot of guys have that with their RC balance chargers. My LiFePO4 push lawn mower just has a cellog on it that's only hooked up during run time and only ever gets bulk charged to about 75%, because it's a dang lawn mower. Then you have the wide variety of cell and pack monitoring granularity, from pack-level to cell groups down to the individual parallel cell strings. Often times our battery management isn't a unified "system" either, but spread out between Cycle Analyst/watt meters, internal BMS boards, and programmable chargers. With the technology to implement the automation so cheap and readily available, I can't imagine not wanting the extra features unless you really need to pinch pennies.

Some guys have had trouble with the BMS bleed functions over the years, which was a common complaint amongst the anti-BMS crowd. Some of these little things didn't even have fuse protection on them, so there was plenty to be upset about with the state of affairs back then. Many people are not knowledgeable enough to put together disparate components into a symbiotic system or understand all the interactions that need to be accounted for, at least at first. Adding complexity requires adding more contingency and analysis of failure modes.

I was thinking SunKing posted he's retired, and actually manual balancing takes more time, and a good excuse to get out of the house for someone with oodles to spare. It's not a totally bad idea - I know my granddad was in the shop all the time, so he didn't have to listen to my grandma all day every day! "Ok hun, gotta go balance the battery packs - see you at dinner!"

 

[Punx0r]

Sunking's "no-BMS" system does sound to me to perform the functions of a BMS. People who manually monitor and balance charge their RC LiCo packs are sometimes referred to as being a "human BMS".

 

[wb9k]

Perhaps this is indeed a source of confusion for me and others, and if so I apologize for unnecessary heat. The practices often advocated in this debate are in my mind nothing less than a matter of life and death for the users of these cars. I cannot--and will not-- treat those cases as if some mere academic point is being discussed in a vacuum. However, if SK has cell level monitoring and shutoff capabilities to go with, then I'd say he's using an automotive grade BMS that can effectively prevent catastrophic failures. It falls short in terms of required maintenance and the ability to cope well with minor cell anomalies, but that's a choice that can be justified without resorting to the risk of manslaughter.I don't think the car buying public wants that system though, for the reasons I just stated. I do think SK is too cavalier about LFP failure modes and what the worst case outcome is. I know a few guys like that--they scare me.

You're right about early BMS electronics. There was, and too often still remains, plenty to gripe about in many systems. And they can lead to nasty failure modes in some cases. This is a reason to improve them, not eliminate them.

I top balance my mower battery with a good hobby charger at the beginning of the season and use the original lead-acid charger that came with the mower. It cuts off power with each cell at about 3.55, and the pack SOH is even enough that I can just stop mowing when the thing starts to noticeably slow down. I can go all season on one balance charge. I used to do similar with the 1 kW 48V pack in the scooter I used to have. I do similar with the packs that drive my hi fi. In my motorcycle (~3 kW), I have balancers and a symbiotic on-board charger that takes a balanced pack to 3.65V per cell. This results in 95% SOC, maybe a little more--it depends quite a bit on temperature. Any imbalance will be trimmed in tiny increments with each charge cycle. Pack SOH is very even and my motor controller cuts out at 32V, about 2V per cell under load, which is really just fine as long as you're not going there on a regular basis. It's nice to be able to tap that bottom 20% when you really need it. I also monitor pack voltage constantly (there's no cell v measurements visible to me anywhere on the bike.) My intimate knowledge of pack behavior is the only other thing standing between me and a failure like I describe elsewhere in this thread. But I know what the numbers should look like in every scenario, and I can pick up on a problem if there is one.

That's about as big a system as I care to operate with even those minor loopholes, and I would never recommend even that for a lay person. I've got all the batteries I care to babysit and manually balance already--I don't need a 10 or 12 kW 150V monster waiting to kill me while I sleep at night with some amount of drift too small for me to pick up on just watching the pack voltage. The truck will have CAN communication with the pack and display max and min cell voltages on demand--probably at all times. A car is no place to fly blind and the less maintenance required, the better. It is inevitable this will all be made "automatic for the people". Why eschew this feature--and I can only imagine at this point that we are talking very specifically about automatic balancing--as a matter of core philosophy?

 

[SunKing]

Perhaps it would be good to clarify what is meant by "BMS".

Bingo, now you understand me.

You and I cannot define a BMS. There is none in any standard or discipline. What you and most call a BMS is really a Programmable Loop Controller aka PLC.


I can call a BMS nothing more than Dumb Balance Balance Board (I call the suckers Vampire Boards). with a Red and Green light a BMS. It turns on when the cell voltage reaches a certain set voltage and closes a Shunt By-Pass. When the voltage drops, it turns off. It communicates nothing but an indicator light.

Can I take my charger I use for RC planes a Power Lab 8 and install i ton a 24 volt vehicle and call it a BMS. I sure can but it is nothing more than a battery charger with a PLC. My little hobby charger will uun circles around what most most commercial made BMS.

Now as far as my setup goes. I acquired all the parts over a period of 2.5 years before find a donor vehicle, and Ford Think. When I acquired the Orion Jr was at the start when I was still in the BMS camp. It got re purposed during the build as a cell monitor. Fact is my Motor Controller can do just about everything including Coulomb Counting. Hell I started with Vampire Boards initiall, then decide I wanted an Orion Jr and sold the 16 Vampire Boards. Only reason I kept the Orion is because I did not want to use my Powerlab 8 as a monitor.

 

[dnmun]

you are just talking gobbledeegook.

you have no comprehension of how a BMS works and you do not understand conduction or how ions are transported in a lithium ion system.

then you go and insult W9 when he tries to prevent you from misinforming all of these novices who have no clue how deficient your understanding is.

 

[SunKing]

The simple fact is SunKing, you're preaching to the choir. Many hobby-level project here don't use a BMS,

That maybe my error as I thought this Forum was tailored to kids (teens, twenties, and 30's) building e-bikes and smoking weed, with a few savy ole timers helping out I don't do bikes or weeds, but I am ole and savy with a rich history of industrial battery work, and a hobby of building really fast go carts.

Why a fast cart. Simple bragging rights and I got nothing better to do with my money being retired. Hate ham radio operating anymore because all that is left is fossils, and the Smart Phone phone killed the hobby. Anyway I live in a gated community wiht a Private golf course, Private ski/fishing lake, Private streets, and lots of shopping and entertainment nearby accessible by legal and not so legal LSV, PTV, NEV, and Buggies. I play a lot of golf so need a cart anyway.

But come 4th of July we as a community go all out with ole fashion 4th of July from sunrise to after dark. We have a decent parade and carts pull a lot of Floats. But we have Golf Cart Drag Races. See there are over 500 golf carts here. It cost $10 to enter and we have anywhere from 20 to 40 carts to enter, winner takes all in single elimination heats of 1/8 mile. They are all entering to beat me. Well they got a chore to do as no one is even remotely close startin glast 4th when I entered the ole Ford Think. 0-60 in around 4 to 5 seconds and a top speed of 70 to 75. Second place can only muster 36 mph and it takes the full 1/8th mile to get going 36 mph. By the time these guys cross the finish line I am already recharging my battery and drinking a beer at the clubhouse. I can beat most commercial made vehicles in a 1/8th mile drag race. What is really funny is one of my close friends, Jim is a great mechanical engineer and builds his own Buggy like I did. He cannot figure out what I have done this time. Last time he knew was 60 volt Pb, GE Beast DCC motor, 650 amp Altrax Controller and all he can get is 36 mph.

Jim cannot believe he let a Jerk-Off EE beat him at his game. He does not know I lightened th ecart 300 pounds by switching to LFP or using AC -phase Induction motors which can handle a high speed differential ratio, He has no clue I generate 90 foot-pounds of Torque from 0 to 6500 RPM's.

 

[SunKing]

you are just talking gobbledeegook.

you have no comprehension of how a BMS works and you do not understand conduction or how ions are transported in a lithium ion system.

then you go and insult W9 when he tries to prevent you from misinforming all of these novices who have no clue how deficient your understanding is.

[text deleted by moderator]

 

[kd8cgo]

Man dnmun, I swear your posts are the most negative vitriolic stuff I ever read here from a long time member sometimes! I hope you're more pleasant in person!

That being said, I don't find the technical proficiency on display inspiring, SunKing. So far all you have are anecdotes, and professing the merits of bottom balancing, which Jack Rickard came and did years ago, with similar anecdotes, equally useless. Not that the method doesn't work at all, it's just not practical. Half the advantage to a BMS is the monitoring potential, and the better the BMS the more you can get. I personally like data. I like convenience. I like better energy density. Most "kids" probably do too. Hopefully as I age you'll keep revising your kids definition so I can be forever young! Although I haven't come across any actual kids yet here in my 6 years or so, maybe some day. Too many good video games to come out and play I suppose. Oh and the weed, how could I forget the weed. (really?!?)

I really like your stories though, on the other hand. Those are fun for places like general discussion, off topic, or do a Large EV's post with your carts - photos, videos, specs - people love that kind of stuff here! You seem like a cool dude as far as that goes!

 

[wb9k]

Perhaps it would be good to clarify what is meant by "BMS".

Bingo, now you understand me.

You and I cannot define a BMS.

Mmm...I think we can, if only for the purposes of our discussion, and if you're going to advocate "no BMS" it would stand to reason that you would want to define the term, and in fact already have in your own mind. Care to share? It's still not clear to me what "BMS" actually means to you....since you don't need one, but you DO need all that other stuff you have. Do you mean automatic balancing?

There is none in any standard or discipline. What you and most call a BMS is really a Programmable Loop Controller aka PLC.

Not sure what that first sentence means. If you think what I call a BMS is just a PLC, after all I've explained here, then you haven't read very closely, have a comprehension issue, or are just messing with me. The rest of what follows is confusing and more or less meaningless as an answer to the question, hence dnmun's "gobbledygook" comment. Could you please answer the question? I'll try to curtail my cannabis intake long enough to grasp a serious answer.

 

[kd8cgo]

I'm just waiting for the ladder logic source code to come out for the A123 systems stuff, wb9k. I'd love to see who you consulted with on your manufacturing. Allen Bradley, Siemens? :wink: I've got some friends at Siemens so I can get you some discounts maybe. Next time I see them I'll ask them about their Programmable Loop (sic) Controllers for electric bicycles. I'd like to think SK is at most just trying to troll, but I know there is quite a cadre of people over on DIY Electric Car that parrot this like it's gospel. I think it's from Rickard 13:9, Sermon on the Bonnet. It's amusing, at least!

 

[wb9k]

I'm just waiting for the ladder logic source code to come out for the A123 systems stuff, wb9k. I'd love to see who you consulted with on your manufacturing. Allen Bradley, Siemens? :wink: I've got some friends at Siemens so I can get you some discounts maybe. Next time I see them I'll ask them about their Programmable Loop (sic) Controllers for electric bicycles. I'd like to think SK is at most just trying to troll, but I know there is quite a cadre of people over on DIY Electric Car that parrot this like it's gospel. I think it's from Rickard 13:9, Sermon on the Bonnet. It's amusing, at least!

You're cracking me up. Sermon indeed. Actually, A123 has exclusively licensed the Playskool "My First BMS" for all future contracts. You program the loops by arranging these cute little shapes with friendly faces drawn on them. The more bong hits you do with your pet rock, the more intuitive the system becomes. We're also working on diagonal balancing....makes middle balancing look passe.

A couple years ago, when I was looking for a forum to learn from in launching my own series of projects, DIY EC was one of the places I went looking. I had been at A123 for a while by then already, and it was quickly apparent to me that there was a huge voodoo contingent there that was on some kind of Kool-aid. I started hanging out here instead, and I think it's been the right way for me to go. There are some great guys on the other forum, but I find the voodoo gospel crowd difficult to ignore. I care too much about the future of the EV to just laugh them off.

OH....picking up my reworked driveshaft tomorrow.... 8)

 

[dnmun]

travis seemed to be the only competent person over there on DIY. this guy is a disgrace. he simply does not understand that forcing the battery to push current when the battery is at a low SOC is damaging to the battery. he simply does not understand anything about battery chemistry or the dynamics of ion movement from the cathodic matrix into the electrolyte and then to the electrode. when people like this post up their ravings for the newbies to read they all wanna adopt it because it is just what they think you should do with a battery.

we already have people telling them to not charge them fully because it damages them to charge the cell. everybody talks about how you should charge to only 4.1V to increase life span but they do not understand anything about chemistry so the idea that it is the length of time at full charge which is critical is totally unknown to them in spite of my constantly trying to educate them from what we know from the literature. instead it is always just the same old same old undercharge undercharge undercharge. even if the battery has a BMS and will not balance when it is undercharged.

 

[SunKing]

travis seemed to be the only competent person over there on DIY. this guy is a disgrace. he simply does not understand that forcing the battery to push current when the battery is at a low SOC is damaging to the battery.

You are really full of yourself. I run rested voltages of 3 to 3.4. No chance in hell of every operating below 20% and no chance of ever charging one cell past 90%.

 

[SunKing]

Mmm...I think we can, if only for the purposes of our discussion, and if you're going to advocate "no BMS" it would stand to reason that you would want to define the term, and in fact already have in your own mind. Care to share? It's still not clear to me what "BMS" actually means to you....since you don't need one, but you DO need all that other stuff you have. Do you mean automatic balancing?

As I said there is no Industry definition of what a BMS is or what functions it should include.

You can call a BMS:

Vampire Bleeder Boards.
A cell level battery voltage monitor.
Coulomb Counter of AH in/ AH out.
It might even do some control.
It might even have some communications like CAN BUS
Heck it might even be able to offer some protection from over charging and over discharging if you opt to spend more money on control relays.
Or should it do all those things from a Centralized System.

Understand where I am going now. A BMS can be any 1 single thing, a combination, or all of them. Look I am not trying to be a Jerk even though I am one. My point is there is no Industry standard of what a BMS is or does. My Fluke DMM qualifies as a BMS. I now know you are a in the manufacture side which I really appreciate and weigh your words heavily out of professional respect. Having said I or no one else would expect you to only Support the company line. Otherwise you would put yourself in Conflict of Interest, so I have to weigh that when reading your responses. You have to promote the company product line, and you make your B&B living there. I would expect that from any supplier or manufacture that did not offer a product outside of their scope and competing against. But if they also offered a Bottom Balanced a Reps tune would be different. At least they are from the two manufactures who sale BBBMS to my knowledge.

There was a misunderstanding on my part. I assumed incorrectly thinking this was a DIY Forum for E-Bikes and other like 2 and 3 wheeled. My bad. Taking my DIY hat off, and Pro hat on and speak to mass market consumer product a BMS is mandatory. Now I will put back on my DIY hat and say all my responses are in reference of DIY Labor of Love project is what manufactures would say: No BMS, just run Bottom Balanced. Run OCV pack voltages Between the Sheets of 20/80% SOC. Check pack cell voltages once a week.

OK what did I do. Well I wear suspenders with a belt. My initial plan was Traditional BMS with all the Bells and Whistles. Bought the Orion JR two years before I had a donor cart to install it in. By the time it was time to build I had been looking at BB for about a year. By that time I had plan A and B. I decided BB, and re purpose the Jr as a Battery Monitor with two simple controls that are already redundant functions of the Motor Controller built in features. If ever needed it can send a signal to the Controller to operate LVD. The Controller already has a built in LVD I can program to any pack voltage I want. Only difference is one works on Pack Voltage level, and the Jr works on Cell Voltage level.

On the charge side is extremely simple. Use a Telecom Rectifier charging at C/2 on a 100 AH LFP battery. Charge terminates on one of two thresholds are crossed. 1. Jr will terminate when one or more cells reach 3.6 volts, which is cell 4 my weakest battery for the last 8 months. 2. If the Motor Controller pack Voltage reaches 85 to 90% SOC. When finished, my 100 AH cells have 85 to 90 AH.

I do not Balance my cells, only if needed and after 8 months no need yet to re-balance. The Ole Coulomb Counter in my Controller tells me they have not lost any capacity. Jr. has never recorded a fault or induced an operation.

Plan B you ask? No problem, turn on Jr's Vampire boards and program them for 3.4 volt shunts to run Top Balance. No plans to do that yet.

So do I have a BMS? Or do I just have a very expensive Battery Monitor called Orion Jr?