Best BMS or a list of best BMS?

[cassschr1]

The best BMS,...... huh nobodys in love with anybody's battery mudering system. Thats the bottom line. And the problem also. Or at least there not cheap enough for us cheapies

[dnmun]

i think the 'headway' BMSs are the best. the new ones have really high quality mosfets and better thinner design and of course they balance each cell right to 3.65V exactly. the ping signalabs are also nice and the new ones have the leds that light up to show when the cells are balanced. that was why the ping packs lasted so long. but people who let them sit over months without disconnecting the sense wire cable ended up in trouble because of the negligence. so even with a BMS there are people who can damage their battery as well as those who don't use a BMS. just not as fast. and most people we can educate so they don't make that mistake.

cheap is the best reason to not use a BMS.

[cassschr1]

Dmum, are you following the founding power bms thread? I think that would be a nice one but haven't seen enough feedback yet. Its programiable for number of cells and high and low voltage etc, etc. What do you feel about this one?

[dnmun]

a waste of money. you can get a BMS that is used by the best manufacturers for about $100. the output mosfets on the 'headway' BMS will handle the biggest battery you can build. that is why paul and jimmyD carry them.

[999zip999]

Bowlof salad as you read just save more money not less. As the good batteries cost more money.

[chroot]

I gotta disagree with your comments about the headway BMS being best one.

Maybe you saw my thread about headway battery pack with headway BMS got fire by shorted and the BMS is the one started fire. Also they never be exact 3.65v as HVC. They tend overrun up to 3.90v then bleeding down to 3.58-3.60v.

i think the 'headway' BMSs are the best. the new ones have really high quality mosfets and better thinner design and of course they balance each cell right to 3.65V exactly. the ping signalabs are also nice and the new ones have the leds that light up to show when the cells are balanced. that was why the ping packs lasted so long. but people who let them sit over months without disconnecting the sense wire cable ended up in trouble because of the negligence. so even with a BMS there are people who can damage their battery as well as those who don't use a BMS. just not as fast. and most people we can educate so they don't make that mistake.

cheap is the best reason to not use a BMS.

[dnmun]

yes, i remember your fire. the reason a cell runs up to 3.9V is because they get out of balance so one fills up first close to the end, so it take longer for it to balance. i just found that every cell in my headway pack with the headway 16S BMS was 3.65V sometimes 3.66, sometimes 3.67V just my experience.

i have not had a chance to use the new 16S BMS with the digital controls. that BMS pcb is actually made to handle up to 20S, but only 16S is populated. so i cannot offer direct testimony yet.

[JimmieD]

I gotta disagree with your comments about the headway BMS being best one.

Maybe you saw my thread about headway battery pack with headway BMS got fire by shorted and the BMS is the one started fire. Also they never be exact 3.65v as HVC. They tend overrun up to 3.90v then bleeding down to 3.58-3.60v.

In revisiting the thread, to refresh my memory, just for clarification, the BMS that was in your unfortunate fire chroot was a SignaLab V2.5 PCM, but I think I am safe to say that that was not the cause of the fire.

[dnmun]

i think the consensus was that it was a short on the charge cable to the frame. but it was a signalab for sure:

http://www.endless-sphere.com/forums/do ... p?id=88165

[bowlofsalad]

I read http://endless-sphere.com/forums/viewto ... &start=495 this entire thread. I don't think I am going to be making a pack out of old laptop batteries, haha! However, I did see someone made that a123 pack, and at least now I understand what things like 16s17p means. 16 cells in series, 17 of those in parallel.

I still don't have a clue as to who makes the better BMS. Some part of me feels it might not matter so much so long as I am not super ignorant. Using tools like a voltmeter, celllog, cycleanalyst and a BMS collectively feel like a solid way to go.

[SamTexas]

I still don't have a clue as to who makes the better BMS.

Make that 2 of us! When you find out, let me know. But don't listen to anyone's recommendation unless they can back it up with real test data. "It works for me" is not real data. "You have to make this and that change and it will work" is not data, it's hogwash. Specifically you want to know:

1) Does the BMS create an imbalance?
2) Will the BMS guarantee that no cell will ever be overcharged?
3) Will the BMS balance a significantly unbalanced pack in a reasonable time? Overnight is reasonable.
4) When the charger light becomes green, the pack is charged and balanced, RIGHT? If not, what the heck does green mean?
5) It just works, right? NO buts, no ifs.
6) How long does it take for the BMS to kill my battery, if I don't touch the battery for 6, 9 or 12 months? Without a BMS, it would take at LEAST 5 years.

Don't forget to tell me when you find that BMS. I want to buy one too!

[999zip999]

Samtexas what BMS do you use ?

[TMaster]

The best BMS is no BMS.

RC balance chargers and LVC on the controller. Done. No fail. No problems.

Ok ok, this is not benefiting the thread, but I just had to post it.

[bowlofsalad]

The best BMS is no BMS.

RC balance chargers and LVC on the controller. Done. No fail. No problems.

Ok ok, this is not benefiting the thread, but I just had to post it.

It sounds benefiting to me. RC balance chargers? That seems interesting at least. I know nothing on that front, do you have any recommendations for these rc balance chargers in relation to lifepo4? I am assuming they'd work like a charger only it isn't dumb. It will read the voltage from the battery and turn off or slow the flow of power.

Say, for example, one is using an A123 pack from cell_man's website em3ev.com. What RC balance charger would suit that particular battery best?

Also, do you have any examples of said LVC to place on the controller?

[docnjoj]

The best BMS is no BMS.

RC balance chargers and LVC on the controller. Done. No fail. No problems.

Ok ok, this is not benefiting the thread, but I just had to post it.

It sounds benefiting to me. RC balance chargers? That seems interesting at least. I know nothing on that front, do you have any recommendations for these rc balance chargers in relation to lifepo4? I am assuming they'd work like a charger only it isn't dumb. It will read the voltage from the battery and turn off or slow the flow of power.

Say, for example, one is using an A123 pack from cell_man's website em3ev.com. What RC balance charger would suit that particular battery best?

Also, do you have any examples of said LVC to place on the controller?

I use an A123 AMP 20 pack I built with agniusm's kit. I use a Hyperion balance charger at 12S and my LVC is the smartswitch from kfong. Pretty foolproof for about 4 months now of almost daily riding. Hyperion was $130 delivered and I had a Meanwell power supply to power it. Not the cheapest but a 1 time expense that can be use to charge other types of batteries if I need to. I tested it on my garden tractor 12 v LA first.
otherDoc

[999zip999]

On a Cellman build battery you use his charger that matches his BMS.
Docnjoj has a home build and never drains the battery to find the bottom.
I never use the total battery as it will unbalance more as you hit lvc.

[bowlofsalad]

On a Cellman build battery you use his charger that matches his BMS.
Docnjoj has a home build and never drains the battery to find the bottom.
I never use the total battery as it will unbalance more as you hit lvc.

Yes, that is an option, to just use the BMS included with the included charger. But is it possible the balancing battery charger might add another layer of security?

My goal is to make it nearly fool proof. Using a BMS on the battery with a balancing battery charger sounds like dual BMS or BMS redundancy. It might seem like over kill, but that is my style. I wish for there to be a 0% or as close to it as possible chance of things going wrong. It seems perfectly reasonable to me.

I theorize that an "LVC" device can be set at different voltages. Different voltages may point to different depth of discharge (DoD). I assume LVC means the bare minimum in most cases. I don't think I'd ever go down that far no matter the kind of battery I use. If I am using lifepo4, I'd aim for something like 70% DoD, with a123 I'd aim for 80-90% DoD. I know nothing more than the basics concerning batteries. But when comparing ping to cell_man, cell_man is slightly more expensive, but those batteries sound substantially superior.

Just to make it clear, although it may sound silly, I'd love to think that I could plug the battery into the charger whenever I need to, and just leave it plugged in without much or any worries. I've read a few people saying they'd never sleep with a battery charging. But with BMS redundancy, maybe it wouldn't be something to worry about.

[TMaster]

I have my LVC on the controller set for around 56V (2.43V per cell) This gives leeway for the cells that are slightly less capacity, not to hit below 2.0V per cell. My setup in my signature.

But yes thats the only drawback not having a BMS, but it's not much of one. One you charge the cells again they are balanced up.

[Gregb]

I have an iCharger 208B for my cellman built A123 battery coupled witha cellog on the bike and the inbuilt low volt indicator on the throttle with no problems. No problem with going to sleep. The charge finish/time out alarm will wake the dead!!!
atually I have replaced the cellog with a BVM-8s which has an awful screen but a better built in alarm system which will shine a red hiintensity LED at me should I go low volts. (I destroyed 3 cell log alarm O/Ps while fiddling. )

[bowlofsalad]

I have an iCharger 208B for my cellman built A123 battery coupled witha cellog on the bike and the inbuilt low volt indicator on the throttle with no problems. No problem with going to sleep. The charge finish/time out alarm will wake the dead!!!
atually I have replaced the cellog with a BVM-8s which has an awful screen but a better built in alarm system which will shine a red hiintensity LED at me should I go low volts. (I destroyed 3 cell log alarm O/Ps while fiddling. )

Does your A123 cellman pack live up to it's ratings? How many times have you cycled it? Can you write a bit about your experiences with it?

After now doing some reading on the BVM-8s, it seems like an interesting idea, valuable at least. At a glance I am finding two popular brands of this type of charger. Hyperion and icharger. Any reason you chose icharger over hyperion (and likely others).

[Gregb]

I have had no obvious problems with the battery pack (11.5 AH) except that one bank of 3 cells is always last to charge. I have no idea, without rewiring it, whether this is an artifcat of the charger or the cells. I did take it apart with the intention of doing that but it is brass sheeting spotwelded and after a lot of cutting brass to separate the cells, they all looked ok on my single cell charger ( now unfortunately gone to the big barn in the sky where all blown up things go) and then resoldering them back in with much difficulty, I just accept it. That bank doesn't go down any faster or slower than any others and doesn't go any lower so I doubt I have a problem. I have never discharged below 3.1 volts as I only use it as a crutch for my ageing legs and artificial knee on hills I can't pedal up but it has been going fine for over 6 months. It sounds like he has upgraded what he supplies with all this talk of included BMS and chargers. I just bought the bare battery. Its "case" for want of a better term was some fibreglass sheets cut roughly to size and wrapped in a heat shrink outer. It is now the same fibreglass wrapped in shiny gaffer tape.......... works for me. Might build something better one day but as our army says, "form (looks) comes after function......." I am a great believer in "if it works, that's all you need.."
I bought the iCharger after looking around and rad some reports that said it worked and the price was right (for me)...and I already had some 24V power supplies. I have only used it on my 3A one to date but may swap to a 10A one when I get around to it. It has all sorts of inbuilt programming and alarms and monitors etc and different charging regimes.


PS If you buy a BVM-8s or similar, be warned that compared to the cellog, it's screen is bloody awful......

[bowlofsalad]

So far, my conclusion is some sort of redundancy setup for a BMS seems like an excellent option. Concerning batteries, even lifepo4, I think it'd be good to have at least one fail-safe.
There are a couple of threads I have come across on this forum that seem to lean into the realm of a potential secondary BMS to the primary BMS included in many commercial packs.
Celllog 8 isn't unknown, but there are some details about it that were a mystery to myself. I didn't know you could set a LVC/HVC alarm. In addition, it has an external alarm port, so you could set the alarm up to be pretty loud. However, http://endless-sphere.com/forums/viewto ... 14&t=47532 someone in this thread recently suggested an idea that would make it so that what the LVC/HVC was tripped, it stopped the power flow much like a typical BMS would. I don't know how that'd work out, but in theory, it sounds nice.

I am sure there are other versions of alarms or shut offs, the more the merrier. As some may feel, I agree, even the best series of redundency BMS cannot replace the knowledge with dealing with batteries, in other words, you are the primary BMS. I can't really write much on the subject as I have little knowledge of it myself, but if you pursue a multi BMS option as I do, please be sure to still at least have a digital voltmeter, a fire alarm and a plan, maybe a chemical fire extinguisher might not hurt. I wonder if a temperature alarm is viable, if the surface of the battery exceeds a certain temperature, an alarm goes off. So many routes! Exciting.