Lipo BMS

[Spacey]

I think Spacey may have better setting solution and even have a BMS to provide.
You can provide a better BMS to Gow....

Yep can do, it's called a Cell 8 Log from Hobby king, and a Lipo pack large enough that you only use 60% of it to get where you need to go. Occasional balancing using an icharger 1010B+ when the cells get out of balance once a week.

Buy a normal KP style charge that will totally shut off with no trickle charge set for 4.13V per cell i.e 16 cells = end voltage of 66.4V with no trickle charge so that the charger shuts off when pack voltage is reached.

We leave the battery pack few days and right now all of them are 3.32-3.33V. We have many battery packs charge and discharge everyday here. And I can just take some photo as a prove.

Well with those figures it could be anywhere from 20% depleted to 60% depleted or didn't you know that Lifepo4 has a flat discharge curve....and you are supposed to be an expert?

That's why 3.0V LVC is most popolar for no matter EV or cell phone.
Even a good cell phone user know that charge his cell phone when power is low(80% DOD)

That is not 80% DOD more like OMG we have gone past the point of no return on Lipo.....expert indeed! Know your product before you try to sell to people new to this!

[heathyoung]

Charge termination at a specified voltage will not ensure complete charging.

Charge termination should occur at the specified voltage AND C/20 (ie. 5AH cell should stop at 5000/20 = 250mA).

Cell Log 8's are a great lipoly BMS. You can set them to whatever you want your LVC and HVC to be, and use the alarm output to drop the throttle - if you use a 5V reed relay, you can use the throttle power as an 'ignition' signal to turn on your cell-log when the controller is on, and use a 24V reed relay to isolate the alarm outputs to pull the throttle down to ground.

If you but the cheap 6S balancing extension wires, and servo (3 lead twisted) wires you don't even need to faff around with a PCB if you dont want to.

[dozentrio]

I could be wrong but didn't eva-michael say that they would build it to your spec? So if you want a 3.8V LVC, they will make a 3.8V LVC.

I think we shouldn't jump the gun here. Judge the product by its performance rather than anything else.

[neptronix]

3.0v/cell would be way too low for RC lipo such as the hobbyking stuff.

That's just cutting it way too close. Even with a BMS i would not discharge past about 3.3v/cell just to extend the life of the packs by limiting that last ~1% of the charge.

At 3.55v/cell, lipos have got maybe 3% energy left.

[eva-michael]

The infomation from neptronix is good for everyone. Thanks.
My point seems to be misunderstood.....
We are not taking about BMS for a pcs of cell in a cell phone. Here is forum for EV cool guys who uses battery pack but not just a pcs of cell.
Single cell over discvharge protection is 3.0V. But there is also battery pack over discahrge protection which is 3.3V/cell. i.e. For a 7S Li ion pack. It will cut off when drop into 23.1V.

[eva-michael]

[quote="Spacey"][quote]
Buy a normal KP style charge that will totally shut off with no trickle charge set for 4.13V per cell i.e 16 cells = end voltage of 66.4V with no trickle charge so that the charger shuts off when pack voltage is reached.
[quote]
I dont know where you get this Li ion KP charger from as we have ever sent few pcs lifepo4 versions to you only. The settting should match BMS. As the data I provide earlier in the thread. 4.13V per cell is a bit low to make the BMS to balance cells if your BMS setting is similar. That's why max voltage are generally set to be number of cell in seriesx4.2V.

[Spacey]

I had to take the transistor off the chargers you sent me as they did not trickle charge any power through to let the BMS do its job. If the charger just turns off when pack voltage reached and never turns back on again then how can the BMS do its job.

The result was a pack going further and further out of balance even with a BMS fitted, it wasn't until someone on this forum told me about the thread where the Ping battery guy found the same problem. He said that the chargers were set up for Lipo and not Lifepo4.

I told you about the problem in a very long email and showed you how to test and fix them, you never replied back with even a thank you? Once you take the transistor off the daughter board guess what...... the BMS can do its job and the pack very slowly gets balances.

So you probably have a lot of customers thinking that they can just leave their battery on charge and the BMS will do its job, what they don't know is that the BMS will not be balancing their pack....but hey....what do I know, it's not like I haven't built over 30 Headway packs with a huge amount of real world testing. The amount of time I spent having to fix your battery pack from the terrible and dangerous wiring was bad enough.... having complaints from customers about their range getting less and less due to the wrong chargers being sent out wasn't funny wither.

With ebikes probably going to be band in lots of China cities you might want to read up on customer service and how to do business with the West because I think you are going to need it.

[eva-michael]

We also have Ebay shop as a promotion. Till now no bad comment.

Re: Need Help with wiring BMS! Doh!!
viewtopic.php?f=7&t=21070&p=307524#p307524

Is this normal? Headway cells
viewtopic.php?f=14&t=21475&p=313004#p313004.

Cheers Michael,
Have not received the email yet but have sent you an email with the details of the bms needed.

Basically I have one of your 16 cell 48v 12ah Headway packs and will be using an Infineon 40 amp controller, so pop one of those in the package and let me know what I owe you before I damage my headways lol.

Many thanks

Spacey

We dont worry about EVA battery pack as we are very confident of them. Right now we also provide BMS instructions with long details to make sure a good understanding of everyone.
Back to this thread, just hope my lipo data can help anyone here. If anyone have query, I will try to help. Anyways ES has a lot of kind people who is willing to help. This is just a good place.

[GGoodrum]

What Spacey appears to be missing here is that a cell level LVC of 3.0V is under load, which is quite different than a resting voltage. I don't care how high the C rating is on these packs, there can and will be a significant voltage drop, under even moderate loads, especially when the pack nears the end of capacity. Once the load is removed, however, the voltage will always pop back up, usually close to nominal. If you wait until the resting voltage is down below 3.5V, those cells are right at the "cliff" and much closer to dying than if you set the "under load" LVC at 3.0V. From what I've seen, it is probably closer to about 2.5V, but I've only seen this happen once and then the cell died. This was a pack that had a faulty LVC circuit.

-- Gary

[Emoto]

It's called a Cell 8 Log from Hobby king,

Hey Spacey

Do you mean Hobbyking Cell Meter 8 Lipoly Battery Checker http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=15516
How accurate is it anyone tested it with something accurate.

[Spacey]

It's pretty damn good and accurate enough not to worry about. Gives you all the cell voltages very cheaply and is configurable with an audible alarm.

[auraslip]

Epic post Spacey.

Evassemble should look at how much headway headquarters can charge for their packs to get an idea of how much money they could make if they had a good reputation.

Gary - what do you have the LVC set on your LVC boards and BMS?

[Emoto]

It's pretty damn good and accurate enough not to worry about. Gives you all the cell voltages very cheaply and is configurable with an audible alarm.

Sounds interesing,i like the idea of the percentage graph, i use a watt metre with same funcion for my rc models, good for a quick assesment,
But would like to hear from someone who has tested it with something accurate like a fluke... some hk comments said it wasn't accurate.

Plus if you look at the [japanese cellmetre 8], hk use it to test lipos before shipping , and say thats its accurate but its $89 it also balances.
I have this on the way http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9744 for my first build cheap looks like it will have some potencial

[EBJ]

Just wanted to point out that HK apparently isn't selling Celllog 8s's any more (at least they are not on their website at this time).
I did find them for 34 bucks each from:
http://epbuddy.com/index.php?main_page= ... ucts_id=14
I just ordered 2 of these Celllog 8S's and plan on hooking them up to sound an alarm and also cut the throttle input. I haven't figured out how to do that yet, but I imagine it is pretty simple to do. (will post up on that later)

Last thing I ordered from them (the parallel balance cables) showed up in the mail very quickly.

[eva-michael]

[quote="auraslip"]Epic post Spacey.

Evassemble should look at how much headway headquarters can charge for their packs to get an idea of how much money they could make if they had a good reputation.
quote]

Yes. Our prices are 25%-40% less after shipping in retail prices than local selllers.
Also outside package is in different level. No just a simple PVC.... We emphasize on Fireproof material only. No PVC. If we just use normal material and no case structure, we can have more room to bring down prices.

battery pack image.JPG (28.78 KiB) Viewed 540 times

[Spacey]

What is this....the Evassemble sale thread?

If you like shoddy crimped wiring that breaks under vibration or movement on the main feed wires....and yes that happened to two packs, if it wasn't for Beavernator complaining about the wiring I would not have checked. The main positive had frayed to about 5 strands of wire which had 40 amps peak going through it

The best bit though is the BMS sense wires, crimped? Nope....soldered? Nope........they were all twisted around a washer, just hand twisted and loose as well. I lost a cell due to the sense wire coming off and the cell going negative. The washer acts as a cutting edge when the screws are tightened......

Which leads me on to the screws on the actual cells, Michael you might want to go to the gym because a 3 year old girl could have undone some of the screws on the packs I bought from you, now add in a few miles of road vibration and you can see that the pack will fall apart and cause a nasty short circuit at some point, and Headways can pack a punch when short circuited.

Then there is the time it took me to totally dissemble the pack, solder on the sense wires to the bus bars, buy hex screws and decent washers to rebuild the pack....and thread lock for the hex screws.

So please show us all again how great and cheap your packs are, keep calling me out and try to make me look like I am moaning for nothing. I'm cool as I will not ever buy from you again butbthere are others new to this who will be enticed by your cheap prices.

You pays ya money...you takes ya choice.

[eva-michael]

Hello Spacey,
I can provide free battery pack to anyone who you can think it will be fair for a testing.
earlier, you said our BMS not good and Gorde make a threads about his installation of the BMS. This is very fair to let everyone know the result of the BMS testing.
viewtopic.php?f=10&t=28783&hilit=capacitor+bms

If right now, you also doubt about our battery pack. This time, We will provide it free to some one here for testing and post a thread here.
No matter which products you doubt about, I can provide products for testing as we dont want any misunderstanding from our clients over the world.
Forum moderator or some members with good experience will be recommanded.

[neptronix]

Well, i wouldn't mind one of your headway packs. I will even pay for shipping.
They look appealing, but due to your past reputation, i have historically told people to avoid ev-assemble because of bad experiences on the forum.

I would be willing to do a very detailed review ( as usual ). A 36v 10AH pack would be fine.

[eva-michael]

Well, i wouldn't mind one of your headway packs. I will even pay for shipping.
They look appealing, but due to your past reputation, i have historically told people to avoid ev-assemble because of bad experiences on the forum.

I would be willing to do a very detailed review ( as usual ). A 36v 10AH pack would be fine.

.

Hello, Thanks Nepetronix,
Let's work on it. I will arrange the EVA 36V 10Ah battery pack for free to you.
I just give you a PM message.
Please PM me back and leave me your delivery adress with telephone number and I will check the cheapest shipping for you. Via Fedex or UPS to you.
Thanks for your help Nepetronix. Please make a thread about the quality of our battery pack.
This will just make veryone here to feel more confident when they make a purchase.

[Spacey]

Cool, Neptronix will give it a fair appraisal. But I very much doubt it will of the same quality as the ones myself and others bought from you last year.

If you have improved them to a decent specification then great....that benefits everyone. But I only write about my own experiances as I am not alone with being not happy with your service. Crap tends to stick.

I hope. Ypur Liefpo4 chargers have all been tested and had the daughter boards inspected for the transistor that stops the bleeding voltage for the BMS?

[eva-michael]

[quote="Spacey"]Cool, Neptronix will give it a fair appraisal. But I very much doubt it will of the same quality as the ones myself and others bought from you last year.
quote]

No longer wanna keep a discussion with you. At that time, you even did not know how important a BMS in a battery pack will be. And intend to make batteries pack without BMS. That's why I ask you to send back several pcs of BMS and check your problem. This is very simple thing. I dont know how you can sell batteries pack at that time. Ok then stop.

If you just broke one pcs, we can pay for it even we dont know how the problem happened. Regarding a seller you are, we just want to clear out what happen in your case. Support and clear out your case is more important to you than to save dezens of USD to check the issue and clear it out. We are willing to spend more money to send testing battery pack sample. This is deserved as true is more important than a little of Money. Hope you can comprehend. There is another user who face connection issue in ES, we are sending him new bms for him as he only order one pcs and he is a user. We will follow up his case and just do what we can help him to make connection right as per connection instructions this time.

As a man, I wanna stop my mouth now and just do something. Let's do a testing.

Michael

[Spacey]

That's why I ask you to send back several pcs of BMS and check your problem

Michael you are beginning to really piss me off here with your muddying of the waters!

I simply....let's get this straight!!!....

I simply asked you 3 times 1...2....3.....3 emails pleading with you to check my wiring from the diagram I gave you.

You kept saying ... and these are your exact words...."This BMS is different" To which I kept replying "yes I know they are different but how? Please either send me correct wiring diagram or at least check my wiring to see if correct".

You NEVER DID!!!!!

Everywhere you pop up giving crap advice trying to get sales I will be there to give proper advice and advise on my experience with you. You are NOT to be trusted!

[auraslip]

Neither of you are gonna come out of this looking like good.

Spacey got screwed, and got his chance to log his complaint so it will be forever associated with evassemble on a google search. If the vendor wanted to defend himself, the time would of been when spacey originally complained. It's absolutely not worth it to get upset. People can and will decide who they think is the mature party.

Also, I think Neptronix is a great candidate. He really enjoys posting here, so he'll be sure to post all of his experience and hopefully pictures too.

[Spacey]

Sure it's a good idea as long as what is sent to Neptronix is of the same standard as all future packs. Can be dure it will be a lot higher quality than the ones I received.

Anyhow, as you say no one going to look good from arguing, I just don't like getting ripped off. I like to be treated as I treat others, there is a reason why I have over 800 feedbacks at 100% with Ebay.

Headway packs work niceley without a BMS if you charge using an RC balance charger....much less stress if you keep your LVC sensible.

[auraslip]

Yeah... it's pretty shitty. Unfortunately, the damage is done... for both parties.

Your posts probably cost them quite a bit of business