48 v 35.2ah li-ion battery pack

[dogman dan]

Nothing really wrong with the headway plan. Some will call them deadways, but many have made decent bike batteries with them. Run them at 3c or less and they should perform fine.

They are relatively decent in the discharge rate, so just 8 ah of the headways will run a modest powered ebike. At 25 mph, 8 ah should get you about 10 miles minimum.

Headways, Sanyos, pouch lifepo4, or even RC lico, 24 ah of 48v is a big awkward pig of a pack to carry on a bike. It will suck, so perhaps start with just 8 ah, or 16 ah max, and see if the range is enough.

You can build your pack with 8 ah of the headways, including the bms, and later on easily reconfigure to 16 ah later if you wish. Headways bolt up, so very little soldering involvled. That's a huge help to a pack builder.

The bms argument.... I just say if you have a bms, fine. If you trust a bms and never check on it, not fine.

[Humberto]

While you experts are trying to knife each other over which cells I should use, I have a more pressing question. My 48v. Lifepo4 BMS has 16 balance wires, un-numbered. 4 yellow wires are 12" and 14 red wires are 8" long. What is the significance of this color code and different length. This BMS was shipped from the town of Sophia in Europe, with the only instruction on the screen shot above. Will everyone keep in mind that my BMS is 48 v. Lifepo4 and my charger is 48 v 5 A. This is no longer a li-ion issue and even if it was, I don't have a li-ion BMS. This should bring some sanity back to project at hand . If I require 48 lifepo4 cells, does that mean that only 16 cells are in a series, and the rest are in parallel?. Now put away your knives and answer a simple question. Thank you.

[Humberto]

Thank you Dogman, what do you mean by checking the BMS. Do you mean for obvious damage or periodic probing for signs of overheating?. I read that the sole purpose of the BMS is to protect and insure battery life, with equal charging of all cells. Does this rule not apply to the high priced cells, or do they have their own built in protection as in the so-called "protected" cells?. I also found some cells on EBay that were 5000mah, should I give them any serious thought?. Does a 3 or 4 c rating always mean less cells are needed, 45 cells seems like a very small package. At this rate I can forget about going fishing on my bike until the Spring.

[pdf]

You can do it two ways, but you don't mention what capacity you are shooting for. Let's assume for the sake of illustration, that you are building a 16 Ahr 16s pack from 8 Ahr cells. You can either:
1) Make two sets of 16 cells in series and then put the two units of 16s in parallel with each other, or
2) Make 16 sets of two cells in parallel. Connect the 16 units of 2p in series.

Either way, in this example, you use 16 x 2 = 32 cells. If you have a 16s BMS, I THINK you have to use method 2 since it is designed to connect to 16 cells and a group of cells in parallel will look like a single cell to the BMS.

And I think it is less confusing to call the BMS a 16s LiFePO4 BMS. The terminology "48v" is based on very old battery technology but people still use it. In theory, a "48v LiFePO4 battery" could be 15s or 16s, although most people prefer 16s for reasons discussed above. If you know the exact cutoff voltage of your charger, people will want to know that also since it will determine to what final voltage your cells are charged and possibly the effectiveness at balancing the cells. A "48v charger" could be a lot of different things actually, depending on what battery chemistry it was designed to charge.

[dogman dan]

I have no dog in the fight over what cell you use. I'll comment though, about pros and cons of various types. Or the practicality of carrying 25 ah on a bike that isn't a cargo bike. I'm still curious why you need that big a pack. That's enough to ride about 75 miles.

Yes, as above, to use your 16s bms with 32 cells, parallel the cells in pairs. That's 2p Each 2p cell group will then become one cell to the bms. It can get confusing when the word cell is used instead of cell group. It's just easier when talking about a group of paralleled cells to just say cell, since to the battery pack, each group is indeed electronically one cell.

By checking the bms, I mean checking that the bms is doing what you want to your cells, and not failing to function. Make sure the bms doesn't excessively discharge one or more cells when it sits unused a few days. Make sure it does cut off before the whole pack is ruined. Make sure it does actually balance the pack when the charging is done long enough. Make sure it doesn't allow cells to get too overcharged in the process.

If I was building a pack, I would add some 8s jst balance plugs to the pack. That way, a device like a cellog 8 can easily be used to monitor what the individual cell voltages are like as the bms does it's work. You don't have to watch the bms every cycle. I just mean that you can monitor it when you feel like confirming that all is well. With the extra plugs, you can very quickly see when your pack is actually fully balanced, and you can see which cell group was responsible for the bms cut off when you discharge it to 100% depth of discharge. With such monitoring in place, you see trouble brewing in time to get new cells if you will need them, or perhaps prevent a defective bms from ruining an entire pack.

[arkmundi]

By checking the bms, I mean checking that the bms is doing what you want to your cells, and not failing to function. Make sure the bms doesn't excessively discharge one or more cells when it sits unused a few days. Make sure it does cut off before the whole pack is ruined. Make sure it does actually balance the pack when the charging is done long enough. Make sure it doesn't allow cells to get too overcharged in the process.

If I was building a pack, I would add some 8s jst balance plugs to the pack. That way, a device like a cellog 8 can easily be used to monitor what the individual cell voltages are like as the bms does it's work. You don't have to watch the bms every cycle. I just mean that you can monitor it when you feel like confirming that all is well. With the extra plugs, you can very quickly see when your pack is actually fully balanced, and you can see which cell group was responsible for the bms cut off when you discharge it to 100% depth of discharge. With such monitoring in place, you see trouble brewing in time to get new cells if you will need them, or perhaps prevent a defective bms from ruining an entire pack.

Thanks dogman for making the human BMS argument once again! Haahaa! Anyway, the balance harness using jst connectors and two Celllog 8s for my 12s pack, in retrospect, was the most important piece of work in maintaining the health of my pack!

[major]

Anyway, the balance harness using jst connectors and two Celllog 8s for my 12s pack, in retrospect, was the most important piece of work in maintaining the health of my pack!

+1 ^^^^^^

[TwoWayStreet]

The bms argument.... I just say if you have a bms, fine. If you trust a bms and never check on it, not fine.

By checking the bms, I mean checking that the bms is doing what you want to your cells, and not failing to function. Make sure the bms doesn't excessively discharge one or more cells when it sits unused a few days. Make sure it does cut off before the whole pack is ruined. Make sure it does actually balance the pack when the charging is done long enough. Make sure it doesn't allow cells to get too overcharged in the process.

The most convoluted statements I have ever read, by a wide margin. It would take a PhD in Spin Control or in Insolence (to oneself) to make statements like these. So a BMS is fine, but you have to check every function it's supposed to do.

Dogman Edit...

If you have a problem with my statement, dope slap the statement. I'm often wrong or misunderstand something. Calling names or picking fights here is not allowed. Picking a fight with a guy who can edit your every word freely is not a good idea.

[agniusm]

The bms argument.... I just say if you have a bms, fine. If you trust a bms and never check on it, not fine.

By checking the bms, I mean checking that the bms is doing what you want to your cells, and not failing to function. Make sure the bms doesn't excessively discharge one or more cells when it sits unused a few days. Make sure it does cut off before the whole pack is ruined. Make sure it does actually balance the pack when the charging is done long enough. Make sure it doesn't allow cells to get too overcharged in the process.

The most convoluted statements I have ever read, by a wide margin. It would take a PhD in Spin Control or in Insolence (to oneself) to make statements like these. So a BMS is fine, but you have to check every function it's supposed to do.

Like tire pressure, oil, coolant level in your car, they suppose to be fine, but you check them occasionally, do you? You make false, stupid statements here and then houses, sheds burn when people listen to "idiots" here, youtube.
people tend to buy cheap parts from China, what do you expect to work as it should? Buy BMS for 500euro and you'll be fine without making too often inspections. "human BMS" has practically proven to be a lot less reliable than unreliable BMS from china.

Buying from ebay Humberto is as reliable as buying from China.
This connection diagram explains everything:

You have to sit, look, think and you will understand how to connect it. I haven't seen that BMS yet.

[TwoWayStreet]

Sorry, I cannot help you with your ignorance. Just make sure you hide yourself well when your BMS fails and destroys your battery or burns down your home. Don't come here to complain about it, you will not get any sympathy.

You are the one who made false statement like saying genuine A123 is now b-grade because it's discontinued. But I guess you can't help it. Is stupidity something you inherited or did you work hard to get it?

[Humberto]

Thank you Dogman , the BMS schematic shows a lower small photo of 16 red wires all of the same length, but that is not what was shipped to me.

[agniusm]

My understanding is that you should keep all balancing wires same length. You could post a photo of your BMS and some one will know what BMS you have and help you with connecting it. it is strait forward, nothing fancy.
Here is my Panasonic pack, its 5P10S meaning 36V system with 17Ah capacity (3400mah each cell x 5):

you can see 2 5S bricks. 5 cell + connected with 5 cell -, makes a series connection.
Here is a good example of series and parallel connection:
Series:

Parallel:


The C rate is ho fast your cell can discharge. For example you have 1ah cell capable of 1C discharge. This means that it can discharge 1ah in an hour. If it was 5C cell it could be discharged in 20 mins.
For example your controller draws 20 amps and it is 48v controller. that means that you need 20 1ah 1c cells in parallel to satisfy controllers demand without damaging cells. If the cells were 5c you would need 4 cells. If the cells were 3ah and 1c you would need 7 cells in parallel for the same draw.
For a folding bike you need something other than lifepo4. I have compared my 36V A123 20Ah battery pack with my Panasonic 36V 17ah pack. Panasonic battery pack is 60% smaller in size and 51% lighter.
If you need range and your power demands are small to medium i would say to go with lico rather than life. You could get compatible bms from dnmun on these forums who has done some testing on them and they are cheap.
If you need more safe chemistry, long life, go with lifepo4.
We have not heard what you need in terms of range, speed, terrain you will be driving on, finally your folding bicycle brand or photo. This would help deciding on chemistry of the battery, capacity you would need with reserve. After you get your cells, had them done in parallel than series we could help connect proper BMS.
You need to have a plan and not start from the back end

[Humberto]

My lifepo4 48 v. 5 a $115.00 charger arrived today. However the user manual describes it as a li-iron/li-polymer charger, with 2 led, aluminum case, spare fuse, fan cooled, cable to battery is 3 prong with adapter. Cable to wall socket is Euro-type plug with tubular prongs 220 v. Input is listed as 100-120 vdc, 220-240 vdc, 100-240 vdc, 43.8 vdc 54.6 vdc 58.4 vdc 73 vdc 87.6 vdc
2a 3a 4a 5a 6a 8a 10a 12a 15a 20a .

I won't order any cells until everyone weighs in on this charger as appropriate for the project. Why does it sound like this charger is for both li-ion and Lifepo4?.

[agniusm]

Because you can adjust voltage inside the charger. If 48v 16S lifepo is 58.4v, 48v 14s lico is 58.8v

[dogman dan]

The main difference between a lithium charger and a lead charger is that the lithium charger does not float charge. It shuts off more completely so it won't overcharge the lithium.

By adjusting the voltage, you could set it for a lifepo4 pack, a lico pack, a limn pack to name just a few. Unlike the bms, many chargers have a voltage adjustment range.

Looks like your charger model could be used at many voltages, but generally they come as a 48v or 60v or whatever. Then the adjustment is within that range. So a 48v charger might adjust easily from about 50-60v.

On the input side, some chargers have a switch to go from 220 to 110v AC input. Others are built for one voltage. Since yours has a 220 plug, it seems like yours is a 220 version. That could be a problem if you have no switch. American houses generally have 220 only at a stove or clothes dryer. You can get plug adapters.

Plug it in, and see what voltage it puts out on the DC end. "48v" ought to be dishing out 56-60v. 58v is good for many 16s lifepo4 packs, but some bms require 60v.

[Humberto]

Thanks again Dogman, I'm trying to post a photo of my bike and this site continues to say that my image is invalid. What's that all about?. Thanks to the unknown posting from Europe, I found the 50 v Enerdel battery and I'm studying the factory Specs.

[major]

Thanks again Dogman, I'm trying to post a photo of my bike and this site continues to say that my image is invalid. What's that all about?. Thanks to the unknown posting from Europe, I found the 50 v Enerdel battery and I'm studying the factory Specs.

I upload jpeg from my computer as an attachment and then paste the url in as an image.

Also, see this thread for EnerDel info: http://endless-sphere.com/forums/viewto ... 15#p803215

[Humberto]

My bike.

[999zip999]

You did other the charger for a 16s lifepo4 battery ? When ordering you should get all the facts you need for your charger straight first as 110 or 220 and type of battery. This way your wouldn't opening things up and monkeying around. When I have used a BMS I put a set of balance wires for access to balance and monitor. Both your battery and BMS.

[dogman dan]

Likely your pictures are too big to post. I just put pics into Microsoft paint to make them smaller.

[arkmundi]

people tend to buy cheap parts from China, what do you expect to work as it should? Buy BMS for 500euro and you'll be fine without making too often inspections. "human BMS" has practically proven to be a lot less reliable than unreliable BMS from china.

Buying from ebay Humberto is as reliable as buying from China.

Haahhaaa. Much respect agniusm, but I'll challenge you on those statements. First, I'm still doing the human BMS thing and its working our just fine for me. Its really having the Celllogs on on charging and discharging. On charge, its going to beep at me according to the algorithms, meaning if there's too much difference between low & high cells (out of balance) and also if too high (which I've set at 3.62V). I have yet to trip the pack during my rides, but there's a low voltage set too.

As for buying from ebay, I buy ebay all the time and find many great deals. I have yet to be disappointed. Just bought a New Seagate Momentus XT 750GB ST750LX003 7200 RPM Solid State Hybrid Drive for $129 to replace the cheap Western Digital crap put in by Dell into my Inspiron 15R. But in all matters purchase & sale, you can't take other people's opinions at face value, but need to do the research and make wise choices. I make use of all the Internet's rich information gathering capabilities, look at my options and then make the best decision I can.

I want things to work, to last a reasonable amount of time and to have some backing from the manufacturer and/or seller. In the case of a laptop's HDD, two years is just not reasonable, but I can't complain because of the great price I got when first buying it. The Dell Inspiron is a great machine and I'll make it last another three years at least by replacing the HDD with a quality SSHD.

The only thing that's idiotic is not doing your research, opting for price instead of quality, buying from someone of ill repute, not really knowing your source of goods or their nature, buying LiPoo as battery cell stock, just to name a few. The game here in the land of ES is to turn our ignorant children into true warriors, sages and mages and then to go forth and conquer evil in the land of OZ. And as in real life, we can win if we hold together!

[dogman dan]

Like any shopping, the informed buyer buys smart. The uninformed buyer takes a roll of the dice.

I recently saved hundreds of dollars buying some TV related items on Ebay. But another two TV items I needed was cheaper at Walmart. You pick and choose. One ebay item I chose was a stinker. Very cheap, but also very out dated. I studied more and did better replacing it. I was getting set up to convert to antenna and web tv, and telling Comcast to stuff it.

Anyway, you can't just say "every ebay vendor sucks" You can say plenty of them do though.

[agniusm]

Well, my post was related to battery purchase on eBay and I did not say all vendors suck, what I said was it is the same as buying from China nobody knows what they will get.
Arkmundi, you can chalenge me all you want but thats why we have remotes on tv's, so we could swich channels without getting up and if you like charging your battery while babysitting it with a good chance of human error fine by me, but I like that remote, I like being able to plug my scooter and forget until I need it and by the way mine is fine to with bms;) I do agree on smart purchase. You have to wise these days to buy quality stuff without overpaying

P.S. I had to comment further more on this BMS for the sake of my peace of mind. How many laptops, cordless tools, OEM motorbikes, bicycles, vehicles to name the least you find without battery management in place??? The answer to this difficult question is - nil. Why then manufacturers are so stupid investing in such unnecessary "battery murdering system"? The answer is why Arkmundi, TwoWayStreet and all other "BMS - NO!" folks are wrong. Yes, we hear about failed BMS'es, but also we hear about mobile phones light up in peoples pockets. So why nobody gives too much attention to these event when laptops burn houses? because the ratio of people using e-bikes haven't met the fifth the ones using means of communication. New cars engines fail within weeks, and this is fine, errors happen, but when BMS kills the battery, that's f*&ed up, that's battery murdering system. Your right to choose, but there is no reason to lead other newbies in to confusion because you are ignorant because of few occasions that made up your mind. Peace out.

[dnmun]

i also was under the impression he had drained his A123 pack totally dead when he had an accident and left the controller plugged in to the battery. i thought several cells went to zero volts then in that event. or maybe it was someone else who also decided they could get away without using a BMS but when you let the battery drain to zero it is really bad.

but this is what a BMS does. it protects the battery from human lack of oversight, or undersight, if you will.

the BMS not only balances and prevents the cell from overcharging it also will turn off the discharge when any cell drops below the LVC. either on lifepo4 of lipo. that is why they are useful and why all the battery manufacturers use them. hobby king is not a battery manufacturer, they just sell lipo packs for RC guys.

[Humberto]

This is my bike. I hope this will shed some light on just how many AHs I really need for a two hour round trip on the city streets, without pedaling. .attachment=0]my bike.jpg[/attachment]