48V Pack consideration (ping or cellman)

[techboss]

I currently have a 36V 15AH Ping and it is working well for me. With pedal assist I usually have about 50% left on the pack after 30km ride.
(Bike 1): Magic Pie 2 Rear - 32km/h with 36v pack.
(Bike 2): ebikes.ca's 9C Front with Stock 25A Controller

I am looking into getting a 48V pack for one of my bike, and looking into option

A) Cellman's 52V 9ah with BMS and Charger
B) Ping's 48V 10ah with Charger

My Goal: To be able to cruise at >40km/h. I live in a totally flat area with no hills (Manitoba). I believe both batteries above will be able to achieve that.

Questions
*Why is cellman's battery rated better?
*Can a Ping 36V 15AH Mix with a Ping 48V 10ah to make 84V? With a Lyen controller of course.

Help me choose between the 2 packs with cost factored in.

Thanks

 

[dnmun]

if you wish to place the packs in series then you need to use the same capacity. so it would have to be 15Ah wide to match the current ping pack.

28S of lifepo4 is 100V so it would need a high voltage controller. with 15Ah wide, expect 30A continuous from the ping. to 45A max or so. 4.5kW.

 

[docnjoj]

Cellman uses A123 cells which are some of the best in the world. The have C rates pretty close to hobby LiPo but are considered much safer. For this you pay more. They also have a potential much higer cycle life compared to the hobby batteries. They have much higher C rates than Pings cells also.
otherDoc

 

[jpgey]

Cellman

 

[dnmun]

if you place the packs in series, you can only obtain the max of the lower of the two C rates.

so the C rate of the A123 means nothing when it is in series with the ping. so you are really confined to using something that is 15Ah wide and equivalent to the ping pouches.

sun-thing also makes these pouch packs too. shipping is cheap and a 48V15Ah is $404 delivered.

http://www.ebay.ca/itm/LiFePO4-48V-15AH-Battery-Charger-BMS-Rechargeable-Electric-Scooters-Sea-7-8-Week-/130656251541?pt=US_Rechargeable_Batteries&hash=item1e6bb82e95

 

[999zip999]

If you want to series a 36v15ah ping would be best 72v. The cellman 52v A123 11ah is a better battery if just to run the other bike and not series. It's just easier and safer to do that way. Than a 36v15ah and a 48v10ah.

 

[Gregor]

Another vote for cellman: The BMS is more robust and the cells have less voltage sag and a higher C rate.

 

[dnmun]

i will repeat. it does not matter what Crate the A123 has. you can even add lipo of 40C rate in series, but the current supplied by the two batteries in series will be limited by the C rate of the lifepo4 pouches in the ping pack. if the signalab has a shunt cutout at 40A, then 40A is all that you can deliver by any combination of super C rate batteries with it in series.

the sun-thing is the cheapest available with the same pouches as the ping pack. the sun-thing pack also has the fiberglas (he calls them epoxy) plates on the outside to protect it. the BMS will be equivalent to the signalab too i expect and will carry the same amount of current.

so that seems like the cheapest and most effective solution. of course you can buy the cell_man pack for twice the money, but it will still only produce the same current as the ping. otherwise the ping BMS will shut off and all current will cease to flow.

 

[AussieJester]

Cellman

+1 on cellman.. excellent service

KiM

 

[dogman dan]

It's very likely that if you choose a 10 ah ping, you will have a discharge rate that will kill it fairly quickly, unless your controller is 15 amps or less.

So you'd need a 15 ah ping,( or sunthing, whatever) that matches your other one in ah size. Then if you series connected the two, you'd have a higher voltage battery capable of use with a 20-25 amp controller.

So don't go buying a 40 amps controller for 90v.

Buying a 48v, 16 cell pack from cellman is still a great idea. Run your 36v pack for 20-30 miles, then run the 48v pack for another 15-20.

If you are thinking about running 72v or more, It's about time for you to start learning about batteries enough to make the leap into RC Lipo stuff from Hobby King. Once you start running a really high volts pack, you need the c rates and small size so you don't have to carry a large suitcase of battery to have the amps you need. Ever seen a 72v 20 ah headway pack. WOW, it's just too huge to carry around.

 

[techboss]

It's very likely that if you choose a 10 ah ping, you will have a discharge rate that will kill it fairly quickly, unless your controller is 15 amps or less.

Thanks all for your responses. With a 25A Stock controller by ebikes.ca will the above statement holds true for a 9ah Cellman 48V pack?.

 

[999zip999]

No Cellman uses A123 round cells that are 15c and Pings are 3c cells. But I would get a 11ah if it fits, for range and not hitting the bottom of the pack as easy.

 

[dumbass]

No Cellman uses A123 round cells that are 15c and Pings are 3c cells. But I would get a 11ah if it fits, for range and not hitting the bottom of the pack as easy.

Ping now has 3c rated cells? Are you sure? Or are they 3c max draw?

Bob

 

[Speedfreke]

In light of the quality control problem that A123 is having at it's Livonia Michigan plant, buying from cellman might be risky.
There are many in the business community that predict A123 will go under in less than 6 months.
As for Pings, I had two of his batteries - both problematic. Don't think his BMS boards are up to snuff.

 

[dnmun]

there are no quality problems with the A123 cells that he uses. i don't think anyone knows where those supposed defective A123 cells are.

what causes you to think the signalab BMS you use is defective? does it not balance or did the charging mosfet burn out on you?

 

[Speedfreke]

I've had 3 BMS boards on Ping batteries. The 72V Bms blew 2 mosfets and one light stayed on all the time - not charging the corresponding cell.The 60V Bms blew 1 mosfet and one light stayed on and the second (free replacement) 60V BMS - one light stays on all the time and does not charge the corresponding cell. I have to charge it manually but it won't go above 3.2V. Also another cell is only charging to 3.3V but the light does go on when charging erroneously indicating it is fully charged. A bloody mess
I think the capacitors blow too easy. The board is not robust enough.

 

[dogman dan]

Clearly not robust enough your how you ride. Assuming your screen name gives us a clue.

 

[dnmun]

when someone is blowing capacitors on a BMS that don't exist, you gotta suspect the speed is tweaking his view of what a BMS is.

no way to know what happened but there have been a buncha reports of the leds lighting up long before the cells are full on the new v2.5 signalab.

too bad he did not feel the shunt resistor to see if that was where the current went. if it all went into the cell stuck at 3.2V then that in itself woulda been worth a thread.

 

[Speedfreke]

speedfreke is the name of an old friend and doesn't reflect my riding habits. I still use the old crystalyte 20amp controller.
Sorry if I called them capacitors. I think that's what Ping called them when he tried to get me to replace them using parts from the other defective board.

 

[dnmun]

ok, there is a capacitor across each channel, between the top of the next lower cell and the bottom of the top resistor in the resistor divider bridge which is the input to the comparator for that channel on the this old V1 signalab i am looking at right now. if that was shorted then it could affect the balancing or maybe even keep it shut down for HVC or LVC. but yours was locked on 3.2V.

if you have some pictures we can try to help diagnose what happened, and what your reference was about. maybe even review what you thought was your problem when you asked ping so we have an idea of what he meant then.

if the shunt transistor was turned on at a low voltage, like the 3.2V, then the shunt resistor for that channel would be hot hot hot all the time and you would be able to tell it was severely outa balance that way. if the shunt resistor was not getting hot and it was locked on 3.2V that implies the current was still going into the cell.

i still emphasize it is best to use the same kinda cells when connecting in series so they all see the same C rate. you cannot get more current to flow through the signalab BMS than it is rated for, no matter how big the cell_man pack is. everything more than the pouch cells such as ping uses is wasted money.

the sun-thing28 packs are the cheapest pouch packs identical to the ping, and a little bit cheaper than the ping. about 40% cheaper it appears.

 

[dogman dan]

Ok then, 20 amps should not have taxed a signalab bms that hard then. Did you do the other thing that fails em every time? Smother it in a bag? Those bms gotta breathe, just like a controller needs some cooling air.

Just fishing for info. The more we learn here, the more we can pass forward to others.

 

[Speedfreke]

I've read elsewhere on ES yesterday that the achille's heel of Ping batteries is the wire connectors used on the split packs. Apparently if the connector comes loose while riding it will cause a capacitor to blow(?). This will prevent (in my case anyway) the battery from charging properly. What happens is the corresponding cell to the blown capacitor charges faster than the other cells. I watch the charging carefully now but one time, the cell in question charged to 4V while the remaining cells in the 60V pack charged only to 3.3V

 

[dnmun]

nope, not possible. can you take a picture of the capacitor that blew up?

 

[Speedfreke]

I hope you can see the pic as I'm not getting a preview. The red lite might be hard to see as I had the flash on the camera. But there is nothing unusual about the pic except this one lite is on. As I said the corresponding cell ( the one with the negative lead to join the other pack) charges faster and will prevent the other cells from charging to full capacity 3.8v but will get to 3.3v. The white mark on the black cube was put there by myself to remember the location of the lite.