ping 36v 20ah v2.5 questions

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rbelisle1

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Jun 20, 2008
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After 2000 miles on lead and with Dogmans advice, I bought the Ping v2.5 36v 20ah battery for my we bl-36. I ordered the battery on 9/1 and the post office delivered it on 9/11. Very fast shipping!!!!

Every thing is great, but I do have some questions.

1. What are the leds on the bms telling me? It appears that they all turn on when the charge cycle is done, as once they are all on, the charger light goes from red to green. The leds all stay on, as long as the charger is plugged in to the battery, no blinking (ie balancing???).

2. When the pack is removed from the charger, all the red leds on the bms stay on. I am building a box for the battery, so I did a bunch of test fitting and noticed that the red bms led's started to turn blink on and off, without any charger attached. Is this the balancing or is this just the bms drain on the batteries?????

3. The BMS only gets hot when the leds are on. Only the leds get hot. The battery and the rest of the board is cool to the touch. Is this expected?????

4. What voltage should the charger be putting out, with no battery connected to it?? (this is the 36volt 2.5 amp charger that Mr. Li Ping sent with the kit) I need to know as I would like to check mine (with a calibrated meter) and also, I would like to adjust one of my sla chargers (2.5 amp) to work as a backup or for use at work.

thats about it so far, I have yet to make a test ride, but that should be tonight!!!!!

bob in phx
 
the leds are in series with a resistor and that is in parallel with shunt resistor which is that group of surface mount resistors right next to them.

when the shunt voltage reaches a given value then the led starts to avalanche and ignites, with the current limited by the resistor in series.

so when the voltage across all the shunts is high enuff to balance and shut off the charge cycle, all the leds should be lit. but some may not be lit if they did not charge high enuff before the BMS shut down the charge.that seems the way they were meant to be used. i don't know if ping has ever explained to people how they work even. i just learned from readding nikky's thread on the signalab BMS.

i figured out how the v1 works but i can't figure out how the optos work on the v2.5. the circuit current comes off the cells in the same place but ends up doing something different next to the 14 pin package, whcih looks to me like a surface mount version of the original 4011c which also had the gate drive come off pin #3 and the power comes in on 14 and the LVC signal seems to go up to #13 so essentially the same pinout.

would be neat if others who have studied the BMS could explain it too, i have 3 of the v2.5 models. it does appear that he has changed the output FETs from the original irf3205 mosfet to something different entirely. and doc just burned up a charger FET on one of his.

i recommended an idea of adding a large loop of #10 cable soldered onto the tabs on the ground bus on that end, to soak up the heat off that end of the BMS.
 
I'm clueless about the new bms too. But I still offer the same advice to new lifepo4 owners.

Leave it on the charger all the time the first week at least, to get the best possible initial balancing.

The first 10 or so cycles are break in cycles. Easy does it on full throttle, and ride a mile or two, then charge again leaving it on the charger at least awhile after the green light goes on before taking it off for another spin around the neighborhood. By cycle ten, you should see less balancing behaviour from the charger and the pack is ready for a run it till it cuts off test ride to establish a baseline for your normal range. If you aren't getting decent range by then, you have something wrong and need to talk to the vendor.

Ask Ping about charger voltage, my original ping charger on the v1 pack was set to 46.5 volts, and the pack charges to 44 volts. My fast charger that I keep at work, an sla charger is set to 45 volts. They both charge the pack to the same 44v peak, but the 46.5 volt sonelil sla charger I have at home is able to balance it better. If you need a balance every charge, then you have problems, like too big a motor or controller. I rode an entire summer without getting a balance with no problems, till I learned to adjust my soneil.
 
Thanks guys for answering as much as you can!!!

I am looking at adding a heatsink of some to the BMS. I have some (home educated) knowledge of electronics, so heat disapation is my first order of business.

I fully expect this battery to last as my ride is about 7.5 miles, takes about 35 mins and I have cut back the amp draw from the controler from 25 amps to 20 amps. So, its 1c for me!!!!

anyone else have any more information??????

bob in phx.
 
i thought it would be simplest to just solder on a loop of 10AWG stranded, small enuff to fold back into an eye, and you get thermal mass and good conductivity into the pack. but it looks like doc melted his while charging so it was the charger FET which got too hot. or it may not be strong enuff for the charger.
 
It doesn't take much to overheat the bms when charging if it's stuffed in some closed up bag or box. I took mine and put two small spacers under it, and taped it back on to the pack, leaving the fets uncovered. It just takes a tiny bit of air circulation for my bms to stay cool enough charging.

At 1 c, and that % of discharge, you could see what, 4000 cycles? yeah baby. :mrgreen: I am guesstimating at least 10,000 miles out of my ping, I'm close to halfway there now. That would be 800 to 1000 cycles at 80% dod. Then I'll have a battery with perhaps 500 more cycles in it, but not at as high amps or as long range. Or maybe some cells will puff, and I'll just have a 24v pack left.
 
Dogman,
I know that you use an old tool box for you battery box, but how did you provide cooling???? I am custom building my box from aluminum and I put holes front and back to allow air flow while moving. I might even add a "hood" scoop to it, but so far, after my first 1 mile run, the bms was very cool... of course it was only about 95 degrees out and I did take it easy on the throttle...

Charging after the first run, was much different then when the battery was just the out of the shipping box. I now noticed that the charger has gone from green to red a couple of times, This is the balancing after the full charge was done?????

I think that I will expose the FETS and, just as you have done and raise up the board a little!!! I also want to see if I can add a heatsink//

bob in phx.
 
the battery should not be getting hot, but the charging FET and the output FETs on the other end of the BMS can get hot. but just adding some heavy wire as a ground or negative battery lead over to the battery will carry away a lot of the heat. just don't insulate that end of the BMS.
 
Just to be clear, the battery is not getting hot, nor are any of the leads to the controller. The only thing so far is the leds getting hot. The leds are not so hot that I cant hold a finger over them, but they are fairly warm. all the other leds I have ever worked with stayed cool to the touch.

I only want to cool the bms.

bob
 
if all the leds are on, you can turn off the charger. then maybe the voltage on the leds will die off and they will cool down. the shunt resistor is also producing heat. the charging FET will be producing heat while the charging current returns to the battery during charge but i would expect the most heat to be created during the discharge of the large continuous currents through the gang of four mosfets on the end. they are irf3205(55V 12mohm) on the old v1 signalab, but i don't know what they are on this new v2.5 signalab.

the leds should not get too hot though.
 
Is the PCB around the LEDs also hot? They might be getting heated by the power planes (if any) dissipating heat near or under them.
EDIT: n/m, your opening post item #3 tells me that no, nothing but the LEDs are hot. That leaves the other two possiblities below.

Alternately, maybe no dropping resistors were used between the LEDs and whatever drives them, so they are getting much higher current than you'd normally expect.

Or they may have used some high-current high-brightness LEDs, for whatever reason, which can get warm (not usually hot, though). The Philips LumiLEDs I have in my bike turn signals/marker lights, when run at the normal 70mA, do get noticeably warm, but probably no more than 85-90F in an 80F room. But they are also bright enough to leave spots in your eyes if you look directly at them from a foot away. ;)
 
after dr bass burned up his charging FET, and this thread, i went and added some 10G cable to my v2.5 signalab for a heatsink and more conductivity.

on another thread but here is link :

http://endless-sphere.com/forums/viewtopic.php?f=14&t=13055
 
Didn't notice this thread continuing.

If the charger goes green, and then red again later, it's balancing. That's why you leave it on charge overnight instead of getting up to shut it off, or using a timer. Once broken in, you'll seldom see this again. It will tend to just stay balanced unless you have a problem, or a big motor, or run to cutoff regularly.

My first toolbox I put lots of vent holes into, worrying about the temp of the battery itself. Then I noticed that the operating temps for lifepo4 were hotter that anywhere a human could be. Since ambient was 105 or so anyway, I stopped worrying.

The second toolbox on another bike, I just let it vent though the hole for the wires to enter, and it's plenty. I've had bms cutouts when using an insulated bag, that stopped if I just left one corner of the top unzipped to scoop air to the bms. So even in the desert, only the bms really needs the air flow. Mabye mounting the bms inside a box like the controllers have would be good, so the whole box is a heatsink.

I don't like that tape it to the pack method, unless you put some space under it for cooling. seems to me the heatshrink tape is a bad idea too, but my bms took care of that, melting it away from the fets. A cooling fin from wire is a brilliant idea.
 
I got a Ping yesterday in the mail and was freaked about how soon all the red LEDs went solid. It was almost like the pack was pre-charged somehow and I was just topping it off. I guess it flew that way too because I think it got here pretty fast considering customs and all that.

Now I hear a lot of you folks with battery experience saying just run the first 10 or so cycles just down 10-20% off full-charge...maybe just a few miles on a 48v 10ah pack like mine...and then put the thing back on the 2A charger and let it bake for a while...at least I *THINK* that's what I'm hearing??

Damn...I've been running 3 or 4ea. 12v bats (36v/48v) 7ah SLAs in parallel for a while...so this LifePo4 shit is gonna be FUN...I can already tell.

Do you guys fuse anything between bat----> controller or is the controller just kind of an expendable part? With the SLAs I was has fuses between each cell for safety sake....but no fuse between bat & controller. I lost an SLA (AGM) bat once...it just shorted and went completely dark and I had to volt-check each bat to figure out what happened and then rebuild the array with the good three. I used junk bats from an APC UPS...or two..:)

Do you guys pad a lot underneath/around the battery???...and is it safe to leave the bag zipped (I'm using a soft bag)...I remember controller getting hot with 48v SLA array (even when velcroed on outside the bag)...I'm guessing that may happen again...I may even cook a controller....hard to say.....

This electric shit is a BLAST so far!
 
Just a tiny bit of ventilation is needed around the bms, often the hole in a box or bag where the wires come out is plenty. Don't smother the bms with foam padding. My early bms is different, but I had a few cutouts when I used an insulated bag, and had the top completely zipped shut. Battery heating is not a problem but the fets on the bms can get very warm, enough to melt heat shrink stuff.

There are many threads on ways to box a battery. My method involved bending a cookie sheet around the battery on 5 sides and relocating the bms to the side of the battery so it carries a bit flatter. then a few chunks of foam secure it tightly in a metal toolbox bolted to the rack.

The main thing is to avoid a mount that is going to leave it vulnerable. A few sad threads talk about , my bike fell over and ruined a new battery. It take more than a bag to protect a battery.
 
Oh man...that's brilliant!! I'm not even slightly prepared for a crash or a very hard fall...even my lowly SLAs would be DESTROYED in such an event. The good news is the new pack is smaller and about 10 pounds...and the SLAs were double that (or more)....so vehicular stability should be on the increase. The bad news is we're risking $414 and a two-week lead time with Ping over there versus the $0.00 & 9/10 for my freebie SLAs.

I also like your idea of keeping the BMS (display/FETs) clear of contact with the bag/box. The way he has taped the BMS it almost BEGS to be moved out of the way a little...if you know what I mean. It's actually poking a little beyond the rear of the bat.

but I want to thank you guys for putting my engineering hat back on my head for a few minutes...and taking my rider hat and stomping on it for the recommended few seconds...:)

--Matt
 
Well I just wirenutted the thing up for a test run. Super consistent power delivery from the LifePO4 array...even the 48v battery does not overheat the 36v rated controller after 5 or 6 serious uphill pulls.

Ran maybe 2.5 miles through the neighborhood...plugged the thing back into the little 2A charger that we Pingers all know & love and the BMS stayed dark....seemingly EFFING FOREVER...but most likely about 20 minutes....because I came back later and the BMS was completely RED again and the charger green....whew!...that Li Ping is a bit of a heart-stopper....I thought I had smoked the BMS or something....

So after that "Oh shit" moment...I'm back in business...still kind of doing the intial balancing of the array. I guess I'll do a few more runs tomorrow...weather permitting.... :p
 
You should pretty much leave the thing on the charger 24-7 the first week, till the cells break in. Ride some, but leave it charging even after the green light goes on so it can continue to balance the fresh cells. Do the same thing anytime you run it till it cuts off later on too.

Doesn't the lights go on only at end of the charge cycle, when the balancing is happening? I dunno, I just have the ol version 1 antique.
 
Of course you're right and all cells light up at the end of a charge cycle. It just took a seemingly really long time and it is confusing because when the pack is NEW and baking for the first time the green lights do their little dance for a bit and I guess I expected that to happen again when power from the charger is first applied....I guess you NEVER see the green lights AGAIN unless the pack drains down to cutoff voltages??

I think your advice about not running the pack down to cut-out is excellent as well...at least during the first 10-12 charging cycles.

It's also funny how little we know about Signalabs and Ping and all the art/engineering that goes into these products.
 
actually we know fairly well how the ping BMSs work. nikky has a circuit diagram for the v1 signalab and the pinouts on the 4011c cmos comparator are known, and the v2.5 is essentially identical except for the shunt transistors and the leds. the shunt current on the v2.5 is about 60mA and the v1 is about 165mA.
 
Guys like Dnum know all about this stuff, but me, it's like trying to learn to read chinese. My brain works different for sure. I bought my ping so early, they have changed a lot since then.

Your new battery is big compared to your old ones, (slas?) . So don't be suprised if it takes a long time to charge after a good ride. With my 2 amp charger, It can take over 8 hours to charge my 36v 20 ah battery when run to cutoff. My version1 ping bms would do a thing where it turns on and off for a long time at the end of the charge. Once you get the pack balanced, if you treat it right, it will stay amazingly balanced for a long time. So it will behave different while charging once balanced. I think leaving my battery on charge so much is part of why mine has worked so well, and stayed so balanced.
 
at the end, when one of the cells has climbed to 3.9V then the BMS will turn off the charging FET and stop current from flowing into the battery. not even shunt current.

when the cell voltage drops a little to about 3.85V then the BMS will turn the charging FET back on and then the current will flow into the battery some more, but if all the cells have reached the balancing point, then the current is just the shunt current and doesn't go into the battery, just around it through the shunts.

the v1 and v2.5 signalab BMSs are essentially identical except that the v2.5 uses surface mount resistors and the leds to handle the shunt current, and they use a surface mount soic14 package for the comparator 4011c, so the BMS can be much smaller in size, and it produces less heat from the shunt resistors when charging is complete and the current is flowing through the shunt resistors. heat goes as current squared so the v2.5 produces only (60/165)^2 x (66ohm/22ohm)=.13 x 3 or 40% of the heat produced by the v1 signalab.

they don't balance as fast, but less problem of them being enclosed in the battery pack.
 
I have my present 24V 20ah split Ping battery housed in 2 metal cages beside the back wheel.

baksidacykel.jpg


2NARBILD.jpg


I have just bought a bigger 36V 20ah split Ping battery so I will have to expand the metal cages to accomodate the new bigger battery size.
Shall I provide some extra space so the battery can expand it´s size?
Do Ping battery pouches expand in size during charging or are they totally size "Inert"
 
When pouch cells start expanding much, it means the cells are dying. My ping has not changed in size at all in 5000 miles. They are said to perform better when compressed, so that is why all the layers of duct tape are so tight. I wrapped a cookie sheet around mine to make a tight box. I only wanted to protect em if the bike fell over, but it turns out to have been a good thing, adding more resistance to any expansion.
 
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