SLA to LifePo4: First Day...break in needed?

[townunheardof]

Hey,

After 3.5 years with my SLAs on my Wilderness Energy 36v brushless, my 48v 15ah LifePo4s arrived from Hong Kong a week ago and I got them charged yesterday and mounted today.

First impressions: Nicely made, better presentation than I expected, solid pack, duct taping even done neatly and as professional as gray duct tape can be. And at about $450 all in, I'm happy with the price.

Coupla questions:

I haven't been able to find anything clear on this searching the history here....do Lifepo4s need breaking in?

I charged with the 5.0 amp charger all day yesterday, about 10 hours.

This morning I mounted the pack and took a ride. I liked the performance. Seems to have a different power curve than my SLAs, though they are 2.5 years and about 400 charge cycles old. Smoother, a bit faster, more power, but not strikingly more.

Then, about 5 miles into the ride (fortunately I was 1/2 mile from home) power went to virtually nothing. Its like the pack just ran down to nothing.

Is there a break-in period with this chemistry? Do I need to do some shallow charge cycles or something?

I switched to Lifepo4 for greater range and power. 5 miles ain't gonna cut it.

Maybe I didn't charge long enough? Should the first charge time be longer than 10 hours?

Also: Another topic, mechanical: I saw something in here about a Torque Arm. Do I need one?


Town

 

[tostino]

Check the pack voltage when fully charged, and when it cuts out... Maybe you are hitting LVC incredibly early. Also, what motor are you using with the cells? Do you know your amp draw from the pack?

 

[Ypedal]

A 36v controller would have a lvc of 29v, so i'm sure it's not the controller kicking out...

I assume this battery has a BMS ? can you post a link to exactly what battery you have ?

Depending on wich model controller you have, the older WE kits had 20 amp controllers.. the newer one's have more peak amps ...

Are you charging with the provided charger or just a regular SLA charger ? As above, gota volt meter ? pls check hot off the charger and when it cuts out and report back.

8)

 

[Toorbough ULL-Zeveigh]

the second important caveat is that the cells may not deliver the rated performance without a proper break-in period. this is not widely known. but is fairly well established. it is important not to discharge these batteries much beyond 50% for the first 50 cycles or so, or premature failure may result. This is imo one of the major drawbacks of these otherwise very promising cells. unless the vendor performs these first 50 critical cycles, the end user may never see anything like the possible 3000 cycles that make these cells so attractive.

http://www.endless-sphere.com/forums/viewtopic.php?f=1&t=8218&p=124665



my feeling is that with any new battery regardless of chemistry i prefer to take er easy for the first dozen or so cycles even if it's not required, just as a chicken soup thing.
by easy i mean moderate amps as well as amp-hours, say not exceeding 80% of max on either.
bob's 50% DOD & in particular 50 cycles for ferro-phosphate came as quite a shock.
did not expect that big of a difference from what i'm used to with NiMH only requiring a couple of forming cycles.

 

[ElectricEd]

I haven't been able to find anything clear on this searching the history here....do Lifepo4s need breaking in?

I charged with the 5.0 amp charger all day yesterday, about 10 hours.

This morning I mounted the pack and took a ride. I liked the performance. Seems to have a different power curve than my SLAs, though they are 2.5 years and about 400 charge cycles old. Smoother, a bit faster, more power, but not strikingly more.

Then, about 5 miles into the ride (fortunately I was 1/2 mile from home) power went to virtually nothing. Its like the pack just ran down to nothing.

Is there a break-in period with this chemistry? Do I need to do some shallow charge cycles or something?

I switched to Lifepo4 for greater range and power. 5 miles ain't gonna cut it.

Maybe I didn't charge long enough? Should the first charge time be longer than 10 hours?

Also: Another topic, mechanical: I saw something in here about a Torque Arm. Do I need one?


Town

I bought my battery when I first started ebiking (48V 10AH LiFePO4) and ran it for a week before getting a Cycle Analyst. During that week I was having great fun with the accelaration and speed, not realising that I was going beyond the battery's break-in requirements. Twice I ran out of charge on the way home.
After fitting the CA I realised that I had been pulling up to 45Amps and really hammering the battery. I assume that I damaged it because now the most I can get from it is 8AH. I have no idea if the battery started off as a genuine 10AH, but I'm fairly sure that I cooked my battery.
During that week several times the BMS low voltage cutout broke in, cutting supply to the controller. If you turn everything off for a few minutes after the LVC the battery gradually comes back up and you can go again as long as you take it easy.

It would really help to have a CA and limit the amperage to around 10A for the first 10 or so cycles And then gradually bump the limit up to 20A or whatever you feel is a safe maximum. Without a CA you are in the dark and have no idea what's going on. With one, you develop a feel for what power consumption is required for a given ride profile and can modify your riding style to suit. It is without a doubt the best add-on you could have for an ebike.

With only 8AH, I can get 35~40Km (25m) range depending on the route profile. You should be able to come close to doubling that with your battery.

Yes, do use a torque arm, especially if you have aluminium dropouts. As seen on this forum, sometimes even torque arms fail, so it is essential espicially if your motor is on the front wheel.

 

[www.recumbents.com]

Try turning the battery power switch off and back on next time that happens. The BMS in your battery shuts down the battery when it senses that the power output gets too high. Typically this phenomenon worsens after the BMS heats up. You'll learn quickly what the limits of your battery are. I wish I had known this when I started using my first LiFePo4 battery two years ago, as I lost a finger tip trying to figure out what the problem was.

-Warren
www.recumbents.com

 

[townunheardof]

Thanks guys for chiming in...I've always known I'd have to learn alot more about the technology I'm using(there are no corner garages or mechanics [yet] for ebikes), but I've been cruising along blissfully for these 3+ years, and got to know SLA ins and outs pretty well...

But now I'm going to have to figure out a way to check voltage..., check the history logs here to bone up on LVC, try to figure out the amperage of my WE controller...basically take stock, learn to be my own mechanic/diagnostic.

First thing I'll do IS go light on this thing for a couple weeks...charge it, ride it a couple miles, recharge, ride a few more, etc.

It's a Cammy battery. I'll do some of my homework over the weekend and check back in with some answers.

It has the BMS in an attached black pouch.

The Charger is a 5 amp kp600AL (no brand name), has its own fan too. Output 50v DC. Weirdness factor: on one side it says it's a Lithium Iron/Lithium Polymer charger, in nice professional fine print...then on the other side in the cautions it says to only use it for Lead Acid batteries. [pre][googlevid][/googlevid][/pre]

I just went out and rode it again, just 3/4 of a mile or so, after recharging for 11 hours. Seemed a lot faster, stronger this time.

Electric Ed chimed in while I was writing the above...

Ed, wow great advice, I'll get a cycle analyst (where do I get one of these?) ...memo to Cammy... a wise customer service practice would be to include guidelines for break-in and use with each battery shipped....

Town

 

[Ypedal]

www.ebikes.ca and " Cycle Analyst " .. must have for any serious E-Biker ! ( I have 6 of them for my own use ! )

And as far as break in goes, i also tend to take it easy on the first few cycles, 50% or less DOD ( you can roughly gauge how many ah you are using by comparing the charger's rate.. a 5 amp charger will charge 5ah in 1 hour, 2.5ah in 30 minutes.. etc.. )

I have a habit of tearing apart all the packs i get as soon as i get them, probe every cell with a meter and check for obvious problems right from the get go...

Made myself a rig to drain packs on the workbench.
http://www.ypedal.com/Lbd.htm

The BMS will try to correct any ballance issues at the end of the charge cycle.. so leaving the charger hooked up even once it turns green is advised for a while.. if you are willing to cut into the tape.. each series groups of cells should read 3.6v + each when fully charged.

 

[dnmun]

if your charger only puts out 50V, you are not charging the battery up. because of that, the low cells are not balancing by the time it shuts off. so you are running on dead cells already, imo.

you need 59V to charge your 48V lifepo4 pack.

 

[ElectricEd]

The Charger is a 5 amp kp600AL (no brand name), has its own fan too. Output 50v DC. Weirdness factor: on one side it says it's a Lithium Iron/Lithium Polymer charger, in nice professional fine print...then on the other side in the cautions it says to only use it for Lead Acid batteries. [pre][googlevid][/googlevid][/pre]

I'll get a cycle analyst (where do I get one of these?)
Town

Output 50VDC. There's your problem if the stated voltage is it's true upper voltage.
There's 16 cells in a 48 LiFePO4 battery. Charging voltage per cell is approx 3.8V
To fully charge it you need a charger that can give up to 61V and supply with a varying profile to suit LiFePO4 charging characteristics.
With my charger after charging, the battery is at 56.3V. This is a little more conservative than my previous charger (which blew up) which left the battery at 60.1 V.
(Hmmm thinks aside, Maybe this is why I only get 8AH)

You get the Cycle Analyst from Jason at http://www.ebikes.ca/drainbrain.shtml
If you want to get anything ebike or know anything ebike, Justin's the man.

BTW, you'll love the lower weight of the LiFePO4 when you get it up and running. You can use the full charge, not like Lead Acid where you shouldn't deplete it past half charge. A LiFePO4 battery is 3 times the energy density of LA, but is effectively 6 times the energy density because you can use the lot.

 

[townunheardof]

CORRECTION: This Charger is 60 volts. It's very fine print, and the marker checking off "60" made it look like 50.

So, it should be alright. At least that part, anyway.

 

[ElectricEd]

Charging voltage per cell is approx 3.8V

Oops,
LiFePO4 can be 3.6~3.8. This can vary due to state of charge, rate of charge, temperature and other variables. This means a final battery voltage of 57.6 to 60.8V. After a while, this will relax back to a lower voltage depending once again on things like state of charge, rate of charge, temperature etc.
These batteries are not super precise, they are a chemical process that can be affected by heaps of things. Buying LiFePO4s on eBay from China is a bit of a gamble too (that's what I did). You can't even be sure that you've got the right type of battery.
Currently some of the eBay LiFePO4 dealers are suppling a charger which can't be trusted:


Here you are seeing the underside of the charger. I have had 2 of these replaced due to fizzing out within 30 seconds of being connected. The dealer hasn't sent one that works. Looking at various sellers on eBay, most have the same charger. Don't buy one of these chargers because they are dodgy.

 

[dogman dan]

Check the polarity on those fizzy chargers. Not unusual for them to send em out wired wrong.

A new lifepo4 definitely does have a break in period, usually about 6 cycles. Opinions vary about how to ride during that time. I also say, go easy, do some very light discharges, like 1 mile rides, and recharge. Leave the thing charging 23 hours a day at first, or if you use it like I do, Its on charge 23 hours a day forever. In any case, if you do this, and you have a problem, there is no ifs ands of buts about it that you didn't harm the battery. Hopefully you will gain some capacity in the next few cycles. If you have the 18650 round cell battery, I don't think that at those prices you get a pack with matched cells, so it's not unusual to have a few runt cells in there. If they are 1 ah cells, then each runt in a paralell group of cells would lower the capacity of the whole pack by that much. I think these sellers should be cycling the packs before they sell them, but if they did, they would have a huge pile of rejects.

Good luck, and get a voltmeter so you can confirm your voltages both of the battery and the charger. You may just have a weak charger.

 

[gilnet]

uh oh,just when I thought I knew everything,I'm brought back to earth. Realizing I know shit, then when needed to apply to life I don't know shit.I'm positive when I get my first bike,every thing will be in doubt and second guessed every inch of the way.Glad to see you're human

 

[townunheardof]

Okay, here's an update (need some further opinions please...)

Great guidance on breaking in.

I've been keeping the charger on, and taking a light ride every day or so. A mile, two miles. I'm probably about 5 or 6 cycles into the break-in at this point.

Seems smoother and more powerful, better.

But, a new problem: It's cutting off now, every half mile or so. Very inconvenient. Seems especially prone to cutting out at the worse times e.g. going uphill.

When it cuts off, I switch the controller off for a few minutes (as advised here) then switch it back on and it's okay again (for awhile)

(Here's a review: Pack: Cammy 48v 15ah Lifepo4. WE 36v brushless 24" front hub, standard WE controller. Battery pack has Cammy's BMS. 5amp charger from Cammy.)

I mounted the pack in a fairly tight fitting plastic 'tub' like box. Is it possible it's overheating? Would an aluminum toolbox be better? Doesn't seem to be getting hot though. And the weather hasn't been all that hot either.

I don't have a CA yet. I'm trying now to take it easy and get this thing broken in a little, see how it goes.

But this cutting out is very inconvenient. Especially because this is the Wilderness Energy controller with the cute little key. PITA digging this teeny little key out and finding the teeny little slot and giving the *&##&&#*#*#*#* thing a teeny little twist every half mile or so, and having to pedal 50 lbs of bike while it "rests"!!...then going through the whole teeny key thing again to turn it back on...

Any clues? I have found my volt/amp/ohm meter, so I'm ready to take some measurements. Do I have to cut into this beautiful, smoothe duct tape casing? Must I continue to improve my EV tech education? I have really enjoyed this trouble- free/tweak-free SLA existence I've been leading the past 3 years...is that all over?

Town

 

[ElectricEd]

I have had similar symptoms when getting my setup going. It was due to the Hall Effect connector not connecting properly. Everything would work for a while and then start to cut in and out befor stopping. I'd wiggle every connector and then it would run again. It was the dodgy Tamija connector (mistakenly refered to as Mini XLR) on the motor. Some pins were fractured within the body of the connector.
Another cause was the 40Amp Crystalyte controller supplied by Brett White. There was a strand of one of the main motor drive wires shorting to the gate of the adjacent mosfet. It was initially a partial short that would lock the mosfet on, causing both +ve and -ve legs to be on, creating as good as a dead short across the supply. This would cause the LVC (Low Voltage Cutout) on the BMS to kick in.
You'll need a CA or a multimeter across the battery so that you can check the voltage. Try to find what voltage it cuts out at and if it is consistently doing it at the same voltage. The BMS LVC may be set too high, or you are flooring the throttle too much at a low speed, drawing too much current.

 

[icecube57]

Sounds like you have a 50A controller. and the 15Ah round cell pack is no match for that controller. Probably trying to pull 3.5C out of a pack that is only designed to barely put out 1.5 at most or 25-30A. You probably are hitting the Current limit on the bms. But i dont think the cammy packs have a mosfet based bms. I think they only do balancing so you might be hitting the LVC of the controller. My bms is pretty huge and bulky but you say yours is in a small slender black pouch. If it is the lvc of the controller. The reason why you are able to ride about half a mile or so is because there is a surface or floating charge left on the battery and its keeping the voltage high enough until it bleeds off and then it drops to the nominal voltage of 53v. But the way you are talking ... You got a volt drop/sag from hell in order for it to be cutting out so early. Possibly under load on of your cell groups is sagging low because of some runt cells in the pack. Under a 50A load that can happen super quick.

 

[icecube57]

You dont have to take the ductape off. If you are careful you can check the cell groups through the bms connector. You should be able to record 16 voltage readings Post the total pack voltage and the cellgroup voltage. BE CAREFUL!! touch the test lead together and you will have a dead short.

 

[needWheels]

correct me if my math/logic is wrong but
on a 15ah pack of 176 cheap 18650 cells which are 1.2ah arranged in 16s, that's 11 cells
so 13.2a max @ 1c, 26.2a @ 2c

The controller on a WE 36 is 35a, so you will easily go beyond the 2c safety zone for cheap 18650's
(and most likely the BMS will cut off just after 2c)

I want to measure the 16 points at the BMS too but I am terrified of an accidental short because of the amount of juice in these packs.
Are the BMS connectors the positive or the negative?
I wish I had a picture of where exactly to measure each sub-pack, on the connector or on the board?

 

[dogman dan]

Town, your bms may be getting hot. Ventilate the tub, or just try riding with the lid off. I get cutoffs on my ping bms if I put the thing in a bag that is insulated. If I unzip the top and let some wind in, no problems. I'm told that a hot bms will have a lower than normal lvc, which returns to normal if it gets some cooling.

 

[townunheardof]

Hi folks,

it's getting worse.

After another week or so when I couldn't get back to my "break in" recharging/discharging, I did get back to it and now there's a new problem (I'm starting to long for the simplicity of my sturdy old SLA)...

Before getting back to it, I'd done about 5 short rides, to break it in. I was leaving the new 48v pack on the charger, in the garage, in the meantime.

When I got back to it, the charger was unplugged. Battery pack was still plugged into the charger.

Several days before, the kid that mows the grass had unplugged the charger to plug something else in. Never plugged it back in.

So it sat not charging, but hooked to the charger. I think that may have drained it.

Now, it's not working at all. I plugged the charger back in, charged it for a couple days. When I switched the controller on, the LED that shows power barely lit up.

Charged it for a couple more days, same result.

So, apparently sitting on the charger with the charger not plugged in for a couple days has done some damage to something...cells, BMS, something.

Well, I got the voltmeter out, and I'm getting 44.8v out of the pack. Is that bad for a 48v pack? Must be. From some of the other threads I've read, maybe it's not good.

I needed to ride the other day, so I put my SLA back on and everything worked fine. So I know the WE controller is OK.

Now, I want to check (carefully) the voltage of separate cells or cell groups. Somebody said there are 16 of them. But I don't know what to check, where to put the meter leads, so here I am.

Here's a shot of the cammy BMS...

(I'm not sure how to post an image here, but I did what I think might work, and also uploaded it)

....so where do I touch these leads?

Again, I really do appreciate this community, thanks...

Town

 

[needWheels]

Doesn't Cammy advertise their packs come with one of the newer better BMS?
Yours looks like the old flatter one without the heavier heatsinks unless it's an angle I don't recognize.

This is the ad image he uses:
http://www.superetrade.com/images/cammycc/bicycle battery/pic/cc2.jpg

I wonder if Cammy drop-ships just like Mr. Lau
Just out of curiosity did you shipping label have a tracking number ending in HK or was it CN ?

 

[townunheardof]

Needwheels,

It's a DHL shipping number, has no HK or CN on it at all.

Thanks for posting the pic link. No, it's certainly not that better, more robust Cammy BMS. But then, he didn't advertise that one in the Ebay auction I won. His pitch this time was this wonderful 5a fast charger.

Today I got back from a 2 day business trip.

Just now I went back out to garage to check the battery. It's been sitting, unconnected to bike and charger, since I unhooked it two days ago.

I decided to try charging it now, after it sat for a couple days.

I plugged it in to the charger, then plugged the charger in to 110.

The fan built into the charger came on like it always does. Both red lights were lit, which seemed different, I'm not sure. I think usually it's one red and the other off. When it's charged, normally, it's one red and one green.

Anyway, after about one minute the charger made a sharp popping noise, obviously an electrical "event," and then gray/white smoke began spewing out of the fan.

I had to jump over it to get to the plug and disconnect.

Very dramatic.

Obviously this charger is fried.

Anybody have any thoughts, suggestions?

Should I try charging it with the old crummy 3ah charger that came with the WE kit?

I remember reading somewhere (probably here) that I should NOT try to charge a lithium p04 battery with my Batteryminder (my desulfating charger I use on my SLAs).

By the way, was the 44.8 volts I measured sub par for a 48v 15ah pack? Not that it matters much since this charger (we now find out) was suspect all along.

If I get a decent charger, maybe I can save this one yet? I hope?

Town

 

[Joepostal]

oUch I hate when the magic smoke escapes.

I used to de-solder 16 pin chips with a puddle of solder since it was faster than soldapulting it (new word) but what was weird about that is I would test the chip after I got it out and it would still work fine even though I couldn't touch it cause it would burn me.

Anyhow your looking at trying to find all the parts that got destroyed and replacing them. A pop or snap crackle is easy to find but if it took anything else out well that will be hard to find. The good part about this is that you probably only killed one or two parts and nothing else.

Find the parts that gave out trace the circuit and if you can draw the circuit do that as well. Once you identify the parts that exploded get replacements on the internet.

I had never soldered batteries until recently. I used to fix cable boxes in a repair center and like I said I have made huge puddles of solder to remove some part, sometimes you have to. I recently was forced to solder some nicad batteries for my cordless phone and those things were on fire when I was done I thought for sure I broke them... They are fine. What I am really trying to say here is I have never broke anything with a soldering iron but I sure have fixed a bunch of stuff with one.

Volts;
When charging Lithium batteries you must know the maximum voltage that the pack can handle and never charge them above that amount. Say you have a 48 volt LIPO pack but they will probably charge to 51 volts (as an example) so you need a charger that can output 51 volts AND NO MORE. In reality it totally depends on your battery chemistry and then you build the charger to do that exactly. For example I have a 12 volt Lead acid battery and it charges to 12 volt so I hook up my 14 volt charger, fresh off the charger they will show 13.9 volts ( yeah WTF ).

Amps;
The more amps your charger can output to charge the batteries the less time you have to wait for them to be full. There are many problems with high amperage. Amperage is heat. Once you run too many amps through a component that cant handle it the magic gets out and everyone is sad If you have a very nice charger it can handle the heat and gives you much more amps reducing the time it takes to charge.

What could have happened, you could have connected the charger wrong, one of the cells in the pack reversed and was basically a short, the charger was not designed to handle the heat.

Too bad this is so complex but compared to fixing anything on a modern automobile these problems are trivial.

GO Electric

 

[Joepostal]

Now that I have re-read your post I believe a cell in your pack is probably suffering, maybe more.

Your old lead acid charger is not compatible with Lithium in any form. The batteryminder lead acid charger tries to knock buildup off the plates by sending high frequency pulses into the battery. Lithium doesn't have buildup, it has very specific operating characteristics, specifically max and min voltage. If you cause a lithium cell to go below the minimum voltage the cell may die as well as if you try to give more voltage than it can handle it may also die. You may need to send the pack back for repair or take it apart and replace the bad cell(s) yourself.

OR you can find the bad cell(s) and try to revive it, I have heard that you can trickle charge a bad lithium cell that is below it's cutoff voltage and revive it (if it has not reversed). Sorry I am not speaking from experience here but the task is to charge it with a very low amperage charger and to it's specific voltage.

Welcome to the cutting edge.