36v 20ah and 26650 question...

[sangesf]

I bought a 36v 20ah battery from seller DaoJi on eBay...
Battery came today and it just doesn't look/feel correct.
It's supposed to be 36v 20ah made from 26650 cells..
The seller says that the 26650 cells are 3ah each and that the battery is really 21ah.
He says the BMS is set for 3.9v per HVC (really high!) and 2.2v per LVC (too low) and only set for 20a max. The discharge wires are only 14-16ga which seems too small to me as well.
(I WILL be testing out the AH "rating" over the next few days and don't worry, I'll be watching the cells voltage levels, so they don't get too low)

Questions are...

1.) Checked the dimensions of the pack and they are 8.9"x5.5"x5.5" when the auction states that it should be 11.8x4.1x5.9 inches.. Can the 26650 cells be put into a configuration that would match the specs on my battery?

2.) I know 26650 is the physical size, but the seller has not told me what KIND of cell these are.. (supposedly LiFePo4)
Anyone have a clue what they MIGHT be?

3.) Just confirming that those Voltage cutoffs are not good, although my controller has a cutoff of 32.4v (2.7v "per") maybe I'll be ok?

4.) Has anyone else ever bought this battery from DaoJi888/YXM? And if they did get the 36v 20ah, how well did it work / was it close to it's rated specs?

Thank you all in advance.

 

[neptronix]

I can't think of any chemistry that has a cutoff around 3.9v.
I think 2.2 is too low for even lifepo4.

Yes, that is an oddball.

14ga. wire is way too small, that's good for maybe 15 amps, anything above is resistance central..

Why do people buy unproven eBay batteries again?

 

[dogman dan]

Sounds too small in dimensions. I think you got a smaller size by mistake, or horrors, on purpose. What is the weight of the thing? I could not possibly be less than 15 pounds if it is really a 36v 20 ah. And it's lifepo4. Could be smaller if limn.

You are positive, right, that you clicked buy on a 36v 20 ah? Sounds like a 36v 10 ah.

 

[sangesf]

I'm sure I bought the correct one..
Paid the amount for the 36v 20a.
No response yet...
I'll wait one more day and then start the paypal refund process, and I bet I get a fast response then!

 

[Ypedal]

3.9 and 2.2v is ok for Lifepo4, no problem there... i charge my PSI and Headway and A123 and etc using voltphreaks single cell chargers that peak at 3.9 and no problems after years of usage....

At 2.2v the cells are empty but still above 2.0v wich is the absolute cutoff..

pack size however is suspicious... 36v with lifepo4 means 12 cells in series.. 20ah would require 7 in Parallel for 21ah ( 7x 3ah = 21 ) so 12 x 21 = 84 cells... if the seller is inflating capacity (* likely ) 6P x 3ah = 18ah with the moon aligned and tides level.. 72 cells... still not going to fit into that tight of a package..

next issue.. 26650 cells are not 3ah... A123 M1 cells are 2.3ah in that size..

 

[sangesf]

Update:
Spoke with the seller again and he assured me it's 84 cells and 21ah, so...
I weighed it on a digital scale and it weighs 16.7lbs (or 7.6kg, which is .1kg over sellers specs)
So that was good..
After I fully charged it and let it sit on the charger for 6 extra hours (the charger kept blinking from red to green,which I figured was the BMS balancing, until it didn't do it any more..
I pulled the balance leads and they ALL were at 3.75, NOT 3.9 like the seller said, but that's good, I've always charged to 3.7-3.75 per.. After 5 minutes the battery read 44.4v and after 20 mins read 43.8v, so I checked the balance leads again and they were all 3.64-3.67, so again, looks good.
I know my 36v 15ah battery gives me an average of 21 miles (always between 20-22) and always gives on avg 25.5wh/miles..
So yesterday, I rode only on the "36v 20ah" battery and tested mileage..

Well, I got 29.5 miles out of it (even with a moderate headwind) and it still had a no load voltage off 39.1, which was 25.5wh/mile, so I know it's good!
20a max pull and after running the numbers, I realized something..
25.5x29.5 is 754wh, which is why I put "36v 20ah" in quotes, because at 29.5 miles (with a little more room left in the battery, it works out to 20.9ah, as I remembered the seller on eBay said it actually was a 21ah battery, so kudos (so far) for the battery.
The only concern I have really is that the wires for discharge are at best 14ga, but prolly 16ga. And although the BMS doesn't get "hot", it does get "warm" and it's really small. (a little smaller than a Hershey's chocolate bar.)

 

[neptronix]

Cool, you didn't end up with a total piece of crap

14ga is acceptable if you're ONLY going to draw 20amps.. 16ga... yeah, upgrade those if they are of any notable length.

 

[sangesf]

Actually, I pulled the discharge wires off and soldered on 12ga 3' length to my controller.

 

[999zip999]

New battery and had to test out of the box ? One test O.K. Now break it in. Or dump the whole load on the steapest hill. Just to see it cut out.

 

[sangesf]

New battery and had to test out of the box ? One test O.K. Now break it in. Or dump the whole load on the steapest hill. Just to see it cut out.

Live in Florida... No hills..
Have gone through about 30 cycles already..
Haven't run into LVC yet... When I have time, I will and see when it cuts out..
After 29 miles, I'll check voltage every 1/2 mile..
(I don't have a watt meter yet)
Actually, I have a watt meter, turnigy, it lights up but no display...
Anyone know what to do to fix it.

 

[999zip999]

Sounds good. How much ?

 

[dogman dan]

Interesting. The size and weight of the thing is pretty close to a pouch cell pack. If it was 18650's it would have weighed almost 20 pounds and been a LOT larger physically. I was thinking for sure you had been sent a 10 ah pack. Shit happens, and next thing you know you clicked buy on the wrong size, or they shipped the wrong size.

Not so many fragile connections as the 18650 packs, decent size and weight, guess its time to stop bashing round cell packs.

No way to measure capacity? If you run it down completely, we could at least look at the charge time and compare that. You can get a killawatt meter at Lowes home improvement stores now and we could compare that number ( AC into the charger kwh) with charging my packs.

 

[theRealFury]

New battery and had to test out of the box ? One test O.K. Now break it in. Or dump the whole load on the steapest hill. Just to see it cut out.

Live in Florida... No hills..
Have gone through about 30 cycles already..
Haven't run into LVC yet... When I have time, I will and see when it cuts out..
After 29 miles, I'll check voltage every 1/2 mile..
(I don't have a watt meter yet)
Actually, I have a watt meter, turnigy, it lights up but no display...
Anyone know what to do to fix it.

30 cycles in 6 days... man you got the ebike bug bad Still sounds like an half decent battery if its still holding up. Only time will tell though

On the subject of how many amps for what awg of wire, is there a chart somewhere or a way of working it out that will help sangesf, myself and others as its something that i never quite know the answer to?

 

[sangesf]

Sounds good. How much ?

$389 shipped.

 

[sangesf]

Interesting. The size and weight of the thing is pretty close to a pouch cell pack. If it was 18650's it would have weighed almost 20 pounds and been a LOT larger physically. I was thinking for sure you had been sent a 10 ah pack. Shit happens, and next thing you know you clicked buy on the wrong size, or they shipped the wrong size.

Not so many fragile connections as the 18650 packs, decent size and weight, guess its time to stop bashing round cell packs.

No way to measure capacity? If you run it down completely, we could at least look at the charge time and compare that. You can get a killawatt meter at Lowes home improvement stores now and we could compare that number ( AC into the charger kwh) with charging my packs.

Well, it is definitely a round cells pack (I can feel the cells, and I'm unwilling to open the pack until I (hopefully never) have to replace a cell group).
Last night after a long ride (28+ miles) I got home about 6:45, plugged in (5a) charger and checked every half our to see when charger turned green, which it did between 10:30 and 11:00, so it took anywhere from 3hrs 45min and 4hrs 15min.. So 18.75ah to 21.25ah back in..

Today I have a 40+ mile ride, so I'll ride off of this battery until cutoff (watching carefully at the 29.5-30 mile mark to make sure the LVC on this BMS is set for a (relatively) safe level.. Once I get a final mileage total, I'll be able to make a good guestimate as to total AH using a 25wh/mile as a reference.

 

[dogman dan]

Charge time would indicate to me it's a 20 ah. Only about 3 hrs for a 15 at 5 amps. Plus some for the slow bit at the end.

 

[sangesf]

Well.. Went for my 45 mile round trip to work and back..
Here are the results...
1.) At 30 miles, I checked voltage at rest.
(39.4v)
2.) At 31.5 miles
(38.4v)
3.) At 34 miles
(37.8v)
4.) At 35.2 MILES!!!
(37.4v resting voltage)

I did not want to push it to LVC, in case the LVC on the BMS is too low.

But 35.2 miles out of this 36v 20(21)ah battery is just awesome for me.
21.47wh/mile...
80% of the time, I was running at ~20mph, 15% of the time I was WOT and 5% of the time I used my other motor on startup for 5 sec.. All with moderate headwinds.
That was a "normal" ride for me (except that I usually run both motors at the same time), this was just to test the range using one battery in "normal" riding mode.
Tomorrow, I will run, WORST case scenario and run it WOT the entire time and see what range I get.

 

[sangesf]

As a point of reference, my 36v 15ah battery gets me roughly 21 miles on a full charge. (tested a month ago with a watt meter and gave a full 14.8ah before cutoff.

 

[999zip999]

What motor at what amps. ?

 

[neptronix]

Ahh.. if you have no hills then the wire gauge is ok. It will only draw peak amps at startup, not constantly for 10 mins like where i live..

21 miles out of 15ah is pretty bad, i take it you don't pedal?

I get about 2 miles per AH on my 36v setup on moderately hilly terrain, but i pedal like a madman.
You do really need some kind of watt monitoring device O_O

Or if you have an infineon controller, set the LVC in the controller.

 

[sangesf]

Motor is the stock 24v 450w Ananda motor on the Schwinn OCC Electric Chopper.
BMS is set for 25a max
Controller is a GoldenMotor "Magic Controller" 36v 25a with regen and cruise.
I NEVER pedal.
Bike alone, without me on it, weighs ~160lbs

 

[jimw1960]

So, are you going to tell us where you bought this great battery at such a good price, or keep us in suspense? A link would be nice.

 

[theRealFury]

He already said where he got it from and the price in another post.... Cant seem to find it on Ebay though so a link would be nice

EDIT: Found it i think... http://cgi.ebay.co.uk/36V-20AH-LIFE...256?pt=LH_DefaultDomain_0&hash=item1e5b4c36a0

Immediately alarm bells are ringing about that name... wasnt there a scammer with similar name on ebay a while ago? maybe this is someone else though, i could well be wrong.

I bought a 36v 20ah battery from seller DaoJi on eBay...

 

[sangesf]

I know who you're thinking of on eBay.. 3 1/2 years ago, I bout two 24v 30ah batteries who's BMS' died about 3 months into usage and the batteries had horrific problems with welds and the like..

I, personally, was VERY SKEPTIC about this battery..
But my sister was willing to buy me a new 36v battery, because we got an inheritance from a distant aunt. So, I figured, hey it's not MY money, so I told her to purchase that particular one.
36v 20ah for $389 shipped. Took only a little over 2 weeks to get, which is fast (from china).

I've been testing it out thoroughly without a watt meter, because I replaced the 36v 15ah that was running that motor with this new one..
About a month prior to ordering my turnigy watt meter died. But last reading I got from it, was 14.8ah from full to LVC on the 15ah batt, so I used that as a reference point.

The size and weight of this new battery gave me pause, but after testing it with 35 or so cycles, it works better than I hoped.
So kudos to Doaji888 on eBay..
Battery specs from MY measurements...
8.9" x 5.5" x 5.5"
16.7 lbs.

IF (hopefully never) I have a problem with the BMS or cell groups, THEN I'll open up the pack and see what's in there..
But as it stands, it works awesomely.
I'll see if I can get my watt meter working again, or I'll just have to buy a new one OR if someone in south florida can let me borrow one for a few hours, I'll get a more accurate reading.

 

[theRealFury]

Well glad it seems to have all worked out for you. hope you get thousands of trouble free miles with it