Sunthing battery 48V 15Ah

[Ykick]

With a heavy heart I must tell you there is/was no reason to cut the 6 circuit connector from the motor wire. All you needed to do is/was learn how to disassemble the connectors, slip-on whatever axle hardware you desire and push the metal contacts back into the connector housing.

If it were my battery I'd leave it charge for a day or two, disconnect it momentarily, perhaps power cycle the charger and restart charging for another day or two. Rinse and repeat - the circuitry will not allow any damage.

 

[999zip999]

You can put a light bulb on it to drain. Old 100 watt.

 

[dogman dan]

You could just solder the wires back together , after using a tiny screwdriver to depress the tab on the contacts and removing them. Shrink tube to cover the cut.

New plugs and contacts in the USA are easy to obtain from scooter parts web stores.

Noob stuff, we've all done it too. Some like to replace those cheap scooter plugs with much better ones, but I have never had that much trouble with the cheap plugs.

I'd just leave the battery on the charger. But it could need a few light cycles to fully perk up. It's not a ping, so you might be at the fullest it will ever take a charge right now. Depends on how much effort they put into cell sorting the cheapest battery you can get. In other words, they didn't. Or worse, they did, know what I mean?

If they gave you a plug and wire for discharge, just use that at least for now. You won't pull that much amps.

 

[overtonmath]

Once you have it fully charged, it might hold all 60v overnight. It wont do that for all that long though, and normal is for the voltage to drop to 56-58v overnight. In time, possibly pretty soon, you won't see all 60v when you unplug. 2v may vanish the instant you unplug. It's called surface charge. But 55v is definitely not ideal, hopefully you see at least 56v when it's new and fully charged.

Then when you start riding, expect to see about 54v very soon, and most of your ride will be between 52 and 54v. The usable meat of the charge is below 3.5v per cell. The rest above 56v, is the overcharge that is not harmful to lifepo4, but helps the charger and bms balance the pack quicker.

Left the battery on the charger for 3 days straight. When I took it off tonight it showed 59.9 v. I got the motor running and plugged it in and rant the motor till the battery was down to 53.6 and put it back on the charger.

For these initial cycles how low should I allow the voltage to drop? I kind of felt like 53.6 wasn't very much. But you said around the block, so I'm trying to be obedient.

 

[dogman dan]

That's fine, With lifepo4 54v could be anything from 15% discharged to 75%. Voltage won't tell you much till it drops quickly towards 50v near the very end.

Pretty hard to just ride your new ebike around the block and quit, I know. But a few quick short cycles will help it get used to fully charging.

My pattern, using pingbatteries daily was to always leave it on the charger overnight.

 

[overtonmath]

I was trying to figure out how soon I needed to get torque bars put on. I recall the dogman's first ride and his subsequent crash, but if my memory is right it was due to not tightening down the bolt tight enough, not a missing torque bar. I was thinking that I should get torque bars before I do any riding beyond a mile or two. I was going to try and get a friend to make something for me. In fact I gave him a sketch today. I would have happily used the Grim torque bars but they won't fit my 2 inch aluminum alloy skareb forks. Well I can now say that the time to put torque bars on is before the first ride. As I crossed an intersections and went over a small bump, my forks failed, front wheel came out and I was put down on the road. Fortunately I'm not really hurt, nor did it cause any permanent damage to the bike with the exception of the forks. I don't know if the wires inside the battery are alright or not. I didn't test anything except the battery, it was down to 53.1 v, so I put it back on the charger and called it an evening.

The lesson learned is put on those torque bars on day one and don't go for a test ride until you have one installed on each fork arm.

 

[dogman dan]

Ouch.

 

[overtonmath]

I still haven't been able to complete the 3-6 light cycles and am anxious to get those done. The battery now is reading 60v when I take it off the charger, but then drops to about 58.5v after being off the charger for a while.

TORQUE BARS:
I saw the ones at ebike, but don't think they will fit my oversized forks.

I get the idea of how the torque bar works, but am wondering if they have to cover the entire axle. Can I use some old wrenches that cover the axle 3/4 of the way around and then use several hose clamp to clamp to the fork?

I soldered longer wires with heatshrink onto the 6 circuit wire coming from the motor and then put on a new 6 circuit connector. The motor is working even after my crash. The front rim is bent a little.

How low (volts) should I take he battery on first few "light" cycles?? Thansks

 

[dogman dan]

Can you show me a pic of those forks? You need something good for alloy forks, not a funky 10mm wrench torque arm.

This is the TA I use for shock forks.
http://endless-sphere.com/forums/viewtopic.php?f=4&t=15167&p=225525&hilit=Ebikes+CA+torque+arms#p225525

Gotta be pretty oversize for the arms from grin to not fit. They have a long adjustment range compared to the first version.

55-56v is low enough, Mostly you just want to get all the cells charging to full. Above 56v is surface charge, and has no real capacity there. If you are quickly getting the pack back to 60v, then it's good to go now. Holding 58v overnight is excellent, and a sign that you got a good one. As it ages, it will start dropping to 56v overnight, if not immediately. Then when getting even older, it will start holding only 55, then 54. Still usable for a long time though, even when only holding 54v overnight.

 

[overtonmath]

I'm wondering if I will ever get my bike built. After my forks failed I began disassembling my wheel. The nuts at been secured on the axle very firmly. Even though the wheel was no longer connected to the forks, those nuts were still tight. In an effort to loosen them (it was very difficut because the wheel wasn't attached to something) I think I stripped the axle. I obtained another set of forks and was able to get the wheel on without any filing of the dropouts. But when I tried to secure the nuts, they didn't spin very easily on the axle, because the axle was stripped. I worked on tightening those nuts using some vise-grips. As I was spinning the nuts then new forks a had purchsed broke, both dropouts just snapped off.

I'm thinking I need to replace the axle. But that would require taking the wheel apart and rebuilding it, which I have no idea of how to do. If I send it back to Em3ev will they work on it? I'm not sure what else to try. How hard would it be to do it myself?

Thanks, John

 

[dogman dan]

Aww man, you are going through the harsh learning curve I did. I broke everything in the first month. I don't think you can afford to ship it back, and installing a new axle would be tricky. Best bet is to buy a bare motor. Then you can swap in a new stator and axle assembly pretty easily.

It may be possible to repair your threads, but that is not why your second set of forks broke. You must use a c washer, or grind down washers to size to use a motor on an alloy shock fork.

Your forks keep breaking because tightening the nut cracks them if you don't use a C washer. Front motors on alloy shock forks are generally not a good idea for the first bike. Got a cheap steel bike for the next try?

You might be able to use a die, or even just a hacksaw to try to repair the threads on the axle. Then with a new nut, you might be able to get it to hold. If you have enough length left after washers and torque arm, a lug nut has more threads on it than a regular nut.

 

[overtonmath]

Aww man, you are going through the harsh learning curve I did. I broke everything in the first month. I don't think you can afford to ship it back, and installing a new axle would be tricky. Best bet is to buy a bare motor. Then you can swap in a new stator and axle assembly pretty easily.

It may be possible to repair your threads, but that is not why your second set of forks broke. You must use a c washer, or grind down washers to size to use a motor on an alloy shock fork.

Your forks keep breaking because tightening the nut cracks them if you don't use a C washer. Front motors on alloy shock forks are generally not a good idea for the first bike. Got a cheap steel bike for the next try?

You might be able to use a die, or even just a hacksaw to try to repair the threads on the axle. Then with a new nut, you might be able to get it to hold. If you have enough length left after washers and torque arm, a lug nut has more threads on it than a regular nut.

Just returned from a trip and now I"m back to the bike project. Managed to find some steel forks on my trip so I've got some new direction. If I buy a new motor then I won't be using the one I bought correct? If that is the case why not try and change the axle on the one I've got and if I can't manage it then buy a new motor?? Or did you mean to do something different? I still plan on trying new nuts and see if I can get that to work. But if not I'm going to try an replace the axle and if I can't, I guess I'll buy a new motor.

 

[999zip999]

The Dogman easy way out is to buy a new motor, no spokes or rim as is cheaper shipping and just swap the gut's.

 

[Melbourne]

hi overtonmath

How is your sun-thing battery coming along??... Does the Sun-thing Quote Specs - max discharge and AH - meet the actual real world performance... OR are they lying about the battery specs?

I am thinking of getting 36V15ah for my Bafang crank bbs01 36v350w, would you recommend sun-thing battery?

High-capacity 36V15AH LiFePO4 battery parameters:
Discharge cut-off voltage: 33V
Rated discharge current: 30A
Instantaneous maximum discharge current: 45A
Rated charging current: 5A
Maximum charge current: 8A
Battery pack size: 27x16x12cm
Battery pack weight: 6.5kg
Battery pack capacity: 15AH ± 1%
Charge cut-off voltage: 45 V
It is use the 12 pcs 3.3V20Ah Cells.

 

[dnmun]

you can try to find a threaded collar to use instead of just the nut but threaded coupling in the that metric size is unusual to find. but if you have a recessed drop out, aluminum frame, it has to have the C washer inside the recess to eliminate the strain that cracks the aluminum when you tighten the nut on the high spots around the recess.

 

[dogman dan]

Sourcing just the axle is part of the problem with replacing just the axle. You might find an axle from somebody who fried a motor.


Then you likely need more than a hammer to press it out without damaging the stator itself, like bending the stator or mashing the coils. Pressing in the new axle, likely even harder to do unless you have a machine shop press, and the appropriate attachments for that particular pressing task.

The flip side is, it's very easy to swap in an undamaged stator.

 

[overtonmath]

.... a lug nut has more threads on it than a regular nut.

Thank you Mr. Dogman for that piece of advice. Went to AutoZone and purchased two 14mm lug nuts. They worked great. The stripped axle seemed to work great with the new lug nuts Got it up and running. Today I rode about 4 miles and then put it back on the charger. When I started it was at 59.9 volts. It quickly dropped to 55 and then it was mostly at 53 and 52 during the ride back. What I don't understand is why the CA shows it dropping to 47v when I'm going up a hill, but then when I finished the ride and turned the motor off it showed 52v? Did it really only have 47V when it was under stress? Did it really have 52V at the end of the ride?

 

[overtonmath]

hi overtonmath

How is your sun-thing battery coming along??... Does the Sun-thing Quote Specs - max discharge and AH - meet the actual real world performance... OR are they lying about the battery specs?.

I haven't fully discharged the battery yet. Since it took me quite a while to get my bike up and running, I was putting it on a light bulb and repeatedly discharging slightly and then letting it charge overnight, as was Mr. Dogman's advice. It shows over 59 volts when fully charged. I will let you know when I ride it until the BMS turns it off. But is that really advisable? I've also heard that it is really important to charge it immediately after discharge. How much harm will I do to the battery if it is fully discharged at 1PM and isn't charged until 1 PM the following day?

 

[999zip999]

Easies way out is buy a second motor bare and swap it with no rim in shipping ?

 

[overtonmath]

Thank you Mr. Dogman for that piece of advice. Went to AutoZone and purchased two 14mm lug nuts. They worked great. The stripped axle seemed to work great with the new lug nuts Got it up and running. Today I rode about 4 miles and then put it back on the charger. When I started it was at 59.9 volts. It quickly dropped to 55 and then it was mostly at 53 and 52 during the ride back. What I don't understand is why the CA shows it dropping to 47v when I'm going up a hill, but then when I finished the ride and turned the motor off it showed 52v? Did it really only have 47V when it was under stress? Did it really have 52V at the end of the ride?

I took it out the other day and rode about 10 miles with some pedalling. When I was done the CA showed I'd used 472 Ah. That is 2/3 of the 720 Ah I'm suppose to have, but only rode half of the 20 miles I was expecting. The other strange thing was that when I was done with the ride the battery showed 52 Volts.

 

[dogman dan]

Sorry to have overlooked this thread lately.

Good that the lug nuts worked good enough. Sometimes a lug nut fits tighter than the stock nut, and still works on partly smeared threads.

Under load, particularly under heavy load on the hill, you will expect to see some voltage sag. When we talk about the battery voltage, we do expect at least 2v or even more drop under load.

The lvc should stop the discharge when one or more cells drops to the minimum, under load. So it can be possible to unplug the battery when it trips, and then by riding slowly and carefully using minimum throttle, get another half mile or so out of it by lessening the load.

I'm not a bit surprised by your short range. I suspect you were riding at least 20 mph, and likely faster, and may have been affected by weather, or the hill. In time, you can learn to ride so your wh/mi improves a lot.

 

[overtonmath]

I don't think I was being accurate on the amount of battery usage I was using. For some reason, can't figure out why or how, my CA stand alone doesn't clear out to zero even though I disconnect that battery when charging it. When I hook the battery back up the CA shows the Watt hours as being the same as the day before. Can I clear back to zero?

Today I rode 19.5 miles. For the first 15 miles a went pretty slow and peddled the whole way. Then the last five miles I quit peddling and used the motor at about 3/4 throttle (10-15 mph) When I finished the 19.5 miles the CA showed that I had used 400 watt hours. This seems low because I thought a 48V 15Ah battery would produce 720 watt hours. 400 watt hours is only a little over half. But that battery certainly doesn't have a 40 mile range?? Somethings fishy. How many watt hours of the 720 should I expect to get before the bms shuts it off? One last question. I've read that opportunity charging is not wise as it heats the battery up. Is this true for the LiFePo chemestry? I had a chance to do some opportunity charging today, but wasn't sure if I should.

 

[cam3087]

400 watt hours sounds about right for what you did today. Going 24 mph you could get a range of 30-35 miles throttle only. Ive been wrong before but that's just my 2 cents

 

[aroundqube]

Yes, to clear the trip statistics from a recent ride- hold right button down for 1 second. " Reset" will display,and you are done. Continue holding right button down for 6 seconds to perform a Full Reset.

 

[DAND214]

400 watt hours sounds about right for what you did today. Going 24 mph you could get a range of 30-35 miles throttle only. Ive been wrong before but that's just my 2 cents

That would fantastic.

Have you calibrated the CA to the tire size yet, or is it as shipped? If not the milage could be on or off a few.

If not that's in the manual.

It's great that you got over the hard learning curve. It's not all that difficult, but then it can be.

Listen to the answers of the questions you ask, before doing it. It can make it much easier and cheaper too.

Dan