xt 30 connector voltage

[itsmcgee]

what is the voltage coming out of the little yellow XT30 connector on a 36volt bafang BT F100 battery suppose to be?

 

[6zfshdb]

Welcome to the forum!
The short answer is this:
In general, the output voltage of a 36V lithium battery should be between 30 and 42V depending on the state of charge.

On some batteries, the BMS puts the battery into "sleep mode" after a period of inactivity. In this state, the voltage will read zero. Charging the Battery briefly will "wake" it.
If you post more information, like battery age, how long has it been stored, will it hold a charge, etc. you might get a more specific response.

 

[itsmcgee]

The battery is new, as is the whole system. After a great test ride yesterday, I came home and could not get the system to turn on. let me go back. the bike is one of the new lightcarbon gravel ebikes which is a great frameset. Motor M820, battery Bt f100, display DP C030. This was my second ride of about 20 miles. When I dropped the motor to check all connections I found the little yellow xt30 connector was broke where the wire attaches, so just laying there. Might have been broke when I pushed the engine and wiring into the bike during assembly. I attached a new plug and still no go. I tried to charge the battery and only got a green light (full charge) which cannot be correct. Put a volt meter on the yellow plug and it reads 2 volts. I feel confident I screwed something up, I just don't know what. This is my first experience with Bafang as my other 2 ebikes are shimano.

 

[Gionnirocket]

Possible the two wires of the XT shorted when it broke and the battery BMS shut down or is damaged.
Remove the battery and test it apart from the bike. There could be a blown fuse but I don't think you would get 2v reading.
What was the SOC of the battery just before it stopped working?
Check your XT 30 connection... They can be difficult to solder without a lot of heat and experience.
Post a pic of all the battery connections.
Contact the battery supplier for some insight on the BMS safety features.
Confirm that the charger is working.

edit: That said you may want to remove the XT30 and crimp on high quality bullet connectors rated at minimum of 30a
They'll be easier to tuck away as you can do each wire individually.. and take up less space in the wire compartment.

 

[6zfshdb]

I'm not sure about Bafang, but many batteries have an internal fuse. It's possible a short occurred when that XT connector broke and took out that fuse. The manual, either printed or online, should give more information.

Unfortunately, I have no first hand information on your bike. Hopefully, someone with Bafang experience will provide more help.

 

[Chargeride]

Can you boot the BMS with 40v on the battery output?

 

[tomjasz]

Welcome to the forum!
The short answer is this:
In general, the output voltage of a 36V lithium battery should be between 30 and 42V depending on the state of charge.

View attachment 191779

On some batteries, the BMS puts the battery into "sleep mode" after a period of inactivity. In this state, the voltage will read zero. Charging the Battery briefly will "wake" it.
If you post more information, like battery age, how long has it been stored, will it hold a charge, etc. you might get a more specific response.

WOW that graph edited by me when with Lunaticks still pops up. It must be 10 years ago...

 

[harryS]

WOW that graph edited by me when with Lunaticks still pops up. It must be 10 years ago...

Both my Lunaticks packs from 9 years ago still work though,

Can you boot the BMS with 40v on the battery output?

That better not work, if the BMS is doing its job and has shut off the battery. Bad idea if the BMS lets it happen.. The insides might only be at 30V,

 

[6zfshdb]

WOW that graph edited by me when with Lunaticks still pops up. It must be 10 years ago...

Yeah, I have a laminated copy on the wall next to my chargers.

Very useful, thanks for posting it.

 

[Gionnirocket]

Yeah, I have a laminated copy on the wall next to my chargers.

Very useful, thanks for posting it.

I sleep with a copy under my pillow

 

[6zfshdb]

I actually carry a copy of the 52V section in my wallet for quick reference.

You'd think I would have committed the chart to memory by now, but I still need it from time to time.

 

[Gionnirocket]

I keep a digital version on my phone... but I use actual battery capacity(rounded ever so slightly), not practical riding capacity. 39v still being the cut off.
It's just the way my brain works.

edit:... I've been meaning to tweak it and you just motivated me

 

[harryS]

With 52V, 48V and 36V batteries, I use 52, 48, and 36 as the halfway points. Better be turned around and going home by then. If not, it better be downhill.

 

[6zfshdb]

With 52V, 48V and 36V batteries, I use 52, 48, and 36 as the halfway points. Better be turned around and going home by then. If not, it better be downhill.

Or downwind.

 

[tomjasz]

Both my Lunaticks packs from 9 years ago still work though,

pure luck and/or good care. There were so many BMS issues. Having to "jump" to power up was common. I used to dread responding to battery questions when folks were having a problem. I have an old one that I gave to a friend and he still uses it. His bike is throttle only too. And I have an em3ev for 2014 still powering a 350W BBS01(a)

 

[6zfshdb]

pure luck and/or good care. There were so many BMS issues. Having to "jump" to power up was common. I used to dread responding to battery questions when folks were having a problem. I have an old one that I gave to a friend and he still uses it. His bike is throttle only too. And I have an em3ev for 2014 still powering a 350W BBS01(a)

It's been my experience that good quality lithium batteries don't fail catastrophically unless mistreated. They simply lose capacity with time and the number of charge cycles. I have a couple of 8 year olds that are down to just over half their original capacity but still functional. I use them as range extenders on rides where I need slightly more juice than a single fully charged battery provides.