Sunthing Battery 15 Cells?

[geeeyejo1]

Well have had my Sunthing pack for a few weeks now and becoming more familiar with it's status. When fully charged the pack goes to 60.3V. After I disconnect the pack from the charger, the surface charge slowly dissipates and within roughly 24 hours the pack settles at 53.4V. It will then remain at that voltage for several days if not used. From what I have read; this voltage appears low for a 16 Cell pack. I have not experienced any performance issues, no LVC issues and hence am hesitant to cut open the BMS and/or the pack to check individual cell voltages and/or confirm the number of wires from the BMS, etc.
It got me thinking though - is it possible that the Sunthing pack is 15 cells instead of 16? 53.4V for 15 cells would equate to 3.56V per cell. This might also explain his lower pricing on a pack versus other vendors. Once again - not going to rip open the pack or BMS until I experience any performance issue - just wanted to know if 15 cells were a possiblity...

 

[dnmun]

this is a joke.

 

[geeeyejo1]

this is a joke.

Gotta love those cryptic responses Dnmun - thanks for providing this helpful insight to what I thought was a reasonable question....

 

[SamTexas]

It got me thinking though - is it possible that the Sunthing pack is 15 cells instead of 16? 53.4V for 15 cells would equate to 3.56V per cell. This might also explain his lower pricing on a pack versus other vendors. Once again - not going to rip open the pack or BMS until I experience any performance issue - just wanted to know if 15 cells were a possiblity...

Yes, it's a possibility. My new A123 20Ah pouch is charged to 3.65V. After 24hrs, the voltage is at 3.62V. My other no-name, cheap 8Ah prismatic LiFePO4 is charged to 3.60V, after 24hrs the voltage is at 3.52V.

Again, there is nothing wrong with a 15s 48V LiFePO4 pack. 3.2V x 15 = 48.0V, or 49.5V at 3.3V nominal. Consider the extra 1s in 16s pack a gift. Just like LiCo, a 13s pack is 48.1V nominal, so a 14s pack is a 1s gift.

 

[geeeyejo1]

It got me thinking though - is it possible that the Sunthing pack is 15 cells instead of 16? 53.4V for 15 cells would equate to 3.56V per cell. This might also explain his lower pricing on a pack versus other vendors. Once again - not going to rip open the pack or BMS until I experience any performance issue - just wanted to know if 15 cells were a possiblity...

Yes, it's a possibility. My new A123 20Ah pouch is charged to 3.65V. After 24hrs, the voltage is at 3.62V. My other no-name, cheap 8Ah prismatic LiFePO4 is charged to 3.60V, after 24hrs the voltage is at 3.52V.

Thanks - good to know that it is within a reasonable voltage range - honestly as long as I have good range, am not hitting LVC and can cruise at 25mph+ ; I have no reason to start breaking open that neat package...

 

[999zip999]

Only one way to answer your question.
This a new vendor to us. Put on the charger and see if it will pick up some voltage after given a chance ( time ) on the charger to balance and fill the low cells.

 

[SamTexas]

Thanks - good to know that it is within a reasonable voltage range - honestly as long as I have good range, am not hitting LVC and can cruise at 25mph+ ; I have no reason to start breaking open that neat package...

You're welcome. Agreed, no reason to open it up now.

 

[DAND214]

When fully charged the pack goes to 60.3V. After I disconnect the pack from the charger, the surface charge slowly dissipates and within roughly 24 hours the pack settles at 53.4V.

At that voltage you are charging to 4v+ per cell if it is a 15 cell pack.

Sorry I'm in on Dnmun

dnmun wrote:
this is a joke.

Relax, it is a pouch pack battery, they will loose surface charge more than others. If it is a 15 cell it won't last long, chargeing to 4v per cell.
Does it have the LED BMS on it like a Ping? All you have to do is count the LEDS to see how many are there. Or count the resistors.

Dan

 

[dnmun]

the guy who sold it says it is a 16cell pack. you can count the pouches in the picture.

 

[geeeyejo1]

[/quote]

Relax, it is a pouch pack battery, they will loose surface charge more than others. If it is a 15 cell it won't last long, chargeing to 4v per cell.
Does it have the LED BMS on it like a Ping? All you have to do is count the LEDS to see how many are there. Or count the resistors.

Dan[/quote]
BMS is shrink wrapped but will peek closer this weekend - can't I count wires between pack and BMS versus opening the shrink wrap?
If in fact it is 16 Cell isn't 53.4v too low after sitting for a day? - after an hour or two the pack sits at about 55.7 and slowly goes down to 53.4 within the next day... I do have a voltmeter on constantly but understand it only draws about 20MA - could the voltmeter coupled with BMS draw account for the pack going down to 53.4?

 

[dnmun]

yes.

 

[SamTexas]

I do have a voltmeter on constantly but understand it only draws about 20MA -

Are you sure? Are you using an analog voltmeter?

 

[DAND214]

yes.

You say so much with so liitle!

Dan

 

[geeeyejo1]

I do have a voltmeter on constantly but understand it only draws about 20MA -

Are you sure? Are you using an analog voltmeter?

It is a digital voltmeter with an LED display - manufacturer spec is 20MA draw - it is rather bright and makes sense that it is using some current - combined with BMS probably eats 1AH+ per day? I probably should switch it or pull my fuse when not using the pack but I charge a few times a week regardless if I use the bike or not so pack is always being topped off...

 

[geeeyejo1]

yes.

Assume "yes" for all three questions? In the future responses in the format "yes/yes/yes" would be preferred for clarity...lol
Oh wait, I get it - you are saving power consumption on your wireless keyboard... :lol:

 

[SamTexas]

It is a digital voltmeter with an LED display - manufacturer spec is 20MA draw - it is rather bright and makes sense that it is using some current - combined with BMS probably eats 1AH+ per day? I probably should switch it or pull my fuse when not using the pack but I charge a few times a week regardless if I use the bike or not so pack is always being topped off...

I could be wrong here, but I don't think you are reading it right. The 20mA draw is from the voltmeter batttery, not the battery that is being measured.

BTW Dan214 has a point about the upper 4+V.

 

[geeeyejo1]

It is a digital voltmeter with an LED display - manufacturer spec is 20MA draw - it is rather bright and makes sense that it is using some current - combined with BMS probably eats 1AH+ per day? I probably should switch it or pull my fuse when not using the pack but I charge a few times a week regardless if I use the bike or not so pack is always being topped off...

I could be wrong here, but I don't think you are reading it right. The 20mA draw is from the voltmeter batttery, not the battery that is being measured.

BTW Dan214 has a point about the upper 4+V.

This is a small voltage display meter - not a true multi function voltmeter with a battery to power it - it is the $5 or so waterproof unit that has been used by some members available on Ebay - so assuming the 20MA draw is what the display uses? Here is a pic

 

[SamTexas]

OK. I thought you have a regular digital voltmeter. Makes sense now.

 

[geeeyejo1]

OK. I thought you have a regular digital voltmeter. Makes sense now.

I do of course (actually two of them) but not hard wired into my battery pack, lol :lol:

 

[melodious]

I wasn't going to comment but your starting to stray away from the fact you really need to check the # of cells in your pack. THAT will determine the next step on how to deal with your battery. That is, unless you can proove your multimeter & BMS was drawing it down.

 

[parabellum]

Yes, you will find few people just collecting posts here, mostly not informative, with no sense or even not related to the issue (they do not read what your issue is) they just post. I think, you need to count your cells in some physical way, ether counting the ribs on your shrink wrap or balancing wires or examining your BMS, what ever is the easiest way. Anyway, something is wrong, is it 15s or 16s.

 

[parabellum]

P.S. melodious was first writing same conclusion

 

[geeeyejo1]

I wasn't going to comment but your starting to stray away from the fact you really need to check the # of cells in your pack. THAT will determine the next step on how to deal with your battery. That is, unless you can proove your multimeter & BMS was drawing it down.

Agreed - I will take a look over the weekend to confirm number of cells. Does anyone know if there is a standard AH draw from a bms? I have read up to 70MA? If so then how long should a 16s pack remain at the "correct" voltage of 56V or so before the draw of the BMS brings the voltage down?

 

[geeeyejo1]

Update - I charged my pack last night and as usual up to 60.3V - I pulled my blade fuse (cutting power to my voltmeter display) - Just got home about 24 hours later - plugged back in my fuse and she is reading 56.4V - YAAAYYY! Appears that bright LED is sucking more current than I thought - gonna leave it off from now on when not using my battery.

 

[999zip999]

I unplug my battery so nothing drains but that me and my setup.