Sunthing28 Battery Review

Well as per previous post I finally received my 48V15AH LIFEPO4 battery and charger from Sunthing28 on Ebay.
Battery was received exactly in time committed by vendor - he said 7-8 weeks -here today just 7.5 weeks after purchase. Battery arrived in a yellow taped cardboard box secured with two plastic shipping straps. Inside of box battery and charger were centered in a good amount of scrap styrofoam packing. Battery and Charger were both bubble wrapped in a few layers and wrapped in saran underneath for further protection.
Stupid me - didn't realize that LIFEPO4 has leads for power (red and black) along with a plug from the BMS that matches plug on the charger for charging - was thinking I would need to use one standard plug for both - will leave charger plug for now. Power leads were taped to avoid shorting and just needed stripping and connection to my custom controller connector. I connected the bayonet fuse block (not from my kit!) to the positive lead then spliced in a waterproof voltmeter along with the positive lead from the block to the plug that will connect to my controller (thank you Home Depot) I then connected the negative lead to the plug and secured all the assemblies with tape.
The battery was at 51V when I unpacked it and after a quick dinner and the time to make the connections was already up to 54V. Fan came on charger to cool it so appears it is working properly. I just checked and only up to 54.1V - seems like it is charging slower now - red light is still on charger and has not turned green yet so I guess pack is taking it's time to balance. Vendor states fully charged range is 51-57V with a 58.2V maximum range so I assume it is getting there.
I am so tempted to connect her to see if the motor actually works as the bike has been assembled and tweaked for over a month now - just waiting for this battery!
My plan is to let battery balance, once fully charged then connect and run motor with bike lifted for a few minutes. Then balance charge again, then take her for a short test ride. After that my daily use shouldn't deplete more than 1/3 of the capacity and will charge nightly.
My stupid Iphone is having an issue with sending pics to my email but was able to upload first three of package as it arrived. More to follow!

measure the cell voltages while it is charging. see if the cells on the bottom are lower in voltage than the others. measure while charging!

dnmun said:

measure the cell voltages while it is charging. see if the cells on the bottom are lower in voltage than the others. measure while charging!

Click to expand...

Everything is nicely packed including the BMS in shrink wrap - hesitant to start unwrapping to get to the BMS terminals to monitor unless I suspect a problem. Up to 54.4 now - slowly but steadily climbing after about 2 hours or so. How long should I expect this initial charge to take?

Ok Iphone appears to have stopped crapping out - the plastic battery box I planned on using was too small on the ID to fit the battery with padding. I had this padded cooler bag that was a gift from a company function a few years back - fits the battery with several layers of bubble wrap and a good wad of it on the bottom and then fits in the triangle! I plan on strapping it to the top tube with a nice wide velcro strap.
Pic shows my new pack charging and the Home depot plug controller connector (actually works excellent!) along with the voltmeter I secured to my inline fuse block. Working great so far and letting me monitor pack voltage during charging. I "cheated" a little (see other post) and hooked her up for a VERY quick bench test to see if my bike actually works - IT DOES - YAAAYYY!
Will provide further updates on battery after balanced, used, etc - but so far - SO GOOD!

(Admin - may want to move this to "Reviews" - my mistake, sorry!)
Update - after a quick spin around the block last night I let the battery charge over night. I checked after a few hours and charger was green but voltage was only reading 55V. I unplugged and in AM (with LED voltmeter running for a few hours) pack was reading just under 54V. I plugged in again and pack went to 54.7 rather quickly and green light came on indicating a full charge.
Rode to work and used about 5AH for the 5 mile commute. I brought my charger this first day and within two hours charging pack had hit 56V and charger was green. Appears the pack needed to discharge a bit then balance again to get to full capacity. Appears ok and performance was good this AM. After 5 miles of mostly WOT the 54.7V only went to about 52.5V before charging - well above the LVC. Guessing range at 15 miles without peddling at 20mph and 10 miles at WOT without fully depleting the pack.
Will continue to monitor and update but so far so good and appears to be a great value at $426 delivered!

green light on the charger does not mean full charge, it means the pack is not accepting charge any more. since you won't measure the cell voltages there is no way to know which cell is cutting it off.

dnmun said:

green light on the charger does not mean full charge, it means the pack is not accepting charge any more. since you won't measure the cell voltages there is no way to know which cell is cutting it off.

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Thanks - if pack continues to cut off below 56V then I will open BMS and check individual cells. As of last charge 56V at green light should be fine, no?

no, 56V is not charged. 59V is charged. you should not have to open the BMS, just measure on the sense wires. one of the cells is pegged on 3.9V and shutting off the charger. you have to leave it charging to get the pack to balance.

dnmun said:

no, 56V is not charged. 59V is charged. you should not have to open the BMS, just measure on the sense wires. one of the cells is pegged on 3.9V and shutting off the charger. you have to leave it charging to get the pack to balance.

Click to expand...

Ok so leave charger connected to pack when light is green and pack will balance? I also read somewhere that 3.5V per cell is charged for LIFEPO4 - hence 16 cell pack x 3.5 = 56V - is the number actually 3.9V? Vendor states a range of 53 - 57V one hour after pack is charged....

no, fully charged for lifepo4 is 3.65. 3.9V is where the charging mosfet turns off. your pack is not even close to balanced. it has to stay at 59V for along time to balance. that was why i told you to measure the cells, so you would actually know something useful.

Thanks - voltage has been jumping around mid 56V to mid 57V range so heading in right direction - will look to check individual cell voltages off BMS leads this weekend - thanks!

geeeyejo1, how is your battery doing? Please update when you have time.

no update? intrested to know how its going, is it one of sunthings newer model batteries with the a123 style pouch cells that are in blue shrink wrap or the older grey duct tape wrapped ones?

I'm also curious to know if it is a newer blue shrink wrapped ones, or the older grey duct taped models. Is there any other differences between the two?

How is the battery going?

"Vendor states fully charged range is 51-57V"

that's not a good sign