Dongguan Lighting: Purchase 280AH LiFePo4 cells. Purchase & Review

[LukeVader]

Both of my batteries, a 24v BYD battery and a 24v sinepoly. while at rest after a full charge will settle around 3.35 volts - 3.34 volts. That seems to be the average voltage for these batteries at rest after a full charge. The BYD is used and the sinepolys are new.

Ok thanks for that. This is what these cells are doing to me.
Charge to 3.35v take off charger.
2 hrs later cells all at 3.341v
6.5 hrs later cells all at 3.338v
24 hrs later cells all at 3.336v this time. I'm now doing a supervised charge to 3.65v and see where they settle.

 

[bdbugbee]

What size did you cut your copper bus bars to?

Also, in order to speed things up, couldn't you series connect your batteries into their final configuration and use your main power charger source to charge the whole battery bank with a BMS installed to watch individual cell voltages? Then when the highest voltage cell reaches the voltage limit, the BMS shuts down the charging. You could then reconfigure the batteries back to parallel to fine tune the charge at 3.65V from there.

 

[Montana]

Will addressed placement of the charging cables in his top balancing video- his conclusion was that the current involved from that power supply was so small compared to the busbar capability, that charging from one end of the parallel cell pack would be okay. Although saying that, I still hooked my positive and negative charging cables up from opposite ends of the parallel cell pack. That would be more important if you switch to a higher amp charge

 

[Cheesewiz]

Ok thanks for that. This is what these cells are doing to me.
Charge to 3.35v take off charger.
2 hrs later cells all at 3.341v
6.5 hrs later cells all at 3.338v
24 hrs later cells all at 3.336v this time. I'm now doing a supervised charge to 3.65v and see where they settle.

That looks like my cells after surface voltage drop and i'm using 90% capacity set up.

 

[LukeVader]

What size did you cut your copper bus bars to?

Also, in order to speed things up, couldn't you series connect your batteries into their final configuration and use your main power charger source to charge the whole battery bank with a BMS installed to watch individual cell voltages? Then when the highest voltage cell reaches the voltage limit, the BMS shuts down the charging. You could then reconfigure the batteries back to parallel to fine tune the charge at 3.65V from there.

My copper bus bars are homemade. I bought a 12 ft 1/2 copper pipe, it was $16 and a 6ft was $13. Crazy.

I cut it in half then tried to drive over it and squash it with a board. It was too strong and the tip only crushed. I had to cut them 4.5" first on my metal chop saw then I drove over them. That still didn't work out too well because the bottom was flat but the top had two small half spaces in it. It looked like a flattened B sideways. I still had to use a hammer to finish them off.

The thing is l don't have possession of a BMS yet. I've ordered 2 different ones but they are still being shipped.

 

[Sgt Raven]

My copper bus bars are homemade. I bought a 12 ft 1/2 copper pipe because it was $16 cause a 6ft was $13. Crazy.

I cut it in half then tried to drive over it and squash it with a board. It was too strong and the tip only crushed. I had to cut them 4.5" first on my metal chop saw then I drove over them. That still didn't work out too well because the bottom was flat but the top had two small half spaces in it. It looked like a flattened B sideways. I still had to use a hammer to finish them off.

The thing is l don't have possession of a BMS yet. I've ordered 2 different ones but they are still being shipped.

When I ordered my 4AWG cable lugs, the price per piece for 2 or 10, compared to 25 was ridiculous. Even though I'll probably only use half of them.

If you want the pipe bus bars to look pretty. Use a piece of steel, say 100mm x 150mm 6mm thick. Place it over the piece of pipe and hammer on it. They should come out without all the hammer marks on them because you're spreading the force over a larger area.
I could make real nice looking ones with a 20 ton hydraulic press.

 

[LukeVader]

I guess there could be an art to making a "nice" bus bar...... but its a bus bar!!! LOL, hammer away on them, they still work the same.

 

[Sgt Raven]

I guess there could be an art to making a "nice" bus bar...... but its a bus bar!!! LOL, hammer away on them, they still work the same.

Depends on your level of OCD......

 

[JoeHam]

Depends on your level of OCD......

Excuse me but it’s CDO!

You must put the letters in the correct alphabetical order or it’s just crazy! ?

 

[LukeVader]

Update, these cells are more mind boggling to me than I imagined. I put them back on the PS around 14 hours ago @3.64v 7.5A, it took about an hr for the multimeter to read 3.35v again from 3.336v

Ok no problem, so here it is 14 hours later and the PS is still quiet and cool humming away around pumping power into the cells about 7A and the multimeters still reading 3.35v???

Cells are not warm or pillowed, so who knows. Night all.

 

[Sgt Raven]

Update, these cells are more mind boggling to me than I imagined. I put them back on the PS around 14 hours ago @3.64v 7.5A, it took about an hr for the multimeter to read 3.35v again from 3.336v

Ok no problem, so here it is 14 hours later and the PS is still quiet and cool humming away around pumping power into the cells about 7A and the multimeters still reading 3.35v???

Cells are not warm or pillowed, so who knows. Night all.

They're going to reach a certain point and just start filling up real fast compared to this point. Maybe when they hit 3.4V. During my week long discharge test, the battery hung out at 13,4V forever and that is also 3.35V per cell.

 

[LukeVader]

Morning Sgt, yes I remember you mentioning that before but I figure I've got another obstacle over your charge. You only have 4 cells, I have 8. It will take twice as long for me.

So, I ran downstairs into the garage and they're at 3.354V now lol.

 

[JoeHam]

Morning Sgt, yes I remember you mentioning that before but I figure I've got another obstacle over your charge. You only have 4 cells, I have 8. It will take twice as long for me.

And I have 16. But they’re just the 60Ah Fortune cells.

Charging with solar and a BMS so I don’t have to babysit them. And I’m only trying to get to 3.4v.

 

[BigVT]

FWIW regarding the dropping voltage, here is some data from a session when I was charging a 48v pack (from Xuba) with 30A. I'm a newbie and a bit confused with voltage dropping while charging. Seems to be working so maybe it's WAI...

 

[LukeVader]

That kinda makes sense to me @BigVT . The cells were at 3.354V this morning, and now 7 hours later still while being charged they say 3.353V now. ??

 

[Sgt Raven]

That kinda makes sense to me @BigVT . The cells were at 3.354V this morning, and now 7 hours later still while being charged they say 3.353V now. ??

Mine bounced up and down by a few 0.00xV. Part of it could be your DMM. Lots of DMMs are only accurate to 0.5% + 5 counts. That 0.001V could be within it's range of error.

 

[LukeVader]

48hrs later...3.355v still charging.

 

[Sgt Raven]

48hrs later...3.355v still charging.

I know the frustration you're feeling, but believe me, I think real soon they're gonna take off and start filling up pretty fast. You should only have to do this once. Then with a good BMS, you'll be able to charge the battery up faster. I think the change will be around 3.36V. You're getting close.

After my big test, I used a 40A regular battery charger to fill it back up. Just next time I do that, I'll stop at 13.87V and top it off with my bench PS. I was lucky and my Smart BMS worked like it is suppose to when I fast charged it. Because mine went from 13.88V to 14V in the last 10 minute charging period. I had a 10 minute timer set on my phone to keep checking on it. That charging session started out taking 35A and was still taking 20A when it shut off at the end.

 

[elimac_pt]

I had a good quotation from Dongguan. It beats Xuba by a margin. What is the general feeling about both these sellers? I'm kind of undecided...

 

[LukeVader]

They're the same cell as Amy, they have the same QR code so they probably have the same source. Dongguans have been as advertised so far.
Update my cells are @ 3.368V with about 215 hours in them.