Our NEW GO-TO LiFePO4 vendor...09.20.21
- Thread starter ghostwriter66
- Start date
No. No sure for Sweden, but for most EU countries vendors provide a DDP shipping method (Delivery Duty Paid) which includes all customs and vat handlings.
Horsefly said:
Interesting! I was not aware of this.
speculation:
If the anode (+) and the case are insulated from each other and close enough together then they might form a parasitic capacitor that could explain the voltage.
But this kind of assumes there is no such capacitance (or much much less) between the case and the cathode. Otherwise the case voltage would be something less than the battery voltage - which it wasn't.
I've thought of some experiments I could do like try to measure that capacitance, or try to charge up that capacitor ... both of which seem like not such a good idea for a battery rookie. What could possibly go wrong
Or it could simply be cheaper to not add an insulating layer to the "jelly roll" to prevent the anode from contacting the case, and just insulate the case on the outside with pretty blue plastic. Such a layer might also take up space and reduce the volumetric capacity of the battery.
Interesting! I was not aware of this.
speculation:
If the anode (+) and the case are insulated from each other and close enough together then they might form a parasitic capacitor that could explain the voltage.
But this kind of assumes there is no such capacitance (or much much less) between the case and the cathode. Otherwise the case voltage would be something less than the battery voltage - which it wasn't.
I've thought of some experiments I could do like try to measure that capacitance, or try to charge up that capacitor ... both of which seem like not such a good idea for a battery rookie. What could possibly go wrong
Or it could simply be cheaper to not add an insulating layer to the "jelly roll" to prevent the anode from contacting the case, and just insulate the case on the outside with pretty blue plastic. Such a layer might also take up space and reduce the volumetric capacity of the battery.
Horsefly
Solar Wizard
Well, I should point out that although I've tested a couple of cells and don't see any current between the case and either terminal, I still do like most others and try to insulate the case from each cell from other cells and from any possible short to either terminal. I don't think there is an issue, but I don't want to take a chance.Horsefly said:
Interesting! I was not aware of this.
speculation:
If the anode (+) and the case are insulated from each other and close enough together then they might form a parasitic capacitor that could explain the voltage.
But this kind of assumes there is no such capacitance (or much much less) between the case and the cathode. Otherwise the case voltage would be something less than the battery voltage - which it wasn't.
I've thought of some experiments I could do like try to measure that capacitance, or try to charge up that capacitor ... both of which seem like not such a good idea for a battery rookie. What could possibly go wrong
Or it could simply be cheaper to not add an insulating layer to the "jelly roll" to prevent the anode from contacting the case, and just insulate the case on the outside with pretty blue plastic. Such a layer might also take up space and reduce the volumetric capacity of the battery.
Patrick_Cashman
New Member
- Joined
- Sep 15, 2021
- Messages
- 17
On the charging issues - JRed and I recently got my batteries in and top balanced them. He got them a few days before I got there and put them in sets of 4 on a 12V Victron charger without a BMS. 2 of the cells went up to 3.8V before he caught it and shut them down.
I ordered an iCharger S6 which arrived the same day I got there. We hooked up each set of 4 in parallel and charged at 3.65V. The iCharger is awesome, by the way. 40A at any voltage you want up to around 14.6V. (maybe higher, I haven't checked) Most of the sets were full in 10-20 minutes, but 2 of the groups ran much longer. I forget the exact amount of time but it was around 10 hours. From 0 it would have taken 28 hours at 40A, and was nowhere near that.
The 2 cells that went high settled right back down once we put them in parallel. They are now working in the full 16s banks, and are all balanced to within 10mV. There was no swelling at all. So a bit of over-voltage is fine, nothing to worry about. Along the way I did some research and found that people used to charge these above 4V and discovered that battery life suffered, so they gradually eased it back and 3.65 as a max is now a de-facto standard. But that does not mean they can't ever go over that and will immediately die. It's more like many cycles at higher voltages will begin to do damage and shorten life.
I recommend the iCharger. S6 is 40A, X6, X8, and X12 are 30A. All are fairly similar, just have different numbers of balance leads. Their price/performance/precision/flexibility is better than any other charger I've seen for the 0-15V range.
I ordered an iCharger S6 which arrived the same day I got there. We hooked up each set of 4 in parallel and charged at 3.65V. The iCharger is awesome, by the way. 40A at any voltage you want up to around 14.6V. (maybe higher, I haven't checked) Most of the sets were full in 10-20 minutes, but 2 of the groups ran much longer. I forget the exact amount of time but it was around 10 hours. From 0 it would have taken 28 hours at 40A, and was nowhere near that.
The 2 cells that went high settled right back down once we put them in parallel. They are now working in the full 16s banks, and are all balanced to within 10mV. There was no swelling at all. So a bit of over-voltage is fine, nothing to worry about. Along the way I did some research and found that people used to charge these above 4V and discovered that battery life suffered, so they gradually eased it back and 3.65 as a max is now a de-facto standard. But that does not mean they can't ever go over that and will immediately die. It's more like many cycles at higher voltages will begin to do damage and shorten life.
I recommend the iCharger. S6 is 40A, X6, X8, and X12 are 30A. All are fairly similar, just have different numbers of balance leads. Their price/performance/precision/flexibility is better than any other charger I've seen for the 0-15V range.
RandallCothren
New Member
- Joined
- Dec 10, 2021
- Messages
- 3
I wanted to leave a positive review for Jenny Wu.
When I first entered into the Alibaba marketplace I could not get comfortable making a purchase because honestly anything could go wrong. I felt like ordering directly from the mainland could be a very risky venture.
Finally I was nosing around and found some extremely positive reviews about Jenny and people said such great things about her. I decided to take a chance with her as an Alibaba representative. There was no sterilized BOT language, she was absolutely on the money from the minute I contacted her all the way through. I was thankful she was able to find four 3.2, 280 amp hour cells in stock in Houston.
This may not be typical but I received them in one week.
I also decided to order a BMS from Jenny and I waited for a while and after about two weeks I began to wonder what was going on.
They seemed to be in UPS tracking number limbo.
After about another week it appeared that they were lost or stolen and there was some delay on what we were going to do next. I got a little upset and said enough's enough. Either a refund or a replacement.
Jenny came through with an excellent replacement and I received it within a week and I couldn't be more pleased with the customer service she provided.
In other words some aspects of the sale didn't go perfect but she did everything right to resolve it so what more can I ask. I cannot speak for all of Ali baba but Jenny Wu is amazing.
Randall Cothren
Bud Martin
Solar Wizard
- Joined
- Aug 27, 2020
- Messages
- 4,844
There is no need to charge the cell to 3.65V, you really do not gain much of anything, @3.45V is 99.5% SOC, 3.375V is 99% SOC, most in the forum set it to 3.35V (90% SOC)
Patrick_Cashman
New Member
- Joined
- Sep 15, 2021
- Messages
- 17
Thanks Bud. This was my first time doing this so I am not deeply familiar with these charging profiles. That's useful information. I've looked in a number of places for clarity on this point and there is a lot of conflicting information out there.
My main points were that if a cell goes a bit high for a short time it will most likely be ok, and the iCharger is a dope unit that is very versatile and useful.
Alright folks... just made my very first order on cells and on Alibaba in general. Thank you all for the very good reports and hints otherwise i would have probably quit this project.
Went with Daisy Efest from Docan and ordered EVE LF280k cells. now patiently waiting until they arrive in germany
Went with Daisy Efest from Docan and ordered EVE LF280k cells. now patiently waiting until they arrive in germany
Congrats, when will you have Server Rack batteries to sell? Is your company considering this?
sidpost
New Member
Congratulations Jenny!
triplethreat
Solar Enthusiast
- Joined
- Oct 12, 2021
- Messages
- 129
Congratulations young lady.....and many, many years of happiness in front of you.
Snowynorth
New Member
- Joined
- Jan 10, 2022
- Messages
- 177
I'm interested as well. A guy near us builds good batteries at a decent price, but more racks, and walls with quality inside would be of interest.
That's one reason why we put the cells in a compression fixture.
