EVE matched cells, some cells drops very fast

[Honuz]

I think if cells are within 98% capacity, folks have 9 capacity tests to run before complaining..3 each 0.33CA, 0.5CA & 1CA discharges respectively.

I also read something, somewhere in this forum, that as the individual done more testing, their figures came up, the more cycling they done, but i dont understand the mechanism for this happening?
Any idea's how this could be possible?

My nimh charger got a refresh function, it charge the battery then discharge at a known rate and calculate the capacity, then it recharge again and redo the process till the improvement is under a threshold.
I do not know if it apply to LiFePo4, it certainly inherent to the chemistry.

 

[snoobler]

My nimh charger got a refresh function, it charge the battery then discharge at a known rate and calculate the capacity, then it recharge again and redo the process till the improvement is under a threshold.
I do not know if it apply to LiFePo4, it certainly inherent to the chemistry.

That's specifically to address capacity loss due to voltage depression from short cycling and over-charge. It ONLY applies to NiMH and NiCd chemistry. It has no benefit to LFP or any other battery chemistry. In those cases, it's typically detrimental.

 

[Gazoo]

Riden 6012w or 6018w - buy one ---- yes, I found out you have to buy the clock battery - not included; you have to buy a power cord for the power supply - not included; you have to buy the banana post leads with an alligator clamp on the other end - not included; (I bought 20 amp capable silicone ones. buy the better ones assemble it. it works great with good accuracy. I have the Riden 6012w which means wifi. I ordered the 6018w with a 1200 watt power supply.. it is on its way. somewhere on a boat ride but it has been shipped. probably after Christmas before I get to assembly the 6018w. I really like the Riden 6012w so had to order the 6018w as the upgrade to the solar power shed.
we are having a white Christmas here at pilgrimvalley in South Dakota....yea ....ho ho ho! snowed about 5 inches today.

Yes, clock battery and power cord. Banana plugs and alligator clips are crap anyways and so are the DC cables that come with cheap power supplies. I used 12awg silicone wire with 1/4 inch ring terminals for connecting to the battery side, and I used the fork terminals that came with the Riden for connecting to the Riden. I soldered everything.

Bah humbug....lol. I am originally from Montana and miss the snow, but not the cold. Currently in Texas. Enjoy the snow and Merry Christmas..

 

[michael d]

Yes, clock battery and power cord. Banana plugs and alligator clips are crap anyways and so are the DC cables that come with cheap power supplies. I used 12awg silicone wire with 1/4 inch ring terminals for connecting to the battery side, and I used the fork terminals that came with the Riden for connecting to the Riden. I soldered everything.

Bah humbug....lol. I am originally from Montana and miss the snow, but not the cold. Currently in Texas. Enjoy the snow and Merry Christmas..

I lived in Montana for a year and traveled the state extensively for work in 2006. it is a great place for sure.

 

[Pyrofx]

Ride is on the way. What size is the clock batt?

 

[michael d]

Ride is on the way. What size is the clock batt?

cr1220; this what i put in the 6012w, you also need a power cord. i bought one on ebay etc

 

[Honuz]

Y

That's specifically to address capacity loss due to voltage depression from short cycling and over-charge. It ONLY applies to NiMH and NiCd chemistry. It has no benefit to LFP or any other battery chemistry. In those cases, it's typically detrimental.

Thanks, an other confirmation that it.do not apply to Lithium.

 

[Honuz]

Yes, clock battery and power cord. Banana plugs and alligator clips are crap anyways and so are the DC cables that come with cheap power supplies. I used 12awg silicone wire with 1/4 inch ring terminals for connecting to the battery side, and I used the fork terminals that came with the Riden for connecting to the Riden. I soldered everything.

Bah humbug....lol. I am originally from Montana and miss the snow, but not the cold. Currently in Texas. Enjoy the snow and Merry Christmas..

I will solder them too, I'm more confident to soldered connections.
I took the 800w65v that is sold by riden seller. But soon I will get rid of the box and power the riden directly from the Eve battery pack (I will most certainly never use higher voltage then 48v). Will save me the use of the inverter and certainly give me a cleaner signal, and the riden will fit a smaller box...all good.
My house which I'm building will be totally off grid, I try to optimise the use of the inverter.

 

[cinergi]

Had they all been sold as 272's you would be delighted. As 280's, there are a fairly high number below 98% capacity. I'll be interested to see your final tally. How much have you varied the C rates?

All at 15 amps. 8 more cells to go ...

 

[michael d]

I will solder them too, I'm more confident to soldered connections.
I took the 800w65v that is sold by riden seller. But soon I will get rid of the box and power the riden directly from the Eve battery pack (I will most certainly never use higher voltage then 48v). Will save me the use of the inverter and certainly give me a cleaner signal, and the riden will fit a smaller box...all good.
My house which I'm building will be totally off grid, I try to optimise the use of the inverter.

you can buy 48-volt lights and 24-volt lights led type on aliexpress if you search for them. I think one could utilize this to minimize inverter use. the inverter is a power thief for sure. or put up more solar panels and a bigger battery. expensive. always best to conserve energy--- use more insulation in the house was always a priority.

 

[Honuz]

you can buy 48-volt lights and 24-volt lights led type on aliexpress if you search for them. I think one could utilize this to minimize inverter use. the inverter is a power thief for sure. or put up more solar panels and a bigger battery. expensive. always best to conserve energy--- use more insulation in the house was always a priority.

Yes, I will build 2 circuis, one 48v (lights, water pump, aquarium pump..things that can be used at night/day. And a 220v which will be pretty simple, in the kitchen and in the office to use "normal" devices.
There is not that much 48v downlight or led strips, but 24v are pretty common. I've also found some led controllers that connect directly to the 24v and control those leds, some are 2.4ghz, some do not. For the time being the only solution I got is a 48v-24v converter.. between the battery pack and the controller which consume some energy even when sleeping...not a fan. Or I will add a wall switch under those controllers :
Battery pack -> switch -> 48v-24v converter -> Control panel -> lights. (Most of those controllers switch the light on when being powered).

 

[tabs_xyz]

If that ends up coming to fruition and it is verifiable and more transparent than the current situation that will be a very nice option to have available (if it comes in below the cost of buying direct from the manufacturers)

I suspect many folks will continue buying the currently popular unmatched non-grade-A cells, but choice is good, I know I would strongly consider paying the premium for known quality matched cells, particularly if it includes a test report and documentation like CALB cells come with.

I will solder them too, I'm more confident to soldered connections.
I took the 800w65v that is sold by riden seller. But soon I will get rid of the box and power the riden directly from the Eve battery pack (I will most certainly never use higher voltage then 48v). Will save me the use of the inverter and certainly give me a cleaner signal, and the riden will fit a smaller box...all good.
My house which I'm building will be totally off grid, I try to optimise the use of the inverter.

Soldering is clean, convenient, and lasts when done right, with less chance of corrosion and oxidation occurring. BUT...if your goal is to mitigate as much resistance as possible, then consider crimping instead. A good crimper and good quality tinned/copper lugs are superior to solder and has less resistance than even crimp + solder, which is somewhere between, as far as resistance is concerned. Look at any prefab, high current cabling and jumpers, jumper cables, welding cables and clamps. High current tends to melt solder when things go south but the primary reason is lower resistance.

 

[Honuz]

Soldering is clean, convenient, and lasts when done right, with less chance of corrosion and oxidation occurring. BUT...if your goal is to mitigate as much resistance as possible, then consider crimping instead. A good crimper and good quality tinned/copper lugs are superior to solder and has less resistance than even crimp + solder, which is somewhere between, as far as resistance is concerned. Look at any prefab, high current cabling and jumpers, jumper cables, welding cables and clamps. High current tends to melt solder when things go south but the primary reason is lower resistance.

Hello,
You will have to explain why a crimped+solder connection got more resistance (electrically speaking) then just a crimped one. Injection of solder will not prevent cu to be in contact with the lug. It I'll eventually fill some holes (that should not exist in the perfect world).
The big disadvantage of soldering...is in a vibration context where it could make the connection stiffer and could more easily break.

 

[Just John]

Around 90dollars per cell. I was told by the supplier that these are "matched" cells. But I've just read what you guys posted and I think these are not really "matched".

I tried to capacity test, but BMS hit low cut-off voltage too early because of 2 "runner" cells. Then I tried to charge-discharge-charge while figuring out what could have been the issue.

#2 - 0.10 to 0.20 mΩ ( see attached picture for the tool they use to show me the "internal resistance" of each cells)

#3 0.2V difference occurs at any SoC as long as we have more than 20amps. At 10-15 amps, the difference is lower and is tolerable.

#4 I have SMART DALY bms but I haven't changed any settings related to balancing. I just notice that it is enabled during charging. There is a setting called "balanced open start volt" which is set to 3.20V by default, and "balanced open diff volt" which is set to 0.05V my default.

Thank you!

Just an FYI, the meter you show testing the internal resistance of the cells? The manual I have for it specifically states that above 100AH capacity it is inaccurate. (Yes, I have a YR1035+)

 

[Steve_S]

Just an FYI, the meter you show testing the internal resistance of the cells? The manual I have for it specifically states that above 100AH capacity it is inaccurate. (Yes, I have a YR1035+)

I also have a new YR1035+, on my EVE 280's it reports .17mΩ - .18mΩ on the cells.
My 180W capacity tester shows between .13 & .14Ω with a 20A pulling off the cell.

 

[Gazoo]

Soldering is clean, convenient, and lasts when done right, with less chance of corrosion and oxidation occurring. BUT...if your goal is to mitigate as much resistance as possible, then consider crimping instead. A good crimper and good quality tinned/copper lugs are superior to solder and has less resistance than even crimp + solder, which is somewhere between, as far as resistance is concerned. Look at any prefab, high current cabling and jumpers, jumper cables, welding cables and clamps. High current tends to melt solder when things go south but the primary reason is lower resistance.

I don't know about all of that. We are using less than 20 amps depending on the Riden. And I also soldered the ring terminals on my BMS wires. Personally for those types of things I prefer solder over crimping.

If using main battery inverter cables or whatever, then yes crimped is recommended and that's what I use.

 

[Just John]

I am sure you will like it. The 18 amp version came out soon after I received the 12 amp version. It comes with a temp. sensor too which I taped to the top of the power supply.

I am ordering the 18 amp board myself, like you I got the 12 amp kit. So I am just ordering the board and will use the same case and power supply.

One other thing...get the clock battery. Especially if you got the wifi board. You want to put the battery in because the wifi board covers it up and it can be tricky to remove for the battery install as I found out.

Fortunately Amazon delivered the correct battery early the next morning. It is a nice power supply.

 

[tabs_xyz]

Hello,
You will have to explain why a crimped+solder connection got more resistance (electrically speaking) then just a crimped one. Injection of solder will not prevent cu to be in contact with the lug. It I'll eventually fill some holes (that should not exist in the perfect world).
The big disadvantage of soldering...is in a vibration context where it could make the connection stiffer and could more easily break.

I agree with you fully. Some years ago, I witnessed what I stated and I cannot explain it since I'm no chemist. It was an interesting observation for sure. Solder flows onto clean copper surfaces like oil does on metal, making its way into the tightest of joints. Is it possible for solder to make its way between tightly compressed surfaces? I don't see how. I suppose if the solder molecules are small enough, I reckon solder could invade those surfaces and potentially disrupt the physical contact from the heat causing expansion and contraction at a molecular level. That's my totally unscientific hypothesis. I can add that the resistance delta between crimp + solder and just a crimp is very small compared to a soldered lug

 

[tabs_xyz]

I agree with you fully. Some years ago, I witnessed what I stated and I cannot explain it since I'm no chemist. It was an interesting observation for sure. Solder flows onto clean copper surfaces like oil does on metal, making its way into the tightest of joints. Is it possible for solder to make its way between tightly compressed surfaces? I don't see how. I suppose if the solder molecules are small enough, I reckon solder could invade those surfaces and potentially disrupt the physical contact from the heat causing expansion and contraction at a molecular level. That's my totally unscientific hypothesis. I can add that the resistance delta between crimp + solder and just a crimp is very small compared to a soldered lug.

 

[tabs_xyz]

I don't know about all of that. We are using less than 20 amps depending on the Riden. And I also soldered the ring terminals on my BMS wires. Personally for those types of things I prefer solder over crimping.

If using main battery inverter cables or whatever, then yes crimped is recommended and that's what I use.

Well true. I see your point. Dealing with values at 2 or 3 decimals, it just seemed to me that even at low currents, you might be concerned with possible skewed measurements. I've no idea how much shew there would be so thought I'd mention it just in case. I recently got a 6012 myself. Quite a surprising device.