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Anyone mix 280K with 280-non-K cells in a 48v pack?

OffGridIdaho

OffGridIdaho

Hobby Farm in N Idaho
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Jun 18, 2020
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N Idaho
I did not top balance them. We are an off-grid and I cant take my system offline. We were running on 8 non-K 280 eve cells for 1.5years. I bought the new 280k cells and charged them to within .005 +/- a few. I built the pack installed the new 48v system and started charging. Right off the K cells jump to .010 higher. I turned off solar charging and set balance voltage to 3.0v to allow it to balance over night. The cell delta in the AM was .010. The cells looked the same at .010 different during mild discharge.

Once the sun came up and solar power started coming in (5a) I noticed the cells all had the same voltage. 3.33 +/- .001. Why would it change under charge like that suddenly? The cell delta dropped to .005.

I would order 8 more "K" versions to run with the new "K's" but they are out of stock.

Have any of you had success K with non K?
 
Well it's not a 48V but:
Using Flexible Copper Mesh busbars.
This is just part of of my assebly photo's I take. This pack is running just fine but shows it's quirkiness outside of teh working voltage range (not too bad though).
1719849318162.jpeg
 
Unless cell voltage is above 3.4v, don’t worry about cell delta. See if you can get the cells back up to fully charged to see how they are working.
 
740GLE said:
Unless cell voltage is above 3.4v, don’t worry about cell delta. See if you can get the cells back up to fully charged to see how they are working.
Click to expand...
I tried today off solar. I should have charged slower. I set max amps at 30a. The K cells went to 3.5 while the non-K were about 3.35. Cell delta was .4x. Charge got shut off by high cell V.

Tomorrow I will try 10a and see what happens.
 
Low and slow for balancing.

What BMS and balancer do you have?

You may never be able to get the old cells to ballance.

Your new cells might have a rating of 290ah, and your old cells might have worn down to 270ah.

Just know you’re still better off with your new 48v set up.
 
you can mix, but, your balancer will mess the each cell voltages
 
I mean it will work but you’ll be limited to capacity of the old cells and won’t ever get a good balance report, but you still should be able to cycle it without any major issues.
 
740GLE said:
I mean it will work but you’ll be limited to capacity of the old cells and won’t ever get a good balance report, but you still should be able to cycle it without any major issues.
Click to expand...
Crap! That will cost another $1,000.
 
Hmmmm... I showed the 1 pack I have with N & K series.
I did TOP Charge in sets of 4 to 3.65 then again as a whole set and allowed the pack to sit in parallel 24 hours and did another top Charge prior to assembly. Have not noted too much difference "except" when getting over 3.380 they tend to start "wandering" but not enough that the 2A Active Balancer can't sort it. I am using the JK-Inverter edition which seems to be better at Active Balancing than the previous version.
 
Steve_S said:
Hmmmm... I showed the 1 pack I have with N & K series.
I did TOP Charge in sets of 4 to 3.65 then again as a whole set and allowed the pack to sit in parallel 24 hours and did another top Charge prior to assembly. Have not noted too much difference "except" when getting over 3.380 they tend to start "wandering" but not enough that the 2A Active Balancer can't sort it. I am using the JK-Inverter edition which seems to be better at Active Balancing than the previous version.
Click to expand...
I did not top balance. I dont have a charger and I only have the one system, we are off grid. I cannot be shutoff for 1 week doing TB.
So the 280k v2 and the 280k v3 WILL work together? Is there a quick way to top balance? Like a 12hr way? I will have to run a generator 24/7 to keep my chest freezer cold they are full of meat.

If yes can you send me a link to the top balance charger again?

18650 battery said 1.5yr old v2's and brand new v3's might be an issue.
 
Issue: worst case scenario one will be weaker and limit the top of the pack but unlikely to be significant really (my opinion).
I use a charger capable of 45A @ 3.650. It's still "sorta" available but there are new ones at a slightly lower price with a lot more features/functions etc.

See here on this EBAY Search. I cannot suggest any vendors
www.ebay.com

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OffGridIdaho said:
Is there a quick way to top balance? Like a 12hr way?
Click to expand...
One “cheat” you might try is to put some alligator clips on the leads from a bench power supply, set it at constant voltage of 3.6, and give a little boost to one cell at a time, starting with the lowest one.
 
Steve_S said:
Issue: worst case scenario one will be weaker and limit the top of the pack but unlikely to be significant really (my opinion).
I use a charger capable of 45A @ 3.650. It's still "sorta" available but there are new ones at a slightly lower price with a lot more features/functions etc.

See here on this EBAY Search. I cannot suggest any vendors
www.ebay.com

EBC-A40l Electronic Load Battery Capacity Tester for sale | eBay

Get the best deals for EBC-A40l Electronic Load Battery Capacity Tester at eBay.com. We have a great online selection at the lowest prices with Fast & Free shipping on many items!
www.ebay.com
Click to expand...
Im stuck. I cannot afford to buy the batteries and the TB charger. Not sure which to buy? I can afford the new batteries but not both.

I have an iota 45a 12v charger made for LA batteries. Its essentially a semi-smart power supply. Could I disconnect the old pack into 12v groups and charge them up by .150v (the amount they are lower then new pack) and reassemble?

This is 10a and $65.00 would it work?

www.ebay.com

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Output current 0~5A 0~10A 0~5A 0~3A. USB-A/Type-C fast charging function, supporting multiple fast charging protocols. Auxiliary functions USB-A/Type-C fast charging, supporting various fast charging protocols.
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Another choice....$45

 
Last edited:
It's been years since I tried low amp stuff and found I didn't have enough hair left to pull while waiting.
The 12V charge "may" be an idea if it doesn't go out of voltage range.
 
Steve_S said:
It's been years since I tried low amp stuff and found I didn't have enough hair left to pull while waiting.
The 12V charge "may" be an idea if it doesn't go out of voltage range.
Click to expand...
OK, so I need a big amp unit like the 45a?
 
OK thinking outside the cat bag. What if I split the pack and hook my old 24v inverter to the new v3 batteries and run them down .150v
 
Will a 10A charge the 280AH cells, sure but takes forever. That's why I stepped up (also cause I've one a LOT of cells so cost/time has been a factor. TBH, I built 1 pack as a test without Top Charging and doing my routine and there was nothing but issues at both the bottom & top of the working voltage range with cells going all wonky. Only after I took it apart & properly top charged the cells and fully activated the electrolytes did they behave properly.

I hesitate to suggest putting a pack together & using with BMS and trying that route. Some others have done it and seem happy with the result. That has not been my experience and so I go with what I know works.
 
Steve_S said:
Will a 10A charge the 280AH cells, sure but takes forever. That's why I stepped up (also cause I've one a LOT of cells so cost/time has been a factor. TBH, I built 1 pack as a test without Top Charging and doing my routine and there was nothing but issues at both the bottom & top of the working voltage range with cells going all wonky. Only after I took it apart & properly top charged the cells and fully activated the electrolytes did they behave properly.

I hesitate to suggest putting a pack together & using with BMS and trying that route. Some others have done it and seem happy with the result. That has not been my experience and so I go with what I know works.
Click to expand...
OK
Well I guess I have to decide, try to balance what I have or buy new batteries. My first 24v 8 cell pack had no issues at top and bottom without TB. I thought I could do it again, but I see I cannot.

How long does it take to TB a 48v pack with 40a dc power supply?
 
I can't answer that because it all depends on the cells Real SOC.
If cells are NEW or have been in storage longer than 6 months it's a slow charge.
Example, I took 4 "NEW" cells (EVE 280KV3 dual terminal), 6 months old (manufacture date) and had them for 3 months on the floor, so 9 months old.
They started at 3.332 and took almost 10 hours @ 40-44A to reach 3.650 and taking only 3A.
Same Cells (single post though) but that were in production already (transferring cases). Starting @ 3.337V it took 3.5 hours to reach 3.650 and taking 3A These were obviously already full activated as they were in production.

Now, I have just built a set of New Packs with New cells and this is consistent with them. I am also transferring current production packs over to new cases with the new JKBMS Inverter editions and am still Top Charging & Balancing them before reassembly. (I get to do Voltage & IR Validation this way), a good opportunity so I won't miss that option. Again this is pretty consistent.

Now I have 1 pack with BULK EVE 280's, 1 Pack of EVE "280-N" B-Grade, 1 pack of EVE 280-N A-Grade(Matched & Batched), 2 Packs of EVE 280-K V3 (dbl terminal) and 1 pack of EVE-280K-V3 B-Grade Post cells. and then a Frankenstein with 5x280-N & 3x 280-K (post) cells. I've removed the other packs (105AH & 175AH) from my bank and repurposed them elsewhere.
 
OffGridIdaho said:
Well I guess I have to decide, try to balance what I have or buy new batteries.
Click to expand...
I think you’re worrying too much. If your lowest charged cell is at 3.35, you’re still getting 90% of the capacity.

Maybe think about getting eight new cells and replace the older ones. Then you’d be getting closer to 100% of capacity. With the 2A active balancer in your JK, they should top balance pretty quickly, maybe a day or two.

Then be on the lookout for the cheapest 280 cells you can find, to build a second battery with your old cells, as finances permit. They won’t need to be “Grade A” because you’ll be matching them with older 280 cells. Then you’ll have one good “new” battery and a second battery that should be good for 90% or more.

Good luck in whatever you decide.
 
Ok well I ordered the new v3 cells and I am going scratch up enough for a charger. Who needs gas and groceries anyway.

Question, how do I get the cells all about the same V so I can hook in parallel? How do I drain them?
 
Steve_S said:
Issue: worst case scenario one will be weaker and limit the top of the pack but unlikely to be significant really (my opinion).
I use a charger capable of 45A @ 3.650. It's still "sorta" available but there are new ones at a slightly lower price with a lot more features/functions etc.

See here on this EBAY Search. I cannot suggest any vendors
www.ebay.com

EBC-A40l Electronic Load Battery Capacity Tester for sale | eBay

Get the best deals for EBC-A40l Electronic Load Battery Capacity Tester at eBay.com. We have a great online selection at the lowest prices with Fast & Free shipping on many items!
www.ebay.com
Click to expand...
Ugh,

The 40a is located in a rikshaw in china. Like 2-3 weeks to get here. Any other usa alternatives?
 
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