Battery set for the bin today.

Nealh

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As some may be aware I am true diyer and that includes batteries , well today I had to virtually bin a 974wh PF soft pack (a decent size being 7p 13s).
As with all my batt's I check on a 4 - 6 week cycle to see that nothing untoward is occurring, this one only being checked some 4 weeks ago and all looking good as usage hasn't been great during lock down. Knew something was wrong as soon as I turned in the voltage gauge and no reading at all, so took it indoors and pulled the sense connector to measure cells. What a shocker they had all collapsed to less then 1v per group and some as low as 0.4v.

I haven't yet stripped it down to get to the cells but expect either the BMS to be at fault and draining the cells or catastrophic collapse of the cells which seems unlikely not much of a biggy as I bought a job lot of cells (100+) a few years ago for £100 from a battery guy on here so a cheap layout as far as cells's go.
When time allows I shall split the cells in to there groups first then back to singles and check each one to see if any give a clue, as for the BMS not much one can test for except to wire it up to again to test/monitor it on another set up.

I have a pair of aged well used and abused 29E packs of 5p 10s so these I will strip out of the case and reconfigure in to a large 48v soft pack for temporary use , they sag a bit but are usable on low power.

I have two Oxydrive cases and the mount, I liked the case style and prefer them over the Dolphin 09 case. Just now need to source some cells decent cells to re -use them again, previously they were 5p10s using the mediocre Sam 22 & 26F cells. 4p 13s might fit inside if not certainly 4p 12s will.

Good genuine li-on cells are a very thin on the ground at the mo, so will have to see who has any stock. My last cells were genuine LG HG2 from a UK warehouse source so may be my next look to see what they have in stock. I had a mail shot a few weeks back to say they have new Molicell stock, Molicell are a Canadian Co. I believe but like all cells most are produced in the Far East or these in Taiwan, Moli's reportedly are very similar if not clones of the VCT5 & 6. They follow similar mah and current stat's.
On Ecf forum Mooch has tested and rates them as best all round 18650 and better the Sony's excellent VTC5A.

Any one used Nkon at all this year ?
 
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Nealh

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Here is side by side comparison, the Moli certainly holds up beyond 3.5v better.
3.3v in my min discharge. The Moli is 2600/25a rated but for my use well within the current rating for an easy life.

One has to enter the cells to compare in the comparison boxes.
Battery test-review 18650 comparator (lygte-info.dk)

As a 12s they will give me approx 457wh compared to 499wh for 13s.
 
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Nealh

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Now compare the Moli to the Panny PF/PD cell, is the Moli26 18650 a wonder cell ? Specs and independent testing say's yes.
Moli 26 is a match or better on discharge curve (5a) against other top cells like HG2, MG1, though final mah is less but you have to get to 3.3v before it loses out on mah.

Also better then Sam 25R, 35E, on a par with GA .
Only found 2 top cells that better it 30Q & VTC6.
 
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Nealh

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These Moli 26A are looking better esp at £3.58 each delivered.
 
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Gliggsy

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Talking of decent cells, you may be able to point me in the right direction, I fly RC planes all are lipo for the power rating but by weight Li-ion have much higher capacity, I have 3s batteries which can give me up to 40 amps, can you recommend any Li-ion for 3s configuration that will get me a high as possible discharge rating as I'm thinking of building some packs for flying TIA
 

Nealh

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For 3s 25a - 35a cells will give you 75 - 105a & about 2600mah - 3000mah for 3s 1p with 18650 or about 4000mah with 21700.
All depends on space you have and weight limitations you may be able to add 2 or 3p.
Currently really decent 18650 cells are in dire shortage due Covid production also a lot of fakes about, reports are saying that some factories are burning down in China as unstable fake production is causing fires.
A look at a couple of reliable sellers are showing no stock of quality cells.

Any top branded 20 - 35a cell if you can find any from a reputable and reliable source.
You have choice of 18650 or 21700 if they fit.
 
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vfr400

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Talking of decent cells, you may be able to point me in the right direction, I fly RC planes all are lipo for the power rating but by weight Li-ion have much higher capacity, I have 3s batteries which can give me up to 40 amps, can you recommend any Li-ion for 3s configuration that will get me a high as possible discharge rating as I'm thinking of building some packs for flying TIA
It's not possible unless you fly big planes, but then you wouldn't be using 3S. Some 18650s can go as high as 25amps, but not for the length of time you need for an aeroplane. For a reliable 40A, you'd need 3S3P, which would weigh 450g, give about 7500mAh and cost about £60. Stick with lipos - that's what lipos are for.
 

Nealh

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My battery being deconstructed.
Top and bottom fibre glass sheet protector.
DSCF1225.JPG

My nice/neat spot welding before being torn apart.
DSCF1223.JPG

Hard to remove spot welded nickel, the Maletric spot welder does a very good job of welding and is also capable of welding a Ni/Cu interconnector sandwich.DSCF1228.JPG
 
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Nealh

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Unless one is an electronics wizard there is no way of knowing what failed but the obvious point of failure is the BMS for what ever reason, however something drained each cell group and not just the odd one.
Total battery voltage was 5.65v.
Each cell group had some variation and most cell in each group were on a par, I did have the odd cell in a P string reading 0.04v lower then the rest.
Group readings.
1. 0.598v.
2. 0.538v.
3. 0.466v.
4. 0.490v.
5. 0.511v.
6 0.520v.
7 0.470v.
8. 0.450v
9 . 0.505v.
10. 0.476v.
11. 0.501v.
12. 0.470v.
13. 0.464v.

Total = 6.45v though the as there was an odd cell in some of the strings reading 0.40v less then some the actual pack voltage was 5.65v.

All cells now packed up to take to the recycling depot.
What's certain is all groups drained down with only 0.14v being the main difference, so points to the BMS in my eyes unless all cells decided to fairly uniformly self bleed down.
 
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Nealh

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Onwards and upwards, now to think about reinstating my empty Oxydrive battery cases to 12s/44v. I have decided that 12s will be my new default voltage for builds.
 
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Sturmey

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Unless one is an electronics wizard there is no way of knowing what failed but the obvious point of failure is the BMS for what ever reason, however something drained each cell group and not just the odd one.......
Was the battery still connected to the bike or stored off the bike or have you a separate on/off hard power switch? The reason I ask is because its possible for the controller to slowly drain the battery, as with many bikes it still has power connected when turned off by handlebar lcd/led unit.
I have a bike with LCD3 and kt controller with a 1t5 cable with front light. When turned off with lcd, sometimes the front lamp erratically turns on and flashes. So, to some extent, I don't fully trust 'soft' switches and like to see the battery physically disconnected or turned off with a hard switch when storing the bike.
 

Nealh

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Disconnected from the bike and with a BMS switch.
I have a routine of checking various batteries I have as I mentioned on an approx 4 weekly cycle, it's a shame though it only cost me the price of the cells £91, BMS £15 and some Ni.

I have just added a 12s LG HG2 diy water bottle battery to my commute town bike so when I make a new 12s for my touring I will use the bottle battery as well.
 
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Nealh

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The more I look in to things and compare performance the Molicel is looking a hot favourite to buy.
 
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vfr400

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Disconnected from the bike and with a BMS switch.
I have a routine of checking various batteries I have as I mentioned on an approx 4 weekly cycle, it's a shame though it only cost me the price of the cells £91, BMS £15 and some Ni.

I have just added a 12s LG HG2 diy water bottle battery to my commute town bike so when I make a new 12s for my touring I will use the bottle battery as well.
Whatever switches the bleed resistors probably forgot to switch off. I've seen that happen to a few batteries, including Bosch.
 

Nealh

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Placed an order for 40 Molicel from Nkon on May 15th, delivered today May 21 by DPD

they took care of customs/vat paperwork. Great price overall.
Very new cells there, production date is 07 Dec 2020 so pretty much hot off the press nearly.
Mooch tested these and rated them as current #1 cell to buy, also the P28A is almost identical but will a slightly longer run time past 3.2v but that is no use for us ebikers.
Going by Mooch's testing they hold on to the voltage very well.
 

JohnD135

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Placed an order for 40 Molicel from Nkon on May 15th, delivered today May 21 by DPD

they took care of customs/vat paperwork. Great price overall.
Nkon included vat in the price I notice. But do customs charge much more, us not being in the EU?
 

JohnD135

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Yes, ordered 70 Molicel INR-18650-P26A from Nkon. Arrived in about a week and all charged to the same voltage, within 10 or 20mV. I checked one of them for capacity and 4.2V to 3.0V was 2.4AH. Close to the typical figure of 2.6 so I am happy. I am now learning about welding!!
 

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