arkmundi
10 MW
No, no balance wires at all - read the thread. I made a harness, so a 12S string goes into the harness where it can either be monitored, including during charging, or put on the Thunder balance charger if needed.999zip999 said:
Arkmundi's new A123 26650 battery build
- Thread starter arkmundi
- Start date
999zip999
100 TW
8 times- if needed. I just don't get it, but carry on and let us know on the long run.
arkmundi
10 MW
Well, another test of sorts. Unexpected, but useful anyhow. Came home feeling lousy and rather than disconnecting the Watt's Up meter from the battery, which I ordinarily do to recharge, left it connected. Not a big deal except I came down with some common cold that laid me out for a few days - went into slumber, snooze and video mode. Completely forgot the battery. So feeling better and wanting outdoors and on the bike... Whooops, damn if that little meter didn't do me in again, draining the juice from the battery. Down to 4.6 volts. At least it didn't take it to zero like the last time. So that's about 0.4 volts per cell. wb9k had mentioned that A123 cells are very robust and would bounce back from almost total discharge - time to test that with these new 26650 cyclindrical cells. Indeed they did bounce back and seem to accepting and holding full charge. Time will tell.
So the draw of the Watt's Up Meter is 0.09 amps, meaning 2.16ah in a 24 hour period. Hence exhausting my roughly 20ah battery pack in 9 days. But coming home, didn't charge, so maybe had 16ah. Yea, those are the numbers. As a test there are two lessons:
1>> A123 nanophosphate cells will bounce back from a nearly full discharge, though for longevity its not a good practice
2>> it was a battery capacity test that passed great - those cells are what the manufacturer specified, ~2.4 ah per.
So the draw of the Watt's Up Meter is 0.09 amps, meaning 2.16ah in a 24 hour period. Hence exhausting my roughly 20ah battery pack in 9 days. But coming home, didn't charge, so maybe had 16ah. Yea, those are the numbers. As a test there are two lessons:
1>> A123 nanophosphate cells will bounce back from a nearly full discharge, though for longevity its not a good practice
2>> it was a battery capacity test that passed great - those cells are what the manufacturer specified, ~2.4 ah per.
agniusm
1 MW
Maybe the right time to swap human bms to the real one...?
arkmundi
10 MW
Cathode end-cap broke loose from one of my cells, as follows:
Note that there is a plastic spacer between the end-cap and the rest of the cell. I believe this in part provides thermal insulation. Makes me feel a bit better about the solder method I used. I noticed that the cap would heat up, never to the point it couldn't be touched, but that the body of the cell only got a tad warmer while soldering. Not that at this time I recommend the approach - future packs I build will use a home-brew capacitor discharge spot welder to accomplish the connections. Project underway in context of the eBike Workshop with eWorc and Technocopia now underway. The spot welder and other tools being assembled will stay with Technocopia.
Note that there is a plastic spacer between the end-cap and the rest of the cell. I believe this in part provides thermal insulation. Makes me feel a bit better about the solder method I used. I noticed that the cap would heat up, never to the point it couldn't be touched, but that the body of the cell only got a tad warmer while soldering. Not that at this time I recommend the approach - future packs I build will use a home-brew capacitor discharge spot welder to accomplish the connections. Project underway in context of the eBike Workshop with eWorc and Technocopia now underway. The spot welder and other tools being assembled will stay with Technocopia.
arkmundi
10 MW
There was an interesting discussion on the Do cells on final connection before controller work harder ? thread worth making note of with regards to the construction, monitoring, deconstruction and rebuilding of packs. Would apply to all home-brew lithium ion packs.
agniusm
1 MW
I am doing my soldering of 18650 for the first time and I dont like it, at all.
I think tje best solutio so far is by snath, the dimple foam method. I have high hopes for Luke's nanotube compound and combined it should me miles away from any soldering, spotwelding and is diy'er friendly. I am thinking of ordering a 12p form made for the dimples that would contain 2, 4, 6, 8 and 10p configurations in the same unit, laser cutting copper and using available plastic holders.
Easy to replace cells.
No expensive machinery needed
Relatively cheap when you have a form.
I think tje best solutio so far is by snath, the dimple foam method. I have high hopes for Luke's nanotube compound and combined it should me miles away from any soldering, spotwelding and is diy'er friendly. I am thinking of ordering a 12p form made for the dimples that would contain 2, 4, 6, 8 and 10p configurations in the same unit, laser cutting copper and using available plastic holders.
Easy to replace cells.
No expensive machinery needed
Relatively cheap when you have a form.
sharinginfos
100 W
- Joined
- Sep 1, 2022
- Messages
- 172
999zip999 said:
hi 999zip and everyone.
i read about soldering liion and it is not a good idea because it is said it breack the battery because of the heat of the tip of the heater transfer. Is this treath saying that with lifepo4 we can confidently solder on top of cell directly?
If not possible with every cell wich high discharge type name are able to support the heat enough?
thanks
also id like to know what are the risk to solder on the less capable lifepo4 cell? lossing capacity? risking creating a fire situation? what kind of risks?
Any method that heats the cells inside will affect them. The hotter the cell interior gets the worse that will be.
Soldering on the cells is not recommended, even if the solder can be made to stick to them (not all cans are made of solderable material).
Spotwelding can also do it, depending on the point on the cell used and the amount of heat generated in the process, but soldering, especially the ways most DIYers try, is going to keep putting heat into same spot on the cell for a long time and be more likely to damage them.
The specific results depend on the specific damage done, which can't be known for certain without opening up the cell (which makes it unusable).
If the cells are built like the picture Arkmundi shows above, with separated end-caps not directly in contact with the cell itself, it won't be able to transfer the heat the same way and cell damage may be prevented, as long as heat is not applied long enough or intensely enough to get past the end cap to the cell.
The typical end-cap of the positive end of many 18650 cells is separated like this, but it also can be part of the safety-venting system to prevent overpressure and explosion. If the heat gets transferred from the endcap into the vent system and damages the vent it may prevent it from venting in the event of catastrophic cell failure, so the cell would then vent in some other way (potentially explosively).
Soldering on the cells is not recommended, even if the solder can be made to stick to them (not all cans are made of solderable material).
Spotwelding can also do it, depending on the point on the cell used and the amount of heat generated in the process, but soldering, especially the ways most DIYers try, is going to keep putting heat into same spot on the cell for a long time and be more likely to damage them.
The specific results depend on the specific damage done, which can't be known for certain without opening up the cell (which makes it unusable).
If the cells are built like the picture Arkmundi shows above, with separated end-caps not directly in contact with the cell itself, it won't be able to transfer the heat the same way and cell damage may be prevented, as long as heat is not applied long enough or intensely enough to get past the end cap to the cell.
The typical end-cap of the positive end of many 18650 cells is separated like this, but it also can be part of the safety-venting system to prevent overpressure and explosion. If the heat gets transferred from the endcap into the vent system and damages the vent it may prevent it from venting in the event of catastrophic cell failure, so the cell would then vent in some other way (potentially explosively).
sharinginfos
100 W
- Joined
- Sep 1, 2022
- Messages
- 172
agniusm said:
hi who is shath? where can i find a thread of this dimple foam method?
Some very quick searching on the term
dimple foam
provides possible answers and also lists the person you're looking for.
https://endless-sphere.com/forums/search.php?keywords=dimple+foam+&terms=all&author=&sc=1&sf=all&sr=posts&sk=t&sd=d&st=0&ch=300&t=0&submit=Search
dimple foam
provides possible answers and also lists the person you're looking for.
https://endless-sphere.com/forums/search.php?keywords=dimple+foam+&terms=all&author=&sc=1&sf=all&sr=posts&sk=t&sd=d&st=0&ch=300&t=0&submit=Search
999zip999
100 TW
Sharinginfo what battery do you need voltage ah and motor and controller ? After we find this out we can help you better there are some cheap solutions.
sharinginfos
100 W
- Joined
- Sep 1, 2022
- Messages
- 172
999zip999 said:
HI 999zip999 and all
thanks for you will to help
here is a thread i started for my situation https://endless-sphere.com/forums/viewtopic.php?f=14&t=118064&p=1736821#p1736821
THOR's day
1 mW
- Joined
- Sep 8, 2022
- Messages
- 12
arkmundi said:
I did that to my used a123b 12s battery pack that I use in my scooter and it was sitting at 9.8v which is bad really bad but I let it sit for a day and it bounced back to 24v then I hooked it up to the charger 42v and it's been perfectly fine ever since
