Lead acid batteries lose capacity and capability quickly when stored below 100% state of charge. The lower they rest and the longer they stay there, the more they sulfate.
It might only require 1 amp to hold it at 15.7 volts.
Desulfating a lead acid battery might be possible, but would require many hours held at 15.7v., and one needs to be aware of the potential thermal runaway, and excessive gassing., and there is no guarantee it will restore usable capacity.
Is the welding performance with such a battery better or very good? I have already refreshed 7 year old AGM batteries with just sufficiently high voltage and current the sulfation dissolves quickly. I am a true car mechanic.
A sulfated lead acid battery might not be able to deliver the instantaneous welding power needed. A typical car is 220 amps for a few milliseconds and then 120 amps till it catches. As long as voltage stays above 7.5 it is likely to still start.
I have started a big Old V8 with a tiny AGM battery by itself.
It is not the giant task many believe.
A spot Welder will draw far more for much less time and a ârestoredâ Old AGM that can still start a tiny 4 cylinder does not mean it can weld 0.2mm nickel.
my DIY Arduino Battery Spot Welder Kit V4 is limited to 1200 amps. So try with a Varta and 800 amps. Which welder do you use?
Your welding Lead acid battery, or the connections from it to and through your welder, potentially not having enough juice, or allowing enough juice to pass, has nothing to do with my spot welder.
I jumped in only as so many people seem to think old lead acid batteries can be magically restored after being abused.
Abused for lead acid batteries is a dependent on how they were treated.
They ideally prefer a prompt and true recharge to 100% State of charge as often as possible any time they are discharged.
Sitting at 80% charged and less ages them faster.
it takes no less than 3.5 hours to recharge from 80% to 100% state of charge, with lead acid, and only when the battery is still healthy and when it is held in the mid 14v range for that duration. Less healthy lead acids will need slightly higher voltages held longer and sometimes ridiculously longer.
A healthy 800CCA battery should have more than enough for a spot welder.
An unhealthy one, even held at 15.7v via on a 50 amp potential power supply, likely cannot.
I Lived on lead acid batteries for 20 years. I learned how to get good to excellent service life from them in deep cycle duty, and also as starting batteries.
They are finicky in regards to their treatment, and build quality is a huge unknown, as as soon as one brand gains a reputation for longevity, maximum executive profit is not as high as they seem to think they deserve, and can get away with, so corners are cut, quality control reduced, and the battery is designed to just barely last the warranty period.
Hi, quick question about balance wires. So i pulled this off a pack i got from someone with 4 6s 5ah lipo packs wired for 12s10ah. Question is why would the last balance lead be cut off and not used? Used a voltmeter and checked, it is the last lead in both packs i got from him. The connector to the bms and bms only count 12 pins when i thought it should be 13 pins for 12s.
so 2s2p 6s lipos. for 12s2p
the balance leads for the series pair are two sets of 7 wires each. thatâs 14. that should be collapsed down to 13 for a 12s balance lead.
like this:
1a 2a 3a 4a 5a 6a (7a|1b) 2b 3b 4b 5b 6b 7b
since the 7a is also connected to the postive out of lipo a, which is connected in series to lipo bâs negative which is connected to balance lead 1b. you could hook up 7a, 1b, or both and it would all work. Iâm not sure why youâd make one choice or the other thoâŚ
so iâd suspect the disconnected one is 7a or 1b âŚ
however⌠that you say you have only 12 balance leads instead of 13 at the 12s balance connectors wouldnât make sense. so maybe this doesnât help?
I went back and found the bms model: 44V 48V 50.4V 12S 30A 12x 3.6V Lithium ion LiPolymer Battery BMS
The diagram kinda makes sense to me, - is excluded in the pin connector am i correct? But looking at the harness it looks like - is kept and the 12th series is cut. But looking at the bms diagram, if - lead was left out, it matches up to the same side as the cut lead. Putting the 7 pin connector next to my parallel charge board, looks like red is 6th/12th series and - is cut. So maybe the red confused me with being the - since all the other lead were same color. Does this sound correct to you?
ok yeah you got it.
the one thatâs âcutâ / not connected, should go to the lowest potential battery. lowest potential pin. ie â-â [negative]
and itâs not connected because the bms uses the main battery negative lnstead.
so what i said in the prev post doesnât apply except thereâs a similar trick going on.
Been building my first battery 16s6p in a Amazon knock off pelican case. Figured all that extra space in the lid would be perfect for spare parts. The mix of colors is cause I was trying to burn through partial rolls of tpu 
Where do people typically go to source high strand count 8/10/12 awg silicone wire for packs?
Amazon
I had that happen to my eboardsperu pack recently. Was trying to find out why metr showed like 75% charge but the charger said full. Ended up having 1 group completely dead and another .2 low. Replaced both and have been doing good so far on the same bms. So Iâm thinking it was just bad luck but who knows.
Dude this thing is so sweet, Iâve been thinking about doing something similar.
How is the noise?
Thanks! Like rattle noise? I havenât rode it yet Iâm still building the board. But I shouldnât have any noise from It. Thatâs why everything has there own compartments and lids. Then all that gets sandwiched between the box lid and battery. Itâs also printed out of a soft tpu for vibration dampening but it also keeps it quiet. I think if it was printed in hard plastic the parts would rattle like hell.
Yeah rattle noise, I have been trying to find the best way to get tools on my board but anything softcase or other makes soooooo much noise.
Definitely would love to hear what you have to say once you get it running.
I plan on doing a build thread when. I get closer to being done and will update how everything goes. But I have high hopes since I can shake that whole top piece and hardly makes any noise at all. Now I need to figure out a tool and part solution for my street board.
Killer dude, canât wait to see the build thread!
