Hi guys, will this ebay thing actually work, what odds are you giving me, battery is going to be 13 by 13.
8 quid, buy cheap buy twice or...
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Deleted member 4366
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It doesn't matter how much you spend. It has no bearing on whether the item is likely to be faulty, though in my experience, the more expensive ones seem to have more problems.
KISS always works for me.
If you're building a 13S13P battery, wouldn't a higher rated (30A) BMS be better?
KISS always works for me.
If you're building a 13S13P battery, wouldn't a higher rated (30A) BMS be better?
what amp did i buy?
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Deleted member 4366
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Deleted member 4366
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Oops sorry... Im using the 1000wat motor and controler that came with my cyclocicty (think its a stealth)
Bought the bike outright but want more range from her.
Bought the bike outright but want more range from her.
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Deleted member 4366
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Thanks D8v, just got My self the right BMS, have a feeling you just saved me a masive headache down the line, post ya paypal and il send you a drink m8
Still a bit confused about how these things actually balance charge with out touching all 13 batteries individually tho, cant be accurate can it?
Still a bit confused about how these things actually balance charge with out touching all 13 batteries individually tho, cant be accurate can it?
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Deleted member 4366
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You have strings of 13 cells all joined in parallel, so they all hold each other at the same voltage. There's 13 strings of 13 cells in series. Each string has a connection from the positive and negative to the BMS. As the positive of one string is joined to the negative of the next, they share a common wire. That means you need 14 connections to the BMS.
There's 13 chanels on the BMS. Each channel monitors the voltage of one string. If any string goes above 4.25v, the BMS shuts off the negative charging connection. If any string goes below 3.0v, it shuts off the discharge negative.
When you charge the battery, all strings rise in voltage. When any string goes over about 4.15v a transister opens a route to ground through a bleed resistor, so the charge trickles out until it goes down to 4.15v. The charger can fill up faster than the charge can trickle out. It will continue until any cell reaches 4.25v, then shuts off. After that, all cells above 4.15v drain down to 4.15v to balance them.
Its a bit like a row of buckets with a small hole drilled in them all at the same level 2 inches from the top. You can fill them up to the top with a hose, but they always end up with exactly the same level - 2 inches from the top - as long as you fill them past the hole.
Finally, there's normally a shunt on the output negative. The BMS monitors the voltage drop across that, which is proportional to current. When the current goes above the maximum value, the BMS shuts off the output negative.
Some sophisticated ones have temperature detection and manual shut-off (switch).
There's 13 chanels on the BMS. Each channel monitors the voltage of one string. If any string goes above 4.25v, the BMS shuts off the negative charging connection. If any string goes below 3.0v, it shuts off the discharge negative.
When you charge the battery, all strings rise in voltage. When any string goes over about 4.15v a transister opens a route to ground through a bleed resistor, so the charge trickles out until it goes down to 4.15v. The charger can fill up faster than the charge can trickle out. It will continue until any cell reaches 4.25v, then shuts off. After that, all cells above 4.15v drain down to 4.15v to balance them.
Its a bit like a row of buckets with a small hole drilled in them all at the same level 2 inches from the top. You can fill them up to the top with a hose, but they always end up with exactly the same level - 2 inches from the top - as long as you fill them past the hole.
Finally, there's normally a shunt on the output negative. The BMS monitors the voltage drop across that, which is proportional to current. When the current goes above the maximum value, the BMS shuts off the output negative.
Some sophisticated ones have temperature detection and manual shut-off (switch).
Yet another quickie... Is there any reason i cant discharge 16 cells at a time in parallel on my imaxb6, i know it will take a while at 1 amp, but can it be done?
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Deleted member 4366
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Yes. I made a wooden jig when i was testing cells out of MDF. Basically, there was a slot for each of 6 cells with a spring at each end. The springs were connected to a normal 6S balance connector. I have a BC168 charger that has 6 independent channels so I could test 6 cells at a time charging and discharging.
I think it would be better to make a jig and then do your discharge test with 6 in series. That will show the weak ones.
I think it would be better to make a jig and then do your discharge test with 6 in series. That will show the weak ones.
Back with another corner cutting moment, now im trying to build a super cheap spot welder...
14 x 12volt 2.3ah
How would be best to rig them, 2s 7p or 14p
Infact will they even have the beans to work?!
14 x 12volt 2.3ah
How would be best to rig them, 2s 7p or 14p
Infact will they even have the beans to work?!
If they are high discharge ones (not standby) and in good order they should work. I once accidentally welded a 12" adjustable across the two terminals of my boat battery. It was quite an exciting moment while I grabbed the nearest blunt object to break it loose.
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