Maybe <2V per cell being completely dead is from the BMS point of view? A really dead cell should have no energy left which is = zero volts?
Portable charger for travel, library, coffee shop, etc.
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Chalo
100 TW
For that application, I'd choose a MeanWell HLG-320H-54A (which is about the largest and heaviest charger I'd want to carry along with me), dialed down to 52.6V and max current. That would be close to 6 amps. That unit is waterproof, fanless, and potted to tolerate high vibration.
If the BMS is rated lower than that charge rate, then charge the pack through the discharge line. As long as you're not approaching maximum cell voltage limits, and as long as the pack can balance when charging at home, then no problem.
Also, I would bring the battery and charger inside with me in a tote bag, briefcase, or whatever kind of luggage blends into the situation.
If the BMS is rated lower than that charge rate, then charge the pack through the discharge line. As long as you're not approaching maximum cell voltage limits, and as long as the pack can balance when charging at home, then no problem.
Also, I would bring the battery and charger inside with me in a tote bag, briefcase, or whatever kind of luggage blends into the situation.
If they're Lithium Ion cells that are not LiFePO4 or LiTi, then <2v is typically empty, probably below the zero capacity spec of the cell. randomly chosen from google search for cell spec sheet
declaring minimum voltage as 2.5v for that cell.
The cells I use EIG NMC C020
state minimum 2.5v as well.
Other cell spec sheets may differ, but all the ones I've looked at over the years are above 2v.
The BMS should be shutting off output well above that, often around 2.8v, sometimes higher.
LiFePO4 and LiTi are lower voltage types of cells, so the above voltages don't apply there.
For now, there's no way to know (without destructively opening up the cell and examining it microscopically to see if there is damage to the internals) if a cell has damage from overdischarge or not. Maybe someday someone will develop a characterization tool that can tell from the externally available properties whether a cell has specific types of damage.
Without bieng able to tell, it's safer not to use cells that have been overdischarged below the spec sheet values.
Up to you what you want to do, but I would not recommend it, simply because the results of a fire are very bad, even if the risk of one is very low.
declaring minimum voltage as 2.5v for that cell.
The cells I use EIG NMC C020
state minimum 2.5v as well.
Other cell spec sheets may differ, but all the ones I've looked at over the years are above 2v.
The BMS should be shutting off output well above that, often around 2.8v, sometimes higher.
LiFePO4 and LiTi are lower voltage types of cells, so the above voltages don't apply there.
For now, there's no way to know (without destructively opening up the cell and examining it microscopically to see if there is damage to the internals) if a cell has damage from overdischarge or not. Maybe someday someone will develop a characterization tool that can tell from the externally available properties whether a cell has specific types of damage.
Without bieng able to tell, it's safer not to use cells that have been overdischarged below the spec sheet values.
Up to you what you want to do, but I would not recommend it, simply because the results of a fire are very bad, even if the risk of one is very low.
Hummina Shadeeba
10 MW
I think all the Samsung cell data sheets state can revive from 1v.
I spent eons looking on meanwell’s site trying to find the smallest thing that puts out 84-87v an and got nowhere. The voltage ranges have a gap and HV (high voltage) is 90+.
I’d rather the smallest travel charger possible. For commuting to work I can leave it charging for 6+ hours so even 75 watt charging would be good
I spent eons looking on meanwell’s site trying to find the smallest thing that puts out 84-87v an and got nowhere. The voltage ranges have a gap and HV (high voltage) is 90+.
I’d rather the smallest travel charger possible. For commuting to work I can leave it charging for 6+ hours so even 75 watt charging would be good
Chalo
100 TW
MeanWells can be placed in series, with each delivering half the total voltage. If it's a certain wattage you're after, that means you can use two that are half as powerful (smaller) than a single power supply that pushes the same wattage.
Hummina Shadeeba
10 MW
Good to know but I’d like a simple singular thing if possible and less complicated.
Ideal would be a wallwart sized thing. Why none? I’m tempted to learn and make one.
Chalo
100 TW
The most powerful wall warts of normal small size that I've had push about 24-30 watts. The more powerful ones for laptops etc. are close to the size of 2A e-bike chargers, and they push about 60-90W. If you want hundreds of watts from a voltage converter, you have to have enough mass and surface area to move the power and discharge the resulting waste heat.
Hummina Shadeeba
10 MW
Yea I’m looking for something 60-90 watts that is small and no fan.
would these work?
Ill use a bms but still rather not have such extreme voltage adjustment possible from a tiny screw
In the past I had a couple custom made 87v, silent, 80watt, small supplies made by a place on alibaba but they won’t make anymore. They were only like 30$ but lasted maybe a year. They were ideal for traveling being light and could fit in my pocket.
I put an ad on freelancer to make it.
would these work?
ELG-100-C-LED Driver Power Supply Solution - MEAN WELL
Finding suitable LED drivers for LED lighting? A complete range of 8~1000W drivers featuring dimmable, IP67 with global safety certificates and ship from stock.
led.meanwell.com
Ill use a bms but still rather not have such extreme voltage adjustment possible from a tiny screw
In the past I had a couple custom made 87v, silent, 80watt, small supplies made by a place on alibaba but they won’t make anymore. They were only like 30$ but lasted maybe a year. They were ideal for traveling being light and could fit in my pocket.
I put an ad on freelancer to make it.
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Hummina Shadeeba
10 MW
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