12S needs bit higher voltage than 50V 
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I know. Iām planning on charging lower than 50.4V to get more life cycles out of my pack. Like 4.15V or 4.1V per cell.
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Careful if using bms, to check that the balancing at top of charge kicks in.
My BMS is set to kick in at 4.1V per cell so hopefully it will all work as designed.
Has anyone ever used THIS GUY? Its actually pretty cheap for a 12S 4 amp li-ion CC/CV charger and can be used as a portable option. This store has a bunch of diferente chargersā¦i even saw a 96.6V charger for $50.
I think I saw few of those on eBike sites
Ooh thatās cheap today with the sale. And they provide a gut shot so they must be confident in the quality? I feel like buying these chargers is like gambling. Have to put a volt/amp/watt meter on it and watch it close the first few timesā¦
@deucesdown If you wanna see some more pics of the guts check out THIS CHARGER. Despite the encolsure being different, the board layout looks the same. I canāt see any adjustable potentiometers though. I wonder how fine tune the end voltage?
I think i may buy one for science. Worst case scenario is having to hook it up to a DROK (which i will also probably buy to take advantage of the sale).
I know hobby chargers have this buck-boost transition thing, where if the pack voltage is close to the PSU voltage, charger keeps flipping back and forth between buck and boost modes, considerably slowing down the charge. Likely the DPH unit will have similar behavior.
Perhaps instead consider getting a charger with the voltage adjust pot, or a mean well LED driver with adjustable voltage (example HLG-320H-54A for 12s) and maybe inline one of those volt/amp/watt meters.
I mean: You have a 60V power supply going to the DROK which has an Input of max 55V. That sounds odd
it has an adjustable pot. I think I was able to dial it down to a little over 51 volts.
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@PXSS i know this thread is one of your favorite topics, where you better stay silent instead of killing people here 
But do you have any tips on better, cheaper or faster charging instead of our standard cell - bms - laptopbrick?
Like a special Drok to the BMS or something like that?
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My setup includes a few things. Depending on how DIY you want to go or how much $$$ you want to spend.
The stupid expensive stuff: BK Precision 9117 Power Supply (3kW/80V/120A) TI BMS (6-16S BMS with comms) I use these as a combo to charge large batteries. The setup is roughly 5K and way overkill for anything in here but itās really neat cause I can control both of them through a computer and record everything, from individual cell voltages, current going in, which cells are balancing, voltage output.
The expensive hobby stuff: iCharger Duo 4010 (2200W 2 channel 10S balance charger) This is my endgame charger of choice. It can output 1300W per channel and 2200W total. It also has comms and some rc people have even coded a raspberry pi and phone app to control the charger which is pretty cool. For its power supply I made a 36V 2250W power supply out of 3 12V power supplies. Cost like $60 total.
The Cheap stuff: Adjustable power supply from my group buy a year ago. I believe I have a 12S and a 10S version sitting somewhere. BMS from Bestech BMS, I choose a different build than what is commonly used here. The variant I use has the lvc at 2.5V and the hvc at 4.25V. The reason is that the BMS should be your last point of protection and you should really never hit these. It starts balancing at 4.0V so there isnāt an issue there.
The DIY stuff: 60V power supply that can do 2kW out of server power supplies. 6-16S BMS with comms: I built my own version of the same TI BMS I bought for around $100. It was very time consuming and I would probably never do it again Iām planning on making a smaller 10S BMS with comms based on a different TI chip with onboard logging. It should end up being roughly the size of a 4.12 VESC.
I have had some interest in getting a drok but the limited current output is a dealbreaker for me.
My endgame setup is the rc balance charger offboard. Then onboard a small protection board that doesnāt do any balancing, mainly ov/uv/oc protection and cell voltage monitoring with a way to access the logs through Bluetooth.
Iām not going to comment on anyone elses setup as I think a lot of it is irresponsibleā¦
In my opinion no board should go without a discharge BMS and fuse, reason being that just because your cells are balanced fully charged it does not mean they are balanced in a partially charged state.
For example, this battery was perfectly balanced before this discharge cycle and when I charged it back up after the cycle it was still perfectly balanced. I wish I had logged the data from the charge cycles but you get the point. This was a battery that is rated to over 130A and for this test I was pulling 17.5A at the peak. I was testing to see what the health was after some extremely abusive tests.
I did record the end bit of the charge cycle after this test with balancing disabled
As you can see, the cells are balanced within 3mV, so you would never be able to tell that there is something wrong with this battery.
Also, this battery pack was built using genuine cells that have been tested thoroughly. This is not a āyou got a bad cell in that packā scenario. This is the result of a dozen or so abusive tests that I ran on it. It exposed the weaker cells in the pack and the same could happen to anybodyās battery in here without you even knowing.
The only way to protect against it is to set conservative voltage limits. I would set the voltage limit on the pack at 30V which is right around where the lowest voltage cell hits the 2.9V mark.
@TarzanHBK, @b264, @deucesdown, @Okami, @Maxid, I think you guys will find this post interesting.
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faster would mean you want more amps so thereās no point in getting current control unless you have a veeeery powerful charger.
was just watching this guy telling about charging his cells:
he tells how he has no bms and no idea how far his cells has drifted for 2 years in his VW bus and checks them in this episode! some people are safer than others and some people have a youtube channel. heās an example of needing the cc feature of a true lithium charger because his charger is so powerful it would put out more than his cells could take when first put on the charger.
Iām confused by the second graph. it shows a dropping discharge but all the cells seem to be sitting close to each other and still balanced
This is why I suggested to @SimosMCmuffin that a BMS have a tiny discharge circuit, even if itās 500mA, and even if weāre running in bypass. You could use the discharge signal as a logic high/low to the ESC, and when the BMS cuts the discharge the ESC could do a proper cutoff as well. Except just donāt yank the carpet out from under it (by cutting power with the BMS) and disable brakes in the process. Iād rather destroy a battery than my body.
It shows a dropping charge current
how are you seeing there is a bad cell? hows the test work
Look at the first graph. The cells go out of balance as they discharge. The second graph is from the end of the charge cycle immediately after. The cells are still balanced fully charged but not at all when being discharged. Pros of having a discharge BMS and being able to monitor cells while they discharge.
Monster post deserving of sticky status. Thanks for writing this up. Itās like an organized and advanced version of the crap rolling through my brain. 
Bottom balancing instead of top balancing could mitigate this somewhat, as you can get the high voltage alarm while youāre charging, rather than a silent low voltage while riding.
But as usual, the only real way to protect against bad cells is to monitor whatās going on.
And to amplify what you say, all (well, most) packs start healthy, but as they wear out, cells start acting wonky.
In other words, as cells degrade, they lose capacity. The way this manifests in packs is, one cell will go rapidly higher in voltage as you charge and the cell gets full, and/or rapidly down in voltage during discharge when that cell is depleted.
If you top balanced, cells will look even when full, but the bad cell will drop off in voltage more quickly during discharge.
If you bottom balanced, the cells will be even when empty, but during charge the bad cell will go high voltage sooner.