@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 can’t 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.
@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?
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 it’s 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 isn’t 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 I’m 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 doesn’t do any balancing, mainly ov/uv/oc protection and cell voltage monitoring with a way to access the logs through Bluetooth.
I’m not going to comment on anyone elses setup as I think a lot of it is irresponsible…
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 “you got a bad cell in that pack” 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 anybody’s 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.
faster would mean you want more amps so there’s 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. he’s 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.
I’m 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 it’s 500mA, and even if we’re 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 don’t yank the carpet out from under it (by cutting power with the BMS) and disable brakes in the process. I’d 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. It’s 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 you’re charging, rather than a silent low voltage while riding.
But as usual, the only real way to protect against bad cells is to monitor what’s 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.
2.87 to 2.73 is the voltage spread at discharge. not great but not that bad and typically the spread at the bottom is where they spread. the simple cheap solution for me would be setting the pack low voltage cut off a bit higher and I’d just keep going with the cells and see how it does and feel if it’s warm.
Are you talking about the first graph? The blue line dips off the graph, which cuts off at 2.5v. That cell is toast! If you’re top balancing and have no bms for discharge, you’d never catch this unless you’re checking cells after discharge. Well, at some point the pack will blow up or start sagging horribly or BMS won’t allow you to charge I suppose…
that looks like the power line in blue, but the current going up…hummm maybe it is a cell
The board is always attended while riding, but not while charging.
Ah oops
But the point still stands. As packs age the voltage spread will get worse and worse.
Ah sorry that’s a behavioral quirk for me. Always attended during charge. I have a timer on the charger too.
think it is a cell and the blue line on top of the graph is power. a toasted cell.
I still feel safe with just the lv cut off and having it set high, checking the cells individually with a discharge balancer, and bulk charging. just saying. you guys are all into the bms. I know of another pack ruined over the weekend by another faulty bms. they seem more trouble than they’re worth to me at this point. and the common cheaper ones all work while charging,…how would that play out if they cell realllly sucks and the balance discharge function only dissipates a fraction of an amp and you were to hook it up to a high power charger? It seems like it could result in having a bms, and feeling safe, yet not knowing your dud cell is so bad that the bms cant burn off its power as fast as it’s being charged and the cell could still be going way beyond 4.2. No? seems with a typical low discharge bms you cant do a fast charge safely unless you know for sure what your cells are at.
