I don’t understand you guys. how is having ten chargers better than one that you need to hook up twice but ultimately takes less time? There are even wiring diagrams out there on how to split a >6S battery to charge it in parallel.
This proposed mechanism (if you go for multiple cells at a time and not just one) will be a wiring mess, complicated to connect and can do more harm than good.
this can be easily achieved like I explained above with a simple boost converter - no explicit balancing but you can keep it hooked up until it reaches your desired current in the CV phase.
You build this thing by your own and throw everything in a cool housing, then you only have one cable with a few phases out. Different cables with different phases for different boards like 6s or 10s.
Hook it in the wall, hook it to your battery and you´re done. No BMS, no worries to overload your battery. Sounds cool to me
@jmasta use this, TP4056 modules, they are limited to 1A max, but work quite well and are very cheap, now you only need 10 USB wall adapter, again, isolated with one USB each
0.05V is not a huge deal. 0.50V is a different story
If you have a welded pack and you find one cell group very out of balance… What do you do? Your BMS won’t take care of it if the voltage difference is significant. I have a 0.05V difference now. What happens when that grows to 0.10V?
The following scenario resulted in permanent cell damage
Tell me why it won’t work. Provide suggestions if you are so inclined. Not to be rude, but whether or not you see a use for the technology irrelevant. The need exists
We already have that. This thread is about balance charging individual cells simultaneously
I don’t know what to say. I told you multiple times that it will not be that easy (just think about how many power outlets you’ll need for 10 separate USB chargers). One RC charger does what you want - and is easier to use, faster and cheaper.
There is no need for this because the solution already exists.
You need to start thinking what the benefit of your method will be.
Just as an example: I already have my battery set up as two 5S packs that I can charge individually on an 6S charger. This way I can test the individual voltages from time to time. Normally I charge with my DROK. This is as easy and cheap as it can get and I have full control over the voltages I charge my battery to.
As an electronics engineer, there’s a lot… interesting ideas presented here. Surely out of the box ideas for me, but how sensible? Not so much.
The easiest and best practical way would be to wire your S>6 pack so that it can be charged as two S<=6 packs and use RC chargers as @Maxid suggested. Otherwise you’re going to be babysitting your battery pack and checking cell voltages and adjusting your charging currents and voltages. A RC charger will lower the charge current once a cell hits 4.2 V and then trickle charge the rest of the way while discharging the 4.2 V cells so they don’t overcharge.
Other possibility is the @raphaelchang 's BattMan BMS module.
It pretty much comes down to these reasons:
Not everyone uses quality cells.
Not everyone uses quality welders.
Not everyone has good soldering/welding skills.
Any of the above plus not having a BMS will ruin your batteries.
As an example @denton had a battery pack in which welds failed and he was also using a charger with way too high voltage, but since he was using a BMS to charge and discharge no damage was ever done to his batteries.
Someone with a wrong charge voltage is kind of unfair to use though as an argument no?
It is not hard to make a setup without a BMS work well, so I still feel like they are not really necessary.
His charger was not the reason his cells were out of balance, it was the bad welding tabs. Still a valid argument. Look at eboosted and all the trouble he’s having with drifting cells.
It’s not trivial…
One, you have to buy or make a quality welder.
If you are soldering, you have to have good soldering skills and even then by the fact that you’re soldering onto batteries, you will damage them some.
Two, you have to buy quality cells.
Three, you have to have very conservative settings. Have you looked at whitepony’s settings? He only uses like 70% of the available capacity in his cells and doesn’t discharge them at high currents either.
Four, if vibrations work a weld/solder joint off a cell, your pack is F’d. (this is where my example came into play really)
There are plenty of reasons to use a BMS. If you prefer to baby your pack instead then fine, I do it that way just because I like to know the state of my batteries all the time.
Not sure what to say - as usual I get your point but am personally not convinced that a BMS is crucial. Put some balance leads on the pack and check from time to time and it should work fine. I used a DIY welder and have no problems with my packs.
People with faulty packs will obviously benefit from a BMS but I’d rather pay attention when building my pack in the first place and make sure everything is well.
All I am saying is that when you know what you are doing they are not crucial.
When you know what you’re doing, want to be conservative and prefer to do the monitoring yourself, yes. They are not crucial. For everyone else, it kinda is.
I have made the same idea disgussed here.
It consists from 10 of TP4056-modules, 10 of 1A/5V power supplies and 7-segment voltage-meters.
It is able to charge at 1Ah rate. Usually it took about 5h to charge after riding. It has been good enough for me.
Then i attempted to charge simultaneously with 42V/2A charger, and about 3 of the modules died. I don’t know if the 42V charger was the cause or something else. If you think about it, what could be the thing that would kill those modules if it was the 42V charger?
Anyways, it was pain to troubleshoot and repair because of the design i made. I broke it all to pieces except the voltage meters.
Nowadays i’m just charging with only the 42V charger and voltage displays attached, so i see when any of the cells reach the 4,2V. Usually all the rest are about 0,1V-0,15V lower that the best.
I stumbled upon to this thread when i was searching info about those lm2596-modules. The TP4056 is not adjustable, so they can’t really be used on separate charger if you want to auto-cut the voltage when full, because the wires make additional resistance. lm2596 can be adjusted, though it will not cut the charge, but it is still better, because it heats less.
I’m actually moving to “normal” balance-charger now. A FET per cell loses the excess current into heat while series charging. But that’s out of this topic.
But i’ll try the lm2596-modules as parallel-project though
On a side note… I also witnessed that TP4056 overcharges the cell, if left for loo long… so yeh, either manual cut-out or a circuit is needed… otherwise they dont seem very reliable when in parallel config
