Make Your Projects Rechargeable -12v version (MEHS) Episode 68

[@moellersworkshop2116]

I just want to say how much I appreciate your willingness to document this rather complex subject so well, thank you. I say complex because it's not like I can "just try this, or that" and hope it works while the possibility of exploding batteries from taking a guess exists.

[@honestinsincerity2270]

Man, these videos are so helpful. By far the best content on 18650s and custom battery packs I've found so far

[@Tom2112Tom]

Thank you for doing this video! I've been scouring the Internet to try to figure out how I can power my 12v project with both external power and 18650 batteries. You see a lot of videos on how to protect the batteries, and a lot of videos about how to charge the batteries. But no one seems to be able to put the two together AND add the ability to power your project externally while also charging your batteries! Thank you, thank you, thank you!

[@michaelsstuff4402]

- Glad you liked it. Cheers.

[@d.thorpe2046]

exactly the video I needed. subscribed. thanks from edmonton alberta

[@dgkrompholz]

Very informative. I would love to see you go from this prototyping stage to a simplified, finished product. Ideally the cost of parts excluding the batteries would be under $25 (the cost of a talentcell 12v 18650 battery pack off Amazon). The video would explain best practices in assembling the pack at each step of the way. Thanks!

[@azzebouz8483]

Thank you very much for this video. Exactly what I was looking for . Please can you explain more how to add a relay in this project

[@MichalsonCZ]

Wow, these videos are super! Thank you very very much for a clear explanation including great animations.

[@michaelsstuff4402]

Thanks very much.

[@TejKiran]

Awesome!! Thanks for all the great videos on lithium based power circuits. These have been a great help to me :)

[@michaelsstuff4402]

- Hi. Glad to hear they are helpful to you. Thank you.

[@pruff5072]

I was trying to think of how you could prevent the battery charging circuit from running when you have external power available. Maybe you could have a microcontroller monitor the charger circuit output line as well as the external power supply line then only allow a relay to close between the external power supply and the boost converter after a certain period of time has passed or if the external power source goes low (in anticipation of it returning). Something like a latching relay might be better or even a solid state relay but I don't know enough about them. The microcontroller would need a big capacitor to give it enough charge to switch the relay contacts closed once the external power supply went low. Otherwise, the microcontroller would be unpowered when the external power supply was unpowered. Or maybe the uC could use power from some of the batteries so that it would not need a substantial buck converter for it to be powered. But I'm not sure if the charge controller would be able to supply more charge to individual batteries as opposed to the whole batter pack at once.

[@johnmaclean2466]

When both are connected to the load and the 12v supply is interrupted, what prevents the Batt from feeding back into the step up converter creating a closed loop ?

[@flokifpv1803]

Good point, a one diode would solve this I think m

[@arielz6118]

Thanks!!! I found it very well explained. Just to be sure, and as you also said in your MAX745 video "It may be overkill". What would happen if insted of using that MAX745 module you would just set the STEP UP mudule to 12,6 V output dirctly to de BMS? In my layout I was already thinking of using a STEP UP module between a 5V solar panel and the BMS.

[@RobsonWilliam82]

You can do that, but you need a boost module with voltage AND current regulations, cuz Li-ion need CV-CC charging. You will need some kind of indicator show when current drops to zero, so you will know it's fully charged. Also you can add a tiny balance board.

[@honestinsincerity2270]

So, in the case of the schematic at the very end, you'd want an NC relay which is then actuated by the constant 12V power supply to open whenever its connected, correct? I just don't understand the sentence at the end where you said it could "switch off or on" depending on how it's connected. I can't see another way to configure the relay that would really work and I think I'm missing something.

[@mutuasamuel1661]

i would wish to see you elaborate on how to use the 3s 18650 battery pack with a solar set up.

[@andrewvollmer4881]

This is by far the most in depth video i’ve seen on this topic so far! However i maybe not be thinking here, would it be possible to put a switch in between the project and the power supply that is charging the batteries, to stop the project from working while you charge it?

[@michaelsstuff4402]

- Hi. yes, just add an inline switch between the battery pack and the project. Cheers.

[@bardenegri21]

Love it! That's what I'm planning to use for my arm laptop. Thanks for the video it's great!

[@michaelsstuff4402]

- Hi. Great. Thanks. In a small sized project try to fit in the relay option as it generates a lot less heat. If you cant make it fit just make sure you have plenty of ventilation in your project. Cheers.

[@bardenegri21]

My Electronics & Hacking Show I'm going to try a mosfett based solution to disconnect the power if the heat of the diode based version is too much, I'll report back if it's worthwhile. I found a 10a 60v diode that has a mosfett-like package (superior cooling), its the MBR 1060. I'll see how it goes.

[@michaelsstuff4402]

- Great. Let us know.

[@poneill65]

I'm missing something here,.. What exactly is this "MAX745" board doing in this setup? You have the 3S BMS protecting the cells against over/under voltage. You have the Boost regulator providing 12.6+3v This "MAZ745" is only connected across the entire 3S pack so is not doing any 3S balance/protection. What, of any value, is this rather fancy board doing that the boost converter connected directly to the 3S BMS wouldn't? (in your review of this MAX745 circuit you say the trimmer pots can adjust the PER CELL voltage to 4.1-4.3v which would require connections to the intermediate points but I see no such connection points on that MAX745 board)

[@MCsCreations]

Really nice project, man! Fantastic!

[@michaelsstuff4402]

- Thanks.

[@downundergarage6968]

Newbie question here, why do you need a BMS (in this particular example) it is more like a protection board vs BMS. In your previous vid, you have indicated that this particular BMS will not properly charge the 3S pack (from memory it was giving the 3 cells only 1A in total).. So why put MAX745 in front of it if it is not going to pass the proper charge CC/CV? Sorry I must be missing something.. rest of the vid made perfect sense to me inc the relay switch on the output.

[@michaelthurley3319]

Howdy. Good question. The bms is required to combine cells into a battery of X volts, in this case 12v or there abouts. The bms will provide protection to each cell. The level of protection depends on the bms but most do under and over voltage and or current. The max745 is a proper lithium charging circuit / ic that can properly charge a 12v battery. I said battery meaning there needs to be a bms in the mix to turn our 3.7v cells into a 12v battery that the max745 can charge cc/cv. The bms alone won’t do cc/cv charging to the cells if you simply apply a 12 to 12.6v supply. Hope that makes sense. Cheers.

[@Min3cr4ck]

Nice and easy to follow. Cool Video!

[@michaelsstuff4402]

- Thanks.

[@270785dar]

Another solution to disconnect the battery when external power is connected, is to use a MOSFET. This would reduce the power loss in the form of heat when using diodes.

[@michaelsstuff4402]

- Hi. Yes absolutely, a MOSFET is a good way to go.

[@davidstanden480]

I have a Celestron CPC HD Deluxe telescope that runs on 12v DC. This video makes me think I could use your set up to power it. I am thinking I could 'hide' the electronics in one or both of the fork arms of the mount as they a partially hollow. The scope uses 2 Amps max to power the slewing motors. The power draw is considerably less, about .2 Amps when the scope finds an object and just tracks it using the same 2 DC motors. Questions: Can I use 6 batteries in parallel, instead of 3 in order to have more lasting power? Do you think your design will work for my application? Thanks, David

[@michaelsstuff4402]

- Hi. Yes this would work very well for your application. You could expect to get up to 10hrs of run time from a 3S pack and up to 20hrs from a 3S 2P pack as you suggested. The BMS and cells can easily deliver up to 10A so your 2A draw is well within tolerance. Cheers.

[@davidstanden480]

is it possible to add a 'battery percent voltage display'? where in the circuit would you add it? I am guessing it would draw some small amount of power from the system? I was thinking of something like this one on eBay... www.ebay.com/itm/2S-3S-4S-6S-7S-Lithium-Li-ion-18650-battery-Capacity-Guage-Indicator-VoltMeter/322602341414?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D52973%26meid%3D1b0b6011695a4254a1714f945cd5fe6f%26pid%3D100678%26rk%3D5%26rkt%3D8%26sd%3D113137724344%26itm%3D322602341414&_trksid=p2481888.c100678.m3607&_trkparms=pageci%3A49ae61e5-82d5-11e8-bdff-74dbd180a1a4%7Cparentrq%3A7af653c51640a9cd6d4e35abffed4865%7Ciid%3A1

[@michaelsstuff4402]

- Hi. Yes they work fine. If power draw is a problem, as an option I would connect the gauge with a momentary switch. That way the gauge would only activate when you hold down the switch which is fine for a quick read. from memory, those gauges only take a second or two to read the voltage. Cheers.

[@DelaneyKassab]

But this won't keep the cells in balance, will it? Does that 3s BMS cut voltage off to individual cells when they hit 4.2 volts?

[@michaelsstuff4402]

Hi. Correct. For a balanced solution you would need to use a balanced BMS. Basically the same approach, just a more expensive / better board. Cheers.

[@sayantan9409]

I wanted to build a 18ah 36v battery pack using lifepo4 6000mah 3.2v (32650/32700) cells. I wanted to make 6ah 36v pack of 3.. And I wanted to charge faster... What should I do? Please help me out

[@mcoydizzon571]

Bms have auto off when its fullycharge sir???

[@liamburge463]

Hey buddy, question for ya:. What if your external supply is higher than 12v - eg 19v laptop charger cable. Would you step down first for the project then step up for the charging? I've been trying to figure out a way to power my led panel via a 4s connection with optional charging via a 19v power supply.

[@michaelsstuff4402]

- Hi. if your led panel draws less than 1.5A the your good to go as the MAX745 charging board accepts up to 20V as the input and will charge the 3S pack up to 2A. A 4S pack get charged at 1.5A from memory. If it draws more then you will need to figure out where best to send the 19V and have it stepped down for the LED panel. Just remember not to step down for the MAX745 board as it needs a minimum input voltage 2V higher than the pack being charged (so 14.6V input for a 3S pack and 17.3V for a 4S pack). Cheers.

[@gopalrajpoot428]

Also for my bluetooth speaker i am trying 4s..so are relays available in market of suitable voltage? or 12v/24v relay will do.. Thanks

[@LucaAlfredoSanzio]

Hi thank you very much for this video. I want to build a 3S3P battery system using an old Laptop power supply at 16V @3.3A. Now I'm trying to understand if this approach (MAX 745 + 3s BMS) is better from balancing point of view w.r.t another one, based on 3 x (isolated DC/DC converter to 5V + TP4056), where each battery is autonomously charged. Personally I prefer your appoach because - afaik -it is cheaper w.r.t the other one (Isolated DC converters cost around 8€ each). But what about balancing process? How is it performed with our design? thank you again.

[@michaelsstuff4402]

- Hi. You do have a form of passive balancing by just using a 3S BMS as each bank will be charged to 4.2V and cells connected in parallel balance themselves out somewhat. Its not perfect active charging and individual cell monitoring but it works as long as the cells have time to rest. You get better results when the cells are matched for storage and performance characteristics, e.g. they delivery almost identical runtime and chargetime. Active is better and there are BMS out there that have individual cell charging and monitoring, just don't remember seeing one for 3S3P. Cheers.

[@redscorpion133]

i ahve a 6s bms 22.2V output and a power supply with 24v 5A how can i charge this bms ?

[@svenema7]

I would need a 6S.. would it be possible to use two MAX745 in parallel and still have all 6 cells connected in series?

[@ModifywithManoj]

What is the input voltage rating for 3s bms

[@michaelsstuff4402]

- Hi. I depends on the chips used on the board but most will easily handle more than 20V. Its normally the current you need to monitor. Cheers.

[@AlexG-sp7qn]

Hello, thanks a lot for this video ! One question : does the relay have a small delay ? I want to power up a raspberry or pc, if i disconnect the power supply, the motherboard will be shut down before switching on to the battery ? If so, how can I avoid this delay ?

[@michaelsstuff4402]

- Hi. There is no relay in this example unless you have implemented one, but I think I know what you're asking. Check how you have everything connected as your Pi should not power off. The Pi will receive power from the external source and the battery bank at the same time. When the external power is off, the Pi will draw all its needs from the battery bank. If you're using a relay and have it wired up correctly, the relay should switch power over much faster than the Pi needs. One switched over, check that you have a good voltage coming from the relay / battery pack, going to the Pi. If not, you have a relay or wiring problem. If all is good then the relay must be really slow. You can replace it or put a large capacitor between the main power and the Pi. This will keep the Pi fed for a second while the relay switched things over. Cheers.

[@AlexG-sp7qn]

Thanks a lot, the relay seems to works fine at same voltage, but now i've got an other issue, i use a boost converter (at the end) to power a 19V project but it doesn't seems to do the job correctly... The motherboard shut down when i change the IN voltage. Do you think a synchronous booster should solve the problem ? But it's expensive... Maybe you know a simple and cheaper way to keep same voltage between battery and power ? Thanks again :)

[@michaelsstuff4402]

- Hi. You will need to describe your project in more detail. It might be that your boost converter is not able to produce sufficient current. Cheers.

[@redangrybird7564]

Ohhhh mate, so daeeengerouuus!! ✌😲

[@miteshdhanani]

As u have made it of 12v but if we want to make it of 7.4v and connect it to a solar 3W 8.97v 3a

[@TheNikolaschoulakis]

This is so cool i been asking all of these questions myself recently and could not find online anything that got to that level of detail for these practical issues, u saved the day for me so thank u. I am trying to build an 18650 based UPS with a 3S4P arrangement and Panasonic NCR18650B 3350mAh Li-Ion batteries. After seeing your video late last evening i ordered the Max745 board (i am in the UK and i could not find any locally available so i ordered from ebay via China) i have already a BMS on the way and a buck/bust converter. Is there a way for you to share with me/us a wiring diagram via email or dropbox etc? I am also interested to find out more about how i could substitute the relay with a solid state device ? Any way to contact you directly for advice too pls?

[@michaelsstuff4402]

- Glad to hear. I will try to put something up on my website this weekend. You're biggest issue will be the switch that cuts in when mains power is cutoff. You can use a high current relay or a MOSTFET and they are each used in roughly the same way. Just google the complete wiring diagram for a basic UPS and you should be fine. A complete UPS wiring example might be better for you anyway as some have a smoothing capacity in the circuit to avoid spikes and dips in power when the power cuts over. As far as connecting power to the MAX745 is just one positive and one negative wire (easy), and its the same for the connection from the MAX745 to the BMS (again nice and easy). Best of luck.

[@marcusgibson1011]

This was very helpful, I'm building a 4s 45/50Ah. I have a laptop power supply rated output 19.5v 4.7A. would this charge this size pack using a BMS and the MAX745?

[@michaelsstuff4402]

- Hi. Yes that sound about right. The MAX745 takes up to 20V (from memory) and 2A charge rate so feeding it 19.5v and up to 4.7A is more than enough (current anyway). Just make sure the MAX 745 is working correctly as some are very fussy and if you're just under the 3V buffer then it won't work. If your 19.5V is under at all or you have a fussy MAX745 then you might run into problems as your pack is 16.8V and you should be giving the MAX745 19.8v ideally. Cheers.

[@marcusgibson1011]

Hi there will MAX745 stop charging once the batteries are fully charged or continue charging causing over charge? Thanks

[@michaelsstuff4402]

- Hi. The datasheet for the IC doesn't specifically state charge termination but the fact it charges correctly using CC and CV means it has a charge termination point. So yes. I can't say for sure at what point it will reassess the cells and start a new charge cycle. Cheers.

[@MrAndreapas79]

Why do you use Hx-s3-01 and Max745... Hx-s3-01 is already a PCB and a BMS, so why you need a supplement charger???

[@OrangeCrush57]

Thanks for posting this. Its really helped me with a portable Bluetooth speaker design. I have a very similar configuration using the 3x18650 (2800ma) batteries in series with 15.4Vdc supplied to the same Max745 board and a 3S BCM with protection. However I am only ever able to achieve .4A from the MAX745. My Power supply is capable of delivering 5A but if I turn the pot on the MAX745 the charge light goes out and max current is .4Amps. My question to you, have you confirmed that the MAX745 was able to achieve half C of the battery (in my case 2.8Ax50%=1.4A)? Not sure if I have a defective MAX745, because it does charge and all my batteries are in good condition.

[@michaelsstuff4402]

- Are you measuring the input to the MAX745 or the output from the MAX745 to the BMS. Yes I tested mine and, from what I remember, it was consistently delivering over 1A output. You say the power supply is capable of delivering 5A but at what voltage and what is the real output? Your power supply needs to be delivering at least 15.6V (up to 19v) at over 2A at the MAX745, not the power supply. That could be an issue worth checking.

[@OrangeCrush57]

Thanks.... I have a similar set up using a step up voltage regulator (6009) delivering 15.8Vdc, so at the input of the MAX I'm seeing 15.8Vdc, and at the output of the max I can tune it to exactly 12.6Vdc. However when I measure the output of the MAX for current or the input to the cells, I'm only seeing .4Amps. This morning I disconnected the MAX and ran directly from my regulated power supply (similar to the one you use) into the 3S BCM and it show a measured current of around 1 Amp.

[@michaelsstuff4402]

Sid Jongsma - And don't forget, the MAX745 is CC/CV so depending on where it is in the charge cycle it might not be delivering the full current range at that time. If you have a data logging meter, use that to see what the MAX745 does over a full charge cycle. Cheers.

[@truthprophesy]

Actually better to add a switch from battery to led light so there is no energy wasted.

[@ituxcoza]

The video links in the description goes to your edit page, not the actual video URLs... Copy the urls from the link below the thumbnail in Creator Studio, not from the Address bar

[@michaelsstuff4402]

- OMG, unbelievable. Thanks heaps for the heads up. Cheers.

[@fagatali110]

Hi, Thanks for shares. Can I use a step up module after battery pack to convert 12 volt to 24 volt? my amplifier input is 24 volt and 5 Amp. I want to make a rechargeable unit for it, If not, can you please recommend a cheap solution?

[@michaelsstuff4402]

24v at 5A is 100 watts. You will need to select suitable BMS to handle the power and you will also need a really good 24v boost circuit and probably 2 x 3S packs to make sure you have enough current and tie them together before the 24v booster. Remember most 18650 cells won't be happy pushing a constant 5Amp output. Cheers.

[@fagatali110]

@@michaelsstuff4402thank you for reply, it was very helpful.

[@geekjon]

You don't mention how much current this would draw if you are recharging batteries and using the light at the same time. How would I calculate that?

[@michaelsstuff4402]

- Hi. The draw depends on the panel you're using. A small panel will pull about 1 amp, a big one up to 3 amps. The charge rate needs to be at least the rate of draw of better. Most modules that charge a bank of cells properly will only do so at 1 to 2 amps. There are a few factors that can impact the numbers but that's a rough idea. Cheers.

[@Optimizemore]

If you don't need both charging and driving the project at the same time, is it really worth it to complicate this much compared to only BMS? For the price of the max745 and buck converter you can buy 5 more batteries (LG 2600mA). Do you think the improved charging and subsequent improved life of the batteries are worth it from a purely monetary point of view?

[@michaelsstuff4402]

TullenSerpen - Hi. Yes very good point and something I was going to discuss in this or a follow up video. Basically it’s good to know an approach like this but you should evaluate your needs for each project and determine if the cost and complication is worth it. Cheers.

[@Optimizemore]

Thanks for the reply :). How about tp4046 in parallel as discussed in the comments on a previous BMS video. Have you looked into that? Would that be cheaper? Or do we need a BMS also in such setup?

[@Optimizemore]

Also, if we really want to maximize battery life should we not cut the charging at 4v and discharge at 3.4 or something?

[@michaelsstuff4402]

- Hi. Yes the TP4056 boards are great and you can string a few together in some instances. The trick is the common ground meaning you can't connect the outputs of the TP4056's together without disconnecting the common power supply. It can be done with FETS or relays but can be fiddly or is not a good fit for some projects. I will revisit at some time. Cheers.

[@michaelsstuff4402]

- Hi. Most good cells are more than happy being drained to 3V, many down to 2.7V. Yes it is documented that a 4V charge will give the cell some charge without stressing the cell meaning you can make the cells last longer. It depends on the use and the needs of the project. Some project designs call for max power and runtime whereas others are less demanding and you may decide to dial back the impact on the cells and trade-off for longer life. Cheers.

[@ognjenme]

This is a nice explanation, if only u could show how to wire everything, i know i am going to mess up for sure if i just try to reapet what i see in video. Thanks!

[@michaelsstuff4402]

- Thanks. Yes others have also asked for that. I will try to cover more detail in upcoming videos. In the meantime you can get good wiring diagrams by googling the parts. Cheers.

[@johnwood4816]

With a 3S 4P configuration would one BMS be OK or would I need 4 BMS units?

[@michaelsstuff4402]

- Hi. One BMS is okay. You can theoretically run any number of cells in parallel so its only the number of cells in series that matters to the BMS. Is say theoretically as the BMS will have power handling limits and if you ran, say 8P, the pack could provide too much current for a small BMS (say 8A). Charging is also an issue as you might not be able to push enough current through to the cells to charge correctly. You can also find BMS that have cell balancing which means the cells in parallel get monitored and managed better than a BMS without balancing. Cheers.

[@johnwood4816]

First, thanks for the quick response. I will use a similar setup that your excellent video explained. For my set up I will though provide the higher voltage using a PSU feeding the MAX745 into the 3S 4P pack. The BMS that I have is 10amp max. The equipment draws approx 5amps, though there is a motor and draws around 1amp, but start up current is unknown. I think I will take your advice and plumb for a 25amp BMS with balancing.. Cheers

[@thekaiser4333]

Where do I get the battery holders for my Lipo-batteries?

[@michaelsstuff4402]

- Hi. I just found these ones on Ebay. Cheers.

[@sIpoolguy]

So- if my project required a 5s- would it work the same, but with a 5s bms, and crank up the pot on the step up voltage regulator to the max 745?

[@sIpoolguy]

..and then beef up the reverse current diode block

[@michaelsstuff4402]

- Hi. Yes with the 5S BMS, no with the MAX 745. Yes just grab the BMS rated for the number of cells and current you are dealing with, 5S in your case. Unfortunately the MAX745 is not rated to charge 5S, only 4S. You won't get enough voltage out of the MAX745 for a 5S pack. Need to find another charging option. Cheers.

[@sIpoolguy]

My Electronics & Hacking Show am I able to charge from a step up voltage regulator? If I found a 12v charger for cheap, but needed 21v to charge my 5s.. could I step up the 12v with a regulator to do so?

[@michaelsstuff4402]

- Hi. Dont forget a Voltage Reg will just dump a fixed voltage at a fixed current into your 5S pack. That's not ideal. The MAX745 provides the correct charging methodology as discussed in other videos. The BMS will kick in if you use a step up reg and the charge in the cells exceeds the max voltage (say 4.25v per cell) but the BMS won't kick in if the reg is pumping 4.2v per cell and not going over. The reg will just keep pumping 2A (or whatever the value) into the cells at 4.2v each until something gives. If you must use a straight reg then you must use a timer. To do it right, you could buy a real 5S charger (turnigy) and setup your project to be charged by that instead of just a static external charger. Cheers.

[@sIpoolguy]

My Electronics & Hacking Show thanks for your time mate!

[@noshybabs]

Any chance you can give us some better circuit diagrams?

[@MohammedRiad]

What cherger would charge this cells thriygh 3s bms is it 5v or 12.6v?

[@michaelsstuff4402]

- Hi. If you are feeding raw power to the cells through the BMS you need to be using 12.6V for a full charge. If you are using a proper charger then the charger will determine the voltage and current required. If you embed your own charger (MAX745) to properly charge the cells through the BMS you usually need to go 3V higher (to15.6V) so the charger has sufficient power to run itself and do the job correctly. Cheers.

[@MohammedRiad]

Thank you.

[@gopalrajpoot428]

ohhh sure we can..btw very good video

[@gopalrajpoot428]

so if we already use a 19v dc adapter..we can bypass step up voltage module??

[@michaelsstuff4402]

- Yes that's correct. The MAX745 will take an input between 15.6v and 20v. Cheers.

[@gopalrajpoot428]

Thank u

[@SARATHKUMAR-ot5kt]

Can I use two BMS One for charging and one for taking output

[@michaelsstuff4402]

Hi. You could try it. You might run into battery fatigue issues or the BMS might react strangely if charging and draining simultaneously but give it a try.

[@Thatoneguy884]

Where is your switch? Couldn't you put the on off switch between the light and the battery eliminating the need for the relay?

[@michaelsstuff4402]

- Hi. yes you can use a manual switch to control flow but most people want the flow controlled automatically through relays. Cheers.

[@noweare1]

Some circuits use a fet between the batteries and panel. The fet is turned off by the presence of the main 12v supply. If you lose power then the fet turns on and allows battery voltage to power the panel. With a manual switch you would have to be there.

[@TwoBones001]

I wonder if it can power a Macbook pro touch bar... can't find any diy project with 18650 batt powering a mac on the go

[@michaelsstuff4402]

- Hi. Shouldn't be that hard. Just need to match up the input power requirements with the output of the power pack. I don't have a macbook handy to test unfortunately. Cheers.

[@sergeantcrow]

Thank you...

[@alexisxyz7531]

I made a 16,8v pack for a 15,6v nicad drill BUT the problem is when i put it under charge voltage starts dropping until i turn the drill off i do not know why i even tried with a 4s2p arrangement and the same happened :( please help me, hy it happens and how can i fix it

[@michaelsstuff4402]

- Do you mean 'when you put it under load'?

[@alexisxyz7531]

@@michaelsstuff4402 yeah, for example conecting to a 12v drill

[@MCPriester]

I would to biult a Powerbank with 24 cels and want to charge it in my car with 12-14,5V / 10A. I´m not shure 3S or 4S and what charging board i need do you have any good ideas? i want to charge every cel with about 1,3-1,5 A. Do you have any tips for good hardware for this project? I think this is a lot of Power and i don´t know which hardware can handle this. THX

[@michaelsstuff4402]

- Hi. The answer would depend on the details of what you're trying to do but the easiest way would be to buy 3 or 6 XTAR VC4 chargers to charge the cells. You would need to use nipple type cells but these chargers are not overly expensive and will run from a 12V car power supply and provide a very good charge to each cell at about 1A each. That would give you a very good outcome and maintain the cells for a long time. Cheers.

[@MCPriester]

yeah this charger is nice but i could only charge single cells but i want to built a big powerbank wich i could charge with one 12V plug in the car with enough speed. the plattform you show is nice but i think for my porpuse a little bit to small. i thought i need a charger board around 36 A at all. i want to charge at 120 W that is the maximum at a 10A fuse for the cigarete lighter in my car. i have a B6 this could handle this but i had to config it at every start of my car, and i want that the charging starts automaticly from crank. i have 2 of the usb charger from ur little powerbank that i want to use/discharge the bank and maby other 12V aplications.

[@michaelsstuff4402]

- maybe take a look at something like hobbyking.com/en_us/turnigy-4x6s-lithium-polymer-battery-pack-charger.html . You can then charge a 24 cells pack properly and the charger body runs from a 12v supply. Cheers.

[@MCPriester]

but idont want to by an expensive charger i only want a pcb like this www.ebay.de/itm/3S-12A-Polymer-Lithium-12V-18650-Battery-Charger-Protect-Board-Module-w-Balance/201912217841?ssPageName=STRK%3AMEBIDX%3AIT&var=501916711079&_trksid=p2057872.m2749.l2649 but that is not CC/CV charging an i need a pcb to handle the charging process

[@MCPriester]

what do you think about the balancer board combined with this ? www.ebay.de/itm/10A-LTC3780-DC-5V-32V-to-1V-30V-Automatic-Step-Up-Down-Regulator-Charging-Module/162779435490?hash=item25e66911e2:g:P~YAAOSwy~BaHmt6

[@TheNikolaschoulakis]

Pls post a URL link of the BMS u r using

[@michaelsstuff4402]

- Hi. Search Ebay for item number 253459423969. Cheers.

[@faithlessmedevil]

i use 26650 @ 5400 in 12v series... would this work for this project?

[@faithlessmedevil]

not 5400mah only 5100mah oooops

[@michaelsstuff4402]

- Hi. Yes. These BMS can be used with any Lithium 4.2v cells. The only caveat is the current rating of the BMS and the draw of your project. e.g. don't use an 8AMP BMS for a project with a 25AMP draw. Cheers.

[@faithlessmedevil]

thanks for that... i have a bms with a 20amp max current

[@faithlessmedevil]

also i used a stepdown rather than a step up for my charger draws upto29v of power

[@ravenmooore]

Does this balance the cells?

[@michaelsstuff4402]

- Hi. No it doesn't but similar models are available that do. Cheers.

[@SuperOtter100]

Hi, First of all thank you so much for the Info, great content. I just have one question, if you don't want to power your project from the power supply, but simply want to charge the batteries, whilst powering the project from the batteries only, would the circuitry change? Basically 12V goes only to the Boost regulator, that feeds the Max745, that Supplies the BMS, and then the project connected directly to the BMS. This is so that the project works almost as an uninteruptable power supply. Is this possible by just simply not connecting the project to the 12V Power supply, and is there any negatives for doing it this way (e.g. affecting the lifespan of the cells etc?)

[@michaelsstuff4402]

-Hi. Yes that would work, and is kind of the point. The main thing to watch is the total draw of the project compared to the input charge rate. E.g. if the project draws 2A at 12v and the charge rate going into the cells is 1.5A at 12v then at some point the cells are going to be fully drained and the project will turn off. If this isnt the case then you're good to go. If it is then you need to establish a bypass for the external power to go to the project and charge the cells simultaneously, trickier than it sounds. Cheers.

[@SuperOtter100]

@@michaelsstuff4402 Thanks for the prompt reply! Guessed that much. My Project actually runs 4 of these Circuits, 4 Step Up converters, feeding into 4 Max745's, feeding 4 BMS Balance Boards, charging 3 cells each. From the BMS, i then feed into 4 x (5v 2A) - Buck boost converters, to get me 4 x 5v Circuits, from the 4 12v Battery Banks. Each of these 5 v Circuits then powers a set of components. The first is a Raspberry PI 4, which should not draw more than 640 mA under full load, the Second powers a bunch of low power sensors (PIR, DHT, CO2, etc), the 3'rd and 4'th both powers 5xESP32 Dev Boards Respectively (each which will pull a max of 260 mA). So on each of the 4 Circuits, I'm well below or just touching 1 Amp. Once my PCB arrives, and I get it all soldered together, I'll post with the results. If the BMS can't charge quicker than I drain, I'll feed the 5v buck-boost's with the 12V input as well, and add the Diodes. Once again, thank you for sharing your knowledge, hope the Subscription and Bell icon helps with the growth of your channel!

[@sahilranaled5117]

How to charge in 1 habrs

[@MrBrymstond]

My Electronics & Hacking Show+ As a perfect replacement for the not so ideal diode, go to ebay and type in "Ideal Diode". These are 100% blocking and the function using P Channel Mosfets. Cheers.

[@michaelsstuff4402]

- Thanks for the tip. Cheers.

[@Charlie90071]

first :D

[@michaelsstuff4402]

- :)