Can you post a full schematic of this? It's hard to follow along in the video.
@JWH3
6 жыл бұрын
I ran some simulations on this, you're not going to charge these significantly faster but when I simulate a discharge of these the ESR just isn't as low as is possibly is needed. These caps charged to 2.7 volts in series will only dump 4 joules into a 50mOhm load in 10ms and that's at 90amps. I don't think that's enough. Most capacitive spot welders I've seen use significantly smaller caps and go for lowest possible ESR they can do because that's how you get high pulse currents which is what you need. I could be wrong here mainly cause I don't know what practical terminal resistance is when you actually go to weld with these things. You might be okay if the actual contact resistance is significantly less than 50mOhm but you have the wiring resistance to consider as well. Every single last mOohm matters in pulse discharges. The shape of your tips is actually going to matter pretty seriously here.
@DevelopIT
6 жыл бұрын
Jake, thank you for pointing out the Kelvin leads, I will have a read about these even if they may be of no use here, because it sounds like a useful principle. I'll keep in mind the capacitance issue in case there are problems when I come to try it out. I appreciate the time you took the run the simulation for the Kelvin leads.
@magnuswootton6181
3 жыл бұрын
cant you just increase amps all the way to 10,000 and it charges instantaneously?
@JWH3
6 жыл бұрын
Are you using Kelvin sense lines to measure the caps voltage? Cause if you're measure through your charging leads at those currents the lead resistance will give you an incorrect measurement. You may be and to charge these even faster.
@DevelopIT
6 жыл бұрын
Before I connect the super capacitor I set the 2V7 at the terminals with a multi-meter. After connecting the capacitor and charging it the multi-meter reads about 2V65 steady voltage, I just adjust the voltage up by the 0V05 to 2V7 according to the multi-meter, at that point.
@JWH3
6 жыл бұрын
@@DevelopIT yes but during charging because of the lead resistance (it matters at these higher currents and low voltages) your opamp will read the wrong voltage. I'll run a simulation later just out of curiosity. All Kelvin lead is a sense wire from the cap terminals that is not carrying current. It's as easy to implement as two wires.
@Pendatun123
2 ай бұрын
Sir may ask about self discharge of this super capacitor, if full charge how many days volt drops?
@DevelopIT
2 ай бұрын
I think it depends on the quality of the super capacitors. I have some small 10F capacitors that stay charged for weeks. I don't remember about these 500F ones, but they do loose charge faster.
@Pendatun123
2 ай бұрын
@@DevelopIT 500f?
@mikewood546
5 жыл бұрын
I have a general question about charging super caps vs. batteries. If you have say a 12V 100 ah lithium battery and a pack of 5-6 super capacitors equivalent to the lithium battery, both at 50% capacity, is it possible to charge the supercaps back to 100% faster than recharging the battery? Or would it take the same amount of Time? Thx
@DevelopIT
5 жыл бұрын
Lithium batteries have a C rating, each make and model has it's own rating, you would need to see the specification sheet for the specific lithium battery you are using. The C rating specifies how fast you can charge a single battery. So my cheap 18650 batteries are 1Ah. The discharge rate is specified as multiples of the charge rate, so 2C for mine, which would be 2Ah. I am pulling more than the rating in this video for the lithium batteries I am using. Pull or push too much and there is a risk of damage or fire. Good makes such as Samsung, Panasonic have better capacities, charge and discharge rates. For super capacitors I have never seen a rating. I believe you can charge and discharge as fast as you like. However, the terminals on top of these capcaitors will have a limit as to how much current they can take before they melt, I don't know what that is. Also for capacitors in series you would have to balance charge in the same way you would have to lithium cells as each must not exceed it's rated voltage.
@DSEC_UK
5 жыл бұрын
Great video mate, I'm working on a future video atm where I'll be remapping a car to do really high MPG - obviously weight reduction is key to this. Any chance this kind of technology could replace a 12V heavy battery? if you can help let me know :)
@DevelopIT
5 жыл бұрын
While the engine is running the alternator supplies enough power to run everything plus charge the battery. So to replace the battery you probably only need something that can turn the starter motor enough to start the engine. So to minimize the weight of the battery you would only be able to use things like lights when the engine is running. You could probably get super capacitors to start the engine, but there would probably be a couple of issues. High capacity super capacitors tend to loose power over as little as a 24 hour period and would probably require the engine start on the first few turns of the engine. Li-ion batteries would probably be a better option, if you search eBay for "car jump start", you'll see something which is low weight and capable of starting an engine. You would need to workout how to connect it to also charge itself when the engine is running, which may be simple. And also take into account not running things like lights when the engine is not running the alternator. There may be other issues to take into account though.
@DSEC_UK
5 жыл бұрын
@@DevelopIT Thanks for the reply. The smallest (non-race spec) battery weighs roughly 15kg (ref Halfords) and the race batteries are not really practical/budgeted for making the video. I’ll ultimately want to be selling the remap file for that engine and the steps including the weight reduction process will have to be easily repeatable for the viewers. I’m pretty sure a set of 18650’s + controllers wouldn’t weigh more than 0.5kg - taking into account the map will likely end up being a really underpowered drive. Right off the bat would be a weight saving more than equivalent to the entire rear seats/boot interior being removed. The ambition of the project is to have a modern car exceed 120mpg with a VAG diesel platform.
@S-Tach
4 жыл бұрын
Hi i like you project and demonstration i would like to make one for my spot Welder can you please send me the design and code for this project.!
@DevelopIT
4 жыл бұрын
There is no code. You can get a dual volt meter from eBay, and the video covers the design.
@S-Tach
3 жыл бұрын
@@DevelopIT okay but how do you charge the capacitor can you share the design of charger ?
@Ender_Wiggin
6 жыл бұрын
Do you have the spec of the super cap? ESR
@DevelopIT
6 жыл бұрын
I don't have the spec for this capacitor. I got them on eBay from China and don't really know any more than is written on them, apart from I got them because they where cheap.
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