MakinThings

The 20A is essentially the max the buck converter will output without frying when actively cooled (I would say that if it'ts not ventilated, run it at 30% of max if you can, no more than 50%). Whatever you plug into it will draw a certain amount of current, and that will be controlled by your devices. What you may want to do is put a fuse or breaker that caps the draw at whatever you feel comfortable. When calculating, I would say that phones usually have a max draw of 1.5-2A, and tablets can go 2-2.5. If you are making sure you plug no more than 10A draw in total, then those ballpark figures are more than enough. If you are going in higher amperage in total, make sure that the wire is thicker, especially if it starts getting longer than a few inches.Last think, make sure it's a switchi...

The 20A is essentially the max the buck converter will output without frying when actively cooled (I would say that if it'ts not ventilated, run it at 30% of max if you can, no more than 50%). Whatever you plug into it will draw a certain amount of current, and that will be controlled by your devices. What you may want to do is put a fuse or breaker that caps the draw at whatever you feel comfortable. When calculating, I would say that phones usually have a max draw of 1.5-2A, and tablets can go 2-2.5. If you are making sure you plug no more than 10A draw in total, then those ballpark figures are more than enough. If you are going in higher amperage in total, make sure that the wire is thicker, especially if it starts getting longer than a few inches.Last think, make sure it's a switching converter, not like the one I used (which is fine for the lower amount of energy used at 5-15w)

Well the harder you push batteries, the less you will get out of them. So with 2x 3Ah packs in parallel, you would get a bit more run time than if you took each battery 1 at a time. The same is true from 3 to 4. You do not want to mix 4 and 3 ah batteries, but rather make 2 packs. The reason is that the smaller one will drop voltages sooner, so if the average voltage stays too high overall, you could over-discharge your 3ah batteries and prematurely kill them. If you do go with 3ah and 4ah, you would have to find a way to stop when the 3ah is discharged. They are expensive I agree, which is why some NiCads might be nice for this, especially since you can find people getting rid of them for free if you take your time. The 2x 3ah would give you something like 15-20 minutes run time, which...

Well the harder you push batteries, the less you will get out of them. So with 2x 3Ah packs in parallel, you would get a bit more run time than if you took each battery 1 at a time. The same is true from 3 to 4. You do not want to mix 4 and 3 ah batteries, but rather make 2 packs. The reason is that the smaller one will drop voltages sooner, so if the average voltage stays too high overall, you could over-discharge your 3ah batteries and prematurely kill them. If you do go with 3ah and 4ah, you would have to find a way to stop when the 3ah is discharged. They are expensive I agree, which is why some NiCads might be nice for this, especially since you can find people getting rid of them for free if you take your time. The 2x 3ah would give you something like 15-20 minutes run time, which is respectable. If the 3Ah are much cheaper, then they will probably be better value. At 6ah pack, running the cells at 15 amps (what the controller should top out at), will be reasonable for this kind of battery. If it were a laptop battery, it would destroy it, but power tools can easily draw 10+ amps continuously (with higher spikes) on a single pack. Doesn't mean it's not going to add some wear, but any pack being used at high currents will take extra wear.If you do 2x 4ah and 2x3ah, you should get to know what the safe operating voltages are and install volmeters for each pack. This ads cost and complexity obviously, so it kind of defeats the purpose of this. At that point, you should start learning all the basics and build a pack.But again, if you are using the newer pack, they do auto-shut off and using them in parallel could be tricky. The way to know if it does this is to test the voltage with a voltmeter (not the battery tester button). If it says something like 5-6 volts, then it is in the standby mode, and you will likely have trouble with it.

Something I had not thought about if running these at 18v. If it was a 12v, it will likely be pushing it but work (like I did with 24 to 36), but on a 24v controller, you may be below the safety shutoff and the scooter simply won't accept the pack. I think the normal cutoff for this would be around 20v... so 18v won't work.

Alright, quite a few questions there.There are a few things here. First the 24v controllers are generally rated to 36 volts, but there is no guarantee. In the case of the Razors, when I did find the parts and look up the specs, the 24v did seem to be able to take it. Now, HOWEVER, they do this to have some over head in case parts aren't perfect or whatnot. We are effectively removing that overhead when running at 36 (upwards to 40v when fully charged because of the float charge). MORE IMPORTANT STUFF ON THIS BELOW.Next, yes it has to go through the controller, for a few reasons. One of these reasons is that it controls and limits the current going through the motor, which is important as we will see next.For the batteries, when you say 2x2, I assume you mean 2 series 2 parallel. Series ...

Alright, quite a few questions there.There are a few things here. First the 24v controllers are generally rated to 36 volts, but there is no guarantee. In the case of the Razors, when I did find the parts and look up the specs, the 24v did seem to be able to take it. Now, HOWEVER, they do this to have some over head in case parts aren't perfect or whatnot. We are effectively removing that overhead when running at 36 (upwards to 40v when fully charged because of the float charge). MORE IMPORTANT STUFF ON THIS BELOW.Next, yes it has to go through the controller, for a few reasons. One of these reasons is that it controls and limits the current going through the motor, which is important as we will see next.For the batteries, when you say 2x2, I assume you mean 2 series 2 parallel. Series = more voltage, parallel = more current. BECAUSE the controller limits the current, when it is in parallel, you simply have more runtime AND put less stress on your batteries. This is not universally true, but in this case it is because of the controller, some other devices would just draw more current, overheat, and burn up. That being said, batteries auto-shut off, and I had issues with running them in parallel, older-style Ni-Cad batteries may be better for this. For the series part, it increases voltage. Now what happens is the controller does not limit voltage, so although we don't increase the current going through (which would almost certainly melt things), we are still increasing the total power going through (W=V*A or watts = voltage x amps). This means that some parts are still going to be pushed; the motor for example, would be running at 1.5 times its usual wattage. This will still cause some parts to heat up, and so extended use could cause issues. Case and point, may failure point was my batteries. The terminals got hot, and the plastic of which the batteries are made were not rated for that kind of output. The plastic deformed. Do I care? no. Will you? possibly. If you are worried about longevity/want to use this a lot, you might be better off using only batteries in parallel. Take the hit to speed, but you would be running under spec, so longevity is good, you get the interchangeable packs, the quick charging, and much longer range. Also, although you technically don't get more power, since the batteries are better at taking this than the lead acid batteires, you get a more consistent throughput, so you don't lose as much power when you run it longer because there will be less voltage sag and so a more consistent ride (assuming your battery was sufficiently large in parallel, 8Ah in parallel = good, 16Ah = very easy on the batteries). Feel free to ask more questions, I usually respond within a day or two. By putting it here, we get to share it with anyone else with these questions :) Also, if you want to help me out, subscribe to my ible and youtube!

In should be connected to a pin that you can actuate. When you say 0V it makes me think that you connected it to the ground.When you say that the relay stays on, have you disconnected the VCC? I don't know what module you have, but some relays "stick" by design. Is this what you have? It would really help if you posted the part numbers. Also, sometimes the PI defaults to having the GPIO pins active so that you have to send a first command to actually turn them off (I had to reverse the default setting on mine).

In should be connected to a pin that you can actuate. When you say 0V it makes me think that you connected it to the ground.I don't know what module you have, but some relays "stick" by design and have to be actively turned on or off. Is this what you have? It would really help if you posted the part numbers. Also, sometimes the PI defaults to having the GPIO pins active so that you have to send a first command to actually turn them off (I had to reverse the default setting on mine).

I did start off by making holes, but the stump was still green so large bits, and even smallish ones had trouble. Also the oil would have been burning on the surface, it would not have helped much, and oil needs to be pretty hot to burn and burns real dirty. Getting it under might have worked, but then it would have soaked into the ground.

Absolutely not "5V-35V Drive current 2A(MAX single bridge). Max power 25W Storage". I didn't realize this was AC. Are you modifying an existing device that has physical buttons? In that case, you could just use relays to bypass / be remote versions of the buttons. You would just have to make sure you can't short anything once again though.

Short answer: yes but you probably don't want to. Long answer: for the sake of a DIY project where you want to learn and understand the circuit, you could use 4 relays so that each side of the motor has a + and a - line interrupted by the relay, so that you can turn on pairs of relays to change the side. However, this opens up the risk of a short, and would require some sort of fail safe. You will be better off with one of these modules http://amzn.to/2kIuwQF

Of course, the big advantage of a plotter is that it can print on any flat surface you can place under it. In this ible I only did for very thin ones, but I have another ible coming about doing thicker and double-sided surfaces. It's just that it got to be something like 30+ steps when I put them together, because I did it specifically to draw with a sharpie on copper clad boards to make circuits (etching PCBs). Another advantage is that if the type of ink matters, it can also be the only way to get it done sometimes. Printing a document on this would be a waste of time for sure. Plus, this is also a step 1 for me, as it allowed me to properly get a hang of 2d prints, so that I can move on to my next steps; a cutting blade, and eventually a laser.

ha, that's exactly how I landed here. I need 12x 0.05 ohms at 100W.

the read out is actually going to happen where your multimeter intersects with the shunt, the voltage drop is only occurring between those two leads, so the extra resistance added by the clamps won't play into the voltage drop measurement. circtuit-------+---shunt---+------- where + is where the multimeter reads in, as long as the clamps are before and after it, it will not be part of the shunt.

Right, but stainless requires more than 50 cents, and is not as simple to make into getting a 1:1 readout for simplicity. I have other shunts, but this is certainly going to be my go-to for testing stuff in my workshop. Powertools, welder, and e-bikes aren't going to go belly up on a 5% misread.

haha, thanks! :)

Nice, thanks. It is good in a pinch or for pure hobby usage. I wish we had harbor freight here, I'd have to order directly from China and wait 3 months if I don't want to spend something like 10$ per terminal!

It can pretty much be used as is since it can take AC or DC on the switching side. You would have to figure out if the reset switch on the PC is one where when you press it it opens or closes the circuit. Once you know that, you simply use the relay in a way which works for you. These kinds of relays have the option of always on to off, or always off to on when you apply power to the other side. After that I guess it's just a matter of flipping it back right after you activated it.

Lol, it just means you were doing it right from the start :p. It's also more of an issue with electric cars. The climate control gets used less and it's a heat exchange pump rather than a resistive heating element... But really the worst was when I just did it plain wrong.

For brazing a clamp is certainly better, but for spot welding, I wanted to be able to apply the current in an accurate and localized manner on small work piece.

And thanks :)

Yes and no. First off, it is important to note that mixing batteries that are not identical is not recommended. If you charge them separately, you could make it work, but it would require active monitoring of the batteries and a good understanding of what you are doing. Luckily, the most you could do is damage them, not start a fire as is the case with lithium, but still.. no one wants to damage their batteries. If they were produced at the same time, have similar wear, and are same brand, then you should be good to go, but then you have more things to consider. How you use them would depend on the ratings. Parallel = more power (necessary to accelerate and / or keep the speed up), voltage = more speed. If they are 12V, 3 in series would give you 36v at whatever amp rating it is capable...

Yes and no. First off, it is important to note that mixing batteries that are not identical is not recommended. If you charge them separately, you could make it work, but it would require active monitoring of the batteries and a good understanding of what you are doing. Luckily, the most you could do is damage them, not start a fire as is the case with lithium, but still.. no one wants to damage their batteries. If they were produced at the same time, have similar wear, and are same brand, then you should be good to go, but then you have more things to consider. How you use them would depend on the ratings. Parallel = more power (necessary to accelerate and / or keep the speed up), voltage = more speed. If they are 12V, 3 in series would give you 36v at whatever amp rating it is capable of. If they are 6v, then you will only reach 18V, which will just continuously trip the low voltage protection circuit. Some (rarer) batteries are 24V. Normally companies just slap 2 12v together, but still.. If you do have that, putting 2 in series would burn out the mosfets, so you would have to use them in parallel.

Lol, that's quite the mental puzzle there. Love it!

Thanks. If necessity is the mother of all inventions, frugality is is close second! :p

Thanks. If necessity is the mother of all inventions, frugality is is close cousin! :p

A squirle has been knocking mine down now and then :p

Thanks :) I was thinking of making this into two separate ibles, but I thought it was nice to be able to compare them.

Yeah, it is pretty single use :p

I originally wanted to run the pool pump, but realized it would require too big at the setup compared to mostly free salvage :p. What are you going for?

Haha thanks. After a day in the sun next to those burners churning that machine, everyone was getting a little grumpy :p

Noise? If you mean power spikes and dips, then yes, the capacitor should handle those, but if your mp3 somehow has poorly isolated power that feeds back through the audio jack, I don't know what to say... Can you describe the issue? Also, modern cig lighter adaptors are tiny these days, it's why I recently added to link to one of those cheap flush mounting ones.

It's hard to diagnose like this, but is the noise different/change when the engine gets revved? If so, the capacitor should do the job, you could even put a bigger one if necessary. If not, it's because the power of not isolated, no clue what to do then....

safety sand, always safety sand!

Lol, repetitive maybe, but totally worth it for the xkcd comic :p. They don't explode per say, but violently burst into flames (in the case of lico), but if you pick appropriate cells, the worst reaction from a permanent short would be swelling and venting of hot gasses (that's what those little holes on this site positive terminal are for, and one of the issues with sealed cells or battery packs like pouch cells and laptop bricks). Cell protection would have to be specifically designed; normal protection circuits would not work well here. Tracking temp and voltage are the safe thing to do in this case. A protection circuit would not make the difference between the voltage sag and dangerous discharge levels, so it would be useless as it would either prevent the device from working, or ...

Lol, repetitive maybe, but totally worth it for the xkcd comic :p. They don't explode per say, but violently burst into flames (in the case of lico), but if you pick appropriate cells, the worst reaction from a permanent short would be swelling and venting of hot gasses (that's what those little holes on this site positive terminal are for, and one of the issues with sealed cells or battery packs like pouch cells and laptop bricks). Cell protection would have to be specifically designed; normal protection circuits would not work well here. Tracking temp and voltage are the safe thing to do in this case. A protection circuit would not make the difference between the voltage sag and dangerous discharge levels, so it would be useless as it would either prevent the device from working, or allow I to work too long while giving a horribly misplaced sense of security. Over discharging is an issue because the electrolyte becomes corrosive and eats that the cell, voltage sag does not.

If that's what you understood from the information provided, then yes, absolutely.

Yup, that's why I say not to use lipo cells explicitly even though they are generally considered high power ish cells. They are too severely compromised by being both high power and capacity; they are optimized for weight and cost. I have a 45 minutes video and a ible longer than this one just on selecting proper cells for high power use. I kept it separate precisely because there is so much information.

Yup. I think I am going to update my intro a bit to reflect that; I pretty clearly say in the video that this could be dangerous if not properly done, and I do go over it in the salvaging li-ion ible, but you are right that I don't say it enough in this one. They are emoli Li-MN cells; when new they were rated for continuous use at 40A each and rated for peak (30 seconds) use at 100A. So even though they are old, I am just running them in bursts at what would have been their original rating.

Welp, I just ran them in my spot welder; vaporized aluminum no problem, but the lugs stayed cool as a cucumber. Did not go up from ambiant temperature by more than a degree C

Oh absolutely not for anything in-wall I agree; but anything I DIY / salvage? Heck yeah! Just tested mine at roughly 350A yesterday, and it worked like a charm.

Yup, at 5 minutes per lug (after the first one where I fiddled for the while of course), it saves me 8$ each and the drive out. I just ordered some heat shrink that would fit actually, because my 1/2 rubs on the sheathing when I put it on, sufficiently to heat up and tighten :p no way I would go over my lug at the moment. What did you use the punch for? I was tempted to crimp using the screw driver to jam the pipe down at first, but I was worried the stranded wires would still slip out.

Nice, probably easier than my outer crimping with the rings. What size pipe to wire did you use? Ps. Thanks for the participation, I've sent you a pro membership voucher.

Hehe, you are two steps ahead of me! It is indeed for a spot welder, and I am currently working on an ible for the DIY <1$ lug connectors, after which I will post the spot welder. I decided to break it down because lug connectors are used for so much more than spot welding, and from there I figured that there are probably other uses to this kind of holder as well, especially if it is scaled larger. The lug connector ible is on its way already, but the spot welder is still awaiting a last part (looking for a solenoid that is rated high enough, the cheap ones I have found so far are only 80A). As for the power source, I am using a very unorthodox one... lithium batteries. I know, I know, it sounds crazy and dangerous... you can check out my other ible on that topic https://www.instruct...

Hehe, you are two steps ahead of me! It is indeed for a spot welder, and I am currently working on an ible for the DIY <1$ lug connectors, after which I will post the spot welder. I decided to break it down because lug connectors are used for so much more than spot welding, and from there I figured that there are probably other uses to this kind of holder as well, especially if it is scaled larger. The lug connector ible is on its way already, but the spot welder is still awaiting a last part (looking for a solenoid that is rated high enough, the cheap ones I have found so far are only 80A). As for the power source, I am using a very unorthodox one... lithium batteries. I know, I know, it sounds crazy and dangerous... you can check out my other ible on that topic https://www.instructables.com/id/Make-Lithium-Battery-Pack-From-Salvage/ :p

well I'll be a monkey's uncle. I recently "discovered" your youtube channel, only to figure out 2 months later that I had been following you on here long ago....

Alright, with a bit more time to respond... Putting cells that are similar in voltage in parallel won't affect them adversely. That it why they should be within 0.2v of each other before you start. They should also have similar capacities, and although I exclude my worse ones, I did have a few with higher capacity in there. However, these are cells rated for more than 2c charging, and I was charging them in parallel at an aggregate 0.2c, so that were in good conditions because even when the fully charged ones started dumping their extra capacity in the less charged ones (because they have more capacity to fill), at most it would have been charging the higher capacity cells at 1c. Balancing leads are for series packs, that's when you can really mess up packs if you mixed an matched, and...

Alright, with a bit more time to respond... Putting cells that are similar in voltage in parallel won't affect them adversely. That it why they should be within 0.2v of each other before you start. They should also have similar capacities, and although I exclude my worse ones, I did have a few with higher capacity in there. However, these are cells rated for more than 2c charging, and I was charging them in parallel at an aggregate 0.2c, so that were in good conditions because even when the fully charged ones started dumping their extra capacity in the less charged ones (because they have more capacity to fill), at most it would have been charging the higher capacity cells at 1c. Balancing leads are for series packs, that's when you can really mess up packs if you mixed an matched, and that's where lipos can burst. Remember, in parallel, you increase current business need same voltage, in series you increase voltage, but need same current (the other half can be "close", but should still be very similar, that rule is to remember which one is critical and can lead quickest to a failure) . Again, I would not recommend salvaging lipos, or low power cells, just because of what happens as cells age.

I would not recommend salvaging lipo cells at all as I mention in the beginning, they are too volatile. They also require firebags for safe charging.