Recent content by stargazer193857

This thread is a reason why engineers often don't hire mathematicians, at least not mathematicians who don't also have a degree in engineering. Still, this math guy wants his physics education. Power (heat) = (V^2)/R. I just now realized it, and see you kind of posted it here too. Suppose...

Thank you for that second keyword, design; that got me some good Google results. OK, so the transformer connects their voltages but not their currents. Loads must be in both loops. I have plenty of reading to do.

On the input size, where there is 120V ac, there is a 10amp fuze in series with the 18 gauge copper wire and 60 windings. The ring is solid iron, 5mm tall, square cross section, 30mm outer diameter, 20mm inner diameter, wrapped in one layer of electrical tape to prevent conduction between wires...

Never mind. No You-Tube video is needed. I now fully believe how dangerous it is. Probably a much safer way to do it is to put a resister between the batteries scaled to the voltage difference, and put a heat sink on the resister. I thought of that idea before, but I abandoned it because of a...

Well, mrBigGuy told me by PM that a similar set up would go ka-bam. So I will not try that myself. But I would really like to see a you-tube video of someone else doing it. I know there has to be someone who tried it, given all the skateboard crashes on you tube. But what keywords to use. Anyone...

Suppose you have a full battery and an empty one, both the same type, and you hook up positive to positive and negative to negative, and for this particular battery chemistry, the difference in voltage is great enough to commence charging of the negative one. How much current would likely travel...

20 gauge copper wire is rated for 5 amps. Suppose someone use 18 gauge copper wire and wraps it 60 times around one side of a 1 inch iron ring, with the two ends then connected to a plug. A separate piece of copper wire wraps around the other side 20 times, and goes to a 13.3 Ohm resister. So...

Another safety test is the feel test. If the cell feels hot, turn off the charger. Unfortunately, packs often don't allow a feel. Many commercial battery packs in case each cell in a heat conductive material that dissipates the heat of anyone cell. There are plenty for sale though with just duck...

One fact in one article: Lithium ion batteries have caused phones and laptops to explode if made with non-name brand batteries that don't have the internal protections. In many countries it is illegal to sell sells without a protection circuit, or to hobbyists. To make and sell battery packs...

Thank you for those informative links. I think I'll have two wires attached to each terminal: one to get it in series, and another for connecting all positives to each other and all negatives to each other before and after each charging, when not on the bike, so they can even each other out. I'm...

When I was a kid I once tied two strings to two paper clips, wet the strings, plugged the paper clips into a wall outlet, and dropped the wet strings into a sink full of water. I then put my finger tip in the water. I felt an uncomfortable buzzing sensation, and pulled my finger out. Glad it was...

Thank you, Drakkith, for yet another good explanation. So I will spend a little extra on ten amp hours instead of 7.5, to reduce my C number during charging and discharge and stay well above empty. I'm looking at 0.75C now instead of 1C, unless that is not enough to make a difference. I...

I think since my three series are in parallel, they will be charged the same. No balancing needed. I think I figured out the answer to my question. A battery is like a diode. It has very little resistance one direction and infinite the other direction. Any energy that goes in the charging...

I will post a picture of my circuit drawing for the charger before I build it, and I'll post a picture of the completed charger before I use it. I was going to ask for permission to use one of my university shops. But since the soldering iron is so cheap, I think I'll do it at home. I'll post...

Yes. For a 36v Li-NMC battery, 42v is used to charge it. However, the batter is supposed to be taken off when it reaches 40.5v. 42v actually is not enough to catch it on fire, though a millivolt more might. Charging it to 42v would drastically reduce the number of remaining cycles, and not...