How do you calculate the REQUIRED voltage from a transformer secondary

Started by Anonymous in sci.electronics.design5 years ago 30 replies

How do you calculate the REQUIRED voltage from a transformer secondary? Ok, here's the plan. A friend of mine installed a bunch of LED...

How do you calculate the REQUIRED voltage from a transformer secondary? Ok, here's the plan. A friend of mine installed a bunch of LED fixtures to run off a solar panel and a 12V marine battery. It's drawing about 15amps at 12VDC. It works fine when the sun is shining, but drains the battery when there is no sun. He said he gets tires of having to hook a battery charger to that battery ...


flow battery with water soluble, non metal reactants

Started by Jamie M in sci.electronics.design7 years ago 4 replies

Hi, Here's a link to a paper on a flow battery with non toxic water soluble reactants, apparently 10 times cheaper to manufacture than...

Hi, Here's a link to a paper on a flow battery with non toxic water soluble reactants, apparently 10 times cheaper to manufacture than lithium batteries. I guess to make it even simpler they could remove the separation membrane as I had read about one laminar flow battery experiment did this. https://pressroom.usc.edu/usc-scientists-create-new-battery-thats-cheap-clean-rechargeable-and-...


Charging deep cycle battery

Started by Anonymous in sci.electronics.design6 years ago 37 replies

When I am on the road, my electronics: voice phone, data phone, tablet, GPS and laptop are killing my car battery. Finally, my "short" cycle...

When I am on the road, my electronics: voice phone, data phone, tablet, GPS and laptop are killing my car battery. Finally, my "short" cycle battery gave up. So, I got a deep cycle battery with 600 CCA and 160 AHr @ 1A. I am thinking about getting a 1000W generator to charge it instead of the car engine. What is the practical fast charging current? Can I dump 100Amp (with a cus


12V Auto power converter schematic needed for laptop

Started by Anonymous in sci.electronics.design10 years ago 5 replies

My laptop which is a Lenovo (IBM) T41 needs a 12V auto power adaptor. I've been using a 200W inverter, but that thing likes to run my...

My laptop which is a Lenovo (IBM) T41 needs a 12V auto power adaptor. I've been using a 200W inverter, but that thing likes to run my car battery dead, not to mention that it is constantly screetching an alarm as soon as the car battery is not fully charged. I have never understood why it drains my battery when it's just charging the computer battery, (with computer shut off), but it does. ...


Suggestion - dc / dc converter 500 - 1000W

Started by gm in sci.electronics.design5 years ago 6 replies

Hi. I have played around lead alum battery from John Bedini and i must say i am quite exited about all this. Fast charging ( 12V / 85Ah under...

Hi. I have played around lead alum battery from John Bedini and i must say i am quite exited about all this. Fast charging ( 12V / 85Ah under 45 minutes ), you can discharge it to almost 0V etc. Anyhow, there is bunch info on this on the net. Really good battery, with "small" problem. The standard voltage of fully charged battery is around 11.5 to 12,5 V so when i hook up some standard...


75332P MOSFET drain connected to which battery terminal?

Started by John Doe in sci.electronics.design10 years ago 18 replies

I have a 75332P MOSFET on a cordless drill controller heatsink. I guess it's part of a pulse width modulator. The drain (flange) connects...

I have a 75332P MOSFET on a cordless drill controller heatsink. I guess it's part of a pulse width modulator. The drain (flange) connects directly to one of the battery terminals. Does the MOSFET drain go directly to the battery minus/ground terminal? Or does it go to the battery plus terminal? Thanks. -- My application... I'm desperately trying to develop a better inline ...


USB Battery Charging without Microprocessors

Started by Tim Wescott in sci.electronics.design6 years ago 8 replies

First: Sorry to those c.a.e folks who abhor s.e.d -- hopefully the politics won't bleed onto this thread. On to the real question. It's...

First: Sorry to those c.a.e folks who abhor s.e.d -- hopefully the politics won't bleed onto this thread. On to the real question. It's phrased oddly, but I think it gets to the point best: If I have a dingus with a battery in it, and I want to charge that battery via USB, and I want to get the most out of the USB port, does that dingus have to have a microprocessor in it that talks...


Need Op Amp for design

Started by Leslie Rhorer in sci.electronics.design4 years ago 73 replies

I have a little project am trying to design, and I am running into a little difficulty in the concept stage. I have a device that needs to...

I have a little project am trying to design, and I am running into a little difficulty in the concept stage. I have a device that needs to consume essentially zero power when shut off. A few nanoamps is fine. The device uses a 6S LiPo battery that must be monitored during operation to make sure the battery is not discharged beyond critical limits. To this end, the battery is conn


Battery System Design

Started by OldGuy in sci.electronics.design7 years ago 7 replies

Subsystem consists of: 115 VAC Car Battery Charger 12 V Car Battery 12 VDC to Laptop Power Converter Laptop Charger provides full...

Subsystem consists of: 115 VAC Car Battery Charger 12 V Car Battery 12 VDC to Laptop Power Converter Laptop Charger provides full time current to charge the Car Battery and to power the laptop power converter to laptop. When AC goes off, car battery provides power until depleted. The laptop is to run all the time until battery depleted. Laptop max 90 Watts. 115 VAC Car...


6V battery substitute

Started by David Lesher in sci.electronics.design2 years ago 4 replies

A friend inherited a small dirt bike. It has a quite deceased 6V battery. It's got a coil and points, not a magneto. So it needs a battery,...

A friend inherited a small dirt bike. It has a quite deceased 6V battery. It's got a coil and points, not a magneto. So it needs a battery, or substitute, to run. (He's happy to kickstart.) It gets stored for long periods. He asked if a super capacitor might work. He can charge it before starting. I'm debating in my head if it has a low enough impedance to keep things stable. ...


Tek TPS20xx battery life? JL?

Started by Frank Miles in sci.electronics.design8 years ago 3 replies

I bought a Tek TPS2012 scope (not sure; maybe 2 years ago) for one of my techs. He hasn't used it very much, but its battery is kaput - it won't...

I bought a Tek TPS2012 scope (not sure; maybe 2 years ago) for one of my techs. He hasn't used it very much, but its battery is kaput - it won't even boot unless the plugged into the charger. The charging indicator immediately indicates that it's fully charged (solid green). We should probably try to repeat these conditions so we can verify that the battery is actually getting charged a...


UVLO Re-design

Started by mpm in sci.electronics.design4 years ago 12 replies

I need to redesign an under-voltage lockout for a 48-volt, 100 AH battery. As part of the redesign of other portions of the product, I have a...

I need to redesign an under-voltage lockout for a 48-volt, 100 AH battery. As part of the redesign of other portions of the product, I have a 12-bit A/D input available that I could dedicate to monitoring the battery charge and disconnect it via a FET switch, contactor, or whatever. My question is: After normal AC power is restored, I'll need to reconnect the battery in order to charge it. ...


Battery replacement

Started by Ralph in sci.electronics.design4 months ago 12 replies

I have a remote control car that has a dedicated control and receiver at some unknown to me frequency. Not bluetooth or wifi. It was a...

I have a remote control car that has a dedicated control and receiver at some unknown to me frequency. Not bluetooth or wifi. It was a Christmas toy. It is a substantial car nearly 18" long. It uses a 8.4v nicad battery that I cannot find and really want to NOT use. I can get the battery specs if needed. The car is on vacation in the mountains right now. lol I want to replace with Li I...


Running 3 LED lights on one battery

Started by Anonymous in sci.electronics.design8 years ago 11 replies

I have a six LED lanterns that I bought really cheap. They are similar to those old looking kerosene lanterns they advertise on tv which...

I have a six LED lanterns that I bought really cheap. They are similar to those old looking kerosene lanterns they advertise on tv which use LEDs, but in a less fancy plastic case. The lanterns are designed to use three AA batteries, thus 4.5 volts. I want to connect them to a 12V deep cycle battery which I have connected to a solar cell to charge the battery. What is the easiest way ...


OT: Smartphone always charging destroyed battery?

Started by John Doe in sci.electronics.design2 years ago 54 replies

https://www.flickr.com/photos/27532210@N04/ Another Chinese battery bit the dust here. Noticed my smartphone was bulging, the screen was...

https://www.flickr.com/photos/27532210@N04/ Another Chinese battery bit the dust here. Noticed my smartphone was bulging, the screen was warping. The cause was obvious so, not having a torx t1 screwdriver, I ripped it apart. Tried using a capacitor in place of the stock battery but that didn't work. An 18650 works, but it's charged to 4.36 V. The smartphone is used for Wi-Fi security...


Lead-Acid sealed battery: detect when it's wrong

Started by pozz in sci.electronics.design6 years ago 9 replies

I'm talking about batteries installed in UPS. They are always fully charged and works only for some seconds/minutes after a black-out....

I'm talking about batteries installed in UPS. They are always fully charged and works only for some seconds/minutes after a black-out. Depending on the black-out duration, they can discharge almost completely. After black-out, the battery is recharged again with a simple/complex recharger. After 1-2 years, the battery can't make its job well: immediately after a black-out, the PC swit...


battery packs cell shorting?

Started by Jamie M in sci.electronics.design7 years ago 5 replies

Hi, I made a 14.8V (4s) lithium ion battery pack (18650 cells 4s3p) and after gluing the batteries together into the pack, I used...

Hi, I made a 14.8V (4s) lithium ion battery pack (18650 cells 4s3p) and after gluing the batteries together into the pack, I used a multimeter to check if any of the cases were shorted anywhere (some of the thin plastic covering on the batteries was removed). Before conneting the batteries in series, I noticed that the third and fourth section of the battery (11.1V and 14.8V) had a measu...


Cooling an electric vehicle battery.

Started by Anthony William Sloman in sci.electronics.design3 months ago 52 replies

Electric vehicle batteries are about 85% efficient, but the 15% of the energy that you put in that you don't get out has to appear as heat,...

Electric vehicle batteries are about 85% efficient, but the 15% of the energy that you put in that you don't get out has to appear as heat, generated in the battery. The worst case would presumably be during fast charging. One has to wonder whether anybody has built a battery with heat-pipe down the middle, sticking into heat-sink extrusions projecting from either end. Nobody seems to do...


Death by 9V battery design challenge

Started by Cursitor Doom in sci.electronics.design6 years ago 70 replies

Hi all, Just wondered if it is possible to come up with a circuit which would enable a single PP3 9V battery such as...

Hi all, Just wondered if it is possible to come up with a circuit which would enable a single PP3 9V battery such as this: http://www.canford.co.uk/Products/22913/59-045_GP-1604A-BATTERY-1604-PP3- size-alkaline-Super-series to function as the power source for a taser? I'm sure proprietary tasers are manufactured with far more suitable batteries than a PP3 and it wouldn't be hard to ...


ohm meter battery

Started by Anonymous in sci.electronics.design8 years ago 13 replies

I found this circuit somewhere, (I can't remember) to replace the 1.50 volt= battery in a VTVM. I have an RCA WV98C Senior Voltohmyst VTVM that...

I found this circuit somewhere, (I can't remember) to replace the 1.50 volt= battery in a VTVM. I have an RCA WV98C Senior Voltohmyst VTVM that is in p= erfect condition but doesn't get used very often. This battery retrofit cir= cuit takes power from the 6.30 volt filament transformer and is built aroun= d an LM317. With a trim pot you set it for 1.55 volts and you never have to= change a ...