Backfed MOSFET current limit

Started by Tim Wescott in sci.electronics.design7 years ago 26 replies

Got a circuit. I'm using a high-side P-channel MOSFET to prevent damage when the battery is put in backwards. The FET is put in "backwards"...

Got a circuit. I'm using a high-side P-channel MOSFET to prevent damage when the battery is put in backwards. The FET is put in "backwards" (battery to drain, circuit to source) to point the body diode in the correct direction. When the battery is inserted, a capacitor on the circuit side of the FET charges up, sucking a considerable amount of current very briefly. The current is b...


Can a 12 volt regulatred power supply be used to charge car batteries?

Started by Unlisted in sci.electronics.design1 year ago 25 replies

I have a 12volt regulated power supply that was probably made for using automotive CB radios in a house. It's rated at 3 amps. Can this be...

I have a 12volt regulated power supply that was probably made for using automotive CB radios in a house. It's rated at 3 amps. Can this be used to slow charge 12V car batteries? I have a big car battery charger, which puts out 15 or 60 amps, but I want to trickle charge a battery in severe cold weather. I'm more worried about damaging the power supply than the battery.


Replacement of UPS battery

Started by Andy in sci.electronics.design3 years ago 27 replies

I am learning a lot here. What are your thoughts on this. I understand that an inverter converts dc to ac. What does the last sentence...

I am learning a lot here. What are your thoughts on this. I understand that an inverter converts dc to ac. What does the last sentence mean as far as rating of the inverter?


Battery powered 'scopes

Started by George Herold in sci.electronics.design3 years ago 3 replies

Hi, quick question: Does a battery powered 'scope have inputs that are isolated from each other? Differential inputs? And if so is there a...

Hi, quick question: Does a battery powered 'scope have inputs that are isolated from each other? Differential inputs? And if so is there a cheaper model number to look at? TIA George H.


Need design for motion sensor battery operated LED light.

Started by Anonymous in sci.electronics.design8 years ago 23 replies

Anyone have a design for a motion sensor? Sure, I could just buy the sensor for an outdoor motion sensor light, but I want a circuit to control...

Anyone have a design for a motion sensor? Sure, I could just buy the sensor for an outdoor motion sensor light, but I want a circuit to control a *battery operated* LED light. The purpose is to illuminate the inside of an outhouse (toilet) at a campground, and have it turn ON when someone enters. There is no electricity in the building. I just want something battery operated that wont be ...


controllers; program in C

Started by Anonymous in sci.electronics.design5 years ago 32 replies

Hello. I want to build, for fun, a battery charger and I want to use this as an excuse to experiment with a controller chip that you can...

Hello. I want to build, for fun, a battery charger and I want to use this as an excuse to experiment with a controller chip that you can program in C. Are PIC devices the way to go? I noticed they have a free C compiler available for some of the chips. As always, $$$ is a factor. I see several projects for battery chargers on line, posted by experimenters. I'm still asking here thou. I w...


solar/battery powered wifi camera setup advice

Started by robb in sci.electronics.design6 years ago 7 replies

so i want to setup a remote wifi camera, battery powered with solar charging. Proj Plan: choose smallest setup battery/solar panel / camera...

so i want to setup a remote wifi camera, battery powered with solar charging. Proj Plan: choose smallest setup battery/solar panel / camera that will achieve my goal Goal: Daytime only monitoring , motion detection and occasionally (2 times day connect and stream for few minutes), camera can be off from sunset to dawn. some research on web shows the cameras i am looking at var...


NiCd cell replacements

Started by Andy K in sci.electronics.design7 years ago 14 replies

I will be replacing eight cells in a battery for a cordless drill. 9.6 V The markings did not lead anywhere. DF21NF NiCd Since there are...

I will be replacing eight cells in a battery for a cordless drill. 9.6 V The markings did not lead anywhere. DF21NF NiCd Since there are eight cells in the battery, I think they are 1.2 volt nicads. 1 3/4 X 5/8 are the dimensions if that would help with determining the mAH. Could someone help me in what would be a good replacement ? Thanks.


OT new Li battery?

Started by George Herold in sci.electronics.design3 years ago 21 replies

I heard about this on the radio driving home last night. https://news.utexas.edu/2017/02/28/goodenough-introduces-new-battery-technology Here's...

I heard about this on the radio driving home last night. https://news.utexas.edu/2017/02/28/goodenough-introduces-new-battery-technology Here's the paper. https://docs.wind-watch.org/braga2017.pdf Lunch time reading. George H.


18500 Battery Clip Holder Box Case

Started by Andy K in sci.electronics.design6 years ago 4 replies

I have looked all over but can not find a battery holder for 18500 batteries. Some places list this, 18650 17500 18500 Battery Clip Holder Box...

I have looked all over but can not find a battery holder for 18500 batteries. Some places list this, 18650 17500 18500 Battery Clip Holder Box Case, but is misleading because all these batteries are different lengths. Seems if they make 18500 batteries, someone ought to have made a holder ? Thanks, Andy


LiIon solar charge controller with load output regulation?

Started by Joerg in sci.electronics.design9 years ago 12 replies

Folks, Is there a solar charge controller that provides a hard and (somewhat) regulated 12V-14V output and uses a LiIon battery? The standard...

Folks, Is there a solar charge controller that provides a hard and (somewhat) regulated 12V-14V output and uses a LiIon battery? The standard ones are like this and then the battery voltage fluctuates with the LiIon pack: http://www.solarbruder.com/charge-controller/ephc-for-li-ion-battery-pack Most are for 3-cell and then the low cut-off is around 8V. Way too low, a lot of 12V gear co...


XNRGI Battery

Started by Rick C in sci.electronics.design1 year ago 3 replies

This company seems to have a battery that will provide energy for cars and other applications with a much higher density and lighter weight than...

This company seems to have a battery that will provide energy for cars and other applications with a much higher density and lighter weight than Li-ion batteries. They talk about making "pores" in Si wafers with lithium anode material. Some of what they say is a bit odd. Since the anode is lithium, clearly the lithium is removed and redeposited during use. Yet they claim "No Li


Charger recommendations

Started by Andy in sci.electronics.design3 years ago 17 replies

I am looking at the Nitecore D4 Digicharger/Four Channel Universal Smart Battery Charger/LCD Display and GYRFALCON All-44 4 Channel Digital...

I am looking at the Nitecore D4 Digicharger/Four Channel Universal Smart Battery Charger/LCD Display and GYRFALCON All-44 4 Channel Digital Battery Charger. What do you recommend ? I read where 26650 have a higher capacity than 18650s. Andy


Li-Ion battery shipping

Started by legg in sci.electronics.design2 years ago 13 replies

Having trouble getting replacement 22650 cells. Increasingly rare after 18650 adopted for automotive battery construction. An order placed...

Having trouble getting replacement 22650 cells. Increasingly rare after 18650 adopted for automotive battery construction. An order placed with a recycler in China was cancelled, purportedly due to international shipping regs. For uninvolved single cells? Really? RL


Battery Packs to Use As a UPS

Started by rickman in sci.electronics.design6 years ago 10 replies

There are lots of rechargable battery packs sold as portable charging units for cell phones and the like. They come in many shapes and sizes...

There are lots of rechargable battery packs sold as portable charging units for cell phones and the like. They come in many shapes and sizes and capacities. But I can't find one that says you can use it like a UPS for a device that is powered from 5 volts via a USB cable. I have had little luck asking eBay vendors about this so I thought I would ask here. I'm looking for something in...


Electrochemical CO2 Fixation

Started by Anonymous in sci.electronics.design1 year ago 16 replies

Pairing Li-CO2 battery energy storage with intermittent renewables while scrubbing atmospheric CO2...

Pairing Li-CO2 battery energy storage with intermittent renewables while scrubbing atmospheric CO2 simultaneously. https://phys.org/news/2017-08-battery-inspired-strategy-carbon-fixation.html


Adding a ripple to a DC voltage

Started by Anonymous in sci.electronics.design6 years ago 51 replies

Hi all, I have to add a ripple voltage (1Vrms) in serie to a 24V Battery (to build a test bench). The current is about 30A. I was wondering if...

Hi all, I have to add a ripple voltage (1Vrms) in serie to a 24V Battery (to build a test bench). The current is about 30A. I was wondering if a transformer in serie with the battery could do the job. Cheers, H.


LiPo charging

Started by Andy in sci.electronics.design3 years ago 9 replies

Can I use the same charger I use for my 18650 batteries with a LiPo battery? LiPo battery is 500 mah. Charger puts out 450 ma. Thanks.

Can I use the same charger I use for my 18650 batteries with a LiPo battery? LiPo battery is 500 mah. Charger puts out 450 ma. Thanks.


Lithium ion first time charging

Started by bitrex in sci.electronics.design4 years ago 5 replies

Some consumer products that have lithium ion battery packs recommend charging the device for 8 hours before first use. If a customer doesn't...

Some consumer products that have lithium ion battery packs recommend charging the device for 8 hours before first use. If a customer doesn't follow this procedure, does it cause irrecoverable damage to overall battery life, or is it reversible?


HP3586 Selective Voltmeter Help

Started by amdx in sci.electronics.design3 years ago 1 reply

I bought an HP3596B off Ebay. I have a service manual on order. First thing I did was remove the leaky battery and thoroughly clean the PS...

I bought an HP3596B off Ebay. I have a service manual on order. First thing I did was remove the leaky battery and thoroughly clean the PS board. It looks good, however if I look down to the edge connector inside the unit I can see it has the blue buildup on it from the battery leak. I'll save that until I disassemble to clean and lube the switches. At power up the self calibrati...