Hot answers tagged

6

If you search for "automatic power off car ham" you'll find a number of solutions which don't require additional wiring. When the engine is running the voltage supply is higher than when the engine is off, so these work by sensing when the voltage is high enough, and turning the radio on.


6

Batteries can be approximated as an ideal voltage source in series with a resistor. So it's perfectly normal for a battery's terminal voltage to drop when the current it is delivering increases. To determine whether that's actually a problem, you only need to consider two things: Is the new voltage too low to power your transceiver? Are you exceeding the ...


6

SLA cells are dead easy to recharge, improvising a charger may be as easy as a set of jumper cables. Lithium ion's require active charging circuitry and the failure mode can be catastrophic. That said, the new LiFePO₄ batteries seem to combine the best of both, energy density comparable to lithium ion with the saftey and easy charging of lead acid.


6

If I understand the description correctly: simulate this circuit – Schematic created using CircuitLab If that's all it is, I wouldn't say it's any big deal. Whenever you have multiple paths to ground, current will split between them. It's these currents that keep "ground" approximately the same voltage everywhere: an essential assumption in the ...


5

Voltage drop is caused by internal resistance Using batteries you will always experience a voltage drop when drawing significant currents, due to the internal resistance of the battery. This can be thought of as a resistor that is always in series with the battery, and consumes energy depending on the current drawn from the battery. It’s the main reason ...


5

That's for charging a 3800mAh battery using the side jack. To charge the BL-5L 3800mAh battery you must purchase a: - TYT TH-UVF9 battery charger for 110VAC or - TYT TH-UVF9D for 12VDC. These are fully regulated chargers Plugs directly into side of battery, not a charger base The AC wall wart has a charging indicator. Red while charging, Flashing Green ...


5

Some radios, such as the Yaesu FT-857D, have a feature in the menu that allows you to set the unit to automatically power off after a user-chosen period of time. Search the documentation of your radio for such an option.


4

Nickle Cadmium (NiCd) batteries are still quite popular for a variety of uses, however Nickle Metal Hydride (NiMH) and Lithium-Ion (Li-Ion) batteries have, for the most part, replaced NiCds. Lithium Ion batteries are generally considered the better of the two, but each have their pros/cons. Lithium-Ion Pros: Li-ion batteries have over twice the energy ...


4

Lithium, NiMH, then Lead acid. Lithium batteries are expensive and potentially hazardous. Among these, Lithium Iron Phosphate, or LiFePO4, is supposedly less dangerous, but still needs a charge/discharge controller. You can find replacements for 12v batteries on eBay using LiFEPO4 and capable of high currents of transmitting but those are still several ...


4

If near freezing or colder conditions is one of your possible operating environments, then SLA cells can still be (re)charged at slightly lower temperatures than lithium chemistry cells.


4

When you parallel batteries, the combined reliability generally becomes less than the least reliable battery. In reliability engineering, this follows the equation: $$R_S=R_1*R_2*R_3 \tag 1$$ where $R_1, R_2,R_3$ is the reliability of the respective individual batteries. The older batteries are inherently more unreliable. Battery failure modes can cause ...


4

The FT-60 manual says the battery pack is a NiMH pack ("FNB-83 (7.2 V, 1400 mAh)"); so, as we usually use 1.2V as the nominal voltage of a single NiMH cell, a pack of 6 cells in series. You'd usually make sure not to discharge a NiMH below 1.0 – 1.1 V; going deeper can damage the cell. So, the minimal voltage for a pack of 6 in series would be 6.0 – 6.6V. ...


4

Battery University has some general information on storing batteries. Relevant points: Storing a Li-ion battery in a discharged state will permanently damage it Storing a Li-ion battery at 100% charge is less than optimal around 40% charge is optimal for storage Lower temperatures are better Freezing is bad Leaving the battery connected to the radio or the ...


4

There are a few states of listening that you should think about: listening with the squelch closed, the receiver is probably off for 95% of the time, turned on a couple of times a second to check for a signal. This is the lowest power state. receiving a signal, squelch open, the receiver is fully on. Also the loudspeaker takes some power, not much if it's ...


4

An anecdote: I had problems with my station which included computer-radio interconnections; some of my devices (RTL-SDRs) would lock up when I powered on my Yaesu FT-897. I eventually tracked this down to the power-on inrush currrent of the radio passing through coax shields and the chassis of the antenna switch that both were connected to. I solved the ...


4

With the battery case detached from the device, look at the side with the copper terminals. You should see several seams that can be exploited with a sufficiently thin shim. I carefully used a box cutter on the right hand inner seam of the battery case and separated the battery case into two pieces without actually cutting or breaking any of the small ...


3

I wouldn't risk directly connecting a 9.6v battery to a radio that expects 5-6v. The simplest solution would probably be the diodes mentioned in the comment to your question, but as the battery voltage dropped the voltage reaching the radio would drop as well, and as the battery got low the output voltage after the diodes might be too low to power the radio,...


3

I found the TM-741A service manual. As shown on page 106, the battery can be seen looking into the case from the front after the display panel is removed. Luckily, the spare batteries from my dive computer will work; now I just have to open the radio and solder in a replacement!


3

Check point no 6.7 on this page - http://www.miklor.com/uv5r/UV5R-FAQ.php#Batteries It talks about an extended battery like you have shown here. Also says that it uses a side jack. The port you see here is probably for the side jack.


3

Lithium batteries, either Lithium-Ion (LiIon) or Lithium-Polymer (LiPo) batteries currently have the most capacity for the weight. LiPo batteries are very popular in radio controlled cars and RC aircraft - their power-weight ratio is practical for flying things, and they can give out enough current for brushless DC motors, so they should be good for ...


3

Research automotive relays; They are essentially electronic switches that turn on when a current is present. In my vehicle, I have a large gauge wire and fuse running from the battery to high power pin on a relay under my seat; A small gauge wire runs from the back side of the cigerette lighter (which is only powered when the car is on) to the relay coil ...


2

Double-check to see if your radio can auto-turn off after a period of non-use - mine does and it's quite handy. Failing that, a product like http://www.westmountainradio.com/product_info.php?products_id=apo3_pp can work quite well to do something similar based on the voltage from your alternator/battery "detecting" if your engine is running or not.


2

Most manufacturers publish their power requirements. 20A sounds like a reasonable estimate. The more important part of voltage drop is what's due to your wiring. Small gauge and long runs can cause persistent voltage drops. Using heavier gauge wiring like you are, will solve most of that problem. As was said, temporary voltage drops at the reading on ...


2

You're not getting answers for multiple reasons. 1) Batteries are a science but its surrounded by marketing and astrological tradition (concrete floors, blah blah) 2) If something bad happens they are destroyed or blow up the house or start a fire and no one wants to get involved in that mess. I guess I'm just crazy. 3) You're using stuff from mainland ...


2

It should be fine as long as you don't have it plugged in. If you have it plugged in it makes a lot of noise and it is hard to listen to.


2

I'll bet those old batteries are just plain worthless. Based on our experience with many deep-cycle golf cart and automotive batteries, those 10- and 20-year-old batteries almost certainly are not capable of accepting anywhere near a full charge. At best, some cells may work to some degree while other cells are just plain dead, Jim. ;-) You can determine ...


2

Allow me to refer you to Alan Applegate K0BG's excellent page about mobile radio wiring and grounding. That page recommends that you power the radio with a fused negative lead connected to the chassis, and a fused positive lead connected to the main battery. Here's a picture: Alan's site is chock-full of excellent advice about seemingly every aspect of ...


2

Try reducing the power and see if that helps. If it lets you transmit longer then the battery needs to be replaced. If it shuts off right away at low power then you may have a bad final or other malfunction in the rig itself. If you suspect the battery after this test try to borrow one and see if it does the same thing rather than buy a new one. Unless ...


2

You can get an inverter that will run a 35W, or even a 65W 120V laptop charger from a 12V source for around $25 at any auto parts store. That won't get you internet, but it will get you all-day operation fairly cheaply.


2

I would not be surprised if the audio amp used more power than the rf front, tuner osc, and signal detect combined. Thus listening at some reasonable speaker volume, and using energy to vibrate a physical mass, might consume more power than just retuning and monitoring some level. But measuring your particular radio is much better than guessing.


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