A question about amperage - Videokarma.org TV - Video

decojoe67 · #1 11-22-2016, 06:48 PM

I have one simple question I hope someone can answer for a collector that is not electronically adept. If I used a 6V/4amp lead-acid battery for a '20's radio's A supply (with #12 gauge wire) and could not get audio out of the horn speaker, then upgraded to 6V/12amp battery and did get audio with the rheostats turned-up full, would upgrading to a 6V/20amp battery be to my advantage in any way or just a waste of money?

old_coot88 · #2 11-22-2016, 08:33 PM

Well first off, batteries are rated in capacity expressed as amp-hours (or AH), not just "amps". An AH is the the amperage that the battery can sustain for one hour.

A 6V 4AH battery should be able to sustain 4 amps for an hour (or 2 amps for 2 hours, 1 amp for 4 hours, etc.). Same formula would apply for a 6V battery of any other AH rating.

Upgrading the AH rating, of and by itself, wouldn't give any advantage in performance other than increasing run time.

decojoe67 · #3 11-22-2016, 08:45 PM

Quote:

Originally Posted by old_coot88

Well first off, batteries are rated in capacity expressed as amp-hours (or AH), not just "amps". An AH is the the amperage that the battery can sustain for one hour.

A 6V 4AH battery should be able to sustain 4 amps for an hour (or 2 amps for 2 hours, 1 amp for 4 hours, etc.). Same formula would apply for a 6V battery of any other AH rating.

Thank you so much, but please bear with me, the novice I am in electronics. If I could not get any audio out of the speaker with the 6V 4AH battery then how it is possible that I did with the 6V 12AH one? That was my reasoning for going ahead and trying a 6V 20AH battery. Does this reasoning make sense or can I expect to be disappointed with investing in the 20AH battery other than a longer life?

madlabs · #4 11-22-2016, 09:05 PM

The only thing I can think of is that the battery was low on charge and the voltage sagged. Or perhaps that you had a poor connection and when you connected the other battery you remedied it. Have you repeated the experiment, meaning connect the 6 aH battery and found that once again you do not get full volume? If you do, measure the voltage before and after turning the radio on and see what you get.

decojoe67 · #5 11-22-2016, 09:22 PM

Quote:

Originally Posted by madlabs

The only thing I can think of is that the battery was low on charge and the voltage sagged. Or perhaps that you had a poor connection and when you connected the other battery you remedied it. Have you repeated the experiment, meaning connect the 6 aH battery and found that once again you do not get full volume? If you do, measure the voltage before and after turning the radio on and see what you get.

No, but I understand now how that could've been possible. What has me even more perplexed right now is why the ARBE III has an amp rating of 3.0 if it is an AC unit and amps is all about battery life? Does this mean that I should be able to run the set with the ARBE III?

old_coot88 · #6 11-22-2016, 10:00 PM

Quote:

Originally Posted by decojoe67

Thank you so much, but please bear with me, the novice I am in electronics. If I could not get any audio out of the speaker with the 6V 4AH battery then how it is possible that I did with the 6V 12AH one? That was my reasoning for going ahead and trying a 6V 20AH battery. Does this reasoning make sense or can I expect to be disappointed with investing in the 20AH battery other than a longer life?

Sounds like the 4AH battery's voltage was sagging under load, while the 12AH battery was holding up. Having twice the AH capacity, it can sustain twice the load (12 amps) without sagging (if fully charged). Was the 4AH one fully charged?

You need to put a voltmeter on the battery and monitor its voltage under load. If the 12AH battery holds 6V without sagging, then going to a 20AH battery would be no advantage other than run time.

decojoe67 · #7 11-22-2016, 10:31 PM

Quote:

Originally Posted by old_coot88

Sounds like the 4AH battery's voltage was sagging under load, while the 12AH battery was holding up. Having twice the AH capacity, it can sustain twice the load (12 amps) without sagging (if fully charged). Was the 4AH one fully charged?

You need to put a voltmeter on the battery and monitor its voltage under load. If the 12AH battery holds 6V without sagging, then going to a 20AH battery would be no advantage other than run time.

Thank you. Okay, I am understanding amps now. Yes, the lead-acid 6V/4AH seemed to be fully charged, yet I didn't check it under load. I plan to use that battery one with my ACE V with it's single non-A UV.
In your opinion should the RC work with the ARBE III set at 6V's? They say it provides 3.0 continuous amperes, but this confuses me now. If amperes is the amount of time a battery can deliver it's voltage, why does an AC eliminator that provides and endless supply even have an ampere rating? What does this mean?

madlabs · #8 11-22-2016, 11:24 PM

Amps is the amount of current flow. Amp hours is how much total current a battery can provide. So, if your radio draws one amp of current a 7 amp hour battery could run it for 7 hours. If your radio draws 7 amps the battery would run it for an hour.

So, your three amp power supply can provide 3 amps forever because it is connected to the mains. Your battery has a limited amount of chemicals to produce electricity with and so is rated by amp hours, so you can figure out how long you should be able to run a device on it. Amps and amp hours, while related are two different things.

decojoe67 · #9 11-23-2016, 04:56 AM

Quote:

Originally Posted by madlabs

Amps is the amount of current flow. Amp hours is how much total current a battery can provide. So, if your radio draws one amp of current a 7 amp hour battery could run it for 7 hours. If your radio draws 7 amps the battery would run it for an hour.

So, your three amp power supply can provide 3 amps forever because it is connected to the mains. Your battery has a limited amount of chemicals to produce electricity with and so is rated by amp hours, so you can figure out how long you should be able to run a device on it. Amps and amp hours, while related are two different things.

Thank you. Okay, but taking it one more step, does the 3.0 amp rating of the ARBE III battery eliminator have any importance to the operation of the radio? What would be the advantage/disadvantage if it was say 12 or even 20 amps? Just so curious to know and understand what that amp value in the eliminator means to the user.

Electronic M · #10 11-23-2016, 07:11 AM

3 Amps in the eliminator (assuming it is the supply output for the A output) means means it can only supply 3 Amps to your radios heaters. If your radio draws less than 3 amps it will still work, but if your radio needs more than 3 Amps for it's heaters that supply can NOT be used (over current protection will kick in or the voltage will sag like your battery or the eliminator will burn out....I think it is the former of the three in the case of the ARBEIII).

decojoe67 · #11 11-23-2016, 09:12 AM

Quote:

Originally Posted by Electronic M

3 Amps in the eliminator (assuming it is the supply output for the A output) means means it can only supply 3 Amps to your radios heaters. If your radio draws less than 3 amps it will still work, but if your radio needs more than 3 Amps for it's heaters that supply can NOT be used (over current protection will kick in or the voltage will sag like your battery or the eliminator will burn out....I think it is the former of the three in the case of the ARBEIII).

I spoke with someone I work with that's trained in electronics and he said you have to go above what you need in amps due to loss with the terminal connections and wiring. I need 3.0 minimum, so I am going to just use the ARBE III for the B and the 6V-20AH battery I have on order for the "A". This "Power-Sonic" battery (http://www.atbatt.com/power-sonic-6v...Fc1KDQodpJEK5Q) appears to be designed for several types of applications, so I am fairly sure it will do the job with the limited use the radio will have. I can easily return back to the "A" tubes and just use the ARBE III exclusively, but I really want to stick to my goal of operating the set with the early tubes.

madlabs · #12 11-23-2016, 09:16 AM

Quote:

Originally Posted by decojoe67

Thank you. Okay, but taking it one more step, does the 3.0 amp rating of the ARBE III battery eliminator have any importance to the operation of the radio? What would be the advantage/disadvantage if it was say 12 or even 20 amps? Just so curious to know and understand what that amp value in the eliminator means to the user.

If your radio needs three amp and your power supply can provide 3 amps it will work but the power supply will run hot and most likely die an early death. A wiser rating would be to find a power supply that can provide at least 5 amps. The radio will run the same but the power supply will run cooler. If you had a 20 amp power supply the radio will run the same and the power supply would be essentially stone cold.

So the upshot: Once your power supply's rating exceeds the radio draw by around 20% there is no benefit to using a larger power supply. No harm will be done but your power supply will be under employed. :-)

decojoe67 · #13 11-23-2016, 12:44 PM

Quote:

Originally Posted by madlabs

If your radio needs three amp and your power supply can provide 3 amps it will work but the power supply will run hot and most likely die an early death. A wiser rating would be to find a power supply that can provide at least 5 amps. The radio will run the same but the power supply will run cooler. If you had a 20 amp power supply the radio will run the same and the power supply would be essentially stone cold.

So the upshot: Once your power supply's rating exceeds the radio draw by around 20% there is no benefit to using a larger power supply. No harm will be done but your power supply will be under employed. :-)

Thanks very much. It seems I'm getting more no votes on using the ARBE III for my "A" supply with it's 3.0 only continuous amps, which is the minimum I need. I will use the ARBE for the "B" supply, and the 6V-20amp battery for the "A". This battery I have ordered is designed for prolonged use, so I think it will be fine with the limited use the set will get.

Electronic M · #14 11-23-2016, 02:32 PM

Quote:

Originally Posted by decojoe67

I spoke with someone I work with that's trained in electronics and he said you have to go above what you need in amps due to loss with the terminal connections and wiring. I need 3.0 minimum, so I am going to just use the ARBE III for the B and the 6V-20AH battery I have on order for the "A". This "Power-Sonic" battery (http://www.atbatt.com/power-sonic-6v...Fc1KDQodpJEK5Q) appears to be designed for several types of applications, so I am fairly sure it will do the job with the limited use the radio will have. I can easily return back to the "A" tubes and just use the ARBE III exclusively, but I really want to stick to my goal of operating the set with the early tubes.

He did a very good job summing up what I was saying, except I disagree on terminal losses....You loose voltage with terminal resistance, not current.

IIRC about 2-4 years ago I saw a presentation on the design of the ARBEIII from it's maker at the MARC Extravaganza meet. It seemed like a fairly conservative design to me. If your radio needs 3 amps and the supply can handle 3 amps (on the output terminals you intend to use), then it should probably work....I'd try it, and see if the supply runs reasonably cool, and that it is not adding hum...If you see excessive hum or heat then you are overtaxing the supply and should try another.

decojoe67 · #15 11-23-2016, 07:36 PM

Quote:

Originally Posted by Electronic M

He did a very good job summing up what I was saying, except I disagree on terminal losses....You loose voltage with terminal resistance, not current.

IIRC about 2-4 years ago I saw a presentation on the design of the ARBEIII from it's maker at the MARC Extravaganza meet. It seemed like a fairly conservative design to me. If your radio needs 3 amps and the supply can handle 3 amps (on the output terminals you intend to use), then it should probably work....I'd try it, and see if the supply runs reasonably cool, and that it is not adding hum...If you see excessive hum or heat then you are overtaxing the supply and should try another.

Thank you Tom. I think in the end I'm going to be using the set with the A UV's being I like to play my sets. It's been a very surprising to me to see just how much better the A tube UV's are. It's really like night and day. No wonder I don't see anyone else using the early tubes in the set!