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Author Topic: Will 15.5 volts hurt Icom 880 Rig?  (Read 2432 times)
KA8OCN
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Posts: 47




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« on: January 17, 2013, 07:52:30 PM »

I am playing with setting up a solar power system. I noticed today that the voltage was 15.5 Volts today when the charge controller was conditioning my batteries.
Will this damage my Rigs? I pulled the fuse that feeds my station and after the voltage went back down I put the fuse back in and turned on my Rigs.

I have a Morning Song controller and I called them today, the man said that the controller will do this "Conditioning the batteries, overcharging them" every once in awhile. So this is going to happen again.

Will it hurt my equipment?

Thank you for your time.
Delbert McCord
KA8OCN
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K7KBN
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Posts: 2765




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« Reply #1 on: January 17, 2013, 09:53:06 PM »

A typical "12 volt" power supply actually produces more like 13.8 volts.  Most ham gear designed to be used with an outboard power supply will be happy with anything within 10-15 per cent of that value.  Note the word "most".

Did it hurt the rig?  Probably not, but that's no guarantee.
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73
Pat K7KBN
CWO4 USNR Ret.
WB6DGN
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Posts: 590




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« Reply #2 on: January 17, 2013, 11:17:47 PM »

I mostly agree with Pat, though I think 15% overvoltage is not something I would like to see too often; especially not every time the charge controller cycles.  Theoretically up to a maximum of 16 volts is considered safe but that assumes that all the equipment connected to the supply is well designed.  Good luck, there.  10% of 13.8 volts is 1.38 volts so you should be OK at +- 1.4 volts or from 12.4 to 15.2 volts and I'd try to keep things in that range if possible.
I've noticed a trend lately by some manufacturers to size their capacitor working voltage at, what I consider to be, far too close to the nominal operating voltage of the equipment.  For example, one of the most common electrolytic capacitors I've found in much of my equipment is the 10uf - 16 volt variety.  To my way of thinking, 15.8 volts is just too darn close for comfort.  Wouldn't take too much of an AC signal on that line to exceed the capacitor's working voltage.  These repeated excursions would eventually cause trouble.
Just some pros and cons to help you make up your own mind.
Tom 
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K2OWK
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Posts: 1039




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« Reply #3 on: January 17, 2013, 11:42:24 PM »

Tom. Most electrolytic capacitors are tested at twice there operation voltage, so 16 volt rated capacitors are made to operate up to and including 16 volts without a problem.

73s

K2OWK
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WB6DGN
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Posts: 590




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« Reply #4 on: January 18, 2013, 01:40:41 AM »

Quote
Tom. Most electrolytic capacitors are tested at twice there operation voltage, so 16 volt rated capacitors are made to operate up to and including 16 volts without a problem.

CHINESE capacitors???  They have trouble operating at their rated voltage and they also have trouble keeping their electrolyte inside of their case.  In any case (no pun intended), that's still a bad practice because the DC operating voltage doesn't take into account any signal or noise voltage present on the line.  "In my day", the rule of thumb used to be to select a capacitor rated at 2X the max. anticipated operating voltage.  Maybe they're doing that with the published ratings these days but the offshore junk I've seen doesn't give me a warm and fuzzy feeling to say the least.
Tom
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AA4PB
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« Reply #5 on: January 18, 2013, 05:51:22 AM »

According to the manual, the IC880 is specified for an input voltage of 13.8V +/-15%. 13.8V + 15% is 15.87V so you should be okay with 15.5V - as long as it doesn't go over that.

When you measured 15.5V was that under load (i.e. the IC880 turned on in receive mode)? I would expect that the battery voltage may drop very quickly when a load is applied.
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KA8OCN
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« Reply #6 on: January 19, 2013, 09:00:46 PM »

According to the manual, the IC880 is specified for an input voltage of 13.8V +/-15%. 13.8V + 15% is 15.87V so you should be okay with 15.5V - as long as it doesn't go over that.

When you measured 15.5V was that under load (i.e. the IC880 turned on in receive mode)? I would expect that the battery voltage may drop very quickly when a load is applied.


Yes I did look at the manual and Icom says 16 volt MAX, I sure dont like only .5 volt safety margin.

I have been looking for some kind of voltage regulator on eBay that would protect me around 12 to 13 volts and I have found a few but none can handle the current that may be required during transmit. I have the Icom 880H, Alinco 235 220Mhz Rig, and a Kenwood TS-480 Sat.

If I don't let the solar charger cycle the batteries every once in awhile, It will shorten the life of 680$ worth of batteries.

I'm thinking about picking up a non switching regulated power supply, taking the transformer and the rectifying part out and feeding in my DC into it. What I am not sure about is if the voltage going into it will be enough, most regulated power supply's voltage going into the regulators are around 20 to 24 volts.

Thank to everyone for the replys

Delbert McCord
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AC5UP
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Posts: 3825




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« Reply #7 on: January 20, 2013, 07:39:08 AM »

Here's a Thot:

The DC voltage will go high when there's no load to pull it down to a safer value. There is a fairly simple way to add a voltage selective load that you can research under the name "Shunt Regulator". Imagine a 14 volt Zener diode of the stud mount variety on a small heat sink in series with a 10 Watt resistor of maybe 100 Ohms or so. You know what you're working with better than I do, so work the numbers and you'll get handy with Ohms law as a bonus.

Basic concept is to wire the Zener and resistor in series. Then connect the combo across the DC power leads. If the voltage climbs above 14 the Zener begins to conduct and the resistor becomes a partial load. This will waste some juice, but only at times when you have more than you'd like. When you turn on a radio or other load device the line voltage could drop enough for the Zener to become almost transparent so you won't be wasting power when you want power. If you're a clever bunny you might even find a magic value for the resistor so you can add an LED to tell you when it's working.

How cool would that be?

Should be an easy and inexpensive project that won't cost too much extra to overbuild..................
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KQ6Q
Member

Posts: 965




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« Reply #8 on: January 22, 2013, 08:28:00 PM »

If you're setting up a portable system, you can buy a regulator to take the power from the solar panel down to the 13.5 range. I use a folding GoalZero panel, and a $20 regulator from Radio shack, that's designed for use with solar panels - 7A max. the battery is a GelCell,that helps keep things stable. I'd worry about the over voltage damaging the battery, even more than the radio.
Do plan on using a regulator.
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K1DA
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Posts: 473




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« Reply #9 on: January 23, 2013, 09:59:11 AM »

The regulator end of a big Astron ought to be able to handle the problem.  Bypass the transformer and feed it directly. 
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WB6DGN
Member

Posts: 590




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« Reply #10 on: January 26, 2013, 11:07:15 AM »

Quote
The regulator end of a big Astron ought to be able to handle the problem.  Bypass the transformer and feed it directly. 

The last complete regulator board I bought from Astron was only $20.00 complete for an RS-60M.  That, and a handful of pass transistors will do the job.  Got to be a lot cheaper than a complete supply, even if it needs repair.  The transformer is the expensive part.
Tom
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KD8TUT
Member

Posts: 59




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« Reply #11 on: January 26, 2013, 09:49:52 PM »

Quote
Tom. Most electrolytic capacitors are tested at twice there operation voltage, so 16 volt rated capacitors are made to operate up to and including 16 volts without a problem.

CHINESE capacitors???  They have trouble operating at their rated voltage and they also have trouble keeping their electrolyte inside of their case.  In any case (no pun intended), that's still a bad practice because the DC operating voltage doesn't take into account any signal or noise voltage present on the line.  "In my day", the rule of thumb used to be to select a capacitor rated at 2X the max. anticipated operating voltage.  Maybe they're doing that with the published ratings these days but the offshore junk I've seen doesn't give me a warm and fuzzy feeling to say the least.
Tom

The Japanese electrolytics are just fine.

There was a bit of a scandal in Asian industry, where a Chinese company stole the formula for a type of electrolytic cap form a Japanese firm. But... it gets more interesting... because the formula stolen was the *incorrect* one. Thus the caps produced were garbage and had a MTB measured in months.

This was a big scandal in my industry (IT), because a whole boatload of equipment, most famously from ASUS, failed due to the leaking electrolytics.

Everything from computers to network electronics were affected. And technically competent IT folks actually soldered new caps in (The monitor I'm using is an example of that).

But then again you cannot always tell the source of a capacitor. *shrug*
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K6AER
Member

Posts: 3483




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« Reply #12 on: January 28, 2013, 09:50:02 AM »

One of the problems with higher voltage on a transceiver is the output transistors are directly connected to the DC power source. When the voltage is raised on the power transistors the gain of the device also increases. The power dissipation  increases and in the case of power across the output impedance the power output goes up by the square of the voltage divided into the termination impedance.

Increasing the voltage from 13.8 to 15.7 VDC can increase the output wattage by 28%. Your output wattage was designed by the manufacture to provide normal margins of safety for temperature, surge conditions and don’t forget VSWR from other than perfect loads.  Transistors unlike tubes are very sensitive to VSWR reflection voltage. If the transistor breakdown voltage is exceeded they pop. It has often been said transistor protect fuses.

Many manufactures make charge /pump regulators for solar cell systems. You can see these units at Tessco webs site. These regulators are multi stage units and will condition the battery charging, not only to properly charge the battery but limit current to the battery when they are properly charged. I don’t know the model unit you are using but the 15.5 volt equalize voltage is used about once a month to keep all the cells in the AGM battery exercised so the cells don’t sulfate. This overcharge level is low current and if you were to transmit the load current would drag the voltage down to the normal cell voltage and the battery would be under 14 VDC.
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