Kinetik hc600 rev powering a spectra

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Josh380

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Didn't know where to put this so hopefully doesn't have to be moved. I'm planning on powering a Motorola Spectra (100w) with a Kinetik Hc600 rev. For those of you who don't know this battery, it's a 12v 600w AGM 18Ah (600 cranking amps) battery.

From what I've been told, the spectra draws about 31a. If I leave the float charger disconnected, about how long can I expect to run at full power before I need to recharge? Obviously key up time and frequency will play a factor in the end result, I'm just looking for an average.

I'm sure there's some mathematical equation to figure this all out, but mathematics has never been a strong subject for me.
 

mmckenna

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There are formulas, but it really depends on -exactly- how the battery was manufactured. Since this is a consumer grade battery, it's very unlikely the manufacturer will 1. have this information, 2. provide it to you, and/or 3. have any clue, since it's probably made by a third party.

The battery says "18ah". That is usually 18 ampere/hours over a set amount of time to a certain "end voltage". On the batteries I use, this is commonly an "8 hour rate", or how many ampere hours the battery can provide spread over 8 hours to 1.75 volts per cell.

So, the answer isn't 18 ampere/hours (battery capacity) divided by 31 amps (Spectra draw) = 0.58 hours. If you put a 31 ampere hour load directly on the battery and let it run down, you'd likely see something less than 0.58 hours. If you instead took that 31 amp load from the radio and spread out the drain over 8 - 10 hours, you might see something more than 0.58 hours. Exactly what depends on battery design.

If something ~around~ half and hour is good enough, then there ya' go. If it isn't, then you need to consider other options.

A couple of things I can tell you:

Running a Spectra at 100 watts isn't always a good idea. We used to turn down our 100 watt VHF Spectra's to around 80 watts. They run cooler and last longer. It'll also reduce power consumption.

In Orange County, you shouldn't really need 100 watts to reach anywhere in VHF or UHF range unless you are doing some non-standard amateur radio stuff. Turning the power down to 50 watts will work almost as well. You can make up for the lower power by using better coaxial cable and/or higher gain antennas.

You have to be very careful running trickle chargers on batteries. It's a really good way to destroy them. Ideally you want these to be float charged with temperature compensation. Trickle chargers just keep dumping power into the battery wether it needs it or not, and that can damage it.
 

mmckenna

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OK, I missed that in your original post.

Float chargers are good if they float the battery at the manufacturers recommended voltage. Not all battery chemistries float at the same voltage, so make sure your's agrees with the specs. Since it's designed for automotive stereo use, it's likely this battery will be happy at somewhere between 13.5 and 13.7 volts.
 

mmckenna

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That's probably safe. May not charge it up 100% but a lower float voltage is safer than one that's too high.
 

Josh380

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Ok so I have some testing to do as soon as the battery shows up. I know to check to make sure it's at 12v before I try charging it. We'll see how things work on and off the charger.
 

mmckenna

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It should work well.
While 18 ampere/hours may not seem like a whole lot for running a radio that draws somewhere near 30 amps on transmit, you likely won't be transmitting that much.

Just keep an eye on the voltage. Not sure how Spectras do with low voltage situations. Some radios get wonky, even unstable.

Another option to look at for charging would be a small solar panel with charge controller. The right one would safely keep the battery topped off. Only issue to be careful of would be that some charge controllers can generate RF noise.
 
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