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Running and FT-857 off the battery in my car... Do, or don't? And if do, how?

Discussion in 'General Technical Questions and Answers' started by W4JSG, Jun 9, 2019.

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  1. W4JSG

    W4JSG Premium Subscriber QRZ Page

    This is quite reassuring, WB2WIK.

    For those talking about going ahead and buying a "deep-cycle" battery, I am now beginning to consider that option.

    I might try biking with the 857 in the future, as well, and a separate battery would be a must for that.



     
  2. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    Stuff may have changed over the years, but years ago I was doing consulting engineering for C&D Battery in PA; they manufactured lead-acid batteries for Sears (Die Hard), Mobil, and several brand names and private labeled them. I’m not sure if they’re still around, but they were pretty big back then.

    At that time, the difference between “deep cycle” and the normal “starting” batteries were that the deep cycle models had solid plates, while the regular starting models had plates that were more of a mesh, appearing like a woven sponge to provide more surface area and thus higher starting current. So, the conventional units could produce more “cranking amps” but the deep cycle units could be more deeply discharged repetitively, albeit at somewhat lower current.

    I don’t think there was any other difference, although this was quite a long time ago. All the models were derated various ways above and below 25C ambient: At higher temperatures, shorter life; and lower temperatures, longer life but less capacity. When terminal voltage dropped 10% that was a deep discharge.

    In any case, since I have an FT-857D and have used it mobile, powered by my car battery many times, I’ve found using it for “hours” at a time while parked and not charging was fine and never seemed to degrade anything with typical operating (SSB or CW, just making contacts). You might want to try that while parked at home or somewhere you won’t be in trouble if the battery fails to start the vehicle after an operating cycle before taking it to a remote location.

    If you don’t care about using some gasoline, running the engine while operating will provide somewhat more transmitting power output. The 857D only runs 100W output with about 13.8-14.2Vdc applied; when the voltage is only 12V, output drops to about 80W. Small difference, but if signals are very weak even 1 dB can sometimes help.

    Good luck with your portable ops!
     
    W4JSG likes this.
  3. NG1H

    NG1H Ham Member QRZ Page

    Another point to keep in mind if considering a separate battery is that there is a fairly substantial difference between a real deep cycle battery and what consumer stores falsely label deep cycle. To prevent confusion let's call the false one a marine battery as they often have that name. The marine batteries are slightly more resistant do damage from discharge than a starting battery but not that much so. A real deep cycle battery is going to cost more but last a LOT longer as it is built for this type of use. And due to the longer lifespan will be cheaper in the long run. Don't be a typical ham who can't understand why spending $100 every year is more expensive than spending $300 every 10 years.
     
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  4. ZL4IV

    ZL4IV Ham Member QRZ Page

    For years I have had my 857 permanently installed in my Jeep. I use a Gel battery and an auto switch that disconnects to main battery when engine is not running and when it is running charges the Gel batter. Battery is about 5 years old, just had it checked and is fine. Can't out talk the battery. Most current draw is UHF/ VHF FM, HF SSB is easy on the battery. Paid $120 for the battery, didn't get to technical and the Jeep always starts after working pileups.
     
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  5. WR2E

    WR2E Ham Member QRZ Page

    Is a deep discharge the same thing as a deep cycle?

    So if a SLI battery with a nominal terminal voltage of 12.6-12.8V were to drop to 11.34V that's a 'deep discharge'?
     
  6. AI3V

    AI3V Ham Member QRZ Page

    There is a long running joke that the difference between a cars starting battery and the "marine deep cycle" battery next to it on the shelf at the 'mart is, the "marine" battery has a handle and a sticker with a picture of a boat .

    :)

    Rege
     
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  7. G6YYN

    G6YYN Ham Member QRZ Page

    I run mobile HF, VHF/UHF most days while driving to and around at work and a couple of evening a week Mobile/Portable from my van.
    I don’t have a second battery to power my FT897 o
    I run HF and VHF/UHF most days on my way to, from and while out working during the day, most weeks I also operate Mobile/Portable for a few hours in the evening in a quiet RF area away from where I live.
    I don’t have a second battery to power my FT897 or FT817 but do have a separate DC supply box wired direct to the battery. What I do have now is a Voltmeter display on the Powerpole distribution box that I built and keep an eye on this while operating.
    In 20 years of running with this set up I haven’t had engine starting problems after operating. I do restart the engine if I see the battery voltage dropping or if I am struggling to make a contact in a pile up when trying to get my /M call heard.
    If you are wanting to run your radio while parked for many hours a second battery will be a useful option, what I would suggest before you get too involved with split charge and second batteries is that you go out and give it a good go with the standard set up but do keep an eye on the state of the battery.
    Like most things in life it’s a bit of a compromise, but it can be great fun.

    G6YYN/M
     
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  8. ZL4IV

    ZL4IV Ham Member QRZ Page

    All you need is another battery, preferably a Gel and a VSR, look it up (deliberately didn't say Google, puke..)
     
  9. W5LZ

    W5LZ Ham Member QRZ Page

    Wanna do mobile? Connect to the vehicle battery(s). Wanna do portable? Get a battery you can carry, or drag on a cart. What happens when you run that battery down too far? You are out'a the radio 'bidnezz' for a while, so don't. That means keep it short-n-sweet, or shut up more. Wanna parallel 4 or 10 batteries in your vehicle? Hope you got room for'em ... and your generator/alternator can handle the charging.
    How to connect to the battery? I would run a fairly large wire to the (+) terminal of the battery, or, an unused 'tap' in the fuse block. The thing with the fuse block is that the fuse/tap has to be able to handle the max current of the radio(s).
     
    Last edited: Jun 13, 2019
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