LIon battery for Mountaintopper 3b

Discussion in 'QRP Corner' started by WN4BIY, Jun 27, 2019.

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  1. WN4BIY

    WN4BIY Ham Member QRZ Page

    Can anyone share if they are using a rechargeable Lithium Ion battery pack to power their LNR Mountaintopper? Have been using 9v battery but would like to get a little more power out. Have tried to find a battery pack with the small barrel connector required to fit the radio as well as charger but having no luck.
    If you are using one successfully can you share type and source? Thanks very much!

    Also if there is a better option for battery power please share....
    Last edited: Jun 27, 2019
  2. KG7WGX

    KG7WGX XML Subscriber QRZ Page

    As far as I know, the Mountaintopper series will not handle a voltage higher than 12.0 v. They are designed to run at a lower voltage than the typical 12v rigs.

    I believe others have successfully used Li-Ion batteries with these transceivers with a buck converter to lower the output to 12v or less, but I have no details to share.

    Regarding the power cable, I bought a couple of them from LNR Precision and spliced them to standard 9v battery connectors.

    Link -

    I also found some 8xAA battery holders which had the mating connector built-in, so I can use the same cable to connect to a standard 9v battery or the battery pack.

    Link -

    To use the battery holder, I use 8 NiMH batteries, for 10.4 v and fairly flat discharge curve, or 7 alkaline batteries and a dummy cell, for 10.5v and a steep discharge curve. I think I'm getting 4.5 watts with 10.4 volts. So far I haven't had to build a case for the holder - I just strap it down to a kneeboard or set it on the picnic table beside the radio. I did find that 1 wrap of electrical tape helps keep the batteries in the holder.

    I did see that Buddipole has a 9.9v LiIon battery pack, but it comes with a PowerPole connector. If you use that battery pack, it won't damage the Mountaintopper, but you still have to splice a LNR-compatible plug to its cable.
  3. KG7WGX

    KG7WGX XML Subscriber QRZ Page

    Update -

    Since the last time I looked at AA batteries, there are now AA rechargeable Lithium batteries on the market which are 1.5v each. They actually use standard 3.7v Lithium chemistry, and incorporate a built-in buck device to lower the voltage to 1.5v. (Chinese patent, according to what I read...)

    I found two different variants on Amazon. One uses a coaxial connector (at the + end) with an outer ring for 3.7v charge in a special charger and a standard "button" for 1.5v load connection. The other uses a micro-USB connector for charging each battery and a standard button for 1.5v load.

    The mAh ratings are similar to NiMH, so these would be a flat-discharge power supply, unlike alkaline batteries.

    If the buck circuitry actually regulates each cell's voltage to 1.5v, you could use 8 of these in a pack to get 12v.
  4. N8TGQ

    N8TGQ Ham Member QRZ Page

    Im also using AA NiMH batteries in a holder with the 9v connector built in. 8 batteries for 10 volts or 6 regular AA alkalines for 9 volts. I just cant see an advantage with the lithium batteries to make me want to buy more batteries plus a new charger. Still using my 15 year old Radio Shack charger. Dollar General sells 20 packs of AA alkalines for 6 bucks and they work great for me.
    I get my 9 volt connectors off my dischaged 9v alkalines and solder the plug to that. Be sure of polarity! Plug is the same size as the charger plug for my Yaesu FT250 HT. I get plugs from the cheap wall warts at my local thrift store. Just take the HT in with me and find one that fits. At $1.98 each cant go wrong. Plus the plug is already wired! I think LNR wants ten bucks or more for the same thing.
    Since we're on the subject of the MTR3b, would anyone be interested in a special interest group on site? I thought about creating one but not sure there's enough interest.

    Have fun!
    Rick N8TGQ
  5. WN4BIY

    WN4BIY Ham Member QRZ Page

    Gentlemen, thank you for the great feedback. Very helpful! I would be interested in. MTR 3b interest group. Will be very helpful to me as a new user
  6. KG7WGX

    KG7WGX XML Subscriber QRZ Page

    Would the MTR-4B owners be allowed to join, too? ;)

    I think the series is very similar, and includes the -3B, -4B and -5B.
  7. N8TGQ

    N8TGQ Ham Member QRZ Page

    Thats a good

    Thats a great idea to imclude all the MTR radios! Im gonna check into creating the group & will post the results here.

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