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HTX-202 / IC-02AT Battery Charging Question

Discussion in 'VHF/UHF - 50Mhz and Beyond' started by N7KOM, Oct 7, 2020.

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  1. N7KOM

    N7KOM Ham Member QRZ Page

    Hi All, hope this is the right spot for this question. I recently picked up some used old school HTs for doing SOTA. They came shipped with old mostly dead batteries, so I picked up a new 8.4V 1800mAh Ni-Mh battery off ebay.

    I've search through quite a few threads and can't seem to find a definitive answer as to the best way to charge these batteries.

    The new Ni-Mh battery has two plugs on either side. One says "DC 13.8 V" and the other plug says "Wall Charger". The 13.8V will fit many of the random wall wort chargers I've accumulated over the years including a 12V 500mA wall plug that came with one of the radios. The "Wall Charger" other plug is a smaller diameter that I don't have on hand. One of the old dead batteries also has this plug configuration.

    So.... What's the best way to charge these batteries?

    I also have a BC-35 charging station. Is it safe to charge my new Ni-Mh on this charger? Manual says "Do not attempt to charge anything other than Ni-Ca..."

    Also, what is the recommended plug for powering the radio via the DC plug on top? I've powered the radios using the 12V 500mA wall plug and receive fine, but can't seem to transmit reliably on it.

    Battery works fine for transmitting simplex, but I've had issues hitting repeaters from my 3rd story. Of course will be upgrading antenna soon...

    Thanks for any advice. Pretty excited to get these radios to a mountain top soon.

    Attached Files:

  2. KB0MNM

    KB0MNM Ham Member QRZ Page

    Unfortunately, I have had some experience with Nickel Metal Hydride batteries for portable radios and chargers which did not control the temperature correctly. If you were to look at battery chargers made by a certain manufacturer whose name sounds like laughing, you might note that the newer ones have temperature sensors which are supposed to attach to some battery packs with a magnet. So the answer is ( regarding the BC-35 )- probably not without modification. This does not mean that it might work or not- just that you also could end up with melted plastic around the batteries. The best way is to get a dedicated charger for the Nickel-Metal-Hydride batteries or find a schematic and build one. This has to do with the rate at which the batteries are charged ( percentage of capacity in mAh, typically 10% or less ). The temperature sensor ensures that if the rate is too high, melt down should not occur. The same applies to Lithium Cells ( banned from many airlines ). The wise move is to pick a charger that can charge all three types, without too much excess voltage nor mAh capacity beyond what is needed. There is a company that makes a AA-cell holder, which would make selection easier. In that case, you may want to contact KB5MRP for two or three of the EBL(R) iQuick Intellicharger 18650-BC1 ( EBL Charger 18650/145001/1 PR20200617 ) which will certainly handle AA cells in Nickel Cadmium and Nickel Metal Hydride. Without the discrete AA holder, you will be looking for the correct plug or making a modification to the BC-35. I believe the name of that company which made an AA 'holder' pack "KIT" was "Batteries America" and from New York or nearby. I think that "Mr. Ni-Cd" may not be advertising any more. Please be aware that there are very slight differences in the 'shoes' for HTX-202 and IC-02AT radios- try not to break them with the batteries.
    N7KOM likes this.
  3. KB0MNM

    KB0MNM Ham Member QRZ Page

    Here is a similar post:
    Please read some of the last responses. Haste makes waste. Nickel Cadmium is different than Nickel Metal Hydride- what works for a time may not be a good idea.
    N7KOM likes this.
  4. N7KOM

    N7KOM Ham Member QRZ Page

    Thanks for the info. After reading through your posts and digging as deep as I could into HTX posts and forums, reading through every htx/icom accessory on batteries america, plus some at home experimenting, I think we have some results/conclusions. Posting here, so hopefully this info helps someone out in the future with less digging.

    The battery gets hot when charging the NiMH battery using the 12V 500mA wall wort. I have not charged it for more than an hour with this method. I don't want to push it.
    When charging with my BC-35/CM-35 drop in charger, the battery stays cool. I have not left the battery in for more than 8 hours though, so I don't know if it's reached full charge. Perhaps the "charging" light turns off when the battery is full?

    From Batteries America, the IC-WC, a 12v 200mA wall charger seems to be the recommended plug in charger:

    From the various manuals, for powering the radio directly, 12V 1A wall plug (part no. 273-1653) or 2.5V Regulated power supply (part no. 22-120). At 1A, the radio will only operate / transmit in low power mode (~2W). The 2.5A regulated power supply will allow radio to transmit at 5W.
  5. KB0MNM

    KB0MNM Ham Member QRZ Page

    When that manual was written, NiCads were the rechargeable battery. As you stated, the NiMH batteries can get hot with a 'fast recharge' current set up for the other battery chemistry. If they get too hot, now you have a 'metal fire' which could start the rest of things on fire. So if you choose to power the radio directly, you may want to be sure that either the NiMH battery is removed, or that you disconnect the source very soon after use. If you really must use NiMH cells, again I suggest that you get a AA cell holder so that you can use a regular charger designed for them. Batteries America may still have a kit for that. If you are looking for a tri-chemistry charger, you may want to contact KB5MRP at e-mail I have no financial interest in Batteries America, nor those Radio Shack(R) stores that are still in business because they were not corporate-owned stores. I did some seasonal work for 'The Shack' at one time, and also watched the new movie by the same name. Yet that is an entirely different story. By the way, did you check to see if the drop-in charger contacts have mating contacts on the new battery? It is also common for the contacts in the battery charger to be nearly 'broken' due to battery acid. There are usually springs and 'C' or 'E' shaped clips which hold them in the plastic- parts easily misplaced. Finally, many chargers have a fuse or other device which can 'blow' if the battery draws more current than expected. Again, NiMH is not the same as NiCad.
    Last edited: Oct 11, 2020
  6. N7KOM

    N7KOM Ham Member QRZ Page

    Sorry, did not clarify that when using the radio directly from the wall wort, battery is removed. I haven't inspected the BC-35 contact points too closely, but the "Charging" light turns on when my NiMH is inserted.
  7. KB0MNM

    KB0MNM Ham Member QRZ Page

    Then it may be a 'trickle' ( overnight charger )- at that point, we might think about a 'trickle down economy', where the wealth is *slowly* moved to the 'have nots'. There is not much danger of problems with the NiMH cells if that is the case ( no pun intended- case around the charger ). The only way to verify this would be to supervise a single charge, or open an outside lead ( the center is often for temperature feedback ) for insertion of an ampere meter. Many multimeters can do this, yet the banana jacks are often different than those used for ohms or volts.
    There have been just a few instances where the radio internal voltage regulator has been damaged by 'straight through' automotive adapters. Direct battery charging with a typical vehicle is also a bad move- the typical 13.8 VDC ( alternator running ) even through a cigar lighter socket and fuse might be O.K. with some radios- yet is never O.K. if applied to that coax port on some selected HTX-202 battery packs ( unless modified to limit current to about 200 mAh ). Some 'cords' have this built in- yet that is rare.
    For extended mobile operations, extra batteries and a 50/50 ( talk not much more than 2 minutes / listen at least as long ) duty cycle is wise. There is a default 'time-out' timer in the HTX-202 for 3 minutes, which can be adjusted. Your transmission just 'cuts out' to keep the radio cool.
    N7KOM likes this.

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