Thursday, 25 June 2015

Modernizing Hand-held Battery Chargers

Many of us have an old handie, usually for 2m, that we love. One thats served us well over the years and whos features and ergonomics suit us. For me that device is the Alinco DJ-F1E.

Over the years ive had many handhelds. My first was an Alinco KT-22, a copy of a venerable Icom design and set to frequency using thumbwheel switches. This unit was stolen off my belt outside Doncaster market. It was a big chunky beast, and whilst outside a B&Q store was once asked by a fellow if he could 'borrow my phone' - this was back in the days of TACS analogue mobile phones!

This was followed, after some playing about with a UHF Icom mobile at the start of the UK 'novice' era, with an Icom dual bander, W-21A I think? Not a great radio and this eventually passed on to my protege Bob M1BBV. I then got an Alinco DJ-S1E off of Martin Lynch's stall at Drayton rally one year.

I loved the S1, but it had one drawback - no DTMF! It also had very few memories. But both were upgradable. In time, I added the keypad and the memory unit. I then sold it.

Now, after owning and selling several, im on my third F1E. The F1 differs from the S1 in that it comes with the keypad. Ive since upgraded it with the addition of the CTCSS/DTMF codec and the memory module.

But this brings us back to the big problem - batteries. Over the years, the NiCd packs wear out and fail. Battery technology advances, and when you come to re-cell the pack (quite easy on these) you can no longer get the same capacity cells. Usually not a problem, as the bigger cells just need a little longer to charge. The Alinco stock slow charger is 70mA, although mine runs at 80mA.

This is fine if you've re-celled with say 800mah, over the original 600mah. But, I found  a deal with a fellow SOTA activator for 2500mah (2.5A!!!) Hybrid NiMH tagged cells. The stock charger would take over 50h to charge these, and risks serious damage from overcharging.

So whats the answer? No stock charger for this handheld could cope, and are all very expensive. No 'intelligent' consumer charger can be used as they are tagged cells in a pack, not loose cells.

I then came across a little known aspect of the rather bizarre sport of 'Airsoft'...

For those not familiar with this, Airsoft is an odd activity in which realistic looking plastic guns are used to shoot 6mm plastic balls at people. This is a game enjoyed by people, seemingly all boys, dressed in excessive amounts of surplus kit, using illegal comms in no particular correct manner, all of whom seem to be either built wider than they are tall and with a prediliction for  cake and chips, or overtly macho of the type invariably seen on Ripon station waiting for the train home on the evening of the first day of basic training, or more commonly - at the end of the first day of selection weekend. All strive to cultivate a 1000yd stare and rarely extend their visual range beyond a couple of feet. They pop up all over technical, ammunition and forces forums asking deeply involved questions that they could answer from a copy of 'Soldier', or making comments in threads which demonstrate their complete lack of service/understanding/IQ.

In fact, it seems they cannot be trusted to know what size and voltage battery their gun takes!

Now this leads to a great opportunity! Their battery chargers are cheap, intellegent, automatic. Fitted with a generic model plug, they connect to any NiCd or NiMH pack between 4-10 cells, automatically set the voltage and use deltaV monitoring to asses state of charge and turn off point. At just about £12 inc. postage, I opted for a VapexTech VTE500P. Sold as an Airsoft charger (or, oddly, a model charger for a couple of quid more!), it came with a short adapter cable from the normal model connector to a mini version, which I decided to sacrifice, as I have no need for it, to provide the connections to the Alinco charger.

The idea was simple - remove the power pack and cable from the Alinco charger stand, and replace it with the adapter cable. This done, the next step was to bridge over the current limit resistor in the housing that allowed the stand to be used with the different voltage packs, as this is now done by the new charger. Simples.

Now, the charger will sense for itself whether the pack is the 12v 800mah, or the 8.4v 2500mah. And instead of 50h and the risk of serious overcharging, it will handle the big capacity pack in around 5h, and the little one in about 2h!

And, just in time for the big walk!

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