Yes, but divided by the number of cells, so a 3S pack got about 250-275mA charge rate per cell.
I’m just about to make a Scotman’s KX2 battery charger. I have a genuine Elecraft battery that I have never used, I balked at buying an Elecraft charger because my sporran is very difficult to open! But it will be useful to be able to use the KX2 internal battery for some plans… I found an LM317, a few BC547s and a handful of resistors and I’ll make a 250mA CC charger for the KX2 pack. I’ll be able to drive it from the same unregulated wall wart that powers the old 3S charger from olden times.
Over the years in my job I have worked with many smartphone companies that use our semiconductor designs in their phones. The result is I know how much phones cost to design and make. It’s why I buy cheap end Android phones and not iPhones because I know the cost and don’t want to pay 15000% idiot tax on high end phones. Likewise I know how much it costs to make a constant current charger and having spent a sporran wilting amount on a KX2 I wasn’t prepared to spend about £50 or more on £5 worth of electronics. Especially when I can make such a thing myself and revel in my own smugness at saving some money!
Jim,
Former IATA certified for shipping dangerous goods, until shortly before retirement. You are spot on, have to look at rules for passengers which are different and usually on the airline website. I am certain if we met on the air we could share some interesting stories. Perhaps the most challenging task was shipping a satellite that had explosive bolts, radiated components, custom built batteries and loaded on a C-5A in accordance with AFR 71-4. Our customer was the USAF.
I have just completed it and it worked 1st time I used some gash 5% tolerance resistors so the charge current is 210mA not 260mA but hey it will take 16hrs not 13hrs to charge the battery. My virgin KXBT2 is now on charge.
I now need to find a 17V 500mA wall wart. I used to have loads of them but in a shack clean (first time in 21 years, I binned all the wall warts that were odd voltages. I only have 5, 9 and 12V ones now )
Andy,
Just read your post. I’m all for recycling especially any stuff in a box in the garage.
3S means three cells in series. Do you remove them from the pack for parallel charging? If not why is the charging 0 8A rate reduced by a factor of 3?
This Sporran thing. I thought you said you were born south of Hadrian’s Wall so how come you sport a Sporran now? Yorkshire men are known to keep their purses tightly closed.
Ron, many of my ancestors come from North of the border, Unst in Shetland, Selkirk in the Scottish Borders, so care with opening the sporran comes through my genes! Though the modern proponent of alleged difficulty in Scotsman spending their money was promoted massively by Scottish comedian/singer Harry Lauder (Sir Henry Lauder) who was an extremely successful entertainer around the start and early years of the 20th century. The images he created live on 100 years after he was at his peak. There’s plenty of Scots who self-deprecate and continue to promote the stereotype to this day.
Anyway chargers. The one for the KX2 battery has cost nothing but my time. It’s some guy’s circuit from the net and it works. All built out of parts in my electronics junk box/component stores. In fact whilst looking for a dynamic microphone for an old TR-7010 I bought recently, I found my first soldering iron (Antex Model C) which was a birthday present when I was 12, so 51 years old and still on the same element. Back then everything built started off with buying the components. 50+ years later of Magpie like collecting, I have plenty of semiconductors and resistors and quite a few capacitors. But if I don’t have something, it’s a given it will be a capacitor. The charger does need about 15-16V to overcome input requirements of the LM317 but I have now found a 5V wall wart to use in series with the 12V wall wart that powers the charger you were querying. I used to collect wall warts with religious fervour…just in case. But when the house had new windows I had to empty the shack completely and I disposed of all the odd voltages and non-switching chargers. There’s only about 10 chargers that are orphans (they don’t belong with a device) from a pre-clearance of over 100 items, 5V, 9V, 12V. That’s a habit now borken. Total cost of the KX2 charger, as stated, just my time
I could be wrong about the commercial charger. Sure 800+ mA is drawn from the supply when initially charging, but I’m sure when I charged up a 2S pack (it’s a 2S or 3S smart charger) it was only drawing 500+ mA which is what made me think it was 3x 250mA separate chargers. Since I bought a multi chemistry smart charger I haven’t used it so maybe my mind is playing tricks. I’ll have a look sometime.
The new religion is clearing out “junk” not acquiring more.
Can a bit of this rub off on me please? I often wonder why I have squirreled so much away. For many things there’s virtually zero per cent chance of them being used… anyone need a QQVO2/6?
I’ve got 4x QQV02/06, 6x 5763 power tetrodes, many X79 triode-hexode mixers, N78 output pentodes and a veritable cornucopia of 50s/60s radio/radiogram valves. All NOS, individually wrapped in paper and corrugated cardboard and then boxed. The X79 box says “Marconi X79 17/6 P.T. EXTRA” For non-old-timer Brits, 17/6 is seventeen shillings and sixpence or 87.5p in decimal Sterling. We went decimal in Feb 1971, so that box is at least 53 years old. P.T. was purchase tax, the forerunner to VAT. If that is from 1970 say, the average weekly wage in the UK was £20, so that valve was nearly 1/20th of the pre-tax weekly wage!
If you look at how long it takes to achieve say 2.5 Ah of charge at 0.5A input you should be able to figure if the batteries are isolated and parallel charged or series charged with cell over voltage limiters. Series operation will be three times faster for a given charger current and is what I would expect. It needs three times the cell voltage. I’ve not come across any parallel charging.
I have a 0 - 30 V, 0 - 5 A regulated voltage/current limiting power supply that I use on most of my rechargeable batteries. It lacks a means of monitoring the internal battery temperature but that I could build with enough motivation and a bit of delving in my storages. In the meantime I use a fractional C charge rate and test the temperature periodically by laying a finger on the battery.
I guess I have the collectors sickness bad. As a teenager, on the advice of an older ham, I bought a good number of WW2 surplus circuits containing mil spec resistors and capacitors and I still have 2/3 of them. Sigh.
No QQVO2/6 needed, but don’t throw any QQVO3/10, ECF80 or 82, EF86, ECC83, 6BW6 or EL84 bottles away please Gerald - with apologies for the thread hijack.
I used some gash 5% tolerance resistors so the charge current is 210mA not 260mA but hey it will take 16hrs not 13hrs to charge the battery. My virgin KXBT2 is now on charge.
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