I think you will find that one of the cells used in this series arrangement will have a high internal resistance. You also mentioned a brand that I have seen the worst performance from (my personal experience). I have been using one of the Blue ESR meters (80 bucks) for about 4 years to look at batteries that don't perform well, high resistance in a cell has always been the issue..
Before all the engineers jump on and say there is a difference between resistance and impedance and I don't understand, and this is not the correct way to read internal resistance. I can say that I also understand how to load a battery and at the same time and take a resistance reading of the cell. But who has the time.. I have no intent of testing in a laboratory, when the shop is sufficient. First off make sure you don't use any of the really expensive ESR meters that measure the voltage first and if they see any the go into a capacitor discharge cycle.. that would not be good. I simply hook the battery across the meter and read the resistance.. While this is not a exact laboratory measurement you can tell a lot from the reading.. look at each cell in the string, if one is higher just get rid if it you will see an improvement of string capacity. As an example not long ago I had a battery pack that could last about 5 minutes after it was charged.. reading the whole pack's resistance it showed about 9 ohms of resistance on a 14 volt pack. opening the pack I found two of the cells bad.. one measured 2.5 ohms the other was 3.1, that is 4.5 ohms just from two of the batteries.. the rest were around .85 ohms.. I have also tested thousand of SLA batteries this way, and can tell you instantly if the battery will deliver the rated capacity.. from experience if a cell is more than .8 or .9 I don't use it.. Regards.. Fred I had to post this message two time to get it to the list.. I can honestly say this is the first time since using the internet that my post was rejected for have a digital signature, so will have to remember to turn it off.. The message's content type was not explicitly allowed On 5/6/16 6:06 AM, LA7NO wrote: > KX3 (ser. no. 08146) works OK on external power, but recently I am > experiencing problem using it on internal rechargeable cells. > > The AA cells are relatively new Varta Professional No. 5706, 2700 mAh NiMH. > They have been charged with a techno-line BC-1000. Measured capacity via an > automatic discharge/recharge cycle is according to spec. > > I have attached a 50 Ohm dummy-load to the KX3. When turned on, it indicates > BT 9,7V. BAT MIN is set to 8,2V. > When I press ATU TUNE, it turn itself off immediately. > With TUN PWR set to 0,1W it works OK when pressing TUNE, but BT drops to > 7,6V. > If TUN PWR is set to 1W, it switches off when TUNE is pressed. > > Strange that the voltage drops so much, even if the charger indicated normal > cell capacity when automatically discharging them. > > Any ideas? > > Per-Tore / LA7NO > > > > > -- > View this message in context: > http://elecraft.365791.n2.nabble.com/KX3-internal-battery-problems-tp7617201.html > Sent from the Elecraft mailing list archive at Nabble.com. > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to wd8...@gmail.com -- Fred Moore Ham: WD8KNI Cell 321-217-8699 email: f...@fmeco.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
