Darren 0 Posted July 9, 2006 Share Posted July 9, 2006 I always cycle batteries, especially if they're in a model not flown for a while or one that often gets a quick charge before a days flying. I wonder how many of you do likewise. Is it important I hear you ask? Have a look at my TX pack performance below and see what you think. The battery in my TX is a 2500mAh Ni-Mh pack and I should get loads of time out of it but it seems to be going flat quite quickly. I decided to use my fast charger to cycle it, according to Overlander these cells can be charged at 2.5A and discharged at 10A. I've seen in the past that 'exercising' packs by making them work harder seems to do them good. So I've been cycling it at 1.3A charge and 3A discharge, still quite gentle. The list below gives the capacity at each cycle 1 - 1068mAh 2 - 1185mAh 3 - 1428mAh 4 - 1689mAh 5 - 1848mAh 6 - 1981mAh 7 - 2100mAh and still going. So, if you think your tx or rx packs seem to be giving poor performance - get them down the gym for some exercise Just remember, check out their rating and charge/discharge rates and give them a workout. Link to post Share on other sites
Nutz 0 Posted July 10, 2006 Share Posted July 10, 2006 Darren do you know what the voltage is that you discharge down to? It is that if you have a cell that is not correctly capacity matched or you have weak cell (not saying you do) you will be pushing that cell into reverse polarity on a deep discharge cycle, which can actually shorten the life of the packs. I know Ni-Mh are a pain to get a charge in when they have not been used in a while (like a couple of months), at first they take only a few mHa but on each cycle the take more & more charge until up to capacity. I have tried charging my packs at 1A before but I find the faster I charge them the less capacity they take (i.e. 2000mAh packs take 500mAh), so now I charge them over night before I use them at 0.2A. I had a Sanyo TX pack loose 2 cells recently, the pack was around 6-7 months old but the company I got it from replaced it after asking me if I had cooked the pack. I was thinking maybe charging at a 1A was to much. But after reading the info you (Darren) got from Overlanders I think I was alright. I have a few packs for my RC buggy I am taking out tomorrow and they have not been charged for about a year (discharged to 1.1V per cell & stored). I think I will do a slow cycle to awake them then same rapid exercises. Link to post Share on other sites
Peter 0 Posted July 10, 2006 Share Posted July 10, 2006 I have not recycled batteries since I have been flying (approx 20 years. I do replace batteries very frequently if I haven't flown a model for some time since a receiver pack in the 1800 range is about a fiver these days its not worth the hassle of playing around with old packs. In the cae of transmitters again I rely on the electronics in the tranni to tell me if I see a slight deterioration out they come and are replaced. In my new Multiplex set the charging and discharging curves are shown and recordedin a separate file in the tranni so it is easy to see what is going on also unlike most trannis the multiplex shows amps and volts discharging levels etc. great piece of kit. regards, Peter Link to post Share on other sites
Nutz 0 Posted July 10, 2006 Share Posted July 10, 2006 Well I set my charger for 5 x discharge (0.5A)/charge (0.7A) cycles, cut off voltage 6.0 volts (1.2V per cell) & began cycling those batteries packs that had not been used for well over a year. At first the packs (2 of them) took around 50mAh before saying they were charged on the first cycle. They then took around 120mAh on the second charge & now they have just completed the 4th charge & took 1300mAh. They are currently being discharge before the 5th & final charge. They are both 2300Mha packs for my RC buggy (in Yogas vice) WAKEY WAKEY RISE & SHINE MY PACKS DO Link to post Share on other sites
Darren 0 Posted July 10, 2006 Author Share Posted July 10, 2006 2287, 2335 and 2298mAh on the next cycles so I expect this is the best I'll get. I use a pair of Supernova charger/dischargers and they take packs down to 0.9v/cell and I use a pair of modified meter leads with pins on the end to probe through heatshrink to check individual cell voltage/reversed cells. Increased handling and potential for broken down/reversed cells was one reason we didn't progress very far when doing a battery eval for full size jets - we were considering some new 24v NiCd's to replace the old lead acid. Problem was the voltage standing up when we hit them for 800A during engine starts. No point having a Harrier that can operate from anywhere it likes if the battery wasn't up to a un-supported remote field battery engine start But that was nearly 20 years ago Link to post Share on other sites
Nutz 0 Posted July 10, 2006 Share Posted July 10, 2006 Problem was the voltage standing up when we hit them for 800A during engine starts. No point having a Harrier that can operate from anywhere it likes if the battery wasn't up to a un-supported remote field battery engine start. Could always jump them off of a couple of rangerovers, I bet they can provide some good coldcranking power. Link to post Share on other sites
Darren 0 Posted July 10, 2006 Author Share Posted July 10, 2006 In reality the 24v battery wasn't much bigger than a large car battery and I'm sure a couple of range rovers would be up to the job but ....... Where would you get jump leads that can take 800A and where in some middle east back water would you find a pair of range rovers Link to post Share on other sites
Nutz 0 Posted July 10, 2006 Share Posted July 10, 2006 Middle East? A Couple of Arabs in Mercs "Hey mister can you jump start my jet" Link to post Share on other sites
Peter 0 Posted July 12, 2006 Share Posted July 12, 2006 Nice one Steve, !!! It only happpened once when the mouth of the south was doing his best to win pillock of the year award which by tyhe way he succeeded in doing. xxx Peter Link to post Share on other sites
Peter 0 Posted July 13, 2006 Share Posted July 13, 2006 Steve , Whilst I got the 2nd award for Pillock of the year I was referring to everyones friend Kelvin. Regards, Peter Link to post Share on other sites
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