Andy Stephenson Posted November 21, 2021 Share Posted November 21, 2021 If you have an electronic switch which drains at 5uA when off and you have, say 50mAh left in your battery, you would have 0.05Ah/.000005A = 10,000 hours before the battery is fully discharged. This is over a year. Depending what sort of battery you have its self discharge could be more than the drain of an electronic switch. Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted November 21, 2021 Share Posted November 21, 2021 I once forgot to unplug a pair of LiFe packs after flying, I think they were left 2-3 months and were totally detroyed. Quote Link to comment Share on other sites More sharing options...
Andy J Posted November 22, 2021 Author Share Posted November 22, 2021 (edited) Model uses a 6v 2500maH NiMh battery, so assume there is not a problem if the battery is totally discharged by being left connected for some significant period of time. Edited November 22, 2021 by Andy Joyce Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted November 22, 2021 Share Posted November 22, 2021 3 minutes ago, Andy Joyce said: Model uses a 6v 2500maH NiMh battery, so assume there is not a problem if the battery is totally discharged by being left connected for some significant period of time. Maybe a typo Andy You propose it's ok to leave a pack discharged a significant amount of time? Batteries that we use have not been made yet that can tolerate discharge for long lengths of time; they just se!f destruct in that state. 1 Quote Link to comment Share on other sites More sharing options...
Andy J Posted November 22, 2021 Author Share Posted November 22, 2021 Was aware Lipos are killed by low voltage Denis but thought NiMh was more tolerant to this issue and could be recovered. Given I know the model will be infrequently used suspect it will be better to go down the route of using a hard switch to isolate the receiver supply. Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted November 22, 2021 Share Posted November 22, 2021 You are right about Nimhs having some tolerance Andy. A nihm in good health, fully charged, will hold some charge for quite a while. But a discharged Nihm is very vulnerable, and even when recovered is best not put into the air again. 1 Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted November 22, 2021 Share Posted November 22, 2021 DW, way off topic but do be aware that those very high capacity 2500s will only supply servos with a low drain, also they will not take a high charge rate, ask me how I know. Fine maybe for a Tx but not a flight pack. Not green coloured by any chance are they? I had a cell failure twice with those. Quote Link to comment Share on other sites More sharing options...
Wookman Posted November 22, 2021 Share Posted November 22, 2021 I would be inclined to use a 2 amp AA eneloop pack for better current delivery assuming your 2500 is an AA. Those mag switches have probably got the lowest residual current drain of any. The same outfit also does a battery backer version. I use them in my F3f planes as do many others. Plug it in when I put the model together, unplug it when I put the model away. A standard heavy duty switch is going to be more than adequate but do buy a good quality JR or Futaba one. Quote Link to comment Share on other sites More sharing options...
Andy J Posted November 23, 2021 Author Share Posted November 23, 2021 What I have been buying for flight packs are these Martin. Just read up on high capacity NiMh on the Battery University site and I see that high power batteries have a far shorter life which surprised me. Perhaps a different battery technology would be a better purchase in the future, but given I don't like using UBEC's for the receiver supply due to noise insertion from switch mode regulators, there is little choice. Quote Link to comment Share on other sites More sharing options...
Nigel R Posted November 23, 2021 Share Posted November 23, 2021 Vapex instant are quite good, seem to be rated nearly as well as eneloop IIRC. Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted November 23, 2021 Share Posted November 23, 2021 AJ, I still have some models on Eneloops, nothing wrong with them except the price, so all newer stuff is on LiFe and many are unregulated because the servos I use can cope. Quote Link to comment Share on other sites More sharing options...
Wookman Posted November 23, 2021 Share Posted November 23, 2021 Vapex are good but I will stick with my 2amp AA envelops for a while yet. They suit my sporadic flying sessions and my charging regime. Stick them on charge after breakfast at 0.1C the day before I fly. Take them off before I go out to fly. Works for me. Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted November 23, 2021 Share Posted November 23, 2021 After experimenting with them on charge/discharge cycles I have found 600mA to be ideal to get full capacity. Too high and they peak/false peak early and too low is not enough for the delta peak to be detected reliably. Another thing with these so called LSD packs is that one can easily require 150-200 mA/hr after a week or so left fully charged but not used. LiFe take nothing even if not used for a year. Quote Link to comment Share on other sites More sharing options...
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