jklong03
Squadron leader
Utah, USA (Yes, it is a state!)
Posts: 226
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Post by jklong03 on Jul 28, 2013 10:54:28 GMT 1
I stupidly forgot to disconnect my new Turnigy 2200 mah lipo pack after last our flight and over discharged it! Now I don't have a fancy charging station or anything, just use the one that came with my SC from Hobbizone. Anyway, it was discharged to the point that the charger wouldn't even start a charge. What I did was to connect another pack I had (one of the original ones that came with the plane) in parallel while the bad one was on the charger. That is, I had the bad one connected to the charger and then connected red to red and black to black, that seemed to have "jumped" the bad one enough to get the charger blinking, and after that the "bad" pack took a full charge and is back to normal! But as I said, I do not recommend this to anyone, just reporting what happened for me! I know lipos are not to be taken lightly and doing such a foolish thing as this was probably pretty dangerous, but it was late, I couldn't sleep and was looking for something to do. Oh, I almost forgot, here is a really informative article on RC Lipo batteries, very good reading! Undrerstanding RC LiPo Batteries |
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Post by flydiver on Jul 28, 2013 15:35:20 GMT 1
The ability and success involved with that kind of recovery is pretty variable. The longer and deeper the discharge > the worse the results.
The older the battery > the worse the results.
In all cases you have done some damage, even if you can't see it. Generally this may be seen as a loss in performance.
Recovery attempts like this were far more common a few years ago when lipos were much more expensive. Now, you need to weigh the risks against the much smaller cost.
Note-a not uncommon problem is crumpled/mashed/bent lipos from crashes. The Cub battery box is pretty good protection but stuff happens. Internally a deformed lipo has created some shorts. These can range from trivial and inconsequential to significant. The really bad ones tend to flame up very quickly. The 'hidden' ones can take longer, or may never happen. They may not reveal problems until later. They are pretty safe if handled properly. The key word there is 'properly'.
ANY lipo that has been damaged should be marked and considered volatile. How you deal with it after that is up to your personal risk profile.
Any lipo that has been punctured should be discharged and tossed. You CANNOT fix them. After light bulb discharge, cut the wires, short them together to make sure all the juice is gone, twist together and toss.
You DO NOT have to do a salt water soak. That's OLD information, and never did work. Somehow that's one of those 'old man myths' that persists anyway.
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ted
Flight lieutenant
Lake City, Michigan, USA
Posts: 45 
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Post by ted on Jul 30, 2013 7:25:35 GMT 1
Nice article on "Understanding RC LiPo Batteries". It answered a number of questions for me. Thanks for the link.
But I do have a question about the SupbeCub's battery. When I got my SuperCub last month the instructions said to install the battery, and that the battery will be a tight fit. That's an understatement. The best I could do is leave my battery on a diagonal a little bit, and even with that I had to do a little squishing at the end of the battery to get it inside to the extent that I could close the battery door. But even this seems to run contrary to the advice given above. Is this tight fit O.K.? Was the SC battery compartment originally designed for a smaller battery? How should I approach this in the future? Thanks for any reply.
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Post by flydiver on Jul 30, 2013 7:47:24 GMT 1
Punch a hole in the stupid #$^#$% thing. This is a VERY common mod.
Like a LOT of parts in the Cub is was designed YEARS ago, in this case for a 7-cell lipo and never improved.
some people have ruined batteries getting them in an out pushing, pulling, and mashing wires. Even batteries from the so called same source are not identical. Get one 2-4mm longer and you end up with a problem.
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Post by renard80 on Jul 31, 2013 0:17:44 GMT 1
Nice article on "Understanding RC LiPo Batteries". It answered a number of questions for me. Thanks for the link. But I do have a question about the SupbeCub's battery. When I got my SuperCub last month the instructions said to install the battery, and that the battery will be a tight fit. That's an understatement. The best I could do is leave my battery on a diagonal a little bit, and even with that I had to do a little squishing at the end of the battery to get it inside to the extent that I could close the battery door. But even this seems to run contrary to the advice given above. Is this tight fit O.K.? Was the SC battery compartment originally designed for a smaller battery? How should I approach this in the future? Thanks for any reply. As flydiver says, HobbyZone have neglected to enlarge the battery box to accommodate the larger battery. Absolutely stupid and irresponsible. If you squeeze the battery in too tightly, you risk damaging the leads. The solution is to carve out some of the plastic battery box so that your batteries fit comfortably. Many people do this and mount the battery vertically. I prefer to leave mine mounted horizontally, as HZ intended - but cut out some of the FRONT wall at the bottom of the battery box so that the battery slides in nicely. Use a scalpel / exacto knife to cut away the plastic. But be careful not to let the knife slip, as it may slice through too much - and you can only get a new battery box by buying a whole new fuselage (thanks, HZ!!). |
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ted
Flight lieutenant
Lake City, Michigan, USA
Posts: 45
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Post by ted on Jul 31, 2013 5:28:06 GMT 1
Thanks flydiver and renard80. I think I can make that modification as you describe. I do have an extra battery just a couple of mm longer than my stock battery, but there is no way that would fit the battery box unless it is modified. You people on this forum are really helping me get my Super Cub set up quite nice.
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