Question.... I have one of those plastic Rx battery cases that I have from a car radio....the ones you put batteries in. Is there anything wrong with using those ? I have several sets of hight quality, brand name NiMH bateries.....around 1800 ma, and a good charger for them. I was wondering if it was ok. I plan on securing the batteries in the case with either zip ties or rubber bands and then wrapping it in foam and adding rubber bands to hold the foam. This way I can have more flying time without the need for buying battery packs. I do have a second Tx pack though. This is just a temporary thing until I build up my equiptment "arsenal"


Thanks,

Adam

You can use those kind of setups, they will work.

However, there are a few drawbacks. My first concern is that it is setting up for extra "points of failure" compared to a normal battery pack. All the springs and joints in the plastic holder, plus the contacts between the cells and the holder, it's a lot of extra stuff go to wrong.

Second, any time you have a mecanical-only connection like that, you have some voltage loss. honestly don't know how much voltage you might loose with all those extra connections. I suspect it's not a lot, but then again, those holders are usually meant for the normal disposeable batteries that have 1.5 volts/cell instead of 1.2 for the NiMH cells.

So, before you actually fly it, check the pack with a meter and see how it reads. It should be fine, but better safe than sorry. I'd also check it fairly frequently to make sure everything fits together well, any looseness around the cells would be a bad thing, obviously.

If it was me, and I had the cells, I'd look at getting the materials and equipment or finding someone near by to just put the cells together in to a soldered pack.

Montague had A Better answer than mine so i have withdrawn it

Good info. I actually did test it and inspected it pretty well to make sure it was mechanically sound....at least now. As far as voltage loss goes.....it's reading about 5.25 volts with fully chareged batteries. Like I said, this is only VERY temporary. As far as you're info goes.... I didn't take all that into consideration . If I do use it....trust me.... I will check it before and after every flight just to make sure.


Thanks again


Adam

A word of caution....some weeks ago, I tried this setup (with the battery case) and even I flown with it one time, the next times it didn't work anymore. When I turned on the RX, it lasted about 5-10 seconds before actually responding to the commands of TX and then they seemed very erratic. I checked out everything, switch, cabling, connectors and everything seemed to be correct. The funny thing was that testing it at home, sometimes it worked fine but then when I got to the field, the problem happens again, I even changed to another battery case but the problem presisted. It was until I used the battery pack from another plane that the problem went away. This battery pack has exactly the same type of batteries but soldered. My guess is that the mechanical contact with the spring of the battery case, maybe was causing some kind of RF noise/interference on the RX. Good thing this happened on the ground.

From my experience, I wouldn't reccomend using a battery case for the RX. BTW, I checked it hundred of times with my voltmeter even shaking it by hand or twisting cables and never got anything suspicious from it.

Regards,
Luigi

You know what ?? You guys convinced me!! I'm not even gonna try it and spend the few extra bucks for packs. Besides, $30-$40 is WAY cheaper than losing everything.

Thanks a ton. This is EXACTLY the reason why I come here for advice.


Adam

Cappy delighted you have made the right decision and just to add a little extra convincing consider this: Walk into any LHS in the country that is heavy into RC cars and ask to see the battery holders, you will be directed to a large stock of cell holders for both Tx and Rx's. HMMMM, I wonder why since most of these surface radios come with them already. There simply is only one answer and that is they constantly fail! Otherwise that dealer would not have that large supply. Not a big deal with a car, but airplanes well. Always use hardwired packs in aircraft both Rx and Tx.

John

I would not use them.
The connection is not hard and permanent.
If anything comes loose, you have a crash and a totaled plane.