deke
Flying officer
Posts: 24
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Post by deke on Jul 28, 2009 1:23:42 GMT 1
Hi,
I have the std 7-cell NI-MH 8.4V battery with my Cub and I also have a Li-po battery 3s 20C 11.1V. that fits in the battery box without moding, just wondering if they make an adaptor so I still cabn use both batteries, and will I have to change to a diff prop?
Thanks,
Deke
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Post by duck9191 on Jul 28, 2009 1:42:23 GMT 1
best bet is to get rid of the stock connectors, and go with either deans or ec3 connectors. you will have to change your receiver, charger and all batterys over but it will be worth it in the long run.
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Post by flydiver on Jul 28, 2009 2:53:52 GMT 1
Ditch the stock connectors. They WILL fail on you after awhile-no power at all > crash. You should change to a different prop-GWS 10x6HD is suggested for lipo. Power output is defined by the battery voltage + motor + prop. If you go from 8.4v > 12.6v you increase the power draw substantially (almost double). The motor and ESC are NOT designed for this power level. supercubclub.proboards.com/index.cgi?action=display&board=batt&thread=1831&page=1In addition the low voltage cut-off for lipo and NiMh are COMPLETELY DIFFERENT. You have to pull this jumper for lipo: supercubclub.proboards.com/index.cgi?board=ts&action=display&thread=988If you forget, use NiMh LVC for the lipo and draw it down too low you can ruin it in ONE flight with over discharge. Meaning, it's a pain to switch back and forth. Try the lipo, you won't bother with the NiMh anymore. |
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belem
Squadron leader
Posts: 210
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Post by belem on Jul 28, 2009 4:15:14 GMT 1
I've seen some folks that hook up a home made switch that allows you to use either battery as you choose. I'll see if I can find the thread.
As for the prop you could probably get by with either using the stock prop and not running it at WOT when using the lipo or prop down and just lose some power when using nimh.
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belem
Squadron leader
Posts: 210
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Post by belem on Jul 28, 2009 4:17:30 GMT 1
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Post by flydiver on Jul 28, 2009 6:34:13 GMT 1
As for the prop you could probably get by with either using the stock prop and not running it at WOT when using the lipo or prop down and just lose some power when using nimh. Not running WOT with the stock prop saves the motor somewhat but is actually HARDER on the ESC. The battery eliminator circuit (BEC) in the ESC bring the voltage from battery level to ~5v for the RX and servos. It does this though little resistors called FET's. This makes HEAT. The higher the voltage, the MORE heat it makes bringing the voltage DOWN. So it works harder with a 3S lipo than a 7-cell. At WOT the operating voltage sags more as the motor demands more so the BEC actually works LESS hard than it does at part throttle where the operating voltage is higher. |
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deke
Flying officer
Posts: 24
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Post by deke on Jul 28, 2009 23:05:42 GMT 1
Wow, Thanks everyone for the great help! Looks like I'm going to go to my LHS this weekend as I'm going Lipo. Thinking about getting a watt meter too and a nice lipo charger What size should I get (Battery) with out making to much of a monster, I'm mainly looking for more fly time with a tad bit of a performance boost. Later I will get a new TX & RX Spectrum DX6. ( I think I almost ran out of range already on my second flight) Only going at this at a rate of $200/Month since I quit smoking this is my replacement.  Thanks again duck9191, flydiver, and belem, you guys are great! Deke |
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Post by flydiver on Jul 29, 2009 4:18:42 GMT 1
As a Respiratory Therapist it's rewarding to hear of another person quitting the habit. In this case you get a double benefit.
A wattmeter is a very useful tool. The only thing I use more is my charger.
Batteries sizes are a compromise.
More mA = more time but more weight and larger and more expensive.
More weight decreases performance a bit.
Larger means modding the battery box.
Figure a decent charger will set you back $50-100 + a power supply. There are a number of decent candidates. I'm a Cellpro 4S fan myself-safe, simple, effective. If lipos intimidate you a little (they should) this is the charger to get.
See my other posting on range. You have a problem. Not good.
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Post by ginginho on Jul 29, 2009 9:20:56 GMT 1
Wow, Thanks everyone for the great help! Looks like I'm going to go to my LHS this weekend as I'm going Lipo. Thinking about getting a watt meter too and a nice lipo charger What size should I get (Battery) with out making to much of a monster, I'm mainly looking for more fly time with a tad bit of a performance boost. Later I will get a new TX & RX Spectrum DX6. ( I think I almost ran out of range already on my second flight) Only going at this at a rate of $200/Month since I quit smoking this is my replacement. Thanks again duck9191, flydiver, and belem, you guys are great! Deke Deke, If you go spektrum, don't get a DX6, get the DX6i. The DX6 is DSM and is effectively a dead product line as it can only use DSM Rx's, whereas the DX6i is DSM2 and there are plenty of different Rx's available. I see you started a thread about a Futaba radio. One option (if you feel confident to do a bit of work) is to get a decent second-hand 72Mhz/35Mhz (locale dependant) radio. If it's modular it's an easy change to 2.4Ghz (as and when you want to go that way). If it's not a modular type it can still be converted using the Assan hack module. Doing this can mean that you get a better quality/functional radio for less $$. There is a thread here that various people have changed their radios. Some even keep the 72Mhz/35Mhz, allowing them to keep using their existing Rx's while new models are flown on 2.4Ghz. |
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deke
Flying officer
Posts: 24
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Post by deke on Jul 29, 2009 23:35:41 GMT 1
Thanks Flydiver & ginginho.
Looks like I got lots of hunting to do, and reading as well.
Ya it's been 4 months to the day without a cig, don't even miss it anymore, took about 3 months to get to that point.
Thanks,
Deke
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