LIPO cutoff voltage jumper in SC

[Lipo Cutoff voltage in SC]

The SC esc/receiver is the same as used in the Parkzone FW190. There is a jumper on the esc/receiver unit which changes the cutoff voltage so 3s lipo's can be used safely. From the FW190 manual:

When the jumper is present the auto-cut is set at about 5.7 volts, which works with 6- to 9-cell Ni-MH battery packs. When the jumper is absent, the auto cut is set at about 8.8 volts, which will function correctly with a 3S Li-Po Battery. The battery should be able to safely deliver 13 amps of current.

[swampfox201]

I'm new to this whole battery thing but as I keep adding weight to my supercub I will have to supply more power to keep her up. Right now I am just using 2 stock 7 cell batteries.

I have some questions about lipos. The way I understand it is you can damage a Lipo battery by overcharging it, discharging it too much, or by dropping it. Is this correct? If it is then if you don't remove the jumper and the Lipo battery goes down to 5.7 volts will it ruin the battery? If not then why not leave it in and get more flying time.

Also what is the maximum voltage the ESC/BEC/motor/x-port can take before you burn it out?

Also I keep reading about the fire hazard Lipos can create. Seems like some guys treat them like little bombs and charge them in clay pots. I understand you get more power for the weight compared with NiCad's but not really too excited about burning my house down.

Thanks,
Todd

[cjg]

You are mostly correct. If you charge lipos improperly they really start an aggressive fire. I've seen vids, it isn't pleasant. ALWAYS use a lipo rated charger and I do place mine in clay pots with a smoke detector and a fire extinguisher handy (although I'm not sure a fire extinguisher could extinguish those aggressive flames). Never leave them unattended while charging.

I've not used them in my SC. They would save weight. If you discharge a lipo too much it will be permanently ruined, hence the jumper setting. Even a few moments of flight past the limit can damage them. The batteries are in soft sided cases so they can be damaged by crashes or dropping.

On the other hand, lipos give great performance at low weight, which is why my helicopter uses them.

Don't know about the maximum current on the x-port.

[jrob00]

Hey Guys,

As this question didn't really get answered I thought I'd bring it up again.. I'm looking at some LIPO deals online like hobby-lobby's poly-quest sale (www.hobby-lobby.com/5x5.htm) and the Ebay seller (cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ih=011&sspagename=STRK%3AMEBOFF%3AIT&viewitem=&item=320077377188&rd=1&r) mrmugen recommended.

It looks like getting a 3S 20Cell battery will be okay and that the Mah is more or less not a concern. Is that correct? I'm worried I will pump too much amperage to the ESC and fry it.

The Mah rating is simply capacity right? It sounds like 1300 or so should be fine for a stock Supercub (with the jumper removed). Is there a limit to the capacity the Supercub can handle?

Thanks,
Jason

[mrmugen]

Don't worry about wrecking the esc with amperage.........it's the voltage you need to worry about. I recommend using 1200mah-1500mah lipo's for the SC. The bigger the capacity (mah) the heavier the pack will be. So far the 1500 is the best I've found for the SC. The battery you linked to 2nd are the ones I just tested and they rock! A 1300 will be good too.

[jrob00]

Awesome! Thanks for the clarification!

I'm glad to hear you're happy with the 1500s; I'll be picking up some lipos real soon. ;D

I might go with a lighter battery however as I hope to use them in my future 2nd plane (an e-starter) and from what I've read the lighter the better with that one. (www.rcgroups.com/forums/showthread.php?p=7184231#post7184231)