LiPo thoughts

[Rex R]

in the past month(or so) I've seen a number of folks complaining about their lipos not living up to their expectations etc. etc., well before the beer gets too watered down lets see what we are getting for our hard earned cash. for a 2s2p setup comprised of 4000mah cells we get; 6000mah of usable power that comes in a package that weighs roughly 13 oz,. I've been told that they deliver like an 8cell nimh pack(weight 18 oz.) for voltage. for amps at a sustainable level of 26c(13c per pack) thats over 100 amps for over 3 minutes! maybe its not the 'killer' 200-300 amp packs some folks think they want, but I think I can live with it.

[SJFE]

OH my god LIPOS...Did you know they can explode with out warning and level a city block!!!! Bad bad bad lipos. I figuered I'd get that right out of the way in this thread before token drama post.

[Rex R]

LOL you noticed that I very carefully mentioned no names, or brand names, or how some folks have been having er shall we say 'technical difficulties' with an older battey tech...:). just wanted to point out that even with derating them to more realistic levels, LiPo's represent an advance in power systems.

[sjslhill]

It all depends on what your doing. I have heard that some professional N2 mono setups are pulling 80 constant amps, in this case you need 10,000mah and 20C. Figure out how many amps your going to pull in a constant and go from there.

30 amps needs a 50 to 60 amp constant LiPoly pack to last a long time. I look forward to hooking up the DPR on my Super Vee and see what it does. I'll then test some LiPoly in it. I think everyone needs to parallel in order to keep from over discharging their packs.

thanks,
Steve

[SJFE]

I look forward to hookin it up in mine also:D

[Rex R]

last graph I saw of a sv amp draw had peaks of roughly 60amps was averaging 35-40amps(iirc)

[sjslhill]

If it peaks 60 amps, my 12C packs will be pushed even in parallel. You have to remember though that watts = voltage x current, the higher the voltage the lower the current levels needed. 14.8V of LiPoly should be better than 14.4V of NIMH

[Doby]

I'll be needing some soon for my V24 mod running a LMT 3080, I'll be looking for around 37V, 10,000 mAh .

[sjslhill]

Send me an e-mail and I'll get you a quote if your interested. [email protected]

[ice329]

I will let you know next week... have a few 3600 lipos coming from Steve/BattlePack. I got my pencil out and did some figuring. His 3600
12cConstant/16c bursts lipos should be fine. If I had a charger that could charge 4 cells I would have went with 2 of his 14.8 volt pack and would have enough juice for a long long time. Since my charger only will do a 3 cell lipo I got the 7.4. I really want to see a set of lipos in the white boat. Next week I will post some more info. He mentioned that a low volt cutout, not sure if the SV ESC has one or not so I will guage the run time gradually to see how long I can run on the pack without discharging it to low.

[SJFE]

Buy a stand alon voltage cut off. I'm almost posotive the SV ESC don't have one.

[Doby]

The SV27 speed controller does NOT have a LiPo cuttoff.

[Rex R]

oops my bad. data log was for an h & m viper running a super vee motor and esc.
thread here http://www.rcgroups.com/forums/showthread.php?t=633493
rex

[sjslhill]

Yes

Yes, we know that......

The SV27 speed controller does NOT have a LiPo cuttoff.

[Doby]

BattlePack;
I sent you an E-Mail here for a quote , when you get a chance , I'd appreciate it .