RCCrawler Forums

newtoy · 08-07-2009, 08:59 AM

Being new to the RC game I hear everyone talk about Lipo batteries. What is the advantage over a regular battery? What does it mean when they rate them in "c"? Do they charge faster or just have more mah? Do you need a special charger and ESC?
I know that is a lot of questions I guess I just don’t get it.

stona · 08-07-2009, 09:25 AM

Lipos are lighter than an equivalent nimh

"C" is the capacity of the battery. So a 2500mAh battery has a C of 2500mA. If they say it's a 20C lipo, the battery can be discharged at a rate of 20 times its capacity, so can sustain a 50amp draw.

Yes you do need a special charger, and maybe a balancer to keep the individual lipo cells in your pack equal in terms of voltage.

You don't necessarily need a special ESC. It really depends on how many volts the ESC can handle.

newtoy · 08-07-2009, 09:34 AM

Good to know thanks.
do you think they are worth the extra money?

Offroader5 · 08-07-2009, 09:38 AM

Another plus to lipos is that they are more efficient in power delivery, and can deliver more power in that small package.

I used 8 cell packs of 1500 mah 2/3A nimhs before going to lipo. That's a 9.6v pack. I went to 1100mah & 1290mah 3 cell lipo's and get more run time..plus they are smaller than the same 8 cell brick pack I used to run...not to mention, the 3 cell lipo is giving me 11.1v.

So, I've lessened the physical pack size...lessening the weight at the same time, but gained voltage and a bit of run time.

stona · 08-07-2009, 09:41 AM

Oh, I just remembered, Lipo's shouldn't be discharged below 3 point some volts per cell...i think 3.1V, but not sure. So, either your ESC needs to have a lipo cutoff (it detects the voltage of your pack and cuts out power), or the lipo will have a built in cutoff circuit on the pack itself. This is very important as you can have a fire if you discharge them too low. Can't believe I forgot to mention this lol.

I like my nimh batteries in my other RC's and am quite content with it since I just bash around. I don't have a crawler yet, but I think i'll stick with nimh for that as well. Let's see what the others say around here.

Goose19 · 08-07-2009, 09:56 AM

ok so for my ax-10 im runnin a 2200 mah 2 cell lipo, 7.2 volts i believe. its actually an aircraft battery. i dont have a lipo cut out, and a buddy of mine has a similar battery and doesnt run a cut out either. if i use a multimeter on my connector terminals to determine the voltage?

for example, i do some crawling (and a bit of bashing lol) and strip the cheap axail steering horn. im done, check the battery its at 7.2 V still, does that mean i didnt discharge the battery much at all?

Offroader5 · 08-07-2009, 10:02 AM

Quote:

Originally Posted by Goose19

ok so for my ax-10 im runnin a 2200 mah 2 cell lipo, 7.2 volts i believe. its actually an aircraft battery. i dont have a lipo cut out, and a buddy of mine has a similar battery and doesnt run a cut out either. if i use a multimeter on my connector terminals to determine the voltage?

for example, i do some crawling (and a bit of bashing lol) and strip the cheap axail steering horn. im done, check the battery its at 7.2 V still, does that mean i didnt discharge the battery much at all?

Sounds like very little time was run in that case. The 2200mah would give some pretty good time.

The lowest you'd want to run down that 7.4v 2 cell is to 6v. They say 3v per cell is the cutoff.

newtoy · 08-07-2009, 11:31 AM

Will they really catch on fire? Aside from that whole catch on fire thing it soulds like they are best suited for comps and hard core rigs.

Offroader5 · 08-07-2009, 11:48 AM

Quote:

Originally Posted by newtoy

Will they really catch on fire? Aside from that whole catch on fire thing it soulds like they are best suited for comps and hard core rigs.

They'll only catch fire if you don't treat them right. If you charge them at too fast a rate, charge them too much, or the case of the inner cell gets punctured...that's what you have to worry about. If you follow the correct charge settings for the individual pack, you won't have to worry about the overcharging deal. On the puncturing, if you have pets...keep the packs away from them so they don't bite into them. If the pack is unprotected from rollovers in your rig...sometimes the rocks and stuff can cause damage after time and compromise the casing. If you have a lipo on your rig that could get damaged from rollovers, you can always just put an addiditonal shrink casing over the pack to thicken up its skin.

The "fire" and "explosion" of lipos are usually on the puncturing. Once the chemicals inside a lipo pack come into contact with oxygen...that's when they react badly.

ctraut5 · 08-07-2009, 11:49 AM

They can be dangerous if charged/discharged in an incorrect manner. If used properly they are actually quite safe. Just charge them in a lipo sack or an old crock pot. I have been using them for years in airplanes and crawlers without a problem. Crawlers generally only use 2S or 3S packs and not very high capacity, so they are quite affordable (even for non-comp crawlers).

dunerdude69 · 08-07-2009, 12:16 PM

if you want good and cheap lipos get these 45+ min of runtime
http://ecpower.com.hk/index.php?main...637c14798e3cd5
and for a charger
http://ecpower.com.hk/index.php?main...roducts_id=186

punkuup5150 · 08-07-2009, 01:04 PM

this shows how lipos can go bad. and also how to protect you and your family/house from danger

http://www.liposack.com/Survivors/survivor.htm

newtoy · 08-07-2009, 01:20 PM

What kind of charger would I need? can you get an external shut off to use with a esc that you don't know if it has one?

stona · 08-07-2009, 01:31 PM

Your best bet is to find out the manufacturer for your ESC and see if they have manuals on their site.

But you can get separate lipo cutoffs. Here's one by Novak: http://www.teamnovak.com/products/li...ule/index.html

newtoy · 08-07-2009, 01:35 PM

Thanks that was exactly what i was thinking of.

Madkoifish · 08-07-2009, 02:03 PM

Anyone got any info on balancers? I have a 989 that says itll do them but well, it lacks a balancer. I have looked a bit online and find mostly how each differs by brand or the balancing connector. I was considering those cheapo units on ebay a lot of people run but finding a balancer isnt as easy. Some prices on balancers I found are as much as some high end chargers. O_o

Ktbone · 08-07-2009, 04:28 PM

Get an Astro Blinky balancer. I think I saw one on that R*U website used (cheap).

08-07-2009, 08:59 AM	#1
newtoy Pebble Pounder Join Date: Aug 2009 Location: ST. George Posts: 117	Lipo questions Being new to the RC game I hear everyone talk about Lipo batteries. What is the advantage over a regular battery? What does it mean when they rate them in "c"? Do they charge faster or just have more mah? Do you need a special charger and ESC? I know that is a lot of questions I guess I just don’t get it.

08-07-2009, 09:25 AM	#2
stona Newbie Join Date: Jul 2009 Location: Southern Ontario Posts: 43	Lipos are lighter than an equivalent nimh "C" is the capacity of the battery. So a 2500mAh battery has a C of 2500mA. If they say it's a 20C lipo, the battery can be discharged at a rate of 20 times its capacity, so can sustain a 50amp draw. Yes you do need a special charger, and maybe a balancer to keep the individual lipo cells in your pack equal in terms of voltage. You don't necessarily need a special ESC. It really depends on how many volts the ESC can handle.

08-07-2009, 09:34 AM	#3
newtoy Pebble Pounder Join Date: Aug 2009 Location: ST. George Posts: 117	Good to know thanks. do you think they are worth the extra money?

08-07-2009, 09:38 AM	#4
Offroader5 Picky Fab'r/Acetal Junky Join Date: Jul 2006 Location: Arizona Desert/AJ Posts: 3,073	Another plus to lipos is that they are more efficient in power delivery, and can deliver more power in that small package. I used 8 cell packs of 1500 mah 2/3A nimhs before going to lipo. That's a 9.6v pack. I went to 1100mah & 1290mah 3 cell lipo's and get more run time..plus they are smaller than the same 8 cell brick pack I used to run...not to mention, the 3 cell lipo is giving me 11.1v. So, I've lessened the physical pack size...lessening the weight at the same time, but gained voltage and a bit of run time.

08-07-2009, 09:41 AM	#5
stona Newbie Join Date: Jul 2009 Location: Southern Ontario Posts: 43	Oh, I just remembered, Lipo's shouldn't be discharged below 3 point some volts per cell...i think 3.1V, but not sure. So, either your ESC needs to have a lipo cutoff (it detects the voltage of your pack and cuts out power), or the lipo will have a built in cutoff circuit on the pack itself. This is very important as you can have a fire if you discharge them too low. Can't believe I forgot to mention this lol. I like my nimh batteries in my other RC's and am quite content with it since I just bash around. I don't have a crawler yet, but I think i'll stick with nimh for that as well. Let's see what the others say around here.

08-07-2009, 09:56 AM	#6
Goose19 Newbie Join Date: Aug 2009 Location: Ontario Posts: 22	ok so for my ax-10 im runnin a 2200 mah 2 cell lipo, 7.2 volts i believe. its actually an aircraft battery. i dont have a lipo cut out, and a buddy of mine has a similar battery and doesnt run a cut out either. if i use a multimeter on my connector terminals to determine the voltage? for example, i do some crawling (and a bit of bashing lol) and strip the cheap axail steering horn. im done, check the battery its at 7.2 V still, does that mean i didnt discharge the battery much at all?

08-07-2009, 11:31 AM	#8
newtoy Pebble Pounder Join Date: Aug 2009 Location: ST. George Posts: 117	Will they really catch on fire? Aside from that whole catch on fire thing it soulds like they are best suited for comps and hard core rigs.

08-07-2009, 11:49 AM	#10
ctraut5 Newbie Join Date: Feb 2009 Location: Germantown Posts: 39	They can be dangerous if charged/discharged in an incorrect manner. If used properly they are actually quite safe. Just charge them in a lipo sack or an old crock pot. I have been using them for years in airplanes and crawlers without a problem. Crawlers generally only use 2S or 3S packs and not very high capacity, so they are quite affordable (even for non-comp crawlers).

08-07-2009, 12:16 PM	#11
dunerdude69 Quarry Creeper Join Date: Jul 2008 Location: peoria Posts: 207	if you want good and cheap lipos get these 45+ min of runtime http://ecpower.com.hk/index.php?main...637c14798e3cd5 and for a charger http://ecpower.com.hk/index.php?main...roducts_id=186

08-07-2009, 01:04 PM	#12
punkuup5150 Rock Crawler Join Date: Mar 2008 Location: lodi Posts: 952	this shows how lipos can go bad. and also how to protect you and your family/house from danger http://www.liposack.com/Survivors/survivor.htm

08-07-2009, 01:20 PM	#13
newtoy Pebble Pounder Join Date: Aug 2009 Location: ST. George Posts: 117	What kind of charger would I need? can you get an external shut off to use with a esc that you don't know if it has one?

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08-07-2009, 01:31 PM	#14
stona Newbie Join Date: Jul 2009 Location: Southern Ontario Posts: 43	Your best bet is to find out the manufacturer for your ESC and see if they have manuals on their site. But you can get separate lipo cutoffs. Here's one by Novak: http://www.teamnovak.com/products/li...ule/index.html

08-07-2009, 01:35 PM	#15
newtoy Pebble Pounder Join Date: Aug 2009 Location: ST. George Posts: 117	Thanks that was exactly what i was thinking of.

08-07-2009, 02:03 PM	#16
Madkoifish Quarry Creeper Join Date: May 2005 Location: Auburn Posts: 360	Anyone got any info on balancers? I have a 989 that says itll do them but well, it lacks a balancer. I have looked a bit online and find mostly how each differs by brand or the balancing connector. I was considering those cheapo units on ebay a lot of people run but finding a balancer isnt as easy. Some prices on balancers I found are as much as some high end chargers. O_o

08-07-2009, 04:28 PM	#17
Ktbone Quarry Creeper Join Date: Jun 2009 Location: Who's asking? Posts: 343	Get an Astro Blinky balancer. I think I saw one on that R*U website used (cheap).

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Thread: Lipo questions