RC Truck and Construction

RC Truck and Construction (https://www.rctruckandconstruction.com/index.php)

- Electronics tech (https://www.rctruckandconstruction.com/forumdisplay.php?f=102)

- - Lipo info (https://www.rctruckandconstruction.com/showthread.php?t=674)

I understand Lipo batteries are smaller sized for the same amount of punch.
What all needs to be changed to run lipos?

1. can I run brush type 55t motors?
2. do I need to run special ESC's?
3. what about battery chargers?

Any info appreciated!

Paul had a great post on this at old garden. It was a great guide. The simple answers to your questions are 1. Yes 2. Not required. Lipos require voltage cut off because over discharge is ***aging. Cutoff can be built in to an esc or run as a separate piece. Novak makes cutoff unit for $25 that you can use with your esc. 3. You will need a lipo specific charger but it will be able to charge nicd and nimh too.

Some other little tid bits to know about LiPo packs is that a single LiPo cell is usually rated at a nominal 3.7 volts. Compare that to a NiMh cell, which is rated at a nonimal 1.2 volts. So a 2 cell LiPo pack can provide 7.4 volts, and a 3 cell LiPo pack will supply 11.1 volts. Most brushed ESCs that came out before LiPos did are rated for at least 7.2 volts, if not a little more. A 2 cell LiPo pack can be run safely on any ESC that will handle the typical 7.2 volt, six cell NiMh pack. The extra .2 volts of a LiPo is no concern. As previosuly mentioned, if your ESC does not have a LiPo cut-off programmed into it, or a LiPo mode, then you will want to invest in a stand alone LiPo cut-off unit. You may run any type of motor on LiPo packs, as long as the motor can handle the voltage. Just about all 540 can motors will be fine running up to 12 volts, so unless you run a 4 cell LiPo, there should be no problem. 550 can motors will usually handle 18 volts. Certain brushless motors should be more closely watched, as they do have specific RPM and voltage limits.

One thing about charging the LiPo packs is that they require a balancer, in addition to a LiPo capable charger. The balancer monitors the voltage of each LiPo cell, to prevent any one cell from being over charged. LiPos require some special care. No overcharging, and no over discharging. It is also recommended that you keep LiPos in a fire proof container or bag, while charging and storing them. They are pretty safe and chances are slim that they will burst and start a fire, but it does happen once in a while. More often due to lack of care, or abuse, on the owner's part.

If you are worried about the potential for fires with LiPos, consider LiFe cells instead. They are more robust and forgiving. Similar to NiMh packs, yet the LiFe packs are smaller and more compact too. LiFe cells have only 3.3 volt per cell, so a 2 cell LiFe pack will only supply about 6.6 volts. A 3 cell LiFe pack, 9.9 volts. The LiFe technology is still pretty new, and some of the higher capacity packs are quite pricey, but the dangers that LiPos have are not a concern with the LiFe packs. Also, some places like Max Amps have a gaurantee you can buy with the LiFe packs. So many charge cycles. I don't remember how many, but LiFe packs have the advantage of being charged multiple times a day, if you like, at higher current rates, which means they can be charged faster also. Might be worth looking into, if all that sounds good. Like LiPos, LiFe packs require a charger and balancer capable of handling them.

Thanks for all the info, Nathan. I had heard some horror stories about fires and Lipo's, so I don't think I'll be messing with them now. The LiFe's sound like a better battery for casual use - will have to look into them more...

Hey sorry I missed this.. On the Lipo fires they are few and very far between.. I only use a balance every 5 charges it is not necessary to do it every time unless you are running very hard. The Novak is a great cut off it is the best i think plus they have a warranty on them to boot. Jim if you have questions just give me a call we can chat it over..

Jim, the LiPos catching on fire are more often from abuse or lack of care on the owner's part. They are few and far between, as Paul says, but I still worry, so I don't run them. When you stop to think about it, LiPo packs are everywhere these days. Cell phones, lap tops, electric shavers, ect. You could probably find a few devices in your house that have them. They are just in hiding! :D Living among us already, waiting in the shadows!

Quote:

Originally Posted by Espeefan (Post 8536)

They are just in hiding! :D Living among us already, waiting in the shadows!

Hi Nathan,

Was that one of Optimus Prime quotes from the end of the Transformers 1 movie ?

Cheers Cossett

Quote:

Originally Posted by Cossett (Post 8538)

Hi Nathan,

Was that one of Optimus Prime quotes from the end of the Transformers 1 movie ?

Cheers Cossett

Hi Cossett! I'm a pretty big Transformers fan, but that was not my intention! I think it's close to what Optimus Prime said, but maybe, or maybe not quite 100% accurate. :D

Hey Nathan, I like your avatar!
Still see a few SP GE's around here in original paint, with the yellow number patch.

Hi Jim. Thanks. I'm a big SP fan. Wish it was still around. I hate the patch jobs. :D

I run LiPo's on my stuff .... without any issue ...... I like that they do not have a "memory" - don't need to be discharged to re-charge

Sorry to dig an old thread up - but I have another thread about a charger and ESPEEFAN gave me some great advice, however I was only asking about a charger for my radio. I still have no batteries for my truck, and I came across this thread while searching for some advice. As most of you know I am on a strict budget - so with that in mind, should I just settle for NiMH batteries for now, or should I be looking at LiPO or LiFE? Comments and suggestions are greatly appreciated. I will wait on buying a charger until I know what batteries I am getting for the truck...

Any more a lipo is cheaper than a equal NiMH. I can buy 2200 7.4 lipo for 12.00 off the web..

I would not really waste my time with 2200mah lipos, I have been using these:
VENOM 7.4v 5400 LIPO BATTERY
Did a truck show over Fri, Sat & Sun and changed my first battery at about 11.30 on saturday and had been running with the lights on most of the time.
Would estimate about 4-5 hours running time and 1 1/2 hours to recharge!
http://cgi.ebay.com.au/ws/eBayISAPI....=STRK:MEWNX:IT

I agree with Paul , there are plenty of good deals to find on the lower amp/hrs LIPO's
especially around the 2000 to 2200 mAh range .
I use them myself too . If you want higher capacity , you just run 2 or 3 of them in parallel .

I build Helos for people who want the UH-1 Huey fuselage and nav. lights.
I have had 2 LiPos go up in smoke (out of 30 or so) and they were connected
to nothing! I use the bag just to be safe.

OK - here is what I have put together - please tell me if this looks OK:

Battery: http://cgi.ebay.com/Venom-LiPo-2S-1P...item45fc32f641

Charging Sack: http://cgi.ebay.com/Venom-LiPo-Safet...item5ae1a5f386

Smart Cut Off: http://cgi.ebay.com/Novak-Smart-Stop...item588c3b0d50

Charger: http://cgi.ebay.com/Venom-AC-DC-Pro-...item5ade8db0a0

Please be honest - I do not want to spend a ton of money on something that will not last. I have chosen one vendor so I can combine shipping, however suggestions for other vendors are more than welcome. I appreciate your time checking all the links - thanks a ton!

Quote:

Originally Posted by CrimsonCorsair (Post 32882)

It’s all good stuff , but you can find these Venom LIPO’s for ½ the price if you don’t need the universal plug deal ( which is kind a cool ) .
I have bunch of these Venom’s , the 2100 versions , which are basically the same ,
but I got them without plugs since I use mostly Dean’s plugs .
It all depends if you want to buy more when just one …
There are a few sellers on ebay which sell these regularly for around $10,- $12,- .

As for the cut-off , as stated before , the Novak’s are good ,
but incase you use the LIPO’s together with a Tamiya MF unit not necessarily required ,
since the Tamiya MF units ( for trucks as well the ones for the tanks ) shut down before you reach the critical low-voltage point of the 2S Lipo’s .
I only have voltage monitors installed , like from Maxpro , on most of my MF vehicles

I am using the Tamiya MFU - are you saying that with the MFU I do not need the cut-off? Will the truck just stop or does the MFU give some warning like the cut-off does?

Thanks!

Now on to servos - still doing the reading - lots of good information on this board.

Quote:

Originally Posted by CrimsonCorsair (Post 32937)

So far it worked for me . The MFU shuts down , therefore the motor stops too.
But here is something to consider :
The speaker-system uses a large amount of your overall amp-draw ,
means as louder you got the volume cranked up as sooner it will shut down .
With other words , you are driving with sound and lights and the MFU shuts down ,
and you would turn the sound down or off and lights off you are able to restart the truck and drive it a little longer ( even thought , you shouldn’t do that , since the first shut-down is the sign for the low-voltage of the battery ) .
Such things running a stock motor or a low rpm motor and or even a gear-reduction will effect this too .

I need to work on some of my trucks prior the Indy show anyways ,
so I gone hook up a volt and amp meter and do a video to show you guys what I am talking about