Lipo Battery Questions???

[4wd-n-archery]

Just bought a wraith, rtr. It came with one 3s Lipo. 1800 mah.
Has a brushed motor. I've been told I should stick to 2s. Almost seems a little to fast to crawl right now.
I think I'd like to stick to Lipo. Wish they were easier to maintain. All the warnings I read describe them as akin to mini atomic bombs. Scary.
I want to get as much mah as I can fit under the hood. Not stock location.
Any downside to 4-5000 mah batteries?
How long do they take to charge?
I keep reading, and everyone keeps telling me you CAN"T let them run completely down. Also they don't gradually die, it is rather abrupt. Question is, how do I know when I should stop using it, If the only way to tell is it dies, and then it is too late?
Also, Lets say I charge 3 batteries. Go out, and break something in 15 minutes, and I have to order a part and wait for it. What to I do with the remainder of charge on those batteries?

I am sure there is a thread here somewhere, but I can't find it, and it is late, and I am really tired. Not even sure I am making sense. Maybe someone could help me out with a link, or some answers. Also I was told I have to keep them on a trickle charge for maintenance? Do my Onyx chargers have this feature?
I almost want to give up, but this is a pretty serious high quality truck, and I want to maximize the performance as much as I can within reason. Size does matter. ( in this case smaller is better.).

Thanks every one.

 

[Meatwad]

Everything is a bomb... from a pressure cooker to your car's fuel tank to a nimh cell to your mobile phone. Basically treat things with respect and they'll treat you well. It is best to either use a safe charging bag and/or charge outside.

A 5000mah is too big for anything crawler/scaler IMO. 2200mah3s packs fit well for myself.

Charge rate depends on your charger and packs pretty much. Any lipo can be charged at 1c, any more than that depends on their quality.

While it is correct that a lipo pack shouldn't be charged to dead.. the lipo cutoff feature is that "abrupt dying", not the lipo itself.

Read this thorougly.. some info is outdated but alot of guidelines and rules for safety are general:
Understanding RC LiPo Batteries

 

[4wd-n-archery]

Wow. Thats alot of information. Perfect. I'm starting to get it, and I will definitely consider your advice.

 

[Trubble]

I've been told I should stick to 2s. Almost seems a little to fast to crawl right now.

I'm of the opinion that Wraiths and SCXs are coming from the box over-geared. (20/87 out of the box, no?) And with both those trucks using lower turn motors, tall gears are an even worse idea. I'd rather see you stick with 3S, but pick up a 14 and a 16 tooth pinion, assuming you're still running 48 pitch gears. Dropping pinion sizes will bring your speed down nicely, and should keep your motor cooler, too.

I want to get as much mah as I can fit under the hood. Not stock location. Any downside to 4-5000 mah batteries?

5,000 mAh batts can get a bit heavy, and sitting that high up in the chassis can make for some disappointing sidehilling/downhilling.

How long do they take to charge?

Depends on your charger.

I keep reading, and everyone keeps telling me you CAN"T let them run completely down.

Runnin' 'em flat is usually what de-stabilizes them, then they swell up, and either puff smoke, and/or catch fire. On a low geared Scorpion with a high turn motor, you may not get the smoke or fire, but with the heavy amp draw of a low turn motor, tall gears, a (relatively) heavy truck, and an aggressive trigger finger during a climb, things can go bad, real quick.
With all my LiPos, there's been a noticeable point at which the truck slows down. At that point just stop.

Question is, how do I know when I should stop using it.....?

Could buy LVAs (Low Voltage Alarms). These are usually good for kids who refuse to stop playing, gives them (and anyone else in the area) a clear signal it's time to stop. If it's obnoxious enough, the kid won't want to run around with it beeping and screeching at him/her.
If your truck's ESC has a LVC (Low Voltage Cutoff) you can set that, and that'll make it very unappealing to drive with a low battery by cutting out to the point where the truck's got no power to crawl over anything, or it'll stop the truck completely. I set mine a bit high at 3.5 volts per cell, but that's just me.

Also, Lets say I charge 3 batteries. Go out, and break something in 15 minutes, and I have to order a part and wait for it. What to I do with the remainder of charge on those batteries?

LiPos are a LOT nicer than the old NiMhs/NiCads as far as developing a memory. If it's only a week or two, I'd leave 'em.
Could solder up a light-bulb discharger, but then you're in a position where you'll need other voltage monitoring equipment, too. I use a Hyperion EOS Sentry battery checker, quite the handy little unit, love it. Some use the cell display on their charger. Some LVAs are also digital battery checkers.

Also I was told I have to keep them on a trickle charge for maintenance?

No.
Overcharging LiPos is also a sure-fire ticket to destroying them, and anything flammable around them........ like your house.
Every LiPo charger I've ever heard of shuts off completely after the charge is done. At that point, disconnect your LiPo and don't ever leave it connected to anything.

Do my Onyx chargers have this feature?

For MiMhs and NiCads, probably, but don't use those profiles for charging LiPos.
I don't recall you mentioning which Onyx you have. If you're playing with LiPos, I sure hope its a 230, 235, or 245.








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[summitcrawler]

everything you need to hear right there^^^^

 

[4wd-n-archery]

This is great. Way, WAY more info than I was given by 3 different guys that I asked at the hobby shop, and this way I can go back and refer to the info periodically. Thanks.

 

[heartless]

some of the more advanced chargers have a "storage" setting for charging/discharging to a safe storage voltage. Read the manual for your charger to see if yours has that capability.

Definitely get a Lipo charging bag and use it - even on Nimh/Nicd batteries - cheap insurance! Our local indoor track requires the use of a proper charging bag for charging any kind of battery - no bag? No charging!

for physically storing the batteries, we have a couple of old smaller sized military ammo cases - 1 for the lipos, and 1 for the Nimh/Nicds

 

[crawl33oh]

Everything is a bomb... from a pressure cooker to your car's fuel tank to a nimh cell to your mobile phone. Basically treat things with respect and they'll treat you well. It is best to either use a safe charging bag and/or charge outside.

A 5000mah is too big for anything crawler/scaler IMO. 2200mah3s packs fit well for myself.

Charge rate depends on your charger and packs pretty much. Any lipo can be charged at 1c, any more than that depends on their quality.

While it is correct that a lipo pack shouldn't be charged to dead.. the lipo cutoff feature is that "abrupt dying", not the lipo itself.

Read this thorougly.. some info is outdated but alot of guidelines and rules for safety are general:
Understanding RC LiPo Batteries

I have to disagree with you there a bit, as far as the 5000mah is too large. I might have gone a little overkill when I bought my battery, but I got a 5000mah Duratrax Onyx hardcase 2s Lipo, on a full charge it will run for a good 4 hours, now size wise is where it sucks because it is a little bulky, but its not much larger than a standard NIMH pack

 

[k7zpj]

Just bought a wraith, rtr. It came with one 3s Lipo. 1800 mah.
Has a brushed motor. I've been told I should stick to 2s. Almost seems a little to fast to crawl right now.

The Wraith will work fine with 3s but you should run an external BEC. The Wraith Beginners Guide has lots of good information including type and size of battery to use.

http://www.rccrawler.com/forum/axial-wraith/323522-wraith-beginners-guide.html

I keep reading, and everyone keeps telling me you CAN"T let them run completely down. Also they don't gradually die, it is rather abrupt. Question is, how do I know when I should stop using it, If the only way to tell is it dies, and then it is too late?

The AE-2 has the lipo cut off set to on from the factory. I would get a Castle Link so that you can change to the cut off voltage to around 3.4v to be safe. Instead of relying on the lipo cutoff, I time my runs so I don't discharge the battery more than 80% of its capacity.

Also I was told I have to keep them on a trickle charge for maintenance? Do my Onyx chargers have this feature?

Lipo batteries need to be stored at 3.85v per cell. Most Lipo chargers have a store mode that will either charge or discharge the battery to get to the storage voltage. Lipos will self discharge so if they have been sitting a couple of months, put them back on the charger on storage mode to bring them backup to the storage voltage.

I almost want to give up, but this is a pretty serious high quality truck, and I want to maximize the performance as much as I can within reason. Size does matter. ( in this case smaller is better.).

Learning the technology is part of the fun of the hobby. There are a lot of scary videos out on the internet about Lipos. Most of them were staged to get a fire. Lipo batteries are safe and they are in millions of smart phones, computers and other computer devices. Don't give up on Lipos, it is just a matter of learning how to properly use, care and store them.

 

[micro racer]

It has already been said a few times in this thread and everywhere, but just don't do anything overtly stupid (or careless) to your lipo battery and you should be fine. You don't have this with a wraith, but if you get a crawler with a lexan body, always put it on when you are rock crawling. The battery is pretty much unprotected with the body off and vulnerable to damage. (Think ointy rock plus wrong-place wrong-time.). I had this happen with my servo in a cms setup.

 

[cormier33]

Lots of great info mentioned above.

Make sure you're ESC is set up for lipo (most that come with brushless are and will have a default lipo cutoff set up) but you need to make sure, so program your esc and follow manufacturers instructions.

As for quality of lipo, this is where it pays off. Check with manufacturer to see how many 'c's' it can be charged at. I have a lower quality lipo that can only be charged at 1c and takes considerably longer to charge then my other lipos that I charge at 3c. Likewise with charger quality (to have the ability to charge at higher rates)

Oh, and +1 on the lipo fire bag! Cheap insurance policy. Discard battery as soon as you notice any swelling/deformation.

 

[el_Fernando]

Good info here. You are in good hands.

Storage wise I keep my lipos in a Lipo sack and then store them in an old toolbox I had laying around. You do that and keep in a cool/dry place they'll be good. Also make sure you do a balance charge on them every few cycles.

 

[4wd-n-archery]

Yes. Alot of great info, and very helpful. I am sure now I will be fine. I do have a BEC, and my esc is set for 3s lipo, which is what I am using.