I have a battery question and some general questions

[BigBrownBeaver]

I didn't run my 3S Lipo battery all the way down. I don't even know where its even ran down too. Its the new Traxxas VXL 4x4. This was the first time running my car and its my first car. I got to run it around for about 20 min then I had to leave. The car was still running strong. Is it safe or fine for the battery to be thrown on the charger to be topped off for the next run, or should I run it all the way down before charging? Also, how do I know when its time to charge the battery? Will my car just stop?



Is there anything I should try avoid doing while driving other then not hitting things? Anything with the controls, starts and stops? Do's and don'ts?



Didn't know if I should put this thread in the Non-crawler section or not. They are newbie questions so I put it here.

[durok]

We ideally need more information - what capacity is the battery (4000mAh, etc), what Traxxas VXL model is it (Slash, Stampede, eRevo, etc), what charger model are you using and what connector are you using (standard TRX connector, are there balance leads on your pack)?

Most likely, if you only ran it for 20 minutes there is still a decent amount of charge left on it.

Just plug it in a Lipo-specific charger and charge it back up.

You'll want it to be balance-charging, if it's using the current TRX battery connectors that's already taken care of in one connector, but if it has a different connector you'll want the balance lead connected to the charger as well as the main battery connector.

You can run it how you want, but check your motor, ESC (Electronic Speed Control) and battery temperature every so often- just touch the motor, the cooling fins on the ESC, and the battery with your fingertip if you don't have a temperature gauge.

You should be able to leave your finger safely on these items for more than a few seconds without feeling as if you are about to get burned.

If they are too hot, park it and disconnect the battery - let everything cool off for a while.

If they are extremely hot you may want to change your gearing to lessen the stress on your electronics.

As far as how to tell when your battery is done - with modern LiPo batteries, as soon as you notice a loss in power - you're DONE, let the battery cool and don't put it immediately back on the charger...

Give it a break of about an hour.

Best thing is to have a couple packs, for uninterrupted fun.

If you are not going to run your pack again for the next couple days or longer, put a "Storage Charge" on your packs.

I Storage Charge my SMC packs to 3.80v per cell.

When I am ready to go run my packs, I charge them to 4.18v per cell.

I don't like to let my packs to go below 3.3v per cell before I charge them - and if my ESC is programmable I set the cutoff point even higher, to 3.7v per cell - this makes them take more charge/discharge cycles before they start becoming unreliable and weak.

These are just basic points to keep in mind.

[BigBrownBeaver]

Thanks for all the info. Its all very helpful. Just want to make the most out of my batteries.

[Derr429]

Make sure your low voltage cut off is on and set so you don’t run the risk of running your battery down to far.

[dacaur]

Lipos dont have the memory effect of old ni-cad or nimh. With lipos, its safe to put them on the charger any time. If you want to run for 2 min then charge it, thats not going to hurt anything. In fact one of the quickest ways to wreck a lipo is to run it "all the way down".
You would think crawlers would be easier on batteries because of the low amp draw, but the opposite is actually true if you run to low voltage cutoff. Most ESC cutoffs are designed for high amp draw applications. When used in low amp draw trucks, they can actually let the battery discharge further than they would in a brushless go-fast truck.

[GLwagon]

When I used to race I would use one battery all day & as long as it wasn't above ambient temperature it got thrown right back on the charger.
I have LiPos that are over 10 years old that still have good Internal Resistance (IR).
At the same time I have put a nail through $20 LiPo's after 2 years because IR of one cell starts to skyrocket & balancing becomes a limiter while charging.

NEVER run a pack below 3.2v per cell.

ALWAYS store the pack at approximately 3.8v per cell.

ALWAYS balance while charging.

DO NOT charge a pack at freezing temperatures & then introduce it into a warm area (voltage rise issues)

DO NOT overload a pack, stay with-in the "C" rating for peak amperage draw.

DO NOT run a puffy/puffed/damaged LiPo unless you are willing to melt your RC car down, it happens.

You'll get many years of use out of LiPo's if you treat them well.

[Browneye]

Hopefully you got a quality digital lipo charger - if not, you need one. And a fireproof charging bag. Lipo's are not something to be casual with - they can be dangerous if mis-handled or damaged, and/or vastly reduced life. If one should catch fire they do not go out 'till they are consumed, and can literally burn your house or car down. I don't mean to alarm, but do some research so you KNOW what you're doing with them.

They have a min-max voltage that should not be exceeded, and stored at 50% charge. A proper charger will do this for you. Basically a minimum of 20% charge and a maximum of 95%.

If you need help with specifics ask here.

[Browneye]

LIPO batts are not for children.