Charging the night before
 

Can i charge my 5000mah 2c lipos the night before a next days race? I go right from work to the track and i wanna get a few practise runs in before racing. Is this safe for the lipos?

I wouldn't leave them charged, fully, overnight personally. That is hard on the batteries and shortens their life. 5000mah packs should give you plenty of practice even with a partial charge. You might just charge it to 8.2 or just when it reaches 8.4 (and starts backing off on amperage).

When I go to the track, I take two cars, both with their own lipo. I practice in one with the charge that was left from the previous week (around storage levels) while charging the other one, then alternate.

That's my game plan.

A night before is ok. LIPO batteries hold its Mah pretty well. Make sure you have it discharged to 50% if you are not going to use it the next day.

I usually charge all my cheap Hobking packs the night before, but then Im racing by noon the next day. Several of my packs have been used this way for hundreds of cycles and still run well. Many Lipo distributors lately have gone to saying do not store them charged, that it is detrimental to their health.

This is from Hyperion - "Storage - Lipo should never be stored fully charged, or with less than 50% of capacity remaining. We strongly recommend Hyperion EOS chargers, as they have automatic STORE functions to insure that the packs are in the range of about 60%~70% capacity (3.78V~3.92V resting voltage per cell). After returning home for the day, simply use STORE MODE to achieve this automatically. Batteries are best stored in a cool, dry environment (2~20 °C or 37~68 °F)."


Note the word 'never'. Storage means anytime the lipos are not being used.

On the night before, charge them to something less than full like 8.2v. You won't miss the 0.2v.

I gotta learn how to use the voltage cut off on my charger to charge it to about 70% then

On a charger with a storage mode shouldn't be that hard to do.....which charger?

Or i could just charge them at work ha

Best to not leave them fully charged, and yes I know many do, I did at first. Not because of losing charge or self-discharge, but because it impacts internal resistance and capacity over time.

But if you do, be aware that charge state changes with temperature. At the very least avoid higher temperatures. Something like leaving them in a hot car in the sun for example after charging at room temp is not good.

What about when I am working during the winter? Is it safe to leave them in the car when its below 30F throughout the work day?

If you read the instructions on some lipos, they give you a temperature range. Below freezing is okay, but ridiculously cold is not. I don't remember what my reedy said, but I've put two of my 2s reedy packs in the deep freeze for storage and they are still in great shape. I remember verifying that the deep freeze was not colder than the temperature reedy said to store them at long term.

I know they don’t perform very well at cold temps, lower Voltage under load.

If you do put them in the fridge, or cold car, suggest an airtight container. Tupperware, Ziplock freezer bag, etc. Let them warm back up still in it. Will help reduce condensation.

Maybe i can just throw them in my cubical during the day and charge them at work before races ha. Hope they dont start on fire!

Personaly I charge mine the day before, not the best I know. With new lipos coming out every 3-4 months my I don't worry about my packs lasting forever anyway, but that's me. Honestly I'm not very nice to my lipos:o but I only race and I run mod. so if they loose a little capacity or a little punch I would never know it..