Running off of storage charge

[TRAT]

I just throw mine away and buy new ones.

 

[ground_zero298]

Full charge, cut off at 3.3. Then storage mode to 3.8 per cell when done. Or if your happy with the run times, full charge and cut off at 3.8. Then when it shuts off you’re already at storage voltage. I set my crawlers up like that.

 

[WickedFog]

Thank you everyone on the information and the articles that you sent me. Don't worry, I have a LVC of 3.3 volts per cell and my battery hasn't ever gone under 3.3 volts, but from what I have been gathering, what I didn't realize is that it is pointless to run a car under 3.7 volts due to the drop in voltage. So just to clarify, on a regular basis should charge my lipo up to 4.2 volts and not let it drop under 3.7 volts?

You can go below 3.7v, all the way down to 3v. But your ESC looks at the voltage as a whole. So if one cell goes to 2.9v and the other is at 3.1, you are hurting the lower cell. So it's best to keep a buffer there and stop running above 3.2v. I set mine to 3.4-3.6v.

And yes, you should always charge your battery to 4.2 to run your car. When done, storage charge to 3.7-3.8v

Full charge, cut off at 3.3. Then storage mode to 3.8 per cell when done. Or if your happy with the run times, full charge and cut off at 3.8. Then when it shuts off you’re already at storage voltage. I set my crawlers up like that.

That's a good idea. I usually stop mine before even hitting lvc, and 9 times out of 10 I am right around 3.8v. But I still toss them on the charger for a quick storage and balance.

 

[ground_zero298]

But I still toss them on the charger for a quick storage and balance.

Mine always hit the storage/balance before getting put back. Just cuts down on the waiting time with the 3.8 cut off.

 

[DarkCows]

You can go below 3.7v, all the way down to 3v. But your ESC looks at the voltage as a whole. So if one cell goes to 2.9v and the other is at 3.1, you are hurting the lower cell. So it's best to keep a buffer there and stop running above 3.2v. I set mine to 3.4-3.6v.

And yes, you should always charge your battery to 4.2 to run your car. When done, storage charge to 3.7-3.8v

That's a good idea. I usually stop mine before even hitting lvc, and 9 times out of 10 I am right around 3.8v. But I still toss them on the charger for a quick storage and balance.

Thank you for the help!

 

[Chipper]

I don’t think it’s hurts it to go to your lvc at 3.3 volts. Then charge up to storage as soon as you can. My 2-3s batteries still give a good response until they hit LVC. My big rock is still doing wheelies on 3s until lvc kicks in. Just my opinion. Had my batteries for over 2 yrs. No problems yet.

 

[cimh]

I am very grateful for this thread. I sometimes run my scx24 off a storage charge until the deadbolt starts to go slow or stop. I unwisely assumed that it would cut off at a safe point. Of course this cannot be true because the balance lead is not connected so the ESC has no way of knowing the voltage of each cell. I put this to the test tonight with a balanced lipo to start with both cells at 3.81v. When the scx stopped after about 25 minutes one cell read 3.16 and the other 3.4v. Not good. So it seems that you can only trust the ESC to keep the battery safe if all the cells in the lipo are in equal health and it seems that they are not for this battery.

My solution: I have orded a micro low voltage cutoff for the vehicle.

However: Would I be right in assuming that this is not about running from storage voltage but more to do with not trusting the ESC cutoff and monitoring the voltage of all cells at all times especially if your battery is not in the best health?

I am using the stock battery: Horizon DYNB0012. Resistances are 135 and 160 ohms. This battery has probably been used less than 20 times. My current charger is the SKYrc e680. I have never known this battery to get the slighlest bit warm either charging or running. I guess that's because the scx24s take so little current. I do use a battery temperature monitor when charging just in case and am always in the room.

I have read about Lipo's but sometimes we need to make mistakes to really learn the lesson

 

[tntpoof]

your battery cells are not reading 135-160 ohms if it was they or esc would go up in smoke as resistance is to high. i think its in the Milla ohm range. 20 minute run from a storage charge to lvc unlikely
Electric RC info, how-tos and such - TJinTech (tjinguytech.com)

 

[cimh]

your battery cells are not reading 135-160 ohms if it was they or esc would go up in smoke as resistance is to high. i think its in the Milla ohm range. 20 minute run from a storage charge to lvc unlikely
Electric RC info, how-tos and such - TJinTech (tjinguytech.com)

Thank you. You are correct, I meant milli ohms.

 

[tntpoof]

even 130+ milliamps is 10x what id consider safe . i do have a few common sence lipo 3600 mah 35c that i like to run got them in a ticket draw back in late 90's they have so much punch they read 25 milliamp's used them in a xxxt with brushed 27t brushed on a tekin 420. there weight and punch woke them up set many tqs with them on carpet offroad

 

[Bri26]

One thing to note is that you shouldn't leave a LiPo battery fully charged for more than 12 hours. Otherwise, you can shorten it's life.

Ideally, the day you want to run the RC vehicle, you fully charge the battery. Then when your done for the day you let the charger bring the LiPo battery to the correct storage voltage so it's ready for next time.

 

[cimh]

even 130+ milliamps is 10x what id consider safe . i do have a few common sence lipo 3600 mah 35c that i like to run got them in a ticket draw back in late 90's they have so much punch they read 25 milliamp's used them in a xxxt with brushed 27t brushed on a tekin 420. there weight and punch woke them up set many tqs with them on carpet offroad

Thank you. I have managed to find a youtube of someone testing new 300mah 2s lipos. Checking 10 different makes the average resistance was 30-50 m ohms / cell. None of the batteries were as high as mine. I understand that small batteries have higher resistance but even so my resistance seems much too high for a 350mah lipo.

What might have gone wrong?

Duff battery? - When the deadbolt arrived with the battery. The included charger would not charge it. The shop sent me another charger that did not work either - maybe the battery was at fault from the off rather than the charger?

Over charging? I own up to not fully understanding the htrc charger. The manual was in chinese english which did not help - so for the first few charges the charge setting was the default 2A rather than 0.3 - 0.4A which would be the 1C rate for my lipo - that might not have helped although the ampage dropped very quickly down to reasonable levels.

Runing the truck till it stopped? - feels like this might result in 1 cell going too low.

I have ordered a new one of a different make and a LVC for the scx24 and I'll see how that goes.

 

[tntpoof]

try a higher amp charge rate be careful .some say 10c charge rate can bring ir down.usually people racers like to see 4 m max

 

[Addict Rc]

i would run it on store mode if thats what your doing then dont just charge the battery normal before use

 

[ground_zero298]

try a higher amp charge rate be careful .some say 10c charge rate can bring ir down.usually people racers like to see 4 m max

Usually need 60-80 amps to perform this. Its usually only pros trying to drop a couple ohms because of the 2s limit. My protek 6100's are all under 8 ohms. When they get to 15 ohm I give them away. Those guys will try to get that 8 down to 3-5. I don't do it for a living and won't risk try to burn one down. If I remember right my bashings and spectrums are around 18-28 ohms, those are 4 and 6 s. Not sure how 2-5 ohms make a difference in real world applications, but some swear by the extra burst they get.

 

[cimh]

I think this Low voltage Alarm could be good for me. It flashes red when a cell starts to struggle. After running the deadbolt for a while, one of the red leds would come on for a second or two when I put the car under increased load, even though I could not see any reduction in performance. Testing the lipo off the car gave me 3.67v and 3.71v. So it looks to me that this provides a neat early warning that one of the cells is starting to feel unhappy and it would be a good time to stop / change batteries. Perhaps the scx24s draw so little current for much of the time that there is a risk that a cell could get too low without really noticing a power loss?

OK it's not pretty - the blue tac tac is there because I do not like the sound these buzzers make!