battery problem

[mikk36]

i've got a problem with my battery, that has been very little used.

yesterday i tried to have some fun with it outside (the temperature was about -3 C, so not very cold) but the battery died in about3 minutes (i kept it in my chestpocket until racing) and it was not cold, when i checked the battery's temp...

what could be the problem??? also when i tried it in the house, it was almost ok again, but soon it cam really empty.

i've got the 7.2V A2 Pro 1900mAh pack. Is it because I don't charge it really full??? I use T2M Rapid Charger 1263, and on the label it says that it charges 7.2V 1800mAh in 30 minutes? how much should i charge it ? is it 35 minutes ? or should i charge it longer ?

or should i get ESC to replace MSC (the servos take a lot of Amps, i know, cause at a certain point, i can't control my car any more, but it keeps running at the last speed/turning point)[V]

[Tamiya1/10]

I am no battery expert...but understand if you don't use your battery regularly you should fully charge and discharge your battery a few times before using it, (recycle your battery) kind of like waking it up from a long sleep get the electrolite working properly. You should alway fully charge your battery else it will have memory where you will never get a full charge.

On the issue where motor runs and the servo stop should be the other way around. Servo has smaller motor thus uses less power and your RC should stop running and you should still have servo/steering use. Is kind like a safety feature and allow you to steer away from a head on with a curb and play with your RC for another day. So it could be your receiver or have you fully extended the antenna on your radio? If your budge allow, I would get a charge that has auto shut off meaning once it senses the battery is fully charge it will stop or go to slow charge mode and you don't have to worry about damaging your batteries.

[ShenUK]

quote: i know, cause at a certain point, i can't control my car any more, but it keeps running at the last speed/turning point)[V]

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i know with the older revivers this happens so don't worry and run out to buy a new one lol unless you want to, you can power your reciver with a battery pack you should have a battery holder that holds 4x 1.5 AA batterys as long as you can find some where to put it on your car you should be ok that way you can still control your car once your 7.2 battery is flat []

[The Slayer]

Agree - sounds like memory effect... need to charge, completly discharge (use a discharger) recharge, discharge etc about 5 times i think, that shoul break its cycle... Use a peak charger as well... no expert, sounds like that though []

[mikk36]

k, i got now another question about my battery

when it stops (it can't move even the motor any more) and when i let it stay calmly for about 15 minutes, then it can still power up for about 15 secs, the question is (i don't have the discharger) when is it totally empty ?

[Lucodeath2]

I used a 30min timer charger and the packs didnt last to long so I got a peak charger and I get more run time.

After 30 mins the fast charge turns off regardless of battery status.

[DJTheo]

quote:when it stops (it can't move even the motor any more) and when i let it stay calmly for about 15 minutes, then it can still power up for about 15 secs, the question is (i don't have the discharger) when is it totally empty ?

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You are right, batteries recover after some time but you dont need to wait for that, the first time it stops its enough,discharging more you could even damage the battery due to individual cell reversion.

Cheers

[Tamiya1/10]

Most people wants hop up parts, faster motor, ESC, higher mah batteries.... and last is the charger. I always tell people to invest in a good charger since you will use it regardless if you running the cheapest to the most expensive RC including nitro. A good charger will discharge and charge your batteries properly. Don't have to get the best charger, unless your budget allows it which is fine. Just get one that has auto charge and discharge function.

You may know this already but after running the RC don't recharge your battery right away, let it cool down first and the same for after fully charging it and the battery is hot don't run it, let it cool down and recharge it again, provided you have a auto shut off charger, to top up the battery.

(Is like golf, most people would invest in a driver or wood because is impressive at T off but neglect to invest in a good putter...forgetting that a putter must be used at least 18 times per round for most player while at tee off one can use any of the irons or woods)

I would say invest in a good charger as it will stay with you regardless and your money goes toward ESC, bearings, other hop up parts and finally servo and radio or battery. (Keep in mind I am not a racer so performance is not important to me.) One can use velcro to secure the ESC and receiver thus allowing them to switch from RC to RC. If budget is tight buy bearings for the gear box only since it will a pain to refit bearing to gear box after assembly.

[WillyChang]

Nah, fully computerised fancy changers are never as good as the basic clockwork chargers.

Like... how do you forcibly turn the knob to make it finish charging the battery faster when your mate's getting impatient??? [][][]

[mikk36]

k, one thing is clear, i don't need peak charger, cause my T2m rapid charger will do the job (i can fully load it, cause i did some calculations and i really don't need to charge longer that 35 minutes and thanks to that charger (it has clock timer on it (manually rotatable) i can set the time myself and the second charging, it cut off at 32 minutes, hopefully the third time i can fully charge it []

ano more question: does the battery deplete at the same speed, when i put it to run full speed at the stand (in the air) ?

[DJTheo]

No, it will take very long time to empty this way, as the motor current depends mostly on load (torque resistance) and not so much on RPM.

Cheers

[mikk36]

quote:Originally posted by DJTheo

No, it will take very long time to empty this way, as the motor current depends mostly on load (torque resistance) and not so much on RPM.

Cheers

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so it will be good to take the last power left in the battery out with that method ?

[DJTheo]

It might be already bit too deeply discharged that way, better drive it till it doesn't move.

Cheers

[GPZ1000RX]

You will have a problem if the batteries are ever allowed to get very cold, don't store them in the roof space,shed or garage. If they do get cold let them warm up naturally to 20c (if possible) before charging.

When charging, you can use any charger, but the battery MUST be at ambient temp to start with. Charge until they get warm (40-45c).

Some chargers use a probe under the heatshrink and switch off at this point.

Serious racers use a pack only once a day, fully discharge it and let it recover until the next meeting. The hot guys carry 5 new packs for racing and 5 last seasons packs for practise and setup!

Cheers, Paul.