hey everyone, so i just bought it second hand not long ago and everything was going fine untill yesterday for no reason at all, the lights started flickering and the steering would be going crazy left to right by itself completly unresponsive. it still goes forward and back but the steering is completly stuffed up and the light on the reciever box is flashig red and green really fast. Does anyone know what it could be ? i was it after every use and wd-40 everything ive already looked and theres no water anywhere. also the servos make a loud buzzing noise when its not doing this even when its not moving.
Also a question about the bateries, im running 2 2s 30 - 40c 5000mah lipo batteries, i have lvc but they dont buzz so i have to keep checking which is annoying. After about 15 mins of use the battery on the esc side will be at around 7.2 then when i go for another short run its like the motor (titan 775) completly sucks the life out and it comes back with somtimes 5 volts in the battery, but then after about 5 minutes it charges right back up by itself, is this normal ? they are pretty much brand new only had a few cycles. Im very new to this and am just trying to learn as much as i can any advice would be very much appreciated
Buzzing servos means they are fighting each other... to the death. One (or both) of them is probably dead or about ready to give up completely. They will need to be replaced... if you replace with stock, be sure to adjust them to stop the buzzing. I suggest getting a single, stronger servo as a replacement.
I suggest getting a LVA... eBay has them pretty cheap... less than $5 shipped to your door. Using a cell checker as a low voltage indicator is dangerous... if the pack voltage is 5v for a 2S, you are over-discharging them; which is very very very BAD. Safe settings for an alarm is 3.4v-3.6v/cell... you are hitting 2.5v/cell; probably should have stopped running them when it it 7.2v... as that is a safe voltage per cell, assuming they are balanced.
The pack acting as it is is completely normal. Once LiPo's are drained to a certain point, they loose their voltage very quickly... they also "bounce back" after a run.
I feel I should add that since you have abused these packs, I would watch them very closely.
If you see any swelling of the pack, STOP USING IT. The pack will need to be complete discharged and disposed of properly.
If you wish, I can post up some LiPo guidelines.
Last edited by JimmyNeutron; 11-29-2012 at 09:44 AM.
Whatever it is I just typed... could be wrong.
almost for sure servo issue.
Do read up on lipo batts they can be VERY damaging if missused.i do not want for you to have something bad happen.
like damage or harm to your home, yourself or your summit
Last edited by jamann; 11-29-2012 at 11:41 AM.
Mountains cant stop me
they have tried
i usually carfully watch my batteries, its only happened twice where its come back at 5 volts but then went back to mid 7s after a few minutes but yeah i really hope i havent destroyed my batteries as they are new and were pretty expensive. If you could please post the lipo guidelines would be very helpful
To see if it is a servo issue unplug both servos. Plug in one and test,does the Issue stop?if yes test the other servo
It's likely the issue.
Sent using lipo power
Mountains cant stop me
they have tried
It only takes one time to cause a ticking LiPo time bomb.
Hopefully, for your sake, the cells recover enough to be used for a while longer.
I apologize in advance for the length of this write up. However, I feel that it is important to have as much factual LiPo information as possible and to have it all in one location.
That being said...
now in session
1) NEVER discharge below 3v/cell
2) NEVER charge above 4.2v/cell
3) NEVER puncture your pack
4) NEVER short out your pack
5) NEVER use a pack that has puffed
6) NEVER charge unattended
7) NEVER charge at a higher C rate than recommended
8) NEVER use a pack that has been over charged/discharged
9) ALWAYS check cell voltage before connecting your pack to anything
10) ALWAYS keep your LiPo pack well balanced
To calculate the charge rate of your pack
mAh x charge C rate / 1000 = charge amps
A 2200mah 20-40C pack that states a 2C charge rate.
2,200 x 2 / 1000 = 4.4
This battery pack can be charged at 4.4 amps.
- Please note that if no charge C rate is stated, 1C is standard.
To calculate the constant discharge rate of your pack
mAh x minimum discharge C rate / 1,000 = available amps
The same 2200mah 20-40C pack.
2,200 x 20 / 1000 = 44
This battery pack can consistently provide up to 44 amps.
To calculate the peak/burst discharge rate of your pack
mAh x maximum discharge C rate / 1,000 = available amps
Again, the same 2200mah 20-40C pack.
2,200 x 40 / 1000 = 88
This battery pack can provide a peak discharge rate of up to 88 amps.
Peak rates are limited in time... unfortunately, this amount of time does not have an industry standard. This is how a lot of inflated discharge ratings can be claimed. In my experience, honest retailers/manufactures of packs will list the constant discharge rating along with the burst discharge rating and not only the burst rating.
When setting up your power system for your RC, make sure that the lower discharge C rate matches or beats the continuous amperage rating of the ESC. I try to beat it by at least 10%. This practice will provide you the most out of your system and it will also keep your batteries from working too hard. A LiPo should NEVER be warm... during use or charging. If it is, you are abusing the pack. Also, the less your pack has to work the longer it will last.
Running two LiPo's in parallel will double run time and also your available amperage... which is handy for high demand systems. Some misinformation I have read about the discharge C rating of packs in parallel is that the rating of the pack doubles. This is not the case. The C-rating of a battery pack is a fixed parameter of that pack; well actually it is the cells within the pack that have the C rating. Connecting two packs in parallel does not change either pack as they still have the same specifications, however it does create a battery "system" with twice the effective C rating. The packs are the same, but the parallel system is now theoretically capable of discharging at twice the Amp rate. This is much like the cumulative capacity available when connecting two packs in parallel.
Running two LiPo's in series will double voltage, therefore nearly doubling the speed of your RC. Capacity remains the same. The two packs ran in series MUST have the same capacity and discharge rate. They should be of the same brand as well as have the same amount of cycles on them.
Be prepared to gear down when increasing voltage on your power system.
There are many charging options out there... it can get really confusing really fast. The best advise I can give is to get the absolute best charger you can afford... your charge system is the backbone of your electric RC hobby, treat it as such. RC's will come and go, but your charge system will remain.
The following features are what I consider to be the absolute bare minimum for a charger... balance charging and a storage charge/discharge feature. Storage voltage is 3.85v/cell. If the charger cannot perform these tasks, look for another charger. If you are going to be charging multiple LiPo's at the same time or 10th scale or larger packs, I recommend getting a charger that is capable of at least 10 amps. Also, ANY half-decent charger can charge multiple LiPo's at a time. It does not require a dual or multi-charger to perform such a task. It only requires the right support equipment... I use a ParaBoard.
Here is what I have done...
this information might help with your decision
I use inexpensive batteries.
I have found them to be very reliable, extremely cost effective, and they have been proven to be under-rated; usually providing more mah and a higher discharge C rate than stated on the pack. SPC is a great brand that under promises and over delivers. There are others that claim extreme discharge ratings that are simply impossible with the technology that is available.
I use an iCharger 206B.
When I purchased the charger, I thought I would never use all 20 amps of its capability. Well, now I rarely charge at anything less than 20 amps lol. I have even considered selling it to get more amperage! I have performed hundreds of charge cycles with this charger and it handles the task without a single issue.
I highly recommend any charger in the iCharger line.
I built my own power supply.
I have ~$30 into my 24v 75a 1800watt power supply.
Sounds complicated, but it really is not that difficult. If you go this route, you are going to want a server power supply as they do not drop voltage when you are pulling amperage like a standard ATX PC power supply.
You can also purchase these pre-built.
I hope this information helps!!
Here are some links to some more:
Whatever it is I just typed... could be wrong.