Rhino 5s1p 4900mAh 20C Lipo Problem
 

HI guy, got to take my 8ight-t to the track yesterday for the first time and loved it. I have 2 batteries a Turnigy 5000mAh 25C 4s1p ZERO issues so far. Then there is the Rhino 5s1p 4900mAh 20C pack. after 1 charge/discharge its now showing only 4 cells when i connect to my charger which is a Thunder T6 6 cell charger/balancer (pic below) this charger has worked flawless with my 2 other packs i have which are for my slash they are 2 cell lipos. Is there some test i can do to find out if i really have a bad cell? Currently the cell is discharged i used the castle creations mamba monster ESC with the voltage cut off set correctly to 15v for a 5 cell pack and it stopped running just like my 4 cell did yesterday when it got to low. Not sure what to do at this point. I know the charger has Lipo Balancing/Lipo Charge/Lipo Fast Charge/Lipo Discharge/Lipo Storage settings i have only ever used lipo Balance on any of my packs. There is also a settings that i cant really make sense of, it reads like this (silly chinese manuals) Heading is as follows:

Voltage Balancing and monitoring during the discharge.
The processor monitors the voltage of the individual cells during the "storage-mode" and the "discharge mode" of the lithum battery pack. It tries to normalize the voltages to be equal. For this feature, the individual plug of the battery pack should be connected to the individual port of the charger. (is this talking about the balancing port? any way here is the rest) If the voltage of one or more of the cells varies abnormally during the procedure, it terminates the process forcibly with the error message. If this happens the battery pack contains the bad cell, or the bad connection of the cable or plug. You can easily know which one cell is bad by pressing INC button at time of showing the error message.

This is word for word from the manual. At any rate i always charge my packs at what i believe is 1C which in the case of the 5 cell pack is 4.9 AMPS because its a 4900mAh pack (correct me if im wrong). Do i need to cycle (charge/discharge) a pack before i use it? I had thought Lipo was different. HELP!


http://site.xheli.com/T6-Charger.jpg

http://www.hobbycity.com/hobbycity/s...R4900-5-20.jpg

WOW 30 views now answers LOL

I would suggest trying to measure the voltage of each cell at the balance tap. If you can only measure 4, it's likely your problem that you have a disconnected balance tap wire.

I have a few diff devices i can use to measure, not sure how tho. Which one should i use? and how?

http://i566.photobucket.com/albums/s...thg/Meters.jpg

OH also my charger gave me this info on the cells. Ideals?

http://i566.photobucket.com/albums/s...g/Voltages.jpg

Of the 6000 odd members, only a few dozen are regular posters, so....

There is a very simple trick you can perform; charge the lipo as a 4s pack until the voltage of each cell is at the nominal level or just over- thats 3.6v each, so the total voltage will be 18v. Now, stop the charge and restart it- the charger should recognize that you have a 5 cell pack and ask you to confirm this before it starts the charge.

Im assuming when you connect it up and select 5s lipo, it only reads the pack as a 4s item? Thats due to the voltage of the pack being lower than the nominal/ resting voltage of a pack that size; the cells are discharged to ~3.0v per cell, but the charger is looking for 3.6v (or 18v vs ~15v, however you want to look at it), so it thinks you have a smaller voltage pack connected up.

Its a fairly common issue, I get the same thing with my Bantam BC6 charger, so I just use that trick and it works every time. You can also charge the pack as a nimh pack at 1c until the voltage hits the needed level, then change it to the correct lipo setting and finish the charge.

I love being right all the time :lol: :yipi:

I like your ideal. so i just set my charger for 4 cells @ 4.9 AMPS and let it do a full charge? Once done the try to charge again as a 5 cell? I should still use the LIPO BALANCE SETTTINGS right? Thanks for all the help you have give/suggested in all my other threads Suicideneil

good job neil...

Yes and no. Set it for 4s lipo and 4.9amps, but only charge it until the cell voltage is 3.6v, and the total voltage is 18v. Then you MUST stop the charge and restart it as a 5s lipo at 4.9amps. Make sure the balancer plug is connected and you select the 'balance charge' mode/option.

I try my best- since it happended to me the first time I used lipos, I kinda scratched my head and had a brain wave, and then after doing some research on this forum I saw people suggesting the exact same solution. Its only easy when you know how.. :yes:

suicideneil, thanks so much, i deleted the other post, i figured this one was way to long and nobody wanted to take a crack at this issue. Im charging now at the settings you specified, Im not to sure on when it will be at 3.6v tho. People keep taking about using a meter to check the voltage but i am not sure on how to do this. suggestions?

http://i566.photobucket.com/albums/s...thg/Meters.jpg

I LOVE YOU MAN! That fixed it. So now comes the part about Low Voltage CUTOFF. what is a good setting being that 3.0 seems to be to low for this pack. anything about that? like 3.2 3.3?

Just keep checking the pack, shouldnt take more than 5-10 minutes- you should be able to view the individual cell voltages like in your pictures above during the charge.

As for the other question, you should have two nice pointy probes with the multi meters, a red one and black one ( + and - ). Set the voltage on the grey one to the '2v' option (adjusts the sensitivity), and plug the probes into the 'A' (red) and common (black) sockets. Now, on the lipos balancer plug, there should be 5 red wires (or coloured wires) and one black one. Place the tip of the black probe onto the metal tab of the black wire in the balancer plug, and the red probe onto each red wire's tab, one at a time & in sequence. You should be able to then see the voltage of each cell, or the combined voltages as you go along the line of tabs so to speak (just deduct the first voltage from the second result, and the 1st and 2nd voltage from the 3rd result to work out the individual voltages of each cell).

Your charger should be fairly accurate with the cell voltages, but you can also buy awesome little voltage checkers that plug into the balance plug and tell you the voltages too:

http://www.hobbycity.com/hobbycity/s...y_Monitor_2-6S Good

http://www.hobbycity.com/hobbycity/s...itor_2-6S_Lipo Very good

http://www.hobbycity.com/hobbycity/s...~6S_(Version_2) Really good

http://www.hobbycity.com/hobbycity/s..._Polymer_Packs Awesome


Mmm, man love...

3.2v per cell should be fine- 2.7-2.9v isnt too bad, but it would be better if they stayed around 2.9-3.1v once they are discharged. Seems like 2 cells are little bit weaker than the other two, but not by much, and since they arent matched cells, thats pretty normal behaviour.

Nice Neil! I gotta get me one of those....the third one down looks promising!

your charger should show you individual cell voltages, or just stop the charger at 18v

ugg to late lol

yeah im pretty new to Lipo, i got scared for a min. thanks for the tips. Im back on track

I've got one- its a really nifty little item, but I havent used the cell voltage recorder function yet, may have to do a little bench test just to see how well it works (cell voltage should still dip down a fait bit just blipping the throttle with the wheels attached). They also have an awesome wireless 2.4ghz version that lets you know the voltages whilst you are driving- now thats an epic feature, like a fuel monitor whislt you are driving so you know when to pit stop...

http://www.hobbycity.com/hobbycity/s...attery__869Mhz

Swanghobby also sell similar items, some abit funkier with LiFe compatibility:

http://www.swanghobby.com/battery-ac...ugs-c-209.html

I've done this myself to speed up lipo charging if the V is too low, but how on Earth are you getting 18V when charging in 4S mode? 4.2V*4= 16.8V

Usually my charger will take it upto 16.8V in CV mode, so the amps slow down, and its not worth charging @ .2A.

I would not ever charge in NIMH mode. Yes you can cheat the charger to force a high amp charge into the lipos, but the charger will not stop running, and will raise the voltage to keep a high amp rate going. It never sees a V drop (like Nimh batts do when full) so it keeps steaming along even if the lipos go way over the 4.2V/cell limit.
This is a recipe to burn your house down. Do not do it.

FYI.. I did this once with an A123 pack before I got a usb adapter to update the charger for a LiFe mode. I got distracted for a sec, walked away, came back to late and my now 5S A123 pack was at 25V/5A and still going (should have stopped at 18V.) Destroyed the whole pack, but fort the A123s are inherently safe and did not burn. Lipos would have caused a fire.


You should just be able to select a 5S batt in the charger and go from there. In certain V ranges it could be a 5S or 4S batt, and chargers default to the lower count for safety. Just confirm its a 5S and go.

At the very worse if you can't, if your charger has a A123/LiFe mode, you may be able to use that mode as a halfway step for a little faster kick. Ie, for a 5S lipo pack, charge as 5S A123 to 18V (full charge is 3.65V/cell), then change to lipo mode.


Otherwise, don't let your batts go so low V. 3.2V/cell is a sfer cutoff, else, as soon as you fell the power start to drop, stop the truck immediately and change the batt. The last few mah kills the voltage and can ruin the batt.

BTW, that thunder charger looks exactly like a Bantam b6 charger. Its prolly a relabel. Maybe that manual for the bantam will be more helpful.

too late my house is burned to the ground and my 3 little kids are dead.... thanks SuicideNeil :(

what battery tray are you using for that 5s? it says its 184mm long, is this true?

i couldnt say now, thanks to neil my house is a puddle of melted electronics and little brittle bones from my kids. Just want you to know that they screamed his name while they burned.

The 5s pack fits fine in my Losi Electric conversion battery tray, with room to spare.

update: pack is exactly 6.75 inches, oh and i replaced the kids off of www.ebaby.com you would be surprised at what you have to pay for a 4 year old these days.

Man, I'd go back and edit some of your post, they are your kids, so I guess you can joke about them how you please, but I think it is bs. Plenty of better ways to get your point across.

0_o


.

I think he was joking... ...at least I hope he was.

Anyways Finnster, 4s = 18v because you only charge the cells upto 3.6v each, then stop the charge & restart it with the charger set for a 5s pack to achieve the full 4.2v per cell. Its a safety feature in many chargers- you plug in a pack, and if the voltage isnt high enough for the pack vs what you've told the charger it should be, then it will assume you're thick and charge the pack as though it were 1 cell smaller. Kind of annoying, but it does save people from tryign to charge a 2s pack as a 3s etc and burning down their house....

:lol::rofl:

His name isn't SUICIDEneil for nothing.....

How does that Hobbycity batt monitor work with two batteries??? Can you only monitor one at a time?

I thought that's what you were saying, but it didn't quite make sense as written. Most of the chargers I have ask you to confirm the higher cell count.

I'm still confused on your math tho, 18V/5=3.6V, 18/4=4.5. 4S=18v?
If I am understanding you, you say charge as a 4S to 3.6V/cell, then stop, then charge as a 5S. Full charge on 5S gets you to 21V.

If you are charging a 4S pack to 3.6, then stopping, that only gets you to 14.4V. It will still "think" is a 4S pack. That's still less than 3v/cell for a 5S anyway, which is bad to begin with. If you do a 4S full charge, you can get upto 16.8, but as said, I would stop mine @ ~16.5V as it goes into CV mode and the amps slow down alot.
(This was done on a charger that would only trickle charge until voltage got over like 3.3V/cell, annoying as hell. I'd cheat it up to 16.xV faster, then go to 5S mode. I wouldn't do this unless forced to tho, that charger was dumb like that.)

You are quite correct, the charger does ask you to confirm you are (in this example) charging a 5s lipo, but it only 'sees' a 4s lipo due to the low-voltage issue. In which case, my charger will charge the pack as a 4s lipo once you press the OK button (it will ignore you telling it you have a 5s lipo hooked up, even with the balance plug connected). That way, all the cells are charged (since they are in series and the balance plug is only for balancing during charging) and you just have to abort the charge once all five cells reach ~3.6v to give a total of 18v. Then retart it with the correct setting of 5s and they will all charge in unison until they hit 4.2v.

I know it kinda sounded like I was saying 'charge 4 cells up until they reach 3.6v/ 4.2v, then stop it & start it again until they all say 4.2v including cell 5', but what Im really saying is 'charge all 5 cells until they get to 3.6v whilst ignoring what the charger tells you about pack size/cell count, then stop the charge and restart it as a 5s pack until its fully charged'. **breath**

okey dokey ;)