guver

My Feedback: (325)

In a series circuit all cells get the exact same current , time and thus amount of capacity added. This is the purpose of the rule "all cells must require the same amount of charge" A balancer will correct minor differences if used.

guver

My Feedback: (325)

This is the part that concerns me , that is the part about using up a certain amount of capacity of the packs. Theoretically if all packs (cells) were at the full level and 800 mah were used from them then 800 could be replaced in series with good results. I guess I'd be concerned that your figure is estimated. Could one have 550 removed and another have 1050 removed?

I have done some basic testing with capacity charging lipos at fast rates and it's pretty accurate , but one MUST know the charger AND the pack and the exact capacity required for charge. It NEEDS to be very accurate. I estimate within 1 mv and 1 mah for fast charging and it gets me close. I have an idea that handiman meant when he asked whether the packs are used together in series. This would be a way to ensure that they all require the same amount of charge. In otherwords if they are used together in series then it's just fine to charge them in series too. If not then it's kindof a guess of how depleted they are , right?

Goldenduff

Buy another charger! 200w chargers are so cheap especially when compared to burning a house down!

Max_Power

Are you still basing this on your 2 previous posts that this 134+ (16.8x8) watt charger is only 50 watts? Seems to me like some people would rather buy new stuff than use their old stuff to its listed capability(which usually has a large safety margin) This post started as how to use my charger and balancer , which are both capable of charging a 4s 5000Mah battery to charge 2 packs in a configuration equal to that.
So is making a harness to place both of these packs on my equinox as a 4s to balance them while charging at 16.8 and 5 amps via my ICE not safe for some reason other than some folks would rather just go buy new stuff? This is where the post started until it was suggested to use the balancer on the side. Because it is within both of their spec. Then we got sidetracked to I needed a bigger power supply, a new charger...that the ice was only 50 watts, incorrect series parallel calculations, etc. I was really just looking for verification of the pinout on the equinox. I am never out of sight of charging lipos , do them in a firesafe container, have 3 fire extinguishers within 50 feet, and 9 times out of 10 do them on my concrete driveway. These packs are driven in the same manner, the same duration in minutes, and are identical, bought at the same time, and have the same number of cycles.. charging them normal with balancer the exact charge they took is always within 100mah(2% variation).. Assuming I check each cell with a voltmeter before charging is there a reason the ice and duratrax can't do this?

Lets say that one did have 550 removed and the other 1050...if the balancer was charging them in series would this (10%) really be more of a variation than the balancer could handle? From reading the exuinox manual it seems to imply that as long as all cells are between 2.75 and 4.2 it can balance the pack.

So once again for clarity, If I wire the 2 packs to my equinox like this and charge as a 4 cell at 3 amps ?? (I will actually go 5amps and build in the high current plug on the balance lead as electrifly recoomends for up to 6 amp charging but I don't want to draw a new picture and dont want people to start on "but you can't balance at more than 3 amps without it tangent")

Handiman

My Feedback: (2)

kahnen

Your just looking for a diagram on how to wire your balancer?
I don't know what type of plug it has but here is some different ones.

Courtesy of this page:
http://www.scriptasylum.com/rc_speed/lipo.html
way on the bottom, in the section of lipo balance connector.

guver

My Feedback: (325)

Yes, this would be a gross imbalance and a lot more then the equinox would like to handle. The manual should really be clearer and should read as follows: All cells need to be equal , but can be at any voltage between 2.75 and 4.2 volts. Hopefully this clears it up.

trax de max

why not just buy a 2s to 4s adaptor.

Max_Power

Trax, what I am talking about is just soldering one up verses buying one, should be the same?? I like many just don't believe in buying things I can make myself with things I already have....Probably a generation gap thing

Handiman, your thinking just isnt right IMHO , if you are charging 4s in series. Does a 2000mah 2s pack take twice as long to charge as a 2000mah single cell pack? Are your 3s airplane packs taking you 3 hrs to charge? no, because although you are charging at the cell mah rating, you are not charging at a 1cell voltage level, you are charging at a 3 cell voltage level. If 2 cells at 6 amps and 8.4v charge at x minutes, at double the voltage(16.8) 4 cells at 6 amps will also charge in x minutes...If you had them in paralell at 2 cell voltage they would take 2x(because there are 2 paths so the current is halved) but that isnt the case in question. You can either wire in series and double the voltage, or wire in paralell and double the amperage if you were trying to make the charge time the same. http://en.wikipedia.org/wiki/Series_...allel_circuits Incorrect information can be as dangerous as unsafe practices in this situation so honestly you might look at that page. I too also am sometimes sitting around doing other things while charging, but other times I am at the track,etc where it would be nice if I could charge 2 batteries in the same time as 1. Guyver the 10%(.4v+-) would be excessive for the balancer?, or the 2.75 to 4.2 that the manual implies?

Max_Power

Kahnen...THANK YOU...your links seem to confirm my schematic plan. Thanks, Todd

guver

My Feedback: (325)

10% depending upon how we define it would be a bad imbalance. I's consider 4.2 and 4.15 to be about 10% and the equinox could probably handle this amount.

4.2 - 2.75 would be over 100% imbalance. The way I calculate charge status is 3.7 0% and 4.2 100%

Let me recap here anyways for my own understanding. You have 5000 mah packs and only pull < 1000 mah from them every run?

ps. You DO have a good understanding of the parallel , series, wattage, current , voltage thing. You're all set.

Max_Power

Yes, about 900 mah on average. I pretty much bought the batteries that everyone seems to run in this "spec" class at the local rc car track, which are about the exact size of the tray in the car. I was pretty surprised when I started running it and figured out that I was using so little of the charge. Funny thing is...The more experienced people have advised me to reduce pinion size which I'm assuming will require even less juice! At least I feel like the batteries should have a long life as I'm only taking 900mah out of a 5000mah 50c pack in 8 minutes! A amazing difference from 4 minute Trex flights on $100 lipos just a few years back! You gotta love the rapid advancement and price drops of electronic technology. Thanks, Todd

Goldenduff

Hi, if you got smaller mah with maybe larger C if needed the car would be lighter and go better?

Max_Power

Why does everyone always want me to go out and spend more money?[8D] Not trying to pick on you personally, but honestly it blows my mind how many RCU responses are to "stop using what you have and go buy this or that" To me its like where Hot Rods went from 1960 to now....from people skillfully tweaking their car when you couldn't even buy a aftermarket cam or headers to what we have now which is just a wallet race where everything bolts on straight from the big brown truck. Its just not "cool" to me, I like to see what I can do with what the average guy has or can afford, or what I've already got. Most of the reason this topic even came up was just me not really wanting to buy more gear. Actually I think my driving skills are the big limiter and its one of those "price point" deals where to get less battery with a higher "c" rating costs more. Like I said before its just too easy to $75bucks yourself to death in this hobby and in my 25 years of rc'ing I just think it honestly detracts from my enjoyment. Its like aluminum parts, they look neat...but most the time are really not as good with all things considered as the stock plastic stuff....But I do appreciate your input and suggestion! Todd

Handiman

My Feedback: (2)

trax de max

It is good to make things work yourself, I have done a few things, but sometimes for small things, is it worth it, To me it has to be cost effective when it's complete.
The topic has swayed of course a bit, I don't even know if you decided on ballancing/not ballancing, connecting in series/not in series. all i know for sure is the charger/ballancer and spec of lipo.
but either way be safe, be happy

gwweber

My Feedback: (24)

CAUTION  I have had a lipo fire due to improper charging.  Live in a apartment and almost had a major issue.  Lots of flames and smoke you would not believe.  SIMPLE  Do not take a chance to keep from buying another charger, NOT WORTH IT.  Every charge with a lipo is a ticking time bomb and you need a balance lead attached.  I now use a hitech X4 charger and have a second one, A hobby king knock-off that works just as well and appears to be the same unit with a different looking push pad and different wording on the start up screen (stored in rom somewhere no doubt).  My lipo bag did not contain the issue at all and my transmitter (NEW DX8 about a foot from the lipo bag) got fried by the exhaust coming out the side of the bag.  I saved money of the junk chargers i was using at the time. but lost a tranmitter and have a large hole in the top of the desk where i was charging. 
Also I stress that I am using what I consider to be a good power supply (25 amp competetion electroncs) and can charge 4 6s packs at up to 5 amps each though i never charge more then 3.5.  The better the power supply the better the charger seams to work.  I see some pretty nice chargers with the power supply built in, but they dont seam to hold up the same and I think it is good to seperate the heat from the power supply and the charger.  Sorry bout the long winded response, but serious, who needs a Liipo fire in their workroom, airplane, heli or car.

guver

My Feedback: (325)

what did you or the equipment do that was improper? What caused the overcharge?

gwweber

My Feedback: (24)

lol   was too cheap to buy the charging boards   MY FAULT   Point being to use the correct equipment because lipos are too dangerous to take chances

Max_Power

So you were parallel charging 2 lipos with no balancer at all? Cmon, give us the juicy details what batteries? what charge rate? identical batteries? Through the discharge leads? Its easier to take heed in your warning if I know what actually happened. Don't think I'm trying to enjoy your horrible experience, I'm just trying to learn from it. Honestly if you told me you were parallel charging a 1000mah 3s and a 4000mah 4s through the discharge ports at 7 amps or something I would have to say thats a entirely different situation than trying to do what we are discussing. This is why I am somewhat skeptical.....All the cases of lipo fire I find by searching there is some admitted human error which a different charger probably would not have changed. I mean, if you punch the wrong button or accidentally set the wrong charge rate, let 2 bare wires touch,etc it really doesn't matter if its a 2s battery or a 4s. Thanks, Todd

Max_Power

One could also argue that if I'm charging 2 batteries at once there is twice as much chance I will be sitting a foot away looking at the screen and batteries if something goes wrong....Many of the fires I see seem to have burnt something down because the user got tired of sitting there waiting and wandered off to fly or go to the other room.

trax de max

if you look at lipos themselves you'll see that there is 2s1p where the is only 2cells
There is 2s2p where there is 4cells but only two is monitored as a 2s1p pack
Then there is 2s3p 6cells but again only 2cells are monitored as a 2s1p pack
Thats without any parallel boards and these charge ok.
But if i was to make/buy something it would have to be in series like max power is doing, even though lots of people use the parallel method i don't trust it enough, I'd like to monitor the cells individually.
We want you to be safe Max and not burn anything down, or damage the lipo. Once you have made something double check again.

Goldenduff

Sorry to be a bit off topic but seeing as we have a few bright sparks in here.....

I have a few 3cell batteries for my small home brew foamies. I have a 1.6m PC-9 which I am thinking of making electric. A 6cell setup is suggested. I know I can wire 2 3cells in series to get 22.2v but my question is;

Any problem with connecting 2 3cells in parallel then connecting that in series to another 3cell in series? All of the lipos will be 4000mah so I would hope to get, in affect, one battery giving 22.2v and 8000mah or am I going to burn stuff to the ground?


Cheers