charging lipo's without balancers

[dkingston]

Originally Posted by JohnRobHolmes

The termination for lipo is 8.4v for two cell packs. You are certainly pushing your luck and greatly reducing pack life by doing this. A perfect "dont try this at home" sort of thing.

I know, I know.


- David

[holycaveman]

Originally Posted by Harvo

So is that an acceptable "balance"? I have the 1300 2S that you sell. I haven't managed to come up with a trinity tap yet. Have you had good luck with those cells staying balanced? Because it might be a while before I can balance that one

I would look at it this way.

Since you don't have a balancer, and John has sells matched batteries. I would not just go charging it everytime. And I think John is saying this also.

Things can happen.

So.....what you should do since you have a good battery and no easy way of balancing it. Is to monitor your voltage of each cell. This is easy to do, and I will post how.

By the above method that I somewhat explained, it should keep you safe.

Because you are monitoring your battery. And if you keep checking it should not be able to be overcharged.

Check your initial voltage drop between cells, on your new battery it should be fine. Then proceed with normal charging. However part way through the charge, stop it. And check your voltage drop again, to make sure things are fine. Then proceed.

Doing it this way you are basically doing what the balancer does, minus bleeding the cells. However the slow charge method does seem to take care of this.

I have my lipo fully drained. So I will post pix of how I have been doing it without a balancer.............More to come

[Harvo]

Originally Posted by holycaveman

I would look at it this way.

Since you don't have a balancer, and John has sells matched batteries. I would not just go charging it everytime. And I think John is saying this also.

Things can happen.

So.....what you should do since you have a good battery and no easy way of balancing it. Is to monitor your voltage of each cell. This is easy to do, and I will post how.

By the above method that I somewhat explained, it should keep you safe.

Because you are monitoring your battery. And if you keep checking it should not be able to be overcharged.

Check your initial voltage drop between cells, on your new battery it should be fine. Then proceed with normal charging. However part way through the charge, stop it. And check your voltage drop again, to make sure things are fine. Then proceed.

Doing it this way you are basically doing what the balancer does, minus bleeding the cells. However the slow charge method does seem to take care of this.

I have my lipo fully drained. So I will post pix of how I have been doing it without a balancer.............More to come

Looking forward to it

[holycaveman]

Alright, I have started my regiment of charging lipo's without balancers.

I don't have a balancer at this time, did have though.

Battery is a 3200mah 3s lipo.
chargers is a thunderpower tp535
fluke voltmeter.

First thing I do is test the voltage of each cell to tell the difference between cells.

The first cell:


Test between red and black wire, be carefull not to touch wires so as to connect them with your probe!! This will short the lipo.

Second cell:


The same black wire as above, and the next black wire


And the third cell:



Testing between the last two black wires, for third cell.





Now the only thing I am concerned about right now is the max difference between cells. In this case its the difference of 3.75vlts, and 3.54

[holycaveman]

So my max voltage drop between cells is .26 volts.

This is pretty poor. And should not be charged at full 1c charge(3.2amps/3200mah)

So I am going to charge this pack at .5amps untill it is within balance limits. Which is around .02vlts, give or take .01vlt. I try to get it within .02vlts before I do a full on charge of 1c.

So .5amps is the lowest setting on my particular charger, and that is what I have to go with, I believe .3amps would be better.



It looks like its set on 2cell, but its 3, camera angle you know. Also as others have stated, its best to have a fireproof container.

Since this is live, you got to wait untill it finishes the charge/balance.

[holycaveman]

Alright its been about 15 minutes or so. Time to check the voltage between cells, charging at .5 amps.

We started out with a drained lipo with a max voltage difference of .26vlts

So after about 15 minutes at .5amp charge. I shut the charger off, unplug the battery, and test for the max voltage differenc(drop)

First cell reading:



Second cell reading:


And third cell reading:



Now we have a difference of only .02vlts.

And now the lipo can be charged at the full 1c which is 3.2 amps, or in my case 3 or 3.5 amps. I have done both to good success. But we will stick with a safe 3amps.

[Calicrawler23]

That's awesome, thanks for the instructions. Mines at 3.78, 3.80, and 3.81.

[holycaveman]

Originally Posted by Calicrawler23

That's awesome, thanks for the instructions. Mines at 3.78, 3.80, and 3.81.

no Problem. The full verdict is still out on this. So always proceed with caution.


When my battery falls into a .03 -.05vlt drop like yours. I usually go with a .5 c charge. Say 2000 mah battery @ .5c would be a 1amp charge. I would rather be safe than sorry. Plus in my findings the lower the rate of charge, the easier it is to keep the pack balanced. And this .5 c charge is just untill the battery balances at .02 or better between cells. Then on to normal charging at 1c.

[holycaveman]

Now its been part way through the full charge, and I am going to check the condition of the cells again.

So I stop the charging, and unplug the battery.

1st cell:


2ond cell:



3rd cell:



Still at a .02vlt max difference. Which is fine.

Now remember weather or not my charge to balance theory is correct or not. What is more important is that you are monitoring the condition of your lipo. You have no balancer, and you don't want to ruin your battery or your house! LOL Of couse not the house because you are charging the lipo in a fireproof container, right!


As long as your balancing stays pretty tight, and you do not charge any one cell over 4.21vlts we should be a happy camper.

Theoretically the tighter your balancing, the higher overall voltage you can carry.

Most balancers balance to a .005 vlt tolerance, if let go untill the blinky stops, otherwise you will be looking at .01-02 volts difference using a balancer. I am happy if I can max out between 4.18 and 4.21vlts, keeping a max voltage drop of .01vlts, maybe .02. without a balancer

[holycaveman]

Couple things to note about reading voltages. I am using a high quality meter. I also use the lock setting. Which locks the peak voltage at the moment. Then when you check another lead, it locks that one.... and so on.

If you have a cheap meter, I would not put to much faith into your readings, they may be fine, but again?.

Also note that your meter may change .01 volts or so if you test it directly again. This is normal. Take the average.

Again the main thing is to monitor your lipo, and stay safe and within their parameters.

[holycaveman]

Chharger alarmed that the battery was at a full charge. So I disconnected the battery and tested the voltage of each cell.

1 cell:



2 cell:



3 cell:



Great, only a .01 voltage drop. However my cell voltage is 4.15/14. So since there is only a .01 difference. I will throw in back on the charger for a .5 amp charge to try and peak it out abit more.



Also this tells me that my battery is safe to charge. Weather or not I have a balancer now makes no difference. Sure I could balance the cells out from .01 to .005. IF I left the balancer on until all lights quit working.

In my experience(which is minimal) I have not noticed a lot doing this.

We will see if the extra .5 amp charge does anything?

[holycaveman]

So finally the end of my charging! LOL without a balancer.

Lets redo my steps abit of charge balancing.

1. measure each cells voltage. = .26 max voltage drop between cells
2. Charged for 15minutes at .5 amps.
3. measured voltage again. .02 voltage drop max Good
4. Charged at full 1c 3200mah @3.2 amps(3amps for me)
5. Half way through (roughly) disconnected battery and checked voltage. = .02 max put back on full charge.
6. Charger said full charge was completed. measured each cell again. Showed only a .o1 vlt difference max with 4.15/14 as peak voltage per cell
7. re charged at .5amps. When charger peaked again.

Last peak charge at .5amps

Cell 1:



Cell 2:



Cell 3:





Not much more overall voltage was achieved, however balance turned out great!!

Now this pack has been so far out of balance it took almost two hours after full charge using a balancer to achieve balance.

I have just about 20 runs on this battery without a balancer. Never would I say throw away your balancer. But I believe this shows how we can effectively monitor our batteries even if we don't have all the bells and whistles.

I like you want my batteries to last and to preform. But sometimes I can't have all the tools I want.

I am a newb to lipo's, so if I posted something you feel is bogus, please for others sake let me know.

Otherwise I hope my learning may help others to understand how these things work a bit more. And vise versa.

[JohnRobHolmes]

The real test of the method: drain one cell 10% and see if it will catch up with your charging method. It shouldn't, since the cells are in series when being charged. If the drained cell happens to catch up I would be quite suprised!

[Calicrawler23]

I guess i shouldn't rely on my $2.99 Harbor Freight Voltmeter. But i will.

[JohnRobHolmes]

Originally Posted by Calicrawler23

I guess i shouldn't rely on my $2.99 Harbor Freight Voltmeter. But i will.

It may not be the most accurate, but it should precise.

[Calicrawler23]

The way i think of it is that if it's off .2 volts on one cell, it will be off .2 volts on the other cells.

[JohnRobHolmes]

Yep.

[Calicrawler23]

I'm testing this method right now. I've got a cell that is nearly 0.1v from the other 2. I'm giving it .2amps charge. If it doesn't get anybetter, i'll try draining the battery a bit and recharge it.


Edit: I gave it 20 minutes at .2amps, and it didn't help. So i drove it for a few minutes and checked it. Now it's around .03 difference between the cells. It's back on the charger at .4amps.

[Pzl1nz]

Originally Posted by Big Bill

Iam new to Lipos also, what are the safety issues you are talking about. Thanks

Fire. From overcharging, etc.

http://video.google.com/videoplay?do...60570423705609

[Pzl1nz]

Originally Posted by Calicrawler23

I guess i shouldn't rely on my $2.99 Harbor Freight Voltmeter. But i will.

I wouldn't trust anything you buy at that store. Find a nice Sperry on eBay