Hi Guys,

I am currently stuck in a dilemma about the usage of my newly purchased GensAce lipo batteries from rcmumbai.

I recently ordered a pair of GensAce 4s 5000mah 60c lipos from rcmumbai. I received my order yesterday evening, delivered via fedEx.

After opening the package, i found two nicely wrapped gensAce boxes with batteries inside. On opening them up, I noticed that the lipos appeared to be slightly bent and puffed, both of them. The level of puffiness seemed almost equal in both lipos. However, since i am a newbie, i am not sure how puffed they are.

When i tried pressing on the puffiness, the lipo still seemed quite hard to the touch, so the puffed up area wasn't soft at all.

I sent an email to rcmumbai today morning letting them know of the state of the batteries (along with pics) to which they responded that the lipos are not puffed, so i called them up.

One Mr. Chintal (I am assuming that's him because he had responded on the email) spoke to me and said that this is how the current stock of batteries arrived from the manufacturer under the assurance that the lipos are fine. Mr Chintal also re-iterated that the lipos are fine, and that others had used them and had no issues.

However, I am a little concerned about the puffiness, since these are new lipos, and I don't want to have bought batteries that are on their way out. Hoping for some directions from all of you in this forum.

Please take a look at the attached pics and let me know what you think. Looking forward to your comments.

How are the Resistance figures?

Unfortunately I havent had the chance to check them yet, although I have a Q200 charger that can do that.

The batt connectors are xt90s, and I dont have the relevant connectors to attach them to the charger yet. I have ordered converters from robu.in today.

In the meantime I used a batt checker to check the voltages: They are 3.82, 3.84, 3.85 and 3.86, varying slightly over multiple passes.

What should the internal resistance ideally be for a new lipo like this one? I can check in a day or two once I get the connectors, now that there seems to be no chance of a replacement anyways. 

I have a gensace 5300mah 65C 2S hard pack which I bought from rcmumbai around 1.5 years back.
They also came slightly bulged.
But did not have any performance issues.
Its gone through around 150 cycles and they still perform the same even the bulginess still remain same as they bought.

Another Bonka 2200mah 35C 3s bought 7 months back from another seller.
That too came slightly bulged.
But did not have any performance issues.
They are done only 20 cycles. bulginess still same as they bought.

My charger cannot check IR.
I am not saying your lipos are good or bad. Check the IR as others said.

Photos of current state.

The problem may not be with "rcmumbai" but with "mumbai"
The extreme humidity and water vapor, even in tiny amounts can quickly cause more unwanted reactions within the cell and produce even more off gassing and puffing.
I know they may be using the best of the best drying agents to keep their warehouse at low humidity... but believe me its hard to keep humidity off at least in Mumbai.   

Definitely agree about the Mumbai weather not being favourable to lipos..

In fact i dont think rcmumbai is in anyways at fault. My only concern is that the lipos shouldnt catch fire or explode or anything, as I am new to the hobby and dont yet have the experience required to identify a potential lipo damage.

Obviously as they are brand new, I am a little saddened....

Hi all,

As of now I have an update. I asked rcmumbai as to what is the guarantee that these batteries will last under normal use even for a smaller time period of 6 months. I need some form of guarantee that what was mentioned by phone holds true and there is indeed no issue in using these lipos, even though what I see with my own eyes isn't very encouraging.

This is with the assumption that rcmumbai are not in a position to give any replacement (again scary because apparently the entire stock is slightly puffed as per our conversation this morning) or refund.

RCmumbai then categorically stated that they 'do not guarantee any of their products', which I again suppose is okay. However, selling supposedly puffy Lipos and not providing a solution??...

I will reserve any more of my comments till I check the resistance of these Lipos in a few days, once I get the correct charger connectors. I will then provide an update here if I see any issues (although I already saw a max. difference of .04v to .05v between the cells.)

Keeping my fingers crossed. 10K is not a small amount...

You should keep a close tab on the Resistance values. I for a few months used a puffed Lipo..... the condition deteriorated exponentially while puffed.... even a simple flight controller started behaving crazy due to irregular current flow.

What resistance values should i look for? In terms of ranges? And what constitutes a dangerous value? I am scared now...

Also, will the resistance values vary...or is it a constant increase over time and usage?

I generally take resistance reading every 15 days.

Now to answer your question..... it depends on C rating etc.... may be this can help... https://www.rcgroups.com/forums/showthread.php?904305-Lipo-internal-resistance

Hey thanks a ton! That was a good read. I am out of station but returning tonight. I have also got the converter delivered so will check the IR and mention it in this forum.

Once again, a million thanks for all the help.

Hi, I now have an update. The IR of one batt is 3:3:3:2 and the IR for the other is 5:3:3:2.

Let me know what you think.

One thing I noticed was that the IR values varied a bit over multiple tries. For example first batt showed 2:3:3:2 once, etc. Same for the second, although the value of 5 remained constant.

One thing to note is that I havent used the batt yet. The values are for brand new, unused one.

if you have not used the batteries and don't believe that thats how all the batteries (same model)  are you can send the batteries back we will give you a refund
thats their shape by default and not puffed , please stop calling them puffed lipos.
All batteries are checked before dispatch and maintained , trust me it takes a lot of efforts to make sure customers get what they pay for.

Hi Mr. Chintal,

I really didnt mean to indicate your service quality in any way. Apologies if it sounded that way.

I hope you understand that I am just scared and hence looking for some reassurance. From the responses i have received, it looks like there isnt a problem. I read up on IR and the numbers also seem fine, so please rest assured I dont plan to return the batts seeking any refund or compensation.

As discussed with you earlier, I will definitely let you know if I see any unusual degradation of performance in the coming weeks.

Hoping to continue doing business with you in the future as well, as all seems good...no hard feelings. 

Thank you for understanding , happy flying