[NSRCA-discussion] LiPo Storage Voltage Question

[Larry Diamond]

Yes, my understanding is the pack was peak charged to 4.2v/c and that over a period of 3 to 4 month later (winter) the pack had puffed and the voltage of one cell increased to ~5.0v/c.

 

We didn’t discuss how it was stored with regard to physical storage; such as…exposure to extreme heat, cold, etc… they are unknowns…

 

He has been in the battery business for a long time (prior to LiPos gaining popularity in RC) and a long time RC guy who is very active with electric RC and continues to push the limit on electric motor systems and the batteries packs.

 

From: Ihncheol [mailto:pnahobbies at sbcglobal.net] 
Sent: Thursday, May 16, 2013 12:17 PM
To: Larry Diamond; General pattern discussion
Cc: pnahobbies at sbcglobal.net
Subject: RE: [NSRCA-discussion] LiPo Storage Voltage Question

 

Larry,

I've never had a pack that actually had the voltage rising above charged 4.2v per cell.

 

Is he telling you voltage increases if the pack was stored in lipo charge bag, fully charged?

 

Not something that I am aware of using lipo for past 9 years.

 

 

Sent from my Samsung Galaxy Note® II




-------- Original message --------
From: Larry Diamond <ldiamond at diamondrc.com> 
Date: 05/16/2013 11:57 AM (GMT-06:00) 
To: General pattern discussion <nsrca-discussion at lists.nsrca.org> 
Subject: [NSRCA-discussion] LiPo Storage Voltage Question 



A few days ago this was a topic dicussed at length about LiPo charging and storage practice.

 

I learned a bit and thanks to all the posts sheading light on the topic...

 

One question that I asked my local battery guy rewarded me with a response I didn't expect. Has anybody else observed this?

 

Here is his claim/actual observation:

 

"If a LiPo is stored after a peak charge the voltage may tend to rise over time to as much as 5.0V+ for a single cell."

 

After the discussion topic on here and discussing the issue with my battery guy, I have came to the conclusion that storing a LiPo battery is much safer at a lower voltage state (~3.9V/Cell) to prevent an inadvertant puff due to an unstable cell(s) climbing voltage over time. I recall the discussion about an unstable pack, but I don't recall any mention of the voltage climbing. Perhaps I missed it and it seems worth revisiting anyway.

 

Basically any LiPo battery stored over a 2 week period should be charged/discharged to a storage voltage or a nominal 3.9v/cell. Storage voltage opinons vary from 50%+ (~3.9v/cell+)

 

Internet references show 50% charge =  nominal 3.85V/cell)

 

Additional thoughts on the peaked battery increasing in voltage over a longer period of time...???????????

 

I just bought six new 5s-LiPo Packs and I'm new to this stuff... So what say you experienced folks?

 

Larry Diamond

 

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