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How to store Lipo;s

R/C Submarine modelers

How to store Lipo;s

Postby Chuck Chesney » Fri Sep 06, 2013 7:28 pm

Been running subs a long, loooong, time but have just purchased my first Lipo to give it a try over the old Nimh's. I have the requisite equipment, a Triton charger and a cell balancer, as well as huge abundance of caution and safety awareness. I do have a couple of questions that I'm sure will be childs play for many of you.
What state of charge should be on a Lipo for relatively long term storage? I'm talking about over winter, here where we have hard water for a few months. Also, is there a stand alone, on board, cell monitor on the market that will cut off the entire battery in the event that the battery runs at or below it's safe voltage? Better a boat dead in the water rather than a battery that's going dangerous due to low voltage, me's thinks. Any other tips regarding the Lipo's are welcomed as well. The boats will use brushed motors and esc's that don't have a voltage cut off.
Thanks,
Chuck
Chuck

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Re: How to store Lipo;s

Postby Giovanni » Fri Sep 06, 2013 9:07 pm

The battery should be charged to 3.85 volts per cell for overwinter storage.
This is always good practice for the whole year then top them up the night before your use.
Some people store them in a crockpot.

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Giovanni

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Re: How to store Lipo;s

Postby Sub culture » Sat Sep 07, 2013 8:57 am

Don't know the specifics of your charger, I use a different model. Mine has a setting built in that can charge the batteries for storage which is about 3.7-ish volts. I store the batteries in a cool place, some people go to extremes and keep them in the fridge- that might cause a bit of domestic friction however.

A tip from the (1:1) electric car people is to use lithium batteries between 20-80% of their capacity, this apparently extends their life considerably. That means not charging them to capacity, and not running them down too much.

The battery tech is improving all the time, what with the growing market for electric and hybrid vehicles and the huge market for potent handheld computers e.g. tablets, smartphones etc. driving the need for better capacity and cycle life.
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Re: How to store Lipo;s

Postby Chuck Chesney » Sat Sep 07, 2013 9:48 am

Thank you very much guys. We have sure come a long way from the early days, haven't we?
Chuck

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Re: How to store Lipo;s

Postby Sub culture » Sun Sep 08, 2013 7:56 am

Yes, primarily because the demand was there for such things. In the next four or five years the battery technology should improve exponentially. Several technologies in development which will offer ten times or more the energy density of todays batteries.
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Re: How to store Lipo;s

Postby bwi » Mon Sep 09, 2013 3:19 pm

Following works for me;

I use a balancer when charging lipo's, I have some offroad cars and use lipo's for batteries. For storage I "storage charge" them for about 80% of their capacity, after 6 months the capacity is only 300mA less then initialy "storage charged". During the "car" season the max charge rate I use is 1C, with 4 x 4000mA 2cell 25c batteries I run the cars continiously the whole day, with no problems@ all. I run competition buggies so the cars are quite demanding on the batteries. The batteries are 2 years old and still reach their capacity without remark. I will definitly use lipo's in my sub (when finished :) ).

Grtz Bart
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Re: How to store Lipo;s

Postby bwi » Mon Sep 09, 2013 4:45 pm

bwi wrote:Following works for me;

I use a balancer when charging lipo's, I have some offroad cars and use lipo's for batteries. For storage I "storage charge" them for about 80% of their capacity, after 6 months the capacity is only 300mA less then initialy "storage charged". During the "car" season the max charge rate I use is 1C, with 4 x 4000mA 2cell 25c batteries I run the cars continiously the whole day, with no problems@ all. I run competition buggies so the cars are quite demanding on the batteries. The batteries are 2 years old and still reach their capacity without remark. I will definitly use lipo's in my sub (when finished :) ).

Grtz Bart


Correction: the "storage charge" value is 50% not of 80 %, sorry about that.

Grtz, Bart
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Re: How to store Lipo;s

Postby chips » Thu Oct 10, 2013 12:09 am

[quote=Chuck Chesney]Also, is there a stand alone, on board, cell monitor on the market that will cut off the entire battery in the event that the battery runs at or below it's safe voltage? Better a boat dead in the water rather than a battery that's going dangerous due to low voltage, me's thinks. The boats will use brushed motors and esc's that don't have a voltage cut off.
[/quote]
There are several after market items that will work.
Kevin McLeod makes a unit called the Lipo Guard, works with 2 and 3 cell Lipo's.
Team Novak has the Smart Stop, works with 2-4 cell Lipo.
Lipo Shield is another one.

I've used units by Kevin McLeod and Novak in various models.
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Re: How to store Lipo;s

Postby Chuck Chesney » Thu Oct 10, 2013 9:58 am

Hey Chips....thank you very much.
Chuck

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