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Storage level for Lipo


Basil
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4 minutes ago, Basil said:

Thank you gents, 35% it is then. It takes forever using the discharge on a charger. I am using 12v auto bulbs to initiate the discharge, with a check on the charger to finish.

Bas

The other thing to do is to charge your packs after flying to storage level.  That will reduce the time for the full charge when you choose to do that.  That way, you won't end up flattening a pack because you were distracted at a critical moment!  If you do end up with the pack a little below the minimum of 3 v/cell and your charger won't charge them, try selecting NiMh and charging at 50 mA until the lowest voltage cell has gone above 3 v.  Then switch to normal LiPo charging.  If that doesn't work, then the pack will have to be replaced.  I have recovered a pack this way and it went on to give good service.

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Thats good info Peter, I was aware that a lower voltage would present problems . Now I have a possible solution from your advise.

I have some large Lipo's each one is at least several hours to run down on the charger , whereas its in minutes using auto bulbs. I try say 5 mins then after a check work out what time for the rest of the charge, allowing a liitle for the final charger run to the correct level. Far quicker...................

Bas

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Hum, all my lipo chargers/dischargers use a storage voltage of 3.85v to 3.86V (50% cap) by default. These are Thunder Power and I-Chargers. Also all the pamphlets that come with my latest Lipo batteries say to charge the batteries to 3.85 per cell as soon as you receive the battery.

 

The lipo batteries are shipped at 3.7V as a result of the Department Of Transportations (DOT) regulation. DOT is trying to limit the potential energy (danger) when transporting batteries. They are not concerned with battery life. I can't find any data from a battery manufacture or vendor that suggests that 3.7V is to be used as a storage voltage.

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Please, please, please, take note of the individual cell voltage, not some potentially spurious % figure for the whole pack. Such a figure can be very misleading. A  3s1p pack retaining a good state of charge in two cells, but with one cell's voltage significantly reduced can return a % for the whole pack that you would be quite happy with, but one of those cells is in trouble. For storage voltage, charging to a certain percentage simple does not provide you with the information that you need to keep your packs in good health, Measure the individual cell voltages and aim to store the pack with all cells at approximately 3.8 -3.85v/cell, The majority of the wee battery checkers will give the individual cell voltage, which may need clicking a button to cycle through the readings for each cell.

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My old 4 button type charger takes a LiPo to 3.83V/cell but the storage charge also recharges cells automatically to storage if any or all cells are below that level. Very convenient if you have worked a LiPo hard as a storage charge is still all you have to do.

There is still a minimum battery voltage set by the number of cells that prevent the charger starting. It is worth remembering that a "non chargeable" by low voltage LiPo even if you rescue it will have been damaged internally so will either have lost some capacity and/or have a raised the internal resistance. Don't over discharge a LiPo too often.    

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  • 4 weeks later...

I bought a Toolkit RC MC8 Multi Checker.  https://www.hobbyrc.co.uk/toolkitrc-mc8-cell-checker

Because it has a USB output socket and I can recharge my phone, tablet, Powerbank and laptop with it.

That way I don't waste the charge in any fully charged but unused batteries at the field or indoor flying.

Please note it does not automatically cut off when the battery gets to 30 or 40% storage charge point. 

So I either have it alongside me and manually check progress, or I can add a LiPo alarm set at 40% to the battery.

Saves on wasting expensive energy.

John M

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Hi John

 

I'm confused.  This seems to be a battery/cell checker and cell balance.  It doesn't charge or discharge according to the description on the link.  So, how do you use it to discharge your packs?  I may have misunderstood what you said and that you use a separate discharger and then use this checker to check on discharge progress.  Be interesting to know what you meant.

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13 minutes ago, Peter Jenkins said:

Hi John

 

I'm confused.  This seems to be a battery/cell checker and cell balance.  It doesn't charge or discharge according to the description on the link.  So, how do you use it to discharge your packs?  I may have misunderstood what you said and that you use a separate discharger and then use this checker to check on discharge progress.  Be interesting to know what you meant.

 

Maybe

 "Because it has a USB output socket and I can recharge my phone, tablet, Powerbank and laptop with it.

That way I don't waste the charge in any fully charged but unused batteries at the field or indoor flying."

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