Does a 2 year old SV-BAT-320 need a top-up charge?

[dc42]

I recently acquired an unopened SV-BAT-320 that was purchased a little over 2 years ago. I believe it was stored in a garage for all of that time. I am aware that lithium batteries should not be allowed to discharge too far so I am wondering whether it needs a top-up charge to keep it in good condition. I won't be ready to install it and the associated avionics for at least six months.

As far as I can tell, it's a 3-cell LiPo battery. I deduce this from the nominal voltage which is stated as 11.1V and from the stop-charging voltage which the documentation states is 12.25V.

It currently reads 11.90V with no load, which I have read corresponds to about 70% capacity for a LiPo battery. However, the packaging says it is shipped charged to about 35%.

Should I assume it's OK and do nothing? Or charge it? I have a LiPo charger that can handle a 3-cell battery, also I have a variable voltage and current bench supply; however it has 3A maximum output, so not enough to power up the associated Dynon avionics to use to charge the battery as I read it charges at up to 5A.

Finally, as the documentation says the ideal storage temperature is 0C, is there any reason not to keep it in a refrigerator until I am ready to install it, at least during the current hot weather?

 

[Rhino]

Pretty sure you can't use an external charger. It has to be hooked to the Skyview to charge, because the Skyview manages all charging functions. After connecting it, go to Setup Menu - Local Display Setup - Battery Backup (SV-BAT-320) Status, and it should give you all the info you need, including whether the battery is good or not. It will not charge if the bus voltage is below 12.25 volts.

 

[bbaggerman]

I have charged an SV-BAT-320 with a bench supply. I usually current limit to 1 to 2 amps to prevent heat buildup. Seemed to work great.

 

[Rhino]

The 320 has BMS installed that might not care much for an external charger, especially one not designed for that type of battery. Not everyone will have the ability to properly manage the current anyway. Some have fried the BMS with external chargers. While it may be possible, I wouldn't recommend it unless Dynon gave the okay. However, I don't really see a huge need for it here. Lithium batteries last a long time stored at partial charge, and it can actually reduce their lifespan to store them at 100%. I would say the OP was fine as is, but would recommend charging via the Skyview if necessary.

And by the way, unless the design has changed in the last few years, they're standard 18650 Li-ion batteries.

 

[bbaggerman]

I have been troubleshooting a battery charge / discharge problem and so have been doing some testing after bench charging the backup battery. The (assumed) built in Battery Management System (BMS) seems to do a good job managing the battery. When the battery is low it seems to cut out (probably to protect the battery from complete discharge), resulting in a voltage reading of 0.0V. I charge these at a constant current of about 1 amp. After about 4 hours (about right considering it is about a 4 Amp-hour battery) the charge current suddenly drops to zero, as if the BMS manages charging and stops the charges when the battery is completely charged (probably protecting the battery from over charge). So at this point I'd say charging from a constant current bench supply is very well behaved. 1 amp constant current does a good job for me.