Measured voltage after charge cycle only 16.30 volts

Bart · Jun 25, 2016

I posted this problem in another thread but I'm going to start a new one so I don't hijack it.

I have a new solo and 2 new batteries with less than 5 cycles on them.

I just finished a charge cycle on both and the batteries shut off as normal.

With the battery turned on, I measured the voltage in both with 2 separate multimeters.

Battery A is showing 16.22 volts which is 4.050v per cell.
Battery B is showing 16.30 volts which is 4.075v per cell.

When I put both batteries into my solo and power it up, they both report 16.6v in the 3dr solo app and 98% and 99% capacity respectively

I'm charging both batteries with the stock charger.

Shouldn't I be able to measure 16.8v directly from the battery after a complete charging cycle? That would be normal for a 4S lipo.

Pedals2Paddles · Jun 25, 2016

You are correct. I've seen this before as well. I'd bet once you drain them down to empty and recharge, they'll fix themselves and show 16.8 at 100%

Bart · Jun 26, 2016

I've submitted a ticket to 3DR. I flew today with both batteries and took them down to 30%. After a charge I'm still measuring 16.30 on both. Perhaps I have a bad charger.

Pedals2Paddles · Jun 26, 2016

Why are you stopping at 30%? Fly them down to 5-6% and recharge.

Bart · Jun 26, 2016

lol I was in a hurry. I wanted to discharge them so I could see if a charge cycle would fix the issue.

16.30 volts for both batteries seems like a pretty deliberate value though. I wonder if the smarts in the battery are keeping the cell voltage at 4.05 on purpose. Perhaps this is part of a battery break-in period and after x number of cycles it will increase.

The other concern I have is why the solo app is reporting 16.60. What I might do today is take the battery tray out and measure the voltage at the PDB connection when the solo is turned on.

Bart · Jun 28, 2016

Update. I received 2 new batteries from 3DR today (from the BOGOF sale).

I've charged them and they both show 16.30 volts.

Bad charger perhaps?

pyrate · Jun 28, 2016

what voltage are you looking for, 16.3 seems about right. I did find this

9) It is not recommended to “top-off” a fully charged or near fully charged Li-Po battery. Attempting to do so may cause the charger to overcharge the battery, resulting in damage to the battery and possible fire. If the voltage of each cell within the battery is approximately 4.1V or higher, it is best to discharge the battery for at least a short time before attempting to charge it.
Do not charge a 2S (7.4V nominal) battery if it is at or above 8.2V Do not charge a 5S (18.5V nominal) battery if it is at or above 20.5V Do not charge a 3S (11.1V nominal) battery if it is at or above 12.3V Do not charge a 6S (22.2V nominal) battery if it is at or above 24.6V Do not charge a 4S (14.8V nominal) battery if it is at or above 16.4V
10) Li-Po cells should NEVER be charged to more than 4.2V. Any cell that is charged to a voltage higher than 4.2V may be damaged and could catch fire.
Do not charge a 2S (7.4V nominal) battery to more than 8.4V Do not charge a 5S (18.5V nominal) battery to more than 21.0V Do not charge a 3S (11.1V nominal) battery to more than 12.6V Do not charge a 6S (22.2V nominal) battery to more than 25.2V Do not charge a 4S (14.8V nominal) battery to more than 16.8V

Bart · Jun 28, 2016

I was expecting 16.80 (4.2v per cell) which is what most new'ish 4S lipos charge to.

Update: I took the battery tray out so i could measure the voltage with the battery installed and Solo powered up. Where the connection is made to the PDB I measured 16.60 volts which corresponds with what I see in the Solo app.

I don't know enough about smart batteries to explain this but there you go. It's not 16.8 but whatever. I'll update if 3DR responds to my ticket or I learn more.

prowler9 · Jun 28, 2016

Pedals2Paddles said:
You are correct. I've seen this before as well. I'd bet once you drain them down to empty and recharge, they'll fix themselves and show 16.8 at 100%

how empty? Like what %?

I always stop at about 20% - 30%

Pedals2Paddles · Jun 29, 2016

Stopping at 20-30% is a complete waste of time. There is no reason you can't fly it down to 5%.

16.8 volts is full. 16.3 is not full, and something is wrong if that's the best it will do. If both your new batteries are experiencing this as well, I would suspect the charger.

RichWest · Jun 29, 2016

@Bart , I assume you are the same over at DIYDrones -

"A followup to this. I removed my battery tray and measured the voltage at the pdb with solo powered on. Doing this I see 16.60 volts. "

New batteries - voltage only 16.30 after charge cycle

Bart · Jun 29, 2016

Yep, thats me. Even thought I'm not seeing a full 16.8 volts on the new batteries I'm calling this closed. It could just be these batteries are just getting old (shelf life) or that 4.15v is the cap that 3dr set for the cell voltage to extend their life.

Bart · Jun 30, 2016

Update. I chatted with 3DR support and 16.60 is the expected voltage of a fully charged battery. .20v is electronics bleed (assuming smart battery electronics). Good to have the confirmation though.

Pedals2Paddles · Jun 30, 2016

I think I see where they're coming from. 16.8 is fully charged, not 16.6. However, after the battery has been sitting for a while, you power on the solo, connect to the controller, and notice the voltage in the app, I suppoe 16.6 is reasonable. But if you've just removed it from the charger and are checking it with a meter, it should be more than 16.6.

KathyRo · Jul 6, 2016

Bart, there's a new thread regarding this issue:

Solo battery output reduced when not connected to Solo

Pedals2Paddles discovered that you won't see the full charge unless Solo is attached. The conclusion seems to be that 16.3V is "normal".