My radio discharges the battery very fast

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KP3AV
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Joined: Sat Dec 28, 2019 12:04 pm

My radio discharges the battery very fast

Post by KP3AV » Fri Mar 20, 2020 2:27 pm

Greetings friends :!:
I have a problem with my gd77 and that is that the battery does not fully charge, I noticed that problem again, but the battery worked a long time, now the battery does not give me even 7 hours in standby. is there any way to maintain the battery to make it work properly again?
Thank you
PS: Excuse my bad english

kt4lh
Posts: 86
Joined: Sun Jan 12, 2020 4:27 am

Re: My radio discharges the battery very fast

Post by kt4lh » Fri Mar 20, 2020 2:46 pm

Could be your charger is defective, see what your low battery and full battery voltages are.. Offhand not sure what low should be, but full should be around 8.3 after it's been off the charger for a few minutes, but still turned off. I've seen some cases where a failed charger isn't charging the battery properly so it's really never more than a quarter full or such.

VK3KYY
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Location: Melbourne, Australia
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Re: My radio discharges the battery very fast

Post by VK3KYY » Fri Mar 20, 2020 8:42 pm

The OpdenGD77 formware takes more power then the official firmware

It takes around 80mA without the backlight

The battery should be 2200mAH, so the radio should run for 24 hours on Rx.

There is no Standby Mode, it’s either receiving or transmitting

KP3AV
Posts: 4
Joined: Sat Dec 28, 2019 12:04 pm

Re: My radio discharges the battery very fast

Post by KP3AV » Sat Mar 21, 2020 2:22 pm

Now I have changed the charger and I see that it works better. But I could see that the voltage was at 8.3 and 100% when charging the battery with the radio on. Turn off the radio and when you turn it on again the radio indicates that the voltage is at 7.9 and the percentage of the battery drops to 83%. As long as you don't turn off the radio the battery works correctly

kt4lh
Posts: 86
Joined: Sun Jan 12, 2020 4:27 am

Re: My radio discharges the battery very fast

Post by kt4lh » Sat Mar 21, 2020 2:53 pm

KP3AV wrote:
Sat Mar 21, 2020 2:22 pm
Now I have changed the charger and I see that it works better. But I could see that the voltage was at 8.3 and 100% when charging the battery with the radio on. Turn off the radio and when you turn it on again the radio indicates that the voltage is at 7.9 and the percentage of the battery drops to 83%. As long as you don't turn off the radio the battery works correctly
That doesn't make any sense to me; the radio doesn't control the charge. And you should not charge with the radio running anyway. Few chargers handle that situation properly; they won't resume charging once the battery has finished charging and it just continues to drain.

Put the radio in the charger, off, until it finishes charging, remove the radio from the charger, wait about 5 minutes, and check the voltage. Wait another hour or so, check the voltage. Maybe even overnight or something. It should drop very very little, like 8.29 to 8.25 or something max overnight. Again; all with the radio off. To see if the battery is getting charged, and if the battery itself isn't self-discharging too badly.

If that turns out okay, it's possible your radio itself has some issue. Some internal issue that's draining the battery faster than normal. I only get about 12-14 hours on mine on RX, honestly, but 7 hours is quite a bit short.

How long have you had the battery, and have you discharged it to empty and recharged it every day for the last N months/years? If you use the battery like that you could have possibly just worn it out. Full 100->0 cycles you'll see less than 500 of before noticeable degradation of the battery. Recharge at 40% and the battery will last for years.

kt4lh
Posts: 86
Joined: Sun Jan 12, 2020 4:27 am

Re: My radio discharges the battery very fast

Post by kt4lh » Sun Mar 22, 2020 4:53 am

So for giggles today I tracked my GD77's discharge.. I started it a little after 12:30 and I'm headed to bed, but if I remember to I'll track it longer tomorrow.

It's on my hotspot, on a pretty quiet set of static talkgroups. Not sure how much rx activity, but not much. No TX. 5% minimum backlight, 100% max.

30% in first 5 hours, 6%/hr.
46% in first 8 hours, 5.75%/hr
50% in first 9.5 hours, 5.3%/hr
53% in first 12 hours, 4.4%/hr

Interesting that it drops more at the start. At the very beginning this makes some sense, but it continues to drop the entire time. Letting it continue to discharge might bottom out at some point, who knows. I'll let it run longer tomorrow if I remember to turn it on first thing in the morning.

kt4lh
Posts: 86
Joined: Sun Jan 12, 2020 4:27 am

Re: My radio discharges the battery very fast

Post by kt4lh » Mon Mar 23, 2020 2:56 am

Did another run today, very similar numbers to yesterday really. Lower at first, but I think because likely I assumed 100% at first yesterday when it really wasn't; I paid attention today and noticed it started at 94%.

Turned on at 10am, was 94%
12% in first 4 hours, 3%/hr
37% in first 8 hours, 4.6%/hr
47% in first 11 hours, 4.3%/hr
54% in first 13 hours, 4.2%/hr

So assuming the last half of the battery behaves the same as the top half, 22 hours, ish. Again, not good to discharge the battery like that frequently but good to know overall.

VK3KYY
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Re: My radio discharges the battery very fast

Post by VK3KYY » Mon Mar 23, 2020 10:45 am

Display of battery percentage is of battery voltage and not battery capacity.

Its not possible to determine the power consumption by the radio as it does not have the necessary hardware, which mobile phones have, to monitor the current being taken from the battery, to model the probably percentage of capacity left in the phone.

But you'll find even on your mobile phone, with the extra hardware and a team of paid developers, that the battery percentage will not be linear with time of use.

kt4lh
Posts: 86
Joined: Sun Jan 12, 2020 4:27 am

Re: My radio discharges the battery very fast

Post by kt4lh » Mon Mar 23, 2020 4:22 pm

VK3KYY wrote:
Mon Mar 23, 2020 10:45 am
Display of battery percentage is of battery voltage and not battery capacity.

Its not possible to determine the power consumption by the radio as it does not have the necessary hardware, which mobile phones have, to monitor the current being taken from the battery, to model the probably percentage of capacity left in the phone.

But you'll find even on your mobile phone, with the extra hardware and a team of paid developers, that the battery percentage will not be linear with time of use.
Yep, I know it's not exactly perfect. Monitoring current coming off the battery would be better, and you've mentioned 80mA figures before which would come out to 27.5 hours assuming all 2200mAh of the battery are available, so it's reasonably on target.

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