battery calibration

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Joined: Fri Feb 05, 2010 2:23 pm

battery calibration

Postby tonyburton » Thu Mar 10, 2011 10:33 am


Does anyone know any way of calibrating the E1 Chargepak? Mine is totally misreporting its level of charge, meaning that I suddenly get a low battery warning message and the radio switches off, even though the level indicator suggests there's plenty of charge left. It also seems to stop charging too early, too: I leave the radio plugged in to charge, after a few hours the battery icon suggests it has a full charge, but then if I tap the power button (just once – I don't actually need to turn it on properly) it starts charging again, and continues to for another hour or so.

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Joined: Tue Sep 28, 2010 12:34 am

Re: battery calibration

Postby Professor » Thu Mar 10, 2011 12:02 pm

Last edited by Professor on Thu Aug 11, 2011 11:42 pm, edited 1 time in total.
Fora - Where Everyone knows Everything -Everyone Else Knows Nothing

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Re: battery calibration

Postby electric » Sun Mar 13, 2011 10:09 am

I have a ticket raised with Pure technical support at the moment regarding this issue and they have promised to pass this on to the design teams to look into. In my observations the battery meter (icon) does not follow the true discharge of the battery. Firstly let me say I have no issues with battery life, the radio will run for 10-12 hours on a mixture of dab/internet radio playing at about half volume. The battery icon when it works correctly follows this pattern. After a full charge on AC the icon disappears. and then reappears when the mains is removed. The icon has 7 pixels inside a battery shaped outline. The 7th pixel go’s out within approx 1 minute of removing the ac supply, this I think is showing a high floating voltage on the battery due to just coming of charge. The next 6 pixels extinguish approx 1 every 1.5 to 2 hours. The outer empty icon will then show for about 30-45 mins and then it will flash, at this point you will get an intermediate low battery warning which you can reset, the radio will then play for approx 1 hour and give a second low battery warning and the radio will shut down automatically. When it goes wrong the icon appears to freeze at 30-50% level (3 pixels), the radio continues to play for several more hours with no indication that the battery is reaching it critical low level. The next thing you know is that the radio has shut down. I have removed the battery several times and measured the voltage and the battery is defiantly discharged (3.5 volts) but the level meter did not show this. I have even had a battery that has cut off on its own internal safety circuit due to low discharge this battery measured (0 volts) an indicator that this had happened. Normal battery voltage is from 4.2V full to 3.5V discharged. I have suggested to Pure this maybe a bug in the firmware as a factory reset appears to reset the level meter to the correct value but then it will get it wrong again.

Jason Voice
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Joined: Thu Dec 17, 2009 11:27 am

Re: battery calibration

Postby Jason Voice » Wed Mar 16, 2011 12:14 pm

Hi All

There is no real way to 'calibrate' the ChargePAK other than to start it with a good solid charge while the radio is in standby (over night with the radio off). Try unplugging the radio from the mains and remove the battery. Leave for 20 seconds or so and reattach the battery, and then plug the mains back in and leave the radio in standby to charge over night. This will ensure the meter is calibrated correctly to its current state.

As regards subsequent inaccuracies in the meter when using the radio - yes there are going to appear to be more than - say a mobile phone device, which I think is generally what everyone compares to these days.

In the case of mobile phone battery meters, phones have a couple of major advantages over radios, such as the sophistication of battery meter tech which can utilise elegant coulomb counters etc, which although is extremely expensive, can be offset and subsidised by the time the user has to pay for it.
A mobile phone's power consumption is also very easy to read as the current consumption in its modes (standby, idle (waiting for a call), in a call, playing a game, etc) will be pretty stable – and can probably be estimated to a few milliamps. The pone software just needs to use these typical power figures, along with a timer to determine how much power is being consumed by the phone.
On top of this, a phone battery is likely to be a smart battery and will have its own record of charge cycles etc (that can affect battery capacity), and armed with all of this information, the battery life can be calculated very accurately and evenly.

In the case of a radio running a ChargePAK, we have the problem of very variable and high power consumption that is difficult to predict - and this can be reflected in apparent erratic behaviour in the battery meter. This variance is due to the audio, and power consumption is dependent on the volume setting of the radio. However, it’s also dependent upon the ‘loudness’ of the radio station being broadcast – something we have no control over. For example, for the same volume setting, Capital Radio will draw more mA from the ChargePAK compared to BBC Radio3. This is where a coulomb counter would be useful but it would come at a prohibitive cost.

Generally speaking, I think our products handle battery well, but yes you may see some small inaccuracies on occasion depending on how you are using the radio. A user trying to turn up the volume on a low or flat battery will introduce problems that are difficult for us to predict and handle.

I hope this helps.

Jason Voice

Jason Voice, Technical Support Manager

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Joined: Fri Feb 05, 2010 2:23 pm

Re: battery calibration

Postby tonyburton » Sat Mar 19, 2011 3:38 pm

Thanks for the suggestions, both of you. I will try a factory reset and also the unplugging the battery technique.

Having said that, I listen to the radio only using wireless, and I rarely change station or volume. Despite this, on a number of occasions I have had the radio suddenly switch off because of low battery when the battery indicator has suggested it was about a third charged (and not after cranking up the volume or anything like that). I can tell it's going to happen now as it starts to make loud clicking noises through the speaker about ten seconds before it switches off, so if I'm lucky and have the charger nearby I can sometimes catch it. Then it normally resets itself, does the same thing, switches off and resets itself again, and then eventually switches off and won't switch on again without power.

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