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Has anyone noticed that the shelf life of the Nano VNA seems a bit short ?
I had mine charged, and left it on the shelf for a few weeks and it died on me.
Seems to me to be some sort of high quiescent stand-by state possibly through the switch controller ?

Operating life, when charged and immediately used is good though, indicating the battery capacity as being about 400ma.

73 de Andy

I've noticed that my second unit's battery is starting to swell a bit. Time to swap it out.?

I think the batteries used on the copies of hugens unit are of low quality and are not lasting? as long as they should.? It might also be the counterfeit ip5303 charge controllers on some units as well...the ones that fail to sense load after a while and you need to add the power-on button to pin 5.?

YMMV



On Mon, 6 Jan 2020 at 4:38 PM, Andy via Groups.Io<punkbiscuit@...> wrote: Has anyone noticed that the shelf life of the Nano VNA seems a bit short ?
I had mine charged, and left it on the shelf for a few weeks and it died on me.
Seems to me to be some sort of high quiescent stand-by state possibly through the switch controller ?

Operating life, when charged and immediately used is good though, indicating the battery capacity as being about 400ma.

73 de Andy

On Mon, Jan 6, 2020 at 01:37 PM, Andy wrote:

" .. I had mine charged, and left it on the shelf for a few weeks and it died on me."
===========================================================
All battery powered devices exhibit some self discharge during storage. My cellphones and tablets when completely powered down require recharging after a few days. A few weeks in my opinion is a pretty good shelf life for a 400 mAh device. Both of my NanoVNA's were delivered via slow boat from China, and were in transit for over 3 weeks. Both retained enough charge to power on when they arrived.

Depending on supplier, some batteries may be better quality than others so its hard to make a blanket statement regarding battery performance from a product like the NanoVNA that has multiple suppliers. I noticed hugen's new version 3.4 pcb has a 650 mAh battery instead of a 400 mAh one. This should translate into longer operating time, at least until the 4" display is added.

- Herb

I finally found a few posts relating to this in the archives, and have to agree there's a problem. Someone had measured about 60?A of leakage when off - try measuring this on your unit and see how far it's off. At 60?A, this should last several months without charging - if it's flat in a month, that battery's not holding a charge as it's supposed to. (The Injoinic datasheet for their IP5303 says typical of 100?A quiescent current draw when off.)

IMHO, the charging system with the IP5303 is very wrong for the typical battery capacity of 0.4 to 0.45 Ah. Thus I'm worried about my battery now as I charge it. The battery, if you have a good cable and the power supply can do it, will be taking in a charge greater than 1C. This stresses the battery and likely will cause premature battery failure in cheap batteries.

The IP5303 is so inflexible that the only thing I can think of doing that doesn't waste charge energy is adding another battery in parallel, which will give enough load to balance out its seemingly inability to reduce charge rate for smaller cells. The IP5303 probably is expecting at least 1.5Ah of capacity or so, and likely less than 3Ah.

The power wasteful but simple solution is adding a resistor into the USB charging path to limit charge current. Maybe 0.33 ohms or so. This should improve the life of the battery pack, both cycle count and hopefully prevent pack failure, at the cost of charging time (and a resistor).

At the beginning I added ip5303 to NanoVNA just for my convenience. But I didn't expect it to be so popular with the community. Now I have realized that this design is not reasonable and has been improved in NanoVNA-H rev3.4.

hugen

OK well I know that the supplied battery is about 350-400ma and I get about 2.5 hour running time.
That to me says that the battery it good.

So it could be a high leakage / quiescent in the switch controller, or that I'm getting a bit old and forgetting just how
much I may have used my Nano VNA without charging it.

Both a highly possible ;-)

As for shelf life normally.

I have a whole bunch of Li-Ions in use here, 18650's, HT battery packs, spare cell phone packs.

I'd say that I would expect to find a 90% charge from anything from 3-6 months, or even 12 months.

Bit some cells seem to be worse than others, so it's not guaranteed.

The worst case is a spare cell phone battery that holds loses 50% in about 6 months.
These figures assume that I have properly isolated the terminals from the equipment.

Otherwise it is easy to be mislead.

My Wouxun HT's are quite poor in this respect, they would need a good top up charge after a few few weeks if not isolated
due to power switch leakage.

On the other hand, my Baofeng UV5R and others don't seem to give rats ass about storage and easily hold 80% charge for
6 months or more. Not Nano VNA related, but a useful comparison of shelf life.

Sent just for info only...

73 de Andy

On my nanovna clone the battery was slightly bulged from the factory.

It's mad that the known wouxun fault from 2010 still persists (they put the battery voltage measurement voltage divider BEFORE the power switch. So the 1600mAh battery lasts almost exactly a week in storage with that drain). Baofengs have been a bit hit & miss, one holds charge for months easily, while the other only for a few weeks.

Lithium chemistry battery charges have a setting called "Storage Charge". Why? Because storing batteries with a full charge contributes to the swelling that you see. All my RC plane batteries are stored with a charge level of "Storage Charge" usually about half capacity. They keep a long time that way. Yes, I have to charge them before I use them.

I would advise that you put your nanoVNA away after using it without topping the battery. You'll have enough energy to make a quick test or two. If you anticipate needing to use it for a period of time, charge it up or leave it connected to your PC while you measure. But, then put it away with less than full charge.

If you suspect your unit has a drain current while it's on the shelf, charge it once in a while. Not fully. Just enough to bring it back to storage charge level. Don't forget, if you discharge a lithium battery down to about 3 volts per cell, you will likely ruin the battery.

Oh, and NEVER short them. They make GREAT fires.

BruceN / K4TQL

--
*"To invent, you need a good imagination and a pile of junk"* -- Thomas Alva Edison (1847-1931)

On Tue, Jan 7, 2020 at 03:06 PM, BruceN wrote:

Lithium chemistry battery charges have a setting called "Storage Charge".

Interesting, I'd never seen that parameter on data sheets before.
That'll give me something new to study ;-)

73 de Andy

On the nanoVNA(H) the spec on the IP5303 says its standby is less than 100 uA, assuming it's 'Smart load detector' detects the unit has been turned off and puts the chip in standby. For a 450 mAH battery that should be upwards of six months.

LiIon's have very low self discharge and should not be the issue. If the cell is physically puffing up like a party balloon it is being over discharged and the battery will go bad within several months unless you keep up on recharging it every.four or five days. The nanoVNA(H) has a diode from battery in series feeding the Vbat input to the STM processor. Firmware could be causing too much draw on the Vbatt line. I do suspect the IP5305 is charging the battery at too high a rate for the small 450 mAH battery.

The nanoVNA-F is a different animal. It has two 10k resistor divider across the battery providing half supply to one of STM's ADC input for battery voltage monitor. Having 20K across the battery all the time is not good. -F covers some of its problems by its brute force 5 AH battery. .

One thing I can add about STM ADC input Z. The STM spec claims a 100K ADC input Z with wide variation. This is not truly correct and gives designers the impression they need to have low enough divider resistor to prevent the 100k input Z from effecting reading. What the ADC input is really loading the input with is a switched capacitor of 10's of pF. You can fix the loading due to the switching SAR ADC load by placing about a 500 pF cap from ADC input to ground so you can then use higher value resistors in the battery monitor divider network and reduce the off drain loss through the resistors.

I have often thought that there should be a law that all portable devices have a hard off switch or battery disconnect.

Both issues can be fixed by the clever tinkerer. For the NVNA, add a battery disconnect jumper. For the Wouxon, move the voltage divider tap.


73

-Jim
NU0C

On Mon, 06 Jan 2020 20:41:55 -0800
Ismo V??n?nen OH2FTG <ismo.vaananen@...> wrote:

On my nanovna clone the battery was slightly bulged from the factory.

It's mad that the known wouxun fault from 2010 still persists (they put the battery voltage measurement voltage divider BEFORE the power switch. So the 1600mAh battery lasts almost exactly a week in storage with that drain). Baofengs have been a bit hit & miss, one holds charge for months easily, while the other only for a few weeks.