Go930 duration of operation on internal battery

[go930user]

Hi all,

Story is that the battery in my Go930 is showing signs of failure after 15 months. Probably my own fault as I left it docked to a computer permanently for about 2 months and I believe Lithium Ion batteries' do not appreciate such treatment.

Failure mode was only 30 seconds of run time on the internal battery. But after a couple of full discharges and recharges I'm now getting about 45 minutes of run time on the internal battery before automatic shut down.

Is this a typical duration for the internal battery on a Go930?

If it is, it suggests a 1.5 ampere drain from the battery as it is rated at 1300 mAh.

I should add that when running the device is transmitting FM audio as I have not switched this off as I ordinarily use this in the car for music transmission.

Grateful for any feedback

Cheers

Go930user

.

 

[canderson]

You can find recommendations for battery sources and instructions on replacement here:

https://www.tomtomforums.com/tomtom...730-920-930-battery-replacement-tutorial.html

45 minutes is a bit low for 15 months, even with the 'abuse', but I'm wondering how old that battery was before you purchased the unit. The 930 has been around for a while. If you don't see any improvement with a few more charge cycles, and need more than 45 minutes, go ahead and swap it out. It sounds like your battery is now substantially below the original 1300mAh capacity.

If you have any questions on the battery or replacement, be sure to speak up in the thread above.

 

[go930user]

Hi Canderson,

Thanks for the reply and the heads up to the Battery replacement thread. Good work.

I read right through and noticed that a contributor claimed that no damage will be done leaving the unit connected permenently to a computer USB port.

This is not my experience, but in my case the Tomtom was left connected and not switched on. I am reasonably confident that this contributed to the problem although the battery has "recovered" to some extent.

It is my understanding that most of the rechargeable technologies (excepting lead acid accumulators) do not like being "float" charged, I understand that better life is achieved by using a full discharge/recharge strategy. I'll try this on the existing battery for a few days and see if the battery performance improves. I'll let everyone know what happens.

That said I believe that fully discharging the unit to the automatic shutdown point and then fully recharging will improve battery performance, so I would recommend this action on a (say) monthly basis.

Cheers

go930user

 

[Andy_P]

in my case the Tomtom was left connected and not switched on. I am reasonably confident that this contributed to the problem although the battery has "recovered" to some extent.

All Li Ion batteries do have a surprisingly short life-span...

at the moment they are constructed at the factory, their "lifetime clock" starts ticking - whether you use the cell or not

(About NiMH and NiCd and a little about LiIons, too.).

Aging is a concern with most lithium-ion batteries and many manufacturers remain silent about this issue. Some capacity deterioration is noticeable after one year, whether the battery is in use or not. The battery frequently fails after two or three years.

(BatteryUniversity.com).

I believe that fully discharging the unit to the automatic shutdown point and then fully recharging will improve battery performance, so I would recommend this action on a (say) monthly basis.
r

That same site doesn't seem to think so...

Lithium-ion is a low maintenance battery, an advantage that most other chemistries cannot claim. There is no memory and no scheduled cycling is required to prolong the battery's life.

The first site says we are on to a loser with our permanently installed batteries anyway...

Do not keep them in a fully-charged state for long periods. The more complete the charge, the faster the cell is degrading, so it is best to keep them "partly" discharged (say, 25-50% of full charge) if you are going to have them sit around for a long time. If, for example, you have a laptop with a Lithium-Iion battery pack, it is best that you not have it attached when you aren't using the computer on batteries. (Yes, I know: It's a pain to do that - and also have the Laptop not be able to weather power failures. It's up to you to decide if the shortened lifetime is worth the hassle...)

(About NiMH and NiCd and a little about LiIons, too.).

 

[canderson]

Lithium-Ion cells aren't at all fond of trickle charging for indefinite periods. In fact, it really isn't necessary (or even a good idea) to do so for any length of time. How a typical TomTom manages the tail end of a charge cycle, I'm not sure. I've never tossed a meter in-line to see what it's doing.

 

[Andy_P]

The impression I get is that ALL Li Ion batteries need circuitry (either built-in to the battery itself or on the main PCB?) to prevent overcharge and "over-discharge" to stop them dying immediately.

Probably, you get what you pay for, and also this year's batteries may be better than last year's even from the same manufacturer

 

[canderson]

The impression I get is that ALL Li Ion batteries need circuitry (either built-in to the battery itself or on the main PCB?) to prevent overcharge and "over-discharge" to stop them dying immediately.

The charging circuitry is external on all but certain notebook battery packs. The device that must be incorporated into a typical lithium pack (like we use in TomTom) is an overtemp sensor in series with one of the wires that prevents overheating by opening the circuit to the battery if need be. Prevents damage (boom?) during both excessive charge and discharge conditions. Even a decent NiMH or NiCd pack includes one of those. The battery may also employ a thermistor (temperature sensor) to provide temperature sensing back to the charging circuit as a second means of determining when the charge is complete.

All of that said - it's still possible to retain a low level charge on a lithium pack such that neither the thermal breaker nor the thermistor give an indication of an overheating condition, and kill the battery all the same.

Again, I don't know what TomTom has been doing at the end of a charge cycle. It IS permitted for a charger to "top off" a lithium pack when the open-circuit voltage drops a bit (4.05V is commonly used) to compensate for losses that occur from just sitting around for a while. But NO trickle charging!

 

[go930user]

Hi all,

The original battery is gradually improving with sequential full charge/full discharge cycles. It is now providing an hour of battery only duration before automatic shut down. So it will be interesting to see if this trend continues. It seems to be inproving at about 15 mins per charge/discharge.

On the longevity question I can offer some comment based on three cameras with Li-ion batteries. One is a minolta D5 and the others, Panasonics - TZ7 and TZ10. In all cases we use the loaded Battery until the camera stops working and then swap to a spare battery. Recharge the "spent" battery when we get to a convenient place.

Except for a DOA battery bought as a spare, all six of the batteries have been working without any significant degradation, but I always disconnect the charger when I notice the "charge complete" indication. One pair is now five years old, another pair is three years old and the last pair is 1 year old.

Seems to suggest to me that full charge/discharge provides the best performance/longevity.

I'll let the forum know if the "abused" battery shows further improvement.

Cheers

 

[canderson]

Unlike the old NiCd cells, it's not that the full discharge of the lithium pack is preventing 'memory' issues or anything like that. That said, it is possible that you will get the best number of total hours of useful life out of a lithium cell by fully cycling it... but it's as much a function of the quality of the charger as the battery chemistry itself.

One thing to watch: Lithium ion packs do NOT approve of being stored at 100% charge for extended periods. It decreases the useful life. The ideal is to store them at about 50% of a full charge.

 

[go930user]

Hi all,

The improvement to the duration of the OE battery stopped at 60 minutes, so I decided to swap out the OE battery for a new one.

Boy is that "glue" over engineering.

However I did find that Isopropyl alcohol makes for an excellent glue softener and there is very little residue to clean up afterward.

A word of caution however, there is a "gasket" glued onto the PCB that partially surrounds the battery mount area on the PCB which does not like the alcohol, so use it sparingly - I needed about 3 cotton buds full of the fluid to ease the battery away from the PCB with a wedge shaped plastic "chisel".

When I get around to doing some charge/discharge cycles I'll have a handle on duration figures.

Does anyone have a notional figure for what it ought to be?

My 910 had a 2300 mAh battery and lasted about four hours on a full battery charge. I'd expect the 930s consumption to be signifigantly lower than the 910s (perhaps half as much as there is no microdrive to keep running) so that would point to something in excess of 3 hours for a 930 with a full charge on a good battery.

Cheers

go930user

 

[canderson]

When I get around to doing some charge/discharge cycles I'll have a handle on duration figures.

Does anyone have a notional figure for what it ought to be?

It depends a good bit on how you've got it set up. You have features like the FM transmitter, backlight level, Bluetooth -- lots of things will impact battery life. If you get 2-1/2 hours or more after a couple of cycles, I'd consider that a success.

 

[go930user]

Hi all,

I guess I've been successful as, after a couple of charge discharge cycles, the 930 is providing 2 h 45 m of duration from fully charged to auto shutdown.:thumb:

There might be some improvement after a couple more but the duration I'm getting is sufficient for my needs.

The duration indicated was achieved with default screen settings and both bluetooth and FM transmission turned off.

A "nice" extra is that the battery status bar is now showing an almost complete green bar after a full recharge. I'd guess the white bit of the bar is less than 1 mm wide. This is a condition that I have not witnessed on this unit even when new.

Cheers - and thanks for the feedback

go930user