Battery Related Information

[Jay1967]

a suggested replacement logo photo for SatMap

http://www.flickr.com/photos/22623747@N04/2178809932/[img]

[robs1972]

[Jay1967]

[ocam]

Jay 1967 - I agree with Rob but would go further; if you keep things civil and constructive we may yet keep the attention of Satmap and hopefully they'll take notice of user feedback. If you don't like the unit, vote with your feet, get your money back and carry on life without OS GPS rolling maps. I suspect there will still be plenty of people reading these threads long after you've gone back to your Garmin.

Of general interest, I heard that last week a Peak District mountain rescue team used an A10 in the "worst possible map reading conditions" at night to succesfully evacuate a casualty from the hill. As it happens I was staying near Buxton and last Tuesday was the foggiest I've seen for years. (Walking through Lud's Church, a narrow rock chasm near the Roaches, the unit kept lock.)

My own experience of the unit remains positive in all aspects. Mikealder has been right on the button with all his (patient) advice on battery life. The A10 has really boosted my enjoyment of running, walking and cycling in Cornwall (Lizard), the Peaks and around Leics where I live. I can't wait to get into the Lakes and Scotland. My wife's no good with paper map + compass, but more than happy taking charge of nav with the A10.

Anything still to come by way of PC planning and LiPol power options will be icing on the cake. I've waited long enough for a device like this, I for one will be as patient as is necessary for the rest of it to roll out.

Wonder what V1.04 will bring?

Regards

[Jay1967]

[Paul_ffitch]

Back to batteries...

I have a slight puzzle re the issue of the batteries draining while left in the unit, even though it's switched off. I understand what Mike Alder has been reporting, ie a current consumption while switched off measured at 32mA. Indeed, I have just check my Satmap unit with a good digital meter and measured a value that fluctuates between about 31 and 34mA, so a good agreement there.

My puzzle is that at that rate, a battery set made up of 2500mA hour batteries (good capacity NiMH) will last 2500/32 = 78 hours (and no it's not three times that for three batteries, as all the batteries will be draining at 32mA). So a fresh set of batteries will go flat in three days and a bit. But I've had a set of batteries in my unit for ten days since I last used the unit, and that included some actual use while walking. But when I switched the unit on today, it springs to life with four bars, dipping once to three and back to four. So presumably not full, but hardly empty.

So what's going on? The numbers don't stack up. Perhaps the unit has a short period of higher power consumption (32mA) when the batteries are first connected (but before the unit is actually switched on) which then settles to a lower quiescent value atfer a while? The method I used to measure the current consumption required about three hands, so I couldn't measure it, or record it, over a longer period.

Mike A: You appear to have a rather more robust measurement and logging capability. Did you make any longer term measurements of quiescent current?

The reason I am interested in this is that I'd like to know what sort of periods it makes sense to remove a battery, and what sort of periods it wouldn't be so necessary.

[mikealder]

Ok I will waste another set of batteries to answer the question above, all I can think is the device is using the batteries to charge an onboard power capacitor, once charged this current draw would drop to a far lower figure - just a guess mind. I have got used to removing the cells from my device once my walk is over, once bitten twice shy having written off a couple of sets of costly batteries in the early days!

I cannot log current drawn for more than about 80 hours though as the current clamp has its own internal cell that will require changing - this only takes around 2 minutes though.

If you want a cheap source for the Lithiums check out THIS to get free postage you have to purchase 6 packs which is 36 cells - best price I have found to date, and if you live in the NW they have a trade counter near J32 of the M6 so you can buy less packets with no postage costs at all - Mike

[Paul_ffitch]

I've been checking out batteries and battery chargers, and have just bought an Ansmann Energy 8 charger (as recommended by a previous poster), an Ansmann Energy Check battery tester (all types, 10% capacity increment indicators). Also 'X4Energy' 2700mAh NiMH batteries, which work out at £1.93 each inc VAT. All this from http://www.tantronics.co.uk

But while I was searching, I found http://www.battery-force.co.uk/ which sells AA Energizer Ultimate Lithiums at £3.44 for two, ie £1,72 each, plus quite reasonable postage charges. Eg Total of £15.63 for 8 batteries, so net £1.95 each. However the capacity of these Lithiums is quoted at 2900mAh. This is high, but I can't help drawing the conclusion that the 2700mAh NiMH cells I've ordered are much better choice overall (I hope).

[Jay1967]

[Yasack]

OK everyone,

I just need to recap as all this information on batteries is over my head.

I use rechargeable batteries which last between 2-3 hours. This is a problem if I am walking for 6-8 hours. Therefore what is my best solution as I am off to the Brecon Beacons at the weekend and I need something that will last. Could you advice A.S.A.P so I can get what I need ordered.

Regards,


Richard

[lucevans]

[bluewomble]

I have been using Energizer Lithium AA batteries (the same type as the ones that came with the Satmap) a set of those normally lasts me for about 10 hours of cycling.

As other people have said, these batteries are expensive, but they seem to offer the best value for money for disposable batteries.

I haven't tried rechargeable batteries yet, so I can't comment on those... but I would have thought that high power NiMh cells (2800 mAh cells) would give a fairly reasonable battery life, comparable to the energizer lithium cells.

I always turn the backlight down to the lowest usable setting that conditions allow to save power (i.e. I do use it on 100% backlight if it's bright sunshine, about 40 or 50% on a cloudy day and 10% at night)

I also switch the Power Saving mode to switch off the screen after a minute without use.

[Yasack]

[mikealder]

Bear in mind the diference in battery voltage with fresh cells:
NiMH are 1.2V so 3 in series = 3.6V
Lithiums are 1.5V so 3 in series = 4.5V (often these cells can be 1.8V though)

Now consider the voltage at which the device will turn off 3.25V

As the cell lose power due to being used the voltage will drop, with NiMH you can see from the above that they only have to drop 0.35V to trigger the shutdown within the device, the discharge rate and voltage decay curve will be different depending uon the actuall cells employed - Mike

[Yasack]

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