dynamo charging a garmin

[andrew_s]

what about this
i'm handy with the soldering iron?
http://www.ebay.co.uk/itm/NOKIA-DC-...ories_MobilePhoneChargers&hash=item35cf87ed24
Cheers Ed

I'd forgotten those.
Should be OK, apart from the Nokia-specific plug on the end. I'd suggest this Nokia adapter would be better than chopping the end off and soldering on another plug.
Usually the problem with cheap or DIY dynamo to USB adapters is the question of excess power going into heat inside the adapter and cooking it, so I'd recommend only using it to charge, with the dynamo off the rest of the time.

For solar, in the UK you would want something with at least 20x30cm of solar cell area in order to stand a chance of coping with cloudy days, the panel not being square on to the sun, the sun being well off overhead etc.

 

[young Ed]

thanks may well order that nokia kit then cheers for the adapter link now on shopping link
Cheers Ed

 

[andrew_s]

bit pricey though think i may still just use one of these

Cheers Ed

Is it not better to use a Garmin that uses AA batteries than one of those? You'll lose maybe 25% by using the AA to charge another battery compared with using the AA directly.

2xAA in an eTrex 20 will last 20-25h, compared to 10-12h from an Edge, and you get to use all of the capacity as putting 2 fresh AA in is a lot quicker than recharging the Edge battery.
If you ride 8h a day, then you have to charge the Edge every night. If you didn't, it would run flat half way through the next day and you'd be stranded for a few hours whilst it charged. With the eTrex, you run it 2.5 days, then swap batteries. If you've 4xAA rechargeable in total, you only have to charge every 5 days.

 

[Linford]

Charging off a bike is more hassle and expense than it is worth as others have said. I got a pair of heated gloves from Oxford products last month...latest model (RRP=£150 so you expect them to be quality)... each glove has a chipset in it to control the 3 heat settings and they attach to the bikes battery through a loom which runs through the riders suit and plugs into an in line socket on the end of a cable which is near the K in kawasaki in the pic. When I rode the bike out, any change in RPM would make them cut out and they would have to be unplugged and plugged back in again to reset the chip which made them unusable.
I contacted them direct, they had the gloves back and they realised that the glove manufacturers in china had omitted to include a voltage regulator in each of the gloves circuits (oops)

They then had a load of these voltage regulators knocked up to stabilise the voltage to the gloves, and I got mine last week which goes between the suits loom and the bikes loom (pic below) gloves draw 1 amp at 13.4V, but the bikes alternator would increase the voltage up to about 14.8V which was too much for the chipsets to cope with.

You are better going for one of these TBH. It would give you days of charge between stops for your devices and far less risk of overvoltage...incidentally, it takes a bit more effort to cycle with a dynamo running.
http://www.ebay.co.uk/itm/Portable-...749?pt=LH_DefaultDomain_3&hash=item19e24eb685

 

[young Ed]

heated gloves aren't really applicable to this situation but an interesting story all the same considering i will be on both motorbikes and push bikes in the future and my dad is currently on motorbikes
the nokia system cuts out at a certain point to prevent over flow of voltage and this point is higher than my average speed anyway so it's okay and as for the battery as said before wild camping or at camp sites means charging is near on impossible and stopping at a library or cafe for 20 mins doesn't give battery much charge and i don't mind pedalling a bit harder it means my thighs get bigger! and i means i know where to go so all is good
Cheers Ed

 

[Davidc]

A nominally 6v set of AA batteries (alkaline) is 4 cells. When they're new, depending on quality and age, they may give up to 7v (1.75v per cell). I wouldn't connect that to a USB charging port. A made for the job device would be safer, and probably cheaper than an efficient (>85%) and safe DIY solution.

My preference now is a box like the one in Linford's post above, or the one from Amazon in an earlier post.

I have a nominally 10,000mAh one from an ebay seller and it runs my Android phone for an extra 14 hours when it's doing cycle logging/ mapping duty with its display and GPS on continuously, so that would run a Garmin for days. The ones linked to are even higher nominal capacity.

 

[PpPete]

do you reckon 6v will damage garmin as it is meant for 5v usb?
Cheers Ed

I've run an Etrex off a 4 x AA battery holder soldered to a USB - but only with rechargeable AA cells which are a nominal 1.2V (so 4.8 V - which the Etrex considered close enough to USB 5V standard to be happy)
I now use one of those 2x AA "emergency phone chargers" like this which can be had from Chinese ebayers for just pennies, as they can take 1.5V disposables as well as 1.2V rechargeables and still give 5V USB for the Garmin.

However for long periods "off-grid" a Pedal-Power SIC includes both regulator circuitry from the dynamo and a smallish cache battery (which can be charge either by dynamo or from mains). Mine works very effectively at anything above about 5 mph - and I'm led to believe the it deals with very efficiently with the extra volts the dynamo generates at higher speeds. Some of the cheaper alternatives tend to shut down on fast descents to preserve the 'lectronics.

 

[young Ed]

don't the etrex run off aa batteries them selves?
also does the emergency phone charge properly charge your garmin or does it just hold the level of charge neither increasing or decreasing it?
Cheers Ed

 

[mcshroom]

The Etrex, Dakota, Oregon series all use two AA batteries. The Edge series use internal rechargeables.

For multi-day touring I would find the AA option far more suitable. You can get hold of spare AA batteries just about anywhere.

 

[PpPete]

don't the etrex run off aa batteries them selves?
also does the emergency phone charge properly charge your garmin or does it just hold the level of charge neither increasing or decreasing it?
Cheers Ed

The Etrex are designed to run off AA - but (at least the older models) have the option to run off "external power" via a mini USB - which also serves as data connection to download maps, routes etc..
No charging circuitry on the Etrex though. It just uses the external power in place of the internal batteries for as long as it remains plugged in.

We tend to use these at night as it over-rides the back-light timeout feature. If you do a lot of night time riding you'll understand the motivation behind that.

 

[young Ed]

ai' got ye' but i plan to pack up before it's too dark don't much like riding in the dark and don't mind covering less miles per day and doing more days
Cheers Ed

 

[PpPete]

Realistically I don't expect 2 duracell alkaline AA cells to extend the life of the lithium-ion rechargeable in an Edge touring by all that much. Despite the advertising they are not that good and charging one battery off another is not efficient.

 

[young Ed]

have now ordered nokia kit
Cheers Ed