Education required re. Luxos, cache batteries and Garmin

[PloddinPedro]

OK, here's the situation............ Used my nice new Luxos U lamp (the one with the USB charging facility) on LEL. I also had a 6600mAh PortaPow external battery and my Garmin GPSMap62. My plan was to run the Luxos connected to the PortaPow battery and have one of the two PortaPow outputs permanently connected to the Garmin so I could use it with the backlight up as long as I liked. The other PortaPow outlet would replenish my mp3 player as and when necessary. Obviously the Luxos output would diminish at night when the lightsensitive thingy switched on the lamp, but my expectation was that the size of the PortaPow would smooth it all out.

The Garmin wouldn't play. Rigged up as described, I got repeated messages saying 'External power lost - turn off or stay on?' Everything was fine if I connected the Luxos output direct to the Garmin, or if I joined the Garmin and the PortaPow directly together, but it just wouldn't tolerate all being daisy chained together. I was using PortaPow power-only-no-data USB cables throughout. The Luxos lamp has its own small built-in cache battery so in effect I had two cache batteries in series and as stated, the setup would work with the Garmin only if one of them was cut out of the loop.

My electrical education never got beyond Ohm's Law - anyone out there able to educate me as whether what I was trying to do was silly or what?

[chrisbainbridge]

I wonder if the power output of the system was such that it fully charged the Garmin to the point where the current drain for a relatively low demand GPS Map62 was less than the trigger current to keep the portapow switched on.  Some of them when they get to a zero current state turn off to stop damage to equipment.

Can i suggest turning the backlight on at maximum permanently and see if that adds enough drain to keep the portapow running.  Alternatively upgrade to a garmin 810 and keep all the functions running! 

[Deano]

My Portapow won't discharge at the same time as it's being charged itself - I suspect that's the problem.

I hope that's clear - I can charge the Portapow's internal battery, or use the output from the Portapow to run power to a device, but not both at the same time.

Other cache batteries can do both, I believe.

[PloddinPedro]

I wonder if the power output of the system was such that it fully charged the Garmin to the point where the current drain for a relatively low demand GPS Map62 was less than the trigger current to keep the portapow switched on.  Some of them when they get to a zero current state turn off to stop damage to equipment.

Can i suggest turning the backlight on at maximum permanently and see if that adds enough drain to keep the portapow running.  Alternatively upgrade to a garmin 810 and keep all the functions running!

That's a good thought but in fact I did have the backlight at full strength, so probably not the answer.

My Portapow won't discharge at the same time as it's being charged itself - I suspect that's the problem.

I hope that's clear - I can charge the Portapow's internal battery, or use the output from the Portapow to run power to a device, but not both at the same time.

Other cache batteries can do both, I believe.

Ah, that sounds more likely. Probably my best bet is to ask PortaPow themselves.

If that is the answer though, it leads to the next thought/question: have I bought the wrong brand of external battery and if so, which one should I have bought?

More research required methinks!

[Kim]

My Portapow won't discharge at the same time as it's being charged itself - I suspect that's the problem.

Agreed.  It's evidently the Portapow's fault.

You need something that can do both at the same time.  It also ought to be one that won't switch itself off when the load disappears, because that is likely to get annoying.

[Doo]

I had the same light set and used it for lel. The light played up and the usb thingy stopped charging. I have returned it...

[tkatzir]

something that can do both at the same time.

The keyword to search is "pass-through charging"
e.g. HyperJuice. Available in 3600 or 7200 mAh, and various colours.

I don't own one, nor tried them, but this is what they claim.

Tal.

[Polar Bear]

I'm pretty sure tgat my portapow does pass through.  Only problem I can see is that you first start charging, then add devices to outputs.  I guess that if one stops cycling the charging stops but does not restart due to draw already being experienced for the connected devices.

[PloddinPedro]

Thanks guys for several useful replies. I'll talk to PortaPow and then if necessary, look at some of the alternatives.

To be honest, it could all be just academic since the PortaPow on its own will power the Garmin for many hours (I've not worked out yet how to calculate just how long, but 116 hours of LEL didn't seem to scratch the surface!) and I'm not going to be doing that many very long rides!

And I've yet to reliably weatherproof the Garmin, let alone the Luxos. On LEL I did leave the Luxos cabled up throughout. I had the USB/remote tethered to the top tube snug up behind the head tube upper extension and covered by a Zefel pump strap. This seemed to keep out the wet but there were occasions when the Luxos flashed and I read somewhere that this was an indication that wet was getting to it. So I'm not fully confident about reliability. To be fair, I understand B&M do say not to use the USB facility in the wet.

[mkpaa]

My experience from Luxos U is that you should plug usb in when (internal) cache battery is ready (remote has red light). If you are in a long uphill you should unplug it and wait for cache battery to be ready. Otherwise it will not start charging again.
You can use a few plastic bags to cover the remote and Garmin from water. The remote will get wet immeditially if not covered and while my Garmin Edge is fine with water the charging cable isn't.

Garmin telling "External power lost" every time Luxos stops charging is annoying because you have to click it away and it is most likely to happen when navigating slowly in a city.

[PloddinPedro]

mkpaa's post has reminded me about this thread. I did indeed get some info from PortaPow and yes, it's a 'pass-through' issue. The particular battery pack I'd bought doesn't have this facility. However, I have an older, smaller one that does and when I use that everything works fine.

It was useful however to take one extra step and reset the Garmin to 'Spanner' mode so that now when it detects the presence of a USB cable it first asks if it should go to 'Mass storage mode'. All this involves is one button press to confirm 'No' and all is fine.

Wrapping self-amalgamating tape around the B&M USB remote socket seems to have kept out the wet so far.