Non solar portable chargers

Have any of you got a portable battery bank like the Tecknet iep390? http://www.amazon.co.uk/TeckNet-11000mAh-External-Motorola-Blackberry/dp/B0013KD7U6/ref=sr_1_4?ie=UTF8&qid=1338316060&sr=8-4

Im not interested in solar charging but something like the above. Apart from keeping the phones charged, would it have enough oomph to charge a camcorder battery?

Cheers

it would have enough battery capacity but it depends how your camcorder is charged and at what voltage, i would hazard a guess and say this would not charge your camcorder unless it can be charged with a usb connection?

tbh in almost all circumstances it works out better/cheaper to just get spare batteries from ebay for your individual products, what make/model is your camcorder will be able to tell you if i have that information.

I have one of those teknet chargers that I use for my phone and petzl core, they are pretty robust and I get around 5 full charges of my phone from it with a bit left over.

So enough for multi day hikes.

Hi Paul its a Panasonic SD900 if that helps?

Thanks Crag

i cant find a definite answer for the charging voltage of the battery pack but it seems to be a max of 5v the battery pack for the camera is 7.4 so it wont charge it unfortunately, of if it does it will be very very slowly and not worth the effort.

you would be best to take a couple of spare batteries for it like i said before, you can pick up 2500mah batteries on ebay for it for quite cheap, so 4 of them is the equivalent of the battery pack or near enough as its 11000mah in total.

so 2 spare phone batteries and 2 spare camera batteries would be about the same capacity in terms of real world use, probally less weight aswell as that battery pack is near enough 500g.

I have that TeckNet charger and it has been excellent for me on trips ive took it, charges my android phone about 6 times over.I dropped it the other day off the ground and it still works as crag says it does seem pretty robust.

Ok so if i take extra batteries for the camera, what would be a good light power bank to charge the phones with?

anything you like the look of really, its easy to work out capacity is rated in Mah

average phone batteries are around 1100Mah
so a battery pack of around 5000Mah will charge you phone 5 times

just look for something you like the weight of and capacity, i have a veho pebble 5000Mah and weights in at 132g but i never bother i just take spare batteries as 4 batteries for my phone weights quite a lot less than the battery pack.

Merci Paul

Just a note on portable chargers, they will stop charging once the packs mAh rating falls below what it is trying to charge.
So if your phones battery is 1600mAh and the pack only has ~1200mAh left in it, it will stop charging the phone, so a 5000mAh pack will only give around 3 charges.

@crag scrambler: This is not strictly correct: many portable chargers have a built-in d.c. converter to change the internal battery voltage (typically 3,4V for a lithium-ion cell) to the charging voltage for the phone (typically 5V for USB chargers). During discharge, the voltage of the lithium-ion will drop, and the charger will switch off at a safe level (typically 2,2V) to prevent battery damage. The switch-off is dictated by the battery voltage, not necessarily by the remaining capacity.

So would it charge a Sony cx570e camcorder?

Bear in mind that neither batteries nor voltage converters are 100% efficient.

a) You have to put more into a battery than you get out. If you've an 1100 mAh battery, you will have to put about 1250 mAh into it to fully charge it.
b) The voltage converters are only about 90% efficient, and you are converting twice - once from backup battery voltage (3.7 or 7.4V, usually) to 5V USB, and once back from USB to whatever your device battery takes. So call that about a 19% loss.
c) A 5000mAh battery pack will give 5000mAh output under ideal conditions and having been fully charged properly in the first place, but it's quite likely that you'll only get 4500 mAh out of it. (eg a 2500 mAh AA NiMh typically reports 2200mAh on my charger). It's usually a combination of the battery feeling a bit less than perfect, and the charger stopping charge a bit early to avoid damaging it.
It can help to leave the charger running for a couple of hours after the fully charged light comes on - some chargers switch over to a slow trickle/top up charging rate rather than just stop.

Combine these, and 4500 * 0.81 = 3645 / 1250 = 2.9

So assume that your 5000mAh backup battery will charge your 1100mAh phone almost 3 times. You may do a bit better, but don't count on it.

It is not the case that remaining capacity in the charging battery has to exceed the capacity of the charged battery. Switch mode converters can be very good at getting every last bit of juice out of a battery, which is why they are generally set to turn off before the battery is run slow empty it gets damaged.