Paul Hayward's setup seems a bit like ours: A hefty gel-cell, that primarily power the bilge pump, also supplies the old GPS (which is very power hungry!) with power via a long cord. We have a few cameras, and about half uses AAs, while the rest uses their own style batteries. As most of the dedicated chargers to the various cameras, cellphones and video-cameras need 220V AC, we carry an inverter as well, if we bring any chargers along in the first place! Our solar panel is too small to be really useful, but it prevents, hopefully, the gel-cel from losing charge (it's just too small - about 2 sq. ft), and the backing aluminium plate has very sharp corners, so it isn't ideal in any way, but light! So normally, we just don't bring it! The ideal spot for it would be out on the outrigger, but this is yet a pending issue :-)! While I use LiPos in my model planes nowadays, there are quite a few issues here, not just during charging. If you short a pack it will turn into a Molotov Cocktail, and if you plan to use a big pack, as you mention, it will be a bloody big cocktail, no doubt! I can think of better places to be than in the cockpit of a small boat when such a device 'explodes' under the deck. If you use water to put it out the Lithium will react even more violently, I am sure! The batteries are an interesting mix of lithium (which reacts with air, water, etc), plastics, metal and solvents, a jolly fire-enhancing mixture indeed! If you puncture it, it catches fire, if you short, overload, or charge it with a non-prescribed type of charger, the same result (most of the time it takes a few seconds before the mix catches fire, so you might have time to abandon ship)! Some packs carry internal fuses, but that is rare indeed! All responsible modelers I know keep theirs in metal boxes, when not actually up in the air :-)! Wise men! The Eneloop (sp?) AAs sounds interesting, though! My LiPO charger is nice, though, as it is small, and handles charging NiMhs, NiCads and SLAs (Sealed Lead-Acid), as well as various types of Lithium batteries! Tord *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Thanks Tord - that's a very comprehensive list of the dangers of the LiPo cells. I guess we will probably learn to deal with the risks involved - just as now we don't (much) consider the bombs we carry round with 'Primus' or 'Camp-Gaz' written on the side of the tin ;-) Maybe I can have a special 'survival' mechanism that launches a big LiPo cell up into the sky and shorts it out - to produce either a seriously-visible distress flare & thunderclap or else a weapon against big launches on auto-pilot ;-) Instead of carrying the AC inverter, have you thought of attaching one or more 'female' cigarette-lighter sockets to the big battery and then plugging in all the car cables (cigarette-lighter charging cables) for the various devices. That usually saves weight and some inefficiency (as you convert up to 240V and then back down to DC). Even if the inverter is efficient (and at low loads, they rarely are); the plug-packs or wall-warts (whatever name we use) are usually terrible - just feel how hot they get. Best Regards Paul Hayward, Auckland, New Zealand *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On Tue, Oct 20, 2009 at 7:42 AM, Paul Hayward <pdh_at_mmcl.co.nz> wrote: > > Instead of carrying the AC inverter, have you thought of attaching one or > more 'female' cigarette-lighter sockets to the big battery and then > plugging > in all the car cables (cigarette-lighter charging cables) for the various > devices. That usually saves weight and some inefficiency (as you convert up > to 240V and then back down to DC). > I actually like the inverter idea as opposed to trying to match up all the various voltages for batteries and devices that work on a 12vdc battery but I agree that the efficiency is terrible. However it might not be much of an issue depending upon how much solar exposure you can get during the day. With Jennifer's 30watt solar panel I don't think charging power would be an issue unless the day is particularly dark. For one thing, a 12vdc battery won't charge up anything that needs to power another 12vdc device. At least not very well. Fortunately, that's not much of an issue these days unless you have a bank of small batteries you're charging. Most of the devices that you can buy to charge a device or battery that needs less than 12vdc from a car (12vdc) are also pretty inefficient; many of them just use resistance to convert the voltage down to the point where it won't damage the lower-voltage units. Whether the inefficiency of the auto-style converter is equal to the inefficiency of the inverter might be a toss-up. And using the inverter is pretty simply done with components you can buy at Wal-Mart (or wherever) using components you'd just use for your home. I use a 400w inverter which comes with clips for connecting to a battery. At that point I can simply plug two chargers into it or plug an extension cord into it if I need to charge more units. So far I've only used it on the muthah-ship (which, admittedly, has a 260hp engine for charging). But the VHF and the iPhone both recharge in under an hour. I use lithium batteries in the GPS and just carry enough of them so I'm not charging them. Craig Jungers Moses Lake, WA www.nwkayaking.net *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Craig said on Wed, 21 October 2009 07:09: > Most of the devices that you can buy to charge a device or battery that needs > less than 12vdc from a car (12vdc) are also pretty inefficient; Mostly, I use what the manufacturer of the device gave me for using in a car - that way I know it's well-matched. I bought one dedicated 'smart-charger' for NiMH AA & AAA cells. It works _only_ from a 'car' socket (it's not an afterthought capability tacked onto a 110/240 device). As to how efficient the 'from 12v' circuits are, I haven't done any tests other than the old "Is it real hot ?" hand test and they all run so cool as to be undetectable. Some of the cables may be 'smart' and some of the devices themselves may have 'smart' charging circuits - today that doesn't cost a lot. After all, in a car cigarette-lighter environment, a device's power-supply should be capable of surviving quite a wide range of voltage - much wider than my gel-cell puts out. If you make a device that is destined to run from a car socket (most cellphones, GPS, VHFs, etc) they will "see" from about 7 volts (when the engine is being cranked) to 15+ (when charging the 'house' battery at max) - plus some wicked spikes. I believe that many modern devices deal with that range more 'smartly' than by just using a resistor. I realise that we are talking about mA here - so it may be moot. I agree that in a camper or on a yacht or launch it makes complete sense to have a meaty inverter; but on a kayak I don't see the advantage of carrying the inverter's bulk & weight, unless there's something I just can't get to run directly from 12v. Best Regards Paul Hayward, Auckland, New Zealand *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
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