paulos Posted August 24, 2006 Report Share Posted August 24, 2006 hi, are there any electronic boffins or anybody who might be able to help me? ive just bought a new battery for my logun lamp which hasnt been used for about 2 years, in which time ive also managed to "lose" the charger. ie. lent it to a mate, who subsequently did one. ive found another one which i suspect may work but im not sure, its 7.5v output, '-'--C--'+' polarity, and it fits the connection to the battery. will this work or will it blow up and cover me in battery acid? if anyone has any idea id very much appreciate it! paulos Quote Link to comment Share on other sites More sharing options...
plexer Posted August 24, 2006 Report Share Posted August 24, 2006 Have you actually found another charger or just a 7.5v power supply? if it's the latter I wouldn't use it. What sort of battery is it? lead acid, ni-cd, ni-mh, l-ion? Ben Quote Link to comment Share on other sites More sharing options...
pin Posted August 24, 2006 Report Share Posted August 24, 2006 From a brief check the logun lamp uses a 6v lead acid battery. From the very brief manual on the logun site I make the informed guess that the charger is "dumb" as they warn not to leave it on for more than 24hours. I can't seem to find the capacity of the battery supplied, or details of how the plug is wired :yp: Just get one of these http://www.maplin.co.uk/Module.aspx?Module...698&C=SEO&U=mlp and connect direct to the terminals on the battery - it will save all the messing about below, but if you really want to know ;-) .. Have a look at the battery and tell me the capacity, as well as the output in miliamps of that 7.5v charger you have there. You'd have to trace the positive wire back to the battery terminals to know if centre positive was correct or not. 6v Lead Acid packs have 3 cells, to charge them you need to raise the voltage past about 2.15v/cell (6.5v approx). 7.5v would probably be fine, but an unregulated transformer charger (the type you have there) would need to be watched very carefully. As the battery becomes charged the voltage from the charger will rise and you start creating a chemical reaction in the battery, the bad sort IE don't leave it overnight Quote Link to comment Share on other sites More sharing options...
Recurve Posted August 25, 2006 Report Share Posted August 25, 2006 Check out motorbike accessory dealers. M'bikes still sometimes use 6v batteries (lead acid) so chargers are often a stock item. I seem to remember that Gunson do a cheap one. hth Phil Quote Link to comment Share on other sites More sharing options...
markbivvy Posted August 25, 2006 Report Share Posted August 25, 2006 or will it blow up and cover me in battery acid? not if you ask the wife to plug it in. Quote Link to comment Share on other sites More sharing options...
dr_nick Posted August 26, 2006 Report Share Posted August 26, 2006 Ok here is the cheap way, go to wilko's. Buy one of their cheap power supplies, £2.99 ish, set it to 9 - 12 volts (9 better but slower) and connect it to the battery. All chargers do is supply a higher voltage than the battery makes (so the electicity flows into the battery (and this is in very simple terms)). You will have to manually disconect the battery after 8 hours or so and make up your own connectors for charging (maplins do really nice crocodile leads. Else if you want a proper charger and its a 6volt lead acid battery go with the motorbike trickle charger, such as this one http://www.mandp.co.uk/productInfo.aspx?catRef=558541 Quote Link to comment Share on other sites More sharing options...
plexer Posted August 26, 2006 Report Share Posted August 26, 2006 I wouldn't charge a 7.5v at 9v at all. http://www.myra-simon.com/bike/charger.html Ben Quote Link to comment Share on other sites More sharing options...
pin Posted August 26, 2006 Report Share Posted August 26, 2006 Ok here is the cheap way, go to wilko's. Buy one of their cheap power supplies, £2.99 ish, set it to 9 - 12 volts (9 better but slower) and connect it to the battery. All chargers do is supply a higher voltage than the battery makes (so the electicity flows into the battery (and this is in very simple terms)). You will have to manually disconect the battery after 8 hours or so and make up your own connectors for charging (maplins do really nice crocodile leads. Else if you want a proper charger and its a 6volt lead acid battery go with the motorbike trickle charger, such as this one http://www.mandp.co.uk/productInfo.aspx?catRef=558541 Erm deffinately DO NOT DO THIS, this is a sealed lead acid battery and it could explode. 9v is 3v per cell, well over the gassing voltage of a led acid cell and will produce hydrogen which is colorless, odourless and highly flammable. Because this is sealed it will, if left like this long enough, eventually vent and you don't want that (basically this pack is full of nasty acid). Quote Link to comment Share on other sites More sharing options...
dr_nick Posted August 27, 2006 Report Share Posted August 27, 2006 Ok here is the cheap way, go to wilko's. Buy one of their cheap power supplies, £2.99 ish, set it to 9 - 12 volts (9 better but slower) and connect it to the battery. All chargers do is supply a higher voltage than the battery makes (so the electicity flows into the battery (and this is in very simple terms)). You will have to manually disconect the battery after 8 hours or so and make up your own connectors for charging (maplins do really nice crocodile leads. Else if you want a proper charger and its a 6volt lead acid battery go with the motorbike trickle charger, such as this one http://www.mandp.co.uk/productInfo.aspx?catRef=558541 Erm deffinately DO NOT DO THIS, this is a sealed lead acid battery and it could explode. 9v is 3v per cell, well over the gassing voltage of a led acid cell and will produce hydrogen which is colorless, odourless and highly flammable. Because this is sealed it will, if left like this long enough, eventually vent and you don't want that (basically this pack is full of nasty acid). It puts out less than 300ma and you would have to monitor it, but thats all the cheap chargers for recharging all batteries do. All trickle chargers apply a constant voltage with very low amps. A 12volt carger puts out around 15 - 16V. But given, DO NOT DO THIS, this is a sealed lead acid battery and it could explode buy a proper charger. Quote Link to comment Share on other sites More sharing options...
pin Posted August 27, 2006 Report Share Posted August 27, 2006 Its an oddity of the type of cell that creates this problem, other batteries (nicd/nimh) have the same issues but they are not made of large quantities of liquid acid and are a lot more resilient to over voltage than are lead acid cells. Quote Link to comment Share on other sites More sharing options...
P03 Posted August 28, 2006 Report Share Posted August 28, 2006 Having shelled out for a new battery, would it not be better to also buy a new charger from Logun rather than risk destroying your battery? Quote Link to comment Share on other sites More sharing options...
pin Posted August 29, 2006 Report Share Posted August 29, 2006 Ignoring all that has gone before, a purpose designed lead acid charger (like the one I posted for £10 from maplins) is perfectly adequate. No idea what logun charge, might be less, is probably more.. Quote Link to comment Share on other sites More sharing options...
paulos Posted August 29, 2006 Author Report Share Posted August 29, 2006 thanks everyone, so from what ive read is should buy a charger from maplins? right. done. im always reluctant to buy things from official distributors as they just seem to rip people off eg. the battery costs 11 quid from deben, but only a cheeky fiver from maplins Quote Link to comment Share on other sites More sharing options...
pin Posted August 29, 2006 Report Share Posted August 29, 2006 Yep Anything that comes with a rechargable battery will have the battery supplied by one of about 30 companies, be it led acid/gel cell/NiMh/NiCd/Li/Lipo. The way you charge them is the same for the battery type, regardless of manufacturer. Not dissing Logan, or anyone else here, but they have to turn a profit somehow. Making a lamp for a gun is like making a lamp for anything else. It has a reflector, a bulb, power source, casing, switch and mounts. The casing and mounts may have been designed by them, the rest were not designed but specified. This means they have to charge more than it cost them to buy, or they overcharge for the other stuff in the package. The sad fact of the matter is that the marketing costs, writing the manuals and the packaging probably cost them about a quater of the retail price, or more. Then they need to account for warranty, etc. Where am I going with this? Well, manufacturers trade on people being afraid of sourcing replacements from anywhere else. Be that a charger, bulb, plug or anything else that came with it. All companies do this, and the way they get away with it is almost blackmail "will invalidate the warranty" If you know what you are doing you can save a fortune and in most cases the aftermarket part or component will match or beat the original spec at a fraction of the cost. For example the £11 1.2AH battery you have there, I could replace with a unit I purchased from the net, which would last 45% longer (per charge), could be fast charged (20 mins from a car) and would weigh about 1/3 of the original. Cost about £14.50 delivered. Quote Link to comment Share on other sites More sharing options...
clone Posted September 6, 2006 Report Share Posted September 6, 2006 well why dont you share the knowlage and let us make the decission - if you could get a battery that would last 45% more in the field per charge could you not up the wattage of the bulb to give you a stronger beam i know that logun rip of on the bulbs as you can pick them up for 45p each on the net Quote Link to comment Share on other sites More sharing options...
kipper Posted September 6, 2006 Report Share Posted September 6, 2006 or will it blow up and cover me in battery acid? not if you ask the wife to plug it in. B) Quote Link to comment Share on other sites More sharing options...
pin Posted September 6, 2006 Report Share Posted September 6, 2006 well why dont you share the knowlage and let us make the decission - if you could get a battery that would last 45% more in the field per charge could you not up the wattage of the bulb to give you a stronger beam i know that logun rip of on the bulbs as you can pick them up for 45p each on the net Ok. www.cheapbatterypacks.com Click "custom packs start here", choose 6 cells, Sanyo CP2400SCR cells, flat configuration, 18AWG wire. $26, about £14. That would come in at about 350g, and is 2.4ah (double the capacity). You can pick up a charger which will zap these for you in about 20 mins for about £15 from maplin. I use these guys all the time for my planes/helis etc and have found them awesome, even if they are in the states. You could of course find someone in the UK to build you a pack Quote Link to comment Share on other sites More sharing options...
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