I may have missed your main point but I too often have requirements for lots of 12V. At home, I used to use a ordinary car battery on a trickle charger but often found that I ran out of power when doing parallel (several chargers) cycling of large nicad packs. My solution was to use a moderately large (like an optima) sealed lead/acid (SLA) battery which I picked up cheap. This acts as a buffer on a good automotive battery charger. Most of the time the charger is just giving the SLA battery a trickle charge but when I start hooking up my nicad chargers, the automotive charger ramps up and supplies most of the required current (but buffered because of the SLA battery) Not very elegant but it works.
On the road, I have large gauge wire running to the rear of my truck canopy/cap (supplied from twin batteries in my truck). In my RV, I have similar supplies running from the 4 house batteries to an outside hatch which is located nicely under my awning but also under the main settee in the interior. When every else fails, I have a Honda 2000E which does a great job of just being there and working whenever called upon. Phil in Vancouver -----Original Message----- From: Peter Jensen [mailto:[EMAIL PROTECTED] Sent: July 15, 2005 10:25 AM To: soaring@airage.com Subject: [RCSE] 12V supply/optima maintenance I'm putting together a 12V multi-purpose supply for 90% home and 10% mobile use. The "magic field box" thing advertised in the latest Model Aviation would probably work fine, but I already have several of the individual parts (eg. 12v to 120vac inverters) and don't want to pay that much. I've heard that I could just use a normal big battery and cross float it with a power supply with some proper diodes to protect the power supply in the event of a power failure, but I'd rather have a slightly more elegant and idiot-proof solution that also allows me the ability to charge while driving if I'm mobile. Also, there are concerns about the maximum charge voltage for the batteries I'm interested in using. Perhaps someone here has had similar requirements and can help me out. The two items I need are a battery and some sort of charger/maintainer. I've heard good things about the Optima Yellow Top AGM battery (but could easily be swayed elsewhere) and have no idea what I want in a maintainer. Archive research suggests several devices people have used for these batteries in winch operation, which would be similar in discharge requirements to mine. Why: * I'm a ham and would like the ability to operate on emergency power for a while (mostly just 2m/440 stuff and handhelds). * I live near the coast in Florida. I don't mind a few days without power, but my laptop batteries don't even last enough to make it through one DVD. This annoyed me a lot last year. * I use digital cameras and sometimes want to charge batteries en mass while on the road. I'm also thinking about getting some strobes that would run off of a 12V supply and would prefer not to use my car battery. This reason (more than the others) drives me toward a larger (i.e. car battery size or so) setup. Requirements: * 12V system output (thinking an Optima yellow top battery might have the right combination of design and capacity) * entire system should be at least luggable, probably with a little cart * good amount of longevity; I don't mind battery degradation, but it's nice if it would last for a few years with minimal use * completely automatic charge control supplied by a 13.8V source * graceful failover from mains or supply power failure * relative safety (this will be inside a dwelling, not a garage, and although I don't have a meth lab in here, a properly handled lead acid battery probably pales in comparison to the properly stored numerous LiPo packs and misc other junk I have in here.) I can handle the fusing and switching necessary, but I really need suggestions about a good solid charger/maintainer, as the market seems flooded with a variety of devices. I've read other posts in the archive close to this, but none that really answer my question completely. The BatteryMinder from VDC would do almost everything I want but requires a 110V supply. The BatteryMinder Solar sounds like what I want: http://www.vdcelectronics.com/batteryminder_solar_15a.htm , but it's not clear whether I want to power something like that off of one of my fixed 13.8V supplies. Any other suggestions or things to watch out for? Thanks, Peter Jensen Melbourne, FL http://www.diff.net/media/2004_09_26_hurricane_Jeanne_damage/img_2775.htm -- Peter Jensen ... http://www.diff.net/peter ... [EMAIL PROTECTED] RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format