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Thread ID: 69789	2006-06-12 10:11:00	Battery Power	Twelvevolts (5457)	PC World Chat

Post ID	Timestamp	Content	User
462538	2006-06-12 10:11:00	I know I should know how to do this but . . . has anyone ever managed to hook up a any kind of PC to a 12 volt car battery . I mean if you get caught without power, you want to be able to run more than your record player and blender . Now I now this Joe down in Mexico He went there to work on his tan For years he's been plugged into blenders and songs They call him the Twelve Volt Man	Twelvevolts (5457)
462539	2006-06-12 10:13:00	www.dansdata.com	bob_doe_nz (92)
462540	2006-06-12 10:26:00	I know I should know how to do this but . . . has anyone ever managed to hook up a any kind of PC to a 12 volt car battery . [/I]I know this charactor who took the lid of his UPS only to discover that the failing battery that kept it going during power failure was in fact 12v, so he simply ran a pair of wires out to a car battery that sits under the desk . Several hours use he tells me . NICE .	personthingy (1670)
462541	2006-06-12 10:31:00	www.dansdata.com Great site that one. I wonder how long my PC would go if I managed to connect it to the sort of battery that will run a golf cart all day. :-)	Sweep (90)
462542	2006-06-12 11:22:00	www.dansdata.com That's absolutely brilliant!! I want one of those already.	Twelvevolts (5457)
462543	2006-06-12 14:11:00	Be VERY careful . Many of the cheaper inverters (and UPS's) are not "isolated", so one side of the 12v battery is at full mains voltage . Which means contact with either of the + or - terminals of the external battery will deliver a fatal shock . This is due to the use of an "autotransformer" within the unit that keeps the cost down .	godfather (25)
462544	2006-06-13 05:22:00	Be VERY careful . Many of the cheaper inverters (and UPS's) are not "isolated", so one side of the 12v battery is at full mains voltage . Which means contact with either of the + or - terminals of the external battery will deliver a fatal shock . This is due to the use of an "autotransformer" within the unit that keeps the cost down . O dear, it sounds like my friend has either been very lucky, or his UPS with an external battery is/was a quality device .	personthingy (1670)
462545	2006-06-13 05:52:00	Some are fully isolated, some are not. Usually the price is an indication, pretty sure the ones here are not isolated though.	godfather (25)
462546	2006-06-13 11:42:00	Many of the cheaper inverters (and UPS's) are not "isolated", so one side of the 12v battery is at full mains voltage. Can't visualise how that would work GF, unless the LV tap off the auto transformer was at the top of the winding. I would have expected it to be at the bottom and only 15-18 volts above ground. It is a novel idea for sure, especially since the battery common should be ground/neutral and the + terminal being charged at 13 or so volts DC. I can't see how it could get approval for use in NZ either. My education is clearly lacking! Can you draw me a picture in words? Cheers Billy 8-{) :confused:	Billy T (70)
462547	2006-06-13 22:52:00	The issue was covered a few years back in "Silicon Chip", where the dangers were discovered . I do not have any circuitry and don't want to take my units out of service just now to see (too much white stiff around on the ground yet) . But I would not discount the electronics operating at the phase potential rather than the neutral, as much of the electronics in the field I work in does "for reasons of economy" . . . . That could indeed see the tapping at the top of the autotransformer rather than the bottom . The transformer in my units are nowhere near the size one would expect for 600 vA, so they must be autotransformer in nature in my opinion . As for approval, as the batteries are an integral part of the device, in a sealed plastic case, with no provision for any external battery connection they should comply . The same as "live chassis TV" sets comply? Adding larger batteries to cheaper units would see them self destruct anyway, the duty cycle is designed for the time taken to run down the existing batteries, larger batteries (longer time) would cause thermal failure . Anything of the quality that could stand the longer duty cycle would be likely be a fully isolated supply anyway, I suspect . Higher quality inverters that feature isolation typically state "This isolation eliminates the danger of high voltages appearing on the battery input circuits", so the matter is understood? FAQ's from . latronics . com/qa . html" target="_blank">www . latronics . com state: Q: Why is DC / AC isolation important? A: If the DC and AC are not isolated the Inverter would place dangerous AC voltages on the battery terminals and greatly increase the potential for electric shock .	godfather (25)
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