Community Forums

troth · 12-07-2005, 10:43 AM

This device, per their literature, is supposed to protect your "sensitive engine computer system and 12 volt accessories... from momentary surges during jump starting or charging".
I cannot understand how it will protect. Does is "blow a fuse" or give an audible alarm? It looks like a simple LED voltage checker to me, and you have to be there pushing on the button to get it to work. I sent an e-mail asking this question to their tech support, but no response.

http://www.vdcelectronics.com/sureguard_12v.htm
So how does it "protect" from surges?

troth · 12-07-2005, 10:43 AM

This device, per their literature, is supposed to protect your "sensitive engine computer system and 12 volt accessories... from momentary surges during jump starting or charging".
I cannot understand how it will protect. Does is "blow a fuse" or give an audible alarm? It looks like a simple LED voltage checker to me, and you have to be there pushing on the button to get it to work. I sent an e-mail asking this question to their tech support, but no response.

http://www.vdcelectronics.com/sureguard_12v.htm
So how does it "protect" from surges?

Gary RVRoamer · 12-07-2005, 01:54 PM

Just a guess, but the box could easily have some electronics that "dump" to the battery ground if a voltage spike surges through the system - which it often does in automotive electronics. I worked with a group developing onboard computer equipment back in the 80's and we saw some really ferocious spikes, even reversing the voltage momemtarily. The automotive engineers were used to it, but us computer jocks were amazed that anything could survive in that environment.

That said, I would be very skeptical if this box provided much useful protection and the car's own electronics are hardened against it anyway. Whether it might help the cell phone you have plugged into the cigarette lighter is anybody's guess.

Personally, I'm not worried.

Radarr · 12-07-2005, 02:40 PM

Just my point of view, but any type of surge protection wether it be 12 volt or 120 volt, would have to be placed in line. That meaning, that these devices would have to have the currant/voltage flow through them, so they can be measured and then open the circuit when the current/voltage was in a fault condition.

What I see of the unit shown, it merely connects to both terminals of the battery. The currant/voltage still passes through the terminals, which are not connected to a disconnect of some sort, so how could it do any kind of protecting. The only thing I can see it doing, is monitoring the current/voltage and the condition of the battery.

radarr

GStream40 · 12-07-2005, 05:09 PM

And of course it is at the miracle price of .....$19.95.....just like on TV ads.

RV Wizard · 12-07-2005, 11:34 PM

My dad always told me "You get what you pay for"! Doesn't sound like much protection.

troth · 12-08-2005, 01:46 AM

Thanks guys.... -And Radarr, I agree, current has to pass through then be able to disconnect to protect. The small (16 ga.) wires can't pass too many amps.
Well I got this freebie after buying a Battery Minder (which I do love). Just wondered if anybody had one and if it was even worthwhile installing this SureGuard. There's just one LED at the top of the rating indicator columns, no actual voltage readout, and you have to push da button each time to test (not a constant display).
I got what I paid for! (yer right Mike!)

Warpath · 12-12-2005, 04:39 AM

Actually, surge devices are not generally put in-line. I am pretty sure the SureGuard utilizes MOV's (metal oxide varistor's) which are fairly inexpensive and are the popular choice for surge protection. (So the cost in this case is not the deciding factor if it works or not)

Most surge devices are utilized in a parallel circuit, the way the Surge Guard is wired. The way a surge device works is when ever a increase in voltage over the normal amount occurs in the line (in this case 12 volts) than that excess is diverted and absorbed through the connected MOV and dumped to the grounded side. So power in this case remains at 12 volts to the vehicles electronics and any excess gets diverted.

Usually the MOV is sized to start clamping down on excess voltage at a somewhat higher threshold value. So it may not start absorbing til the voltage hits say 16 or 18 volts.

The bad side of a MOV is that if it takes a big enough hit, it will blow and than you loose protection. Unless the device has some sort of indicator or you can physically see the MOV's you would not know that you no longer have protection, since power is still going to your electrical devices.

A in-line device as mentioned would be more like a power conditioning unit, which is generally better since the power is always constant and never increases to the threshold value like MOV's, but they are also much more expensive. Inline devices and specifically power conditioners utilize capacitors (as well as transformers) to absorb excess voltage and than evenly distribute that excess power over time.

We actually manufacturer electrical connector assemblies for the solenoid valve industry and utilize MOV's inside our connectors. Solenoid valves have coils which store power when energized. When the power is shut off that stored energy is surged back towards the logic controlers which cause havoc with the electronics. The MOV's work perfect.

Maybe more that you wanted to know.