Automotive Surge Protector 12/24 Volt - Page 1
Forum section: electronics / general

author: Cnd_mecheng
author_rank: Newbie
timestamp: February 12, 2021, 06:23:34 am
content: Hello all,I've seen these used at numerous automotive shops, but I'm not really sure there is any validity behind them. They are sold by many reputable companies like Snap-on, Matco etc (North America), but would this really protect a car's electronics from a badly connected ground clamp?The intended use is to put the clamps on a connected battery before one begins welding on a vehicle, the device would then prevent any spikes that could damage electronics.www. toolsource.com/memory-savers-c-24_31/antizap-clampon-surge-protector-1224-volt-p-131180.html#:~:text=Eliminates%20the%20need%20to%20disconnect,after%20one%20or%20two%20usesThe insides are very simple, and I have a hard time believing this product does anything other than give peace of mind. I'd appreciate any insight on how this would actually function, or if any such product has any scientific basis?

author: srb1954
author_rank: Super Contributor
timestamp: February 12, 2021, 10:48:35 am
content: Quote from: Cnd_mecheng on February 12, 2021, 06:23:34 amThe circuit arrangement seems to be pretty illogical, particularly the ridiculously large cables. The contents of the plastic box would explode long before the cables even got slightly warm.Can you read the full part numbers on diode D11 and gas discharge tube GT11?Knowing those part numbers would help determine if this circuit has any useful effect or it is just a gimmick.

author: nali
author_rank: Frequent Contributor
timestamp: February 12, 2021, 12:13:57 pm
content: Well, I don't know where that patent was filed, but US620091 refers to door seals for safes. I callBut I wonder why bother putting anything at all inside? Love those monster cables along with the tiny PCB traces going to the actual components.

author: Cnd_mecheng
author_rank: Newbie
timestamp: February 12, 2021, 04:54:00 pm
content: Yeah, I also couldn't find anything with that patent number.

author: Gyro
author_rank: Super Contributor
timestamp: February 12, 2021, 04:54:18 pm
content: It looks like a bidirectional TVS, Neon, and Spark gap tube in parallel.The LED looks like it lines up with the 'Correct Connection' hole but the Neon is nowhere near the 'No Protection one'. By the time that starts flashing, all bets are probably off anyway.I suppose the TVS might do something, but the Neon (straight across the leads, no series resistor) and GDT (90V?) are far too high breakdown voltage to help anything.It looks like somebody without a clue just though 'I'll put something together with multi-layer protection'. There will be a much bigger TVS in the engine management unit. If it ever got up to GDT or Neon breakdown voltage, it would already have used the PCB tracks to the TVS as fuses anyway!As for the lead thickness, they're probably the thinnest that will crimp into the clamps and they want it to look beefy too. I'm callingtoo.P.S. I don't know why they bother with the correct connection LED anyway - It looks as if the only polarity sensitive device in there is the LED itself.

author: bdunham7
author_rank: Super Contributor
timestamp: February 12, 2021, 05:24:13 pm
content: Unfortunately the America Invents Act eliminated thequi tamprovision of the false marking statute, otherwise some enterprising attorney would have sued for what is a fairly blatant case of fraud.As for whether the device has any effect, I wouldn't rule it out entirely, but I'm extremely skeptical. The battery is such a low impedance that the only spikes you will see that will activate the neon lamp or GDT would be very short. I don't know the spec on the TVS. I suppose we need to know the effective series inductance of a lead-acid battery to have any idea, but this does look like a placebo to me.OTC is a 'real' tool company, so I'm not sure what is going on with them. This looks bad!Edit: I didn't realize it, but OTC is now owned by Bosch.

author: Cnd_mecheng
author_rank: Newbie
timestamp: February 12, 2021, 05:28:51 pm
content: "The circuit arrangement seems to be pretty illogical, particularly the ridiculously large cables. The contents of the plastic box would explode long before the cables even got slightly warm.Can you read the full part numbers on diode D11 and gas discharge tube GT11?Knowing those part numbers would help determine if this circuit has any useful effect or it is just a gimmick."Sorry, I actually don't have one of these in my possession, I just came across this in my research.Here is the original thread where I found it, but they didn't really go into details about the components.https://www.mig-welding.co.uk/forum/threads/surge-protector-internals.82618/It looks like it they are using a neon indicator lamp (N11) and a Gas Discharge Tube Arrestor (GT11), but considering that the clamps are going to the battery terminals, any higher voltage would already have found a path through the electronics this device is meant to protect?When I saw this device I got the impression that it was as effective as snake oil, but electronics aren't my field and wasn't sure if there was some theory behind this. At $50 USD its not the cheapest thing out there.