Electrical bench testing equipment

[Gary C.]

Re: Electrical bench testing equipment

Jeff,

Don't know if the new battery chargers have full wave rectifiers or not. At best a car 12 v DC battery charger will probably have a low "ripple" DC output.

That's the reason most emergency power supply systems for DC services use batteries between the generator and the load as the batteries act as a filter to smooth out the DC ripple.

A nice filtered 12V DC power supply for bench testing will work good, but they are generally more expensive than a motorcycle or lawn tractor 12V DC battery.

Gary
....

[Jack H.]

Re: Electrical bench testing equipment

As usual I am confused.
Most of these converters list 13.8 Volts - my system is 12 volts. What damage will I cause?
Seems like you can buy one for less than $100. A battery and trickle charger will cost me at least that much.
Maybe I am making too much of all of this (as usual).
Joe

FYI, a good car battery just sitting would have ~12v. While the car is actually running, assuming the charging system (alternator/regulator) is working correctly, the battery voltage is ~13-14v.

As has already been mentioned, there are lots of options on a battery including garden tractor, motorcycle, boat trolling motor battery, junk yard, your old core from latest battery replacement, etc, etc. Many already have ready access to one of those scenarios otherwise they provide more economic alternatives. Unless you're doing a lot of bench work, you can always just pull the battery out of something temporarily too. Just my 2 cents.

[Paul J.]

Re: Electrical bench testing equipment

As usual I am confused.
Most of these converters list 13.8 Volts - my system is 12 volts. What damage will I cause?
Seems like you can buy one for less than $100. A battery and trickle charger will cost me at least that much.
Maybe I am making too much of all of this (as usual).
Joe

Your system voltage is 13.8 volts. That is what the alternator is putting out. The voltage is only 12 volts when you're running on the battery alone. If you look on a car with a fairly accurate ammeter (sic), you can see that it is at 13.8 volts when the car is running.

[Donald O.]

Re: Electrical bench testing equipment

Your system voltage is 13.8 volts. That is what the alternator is putting out. The voltage is only 12 volts when you're running on the battery alone. If you look on a car with a fairly accurate ammeter (sic), you can see that it is at 13.8 volts when the car is running.

Actually, that would take a Volt meter, not an ammeter. The ammeter will only tell you the direction and size of the current.

But you knew that and that was merely a type of typo.

DonO

[Dennis C.]

Re: Electrical bench testing equipment

Try using one of the portable battery jumpers. You wouldn't be running the devices you are testing for very long and since they are used to jump start a car it should be able to run most devices.

They are packaged well and have a handle and wall charger.

Dennis

[Gary C.]

Re: Electrical bench testing equipment

Dennis,

Motorcycle 12V DC 9 amp hour battery and small battery charger, both for less than $40 bucks at Wally World.

Good suggestion - Schumacher XP400 Jump Starter at Wally World $40

• Jump starter has 400-peak amps
• Internal 5-amp hour battery
• Car battery charger includes built-in light
• Charging status LEDs
• Convenient clamp storage mounts
• 12V DC accessory port

Gary
....

[Joe R.]

Re: Electrical bench testing equipment

Joe,

I'm glad I was able to help. Please let us know what you wind up with. If it's a DC power supply, I can help you with acquiring some quality test leads from Pomona Electronics.

Joe

[Thomas H.]

Re: Electrical bench testing equipment

Being in the electronics business, I have access to several power supplies when needed. I find them useful for bench testing parts as Joe is looking to do. There are many varieties of bench top supplies available from distributors new and on sites like ebay for both new and used. A 0 to 18 volt, 10 amp supply will handle most anything you want to test.

I find that having the ability to adjust both voltage and current are useful features. Think of the adjustable current being a current limit. If you have a old part you want to check out, you can adjust the supply voltage to 13.8v and then set a limit for the current to say 5 amps (assuming the device under test is normally rated to pull 2 amps). This way if there is a short circuit in the part, the supply will limit the current to minimize any damage to the device or the wires.

I cautionthose that use a battery for bench top testing. Batteries have a very low impedance and therfore can supply TONS of instantanous current. (I'm sure we've all seen what happens to a wrench that get dropped across a battery............) If you connect a blower that is shorted directly to a battery, either the blower will fry or the wires you are using to connect it will fry. Basically the weakest link will be found very quickly.

If you are going to use a battery for testing anything, you should have a properly sized fuse inline not only to protect what you are testing, but to also protect yourself.

When I started to power up my 60, I used a bench top supply and started with a current limit of 5 amps and everything in the car turned off. Once I applied power and saw that there were no direct shorts (I did check for shorts with a DVM first....) then I bumped the limit up to 10 amps and was able to test all of the circuits in the car. Lights, ignition, signals, etc.....

I personally like the benchtop supply idea, but I have access to them so for me it is easy. A battery will work also, just make sure you have it fuse protected.

Sorry, I normally don't bold things, but very bad things can happen when car batteries are not connected properly.

Tom

[Joseph U.]

Re: Electrical bench testing equipment

Thanks for all of the help. This all started with headlight motos that would not work and the desire to bench test them. I took them out yesterday and disassembled them. Problem obvious - Motor gear stuck - I mean really stuck - can't get it out - anyway - I am still interested in the bench testing idea - have used my battery before and I did make some long test leads (so i would not have to take it out of the car) and did put an in-line fuse on the hot lead just for safety reasons. Never thought of a small tractor battery - good idea - but I know when I need it, it will probably be dead. I have an old battery on the floor - I might try to charge it up - after all for test purposes I don't need it to hold a charge for more than an hour or so. I think I may go to wally-world and look around - and cruise e-bay as well. As always I have learned a lot. Now on the figuring out how to get those stuck motor gears out without breaking the motor casting. Thanks,
Joe

[Dan D.]

Re: Electrical bench testing equipment

Being in the electronics business, I have access to several power supplies when needed. I find them useful for bench testing parts as Joe is looking to do. There are many varieties of bench top supplies available from distributors new and on sites like ebay for both new and used. A 0 to 18 volt, 10 amp supply will handle most anything you want to test.

I find that having the ability to adjust both voltage and current are useful features. Think of the adjustable current being a current limit. If you have a old part you want to check out, you can adjust the supply voltage to 13.8v and then set a limit for the current to say 5 amps (assuming the device under test is normally rated to pull 2 amps). This way if there is a short circuit in the part, the supply will limit the current to minimize any damage to the device or the wires.

I cautionthose that use a battery for bench top testing. Batteries have a very low impedance and therfore can supply TONS of instantanous current. (I'm sure we've all seen what happens to a wrench that get dropped across a battery............) If you connect a blower that is shorted directly to a battery, either the blower will fry or the wires you are using to connect it will fry. Basically the weakest link will be found very quickly.

If you are going to use a battery for testing anything, you should have a properly sized fuse inline not only to protect what you are testing, but to also protect yourself.

When I started to power up my 60, I used a bench top supply and started with a current limit of 5 amps and everything in the car turned off. Once I applied power and saw that there were no direct shorts (I did check for shorts with a DVM first....) then I bumped the limit up to 10 amps and was able to test all of the circuits in the car. Lights, ignition, signals, etc.....

I personally like the benchtop supply idea, but I have access to them so for me it is easy. A battery will work also, just make sure you have it fuse protected.

Sorry, I normally don't bold things, but very bad things can happen when car batteries are not connected properly.

Tom

What Tom has written here is by far the best and safest way to do it. Don't be cheap. A 10 Amp DC power supply is not that much money. They are almost always on e-bay. -Dan-