Ok to use a serious battery charger as a DUT, for testing an Electronic Load? - Page 1
Forum section: electronics / beginners

author: t1d
author_rank: Super Contributor
timestamp: December 05, 2018, 06:57:19 am
content: I have designed an Electronic Load and I am in the power-on testing stage. Here's that thread:https://www.eevblog.com/forum/projects/electronic-load-project-ltv171-irfp250-with-kicad-files/I have two lab-type PSUs. But, even combined, they will not reach the proposed design limit of 30v/2a.Using a car battery was suggested and I think that a reasonable idea. But, I also have a serious charger and using it would be more convenient than disconnecting the car battery... Not to mention the danger of battery explosion, etc.It is possible to turn off the charger's regulation circuitry, so the charger will not be doing the work that I want the e-load to do. It can supply 14vdc at 55 amps.I am really just wanting to make sure that I am not about to do something very dangerous. It seems to me that this type of testing is exactly what the e-load is intended for. But, the charger involves mains level power and is tied to earth, so caution seems prudent. The e-load is not tied to earth.So, is it okay to use the charger for the test? If so, do I need to lift the earth on the charger? Any other precautions needed?Here are the pertinent parts of the manual.PRODUCT DESCRIPTIONIOTA DLS Series Power Converter/Battery Chargers convert 120 volts nominal A.C. to 13.6 volts D.C. As a power supply, its tightly controlled regulation allows the user to operate any 12 volt nominal D.C. load up to the converter’s rated output current. As a battery charger, the converter will maintain the battery, delivering its full-rated current when the battery capacity falls sufficiently low. The voltage is set to deliver its maximum current for the necessary period of time that minimizes undue stress to the battery caused by heating of its cells. This helps to ensure the longest possible life of the battery. Over time, as the battery nears its full capacity, the converter will float-charge the battery to prevent self-discharge of its cells.PROTECTION FEATURESThe IOTA Power Converters/Battery Chargers are designed with high quality components to help ensure years of continuous use. The unit is protected by multiple protection features for a long, trouble-free life. 1) Reverse Battery Polarity Protection. 2) Brown-Out Input Protection. 3) Over-Current Protection - cycle by cycle peak limiting as well as rated current limiting to maximize the life of the converter. 4) Over-Temperature Protection. In addition, it is designed with a unique “proportional” fan control circuit. Fan speed is directly proportional to the converter’s internal ambient temperature. This enables the fan to turn on and off very slowly, minimizing unwanted fan-starting noise.TWO-STEP VOLTAGE JACKThe two-step voltage jack allows switching from a long-term float voltage of 13.6vdc to a ‘high-stage’ voltage of 14.2vdc. When the included dual voltage plug is inserted in the jack*, the voltage rises to 14.2vdc for occasional fast charging. When the plug is removed, the voltage drops to 13.6vdc to reduce battery water loss. WARNING: To avoid battery damage, remove the Dual Voltage Plug when quickcharging is complete. NOTE: If the unit is equipped with an internal IQ4 smart charger, two-step charging is not needed and the Dual Voltage Jack is disabled.Thank you, for your help.

author: t1d
author_rank: Super Contributor
timestamp: December 07, 2018, 01:19:20 pm
content: Bump...

author: ogden
author_rank: Super Contributor
timestamp: December 07, 2018, 01:33:33 pm
content: Sure you can use battery charger to test electronic load. After all electronic loads are used to test battery chargers. Just do not forget to add fuse between two - to not burn anything in case transistor of your load fails. Ouch, just noticed that this is smart charger which 1) may not start w/o battery (0V voltage) 2) may stop charge when your load cannot hold voltage below some treshold. You may try to build test fixture (current limited ~12v supply + diode) which may fool charger and let it start hi-current charge state, thou I have no idea how to avoid charge current termination. One is clear -if your load itself works properlynothing bad with charger will happen in case there's 10A or so, fuse between two. Try it and see how it goes.

author: Mechatrommer
author_rank: Super Contributor
timestamp: December 07, 2018, 01:59:52 pm
content: its ok to use the charger if you dont mind its blowing up...

author: t1d
author_rank: Super Contributor
timestamp: December 07, 2018, 02:23:05 pm
content: Quote from: ogden on December 07, 2018, 01:33:33 pm

author: Kleinstein
author_rank: Super Contributor
timestamp: December 07, 2018, 02:37:27 pm
content: It should be OK with a proper fuse in between. Its there to protect the charger and shunt in the E-Load in case the MOSFET blows. So maybe less than 10 A would be better - just a littler high than the current the load can stand.It's usually better to have one fuse more in the circuit than needed.

author: t1d
author_rank: Super Contributor
timestamp: December 08, 2018, 12:28:55 am
content: Kleinstein, thanks for the help!

author: t1d
author_rank: Super Contributor
timestamp: December 08, 2018, 11:16:19 pm
content: I did the test, using the battery charger. I had no problems. I did add the extra in-line fuse.

author: ogden
author_rank: Super Contributor
timestamp: December 09, 2018, 12:15:18 am
content: Quote from: t1d on December 08, 2018, 11:16:19 pmWhy don't you share your results/measurements, if any? Some may be interested in your findings and performance of your load.

author: t1d
author_rank: Super Contributor
timestamp: December 09, 2018, 02:04:23 am
content: Quote from: ogden on December 09, 2018, 12:15:18 amGood suggestion and I did just that, on the e-load thread, listed above. I hope you will join us, there. Thanks!https://www.eevblog.com/forum/projects/electronic-load-project-ltv171-irfp250-with-kicad-files/