Hi Guys,

I made this for fun and the future.
As my car is aging, wires or connectors performance may decline, more so those in hot engine bay.

There are times real load is required to see cable performance, where resistance test or continuity without real load , won't expose a cable weakness.

The DIY Load Bank Box a simple multiple incandescent bulbs arrangements. The design target primarly is about safety from loose wires if say a bulb with simple 2 wires is being used and variable load capability.
With the car engine and chassis being a negative part of the car electrical system, I hate to see any positive cable copper end dangling around.
Being multiple bulbs of 5 watts x 2, 10 watts x 1, 20 watts x 1 and 50 watts x 1 , I can test from 0.4 amps to 7.1 amps with decent progression.

Incandescent is choosen for a non polarity type bulb and its lower glow is visible if voltage drop occurs.

There is also a buzzer of very low power demand, like 2 milliamps or so and it is polarity protected as per test lead color.
This buzzer can sound at as low as 5 volt and limit is 24 volt.

While making this DIY Load Bank, I also made it to be amperage tester assisting system for the purpose of very low milliamps parasitic drain monitoring or
simply wherever an amperage demand up to 20 amps is to be verified, but only for short duration under 3-5 minutes if 20 amps.

Wiring schematic is below :

For those who are wondering, why would I fused at 3 amps, both the sensing for voltage positive and negative downstream of the Wago 221-Voltage ?
This is to save a hassle where by mistake if I or anyone borrowing my DIY Load Box, was rigging his DMM in amperage mode and forgot to rig it back to voltage mode. Bang !!, DMM internal fuse will blow.
The hassle is the Fluke internal fuse for amperage protection, in my country cost US$20 each, yeah...insane. I rather pay for a US$0.30 German Flosser or US made LittleFuse ATO/ATC fuse, those 3 amps.
Only those 2 brands I dare to buy locally, if for ATO/ATC fuses. The unknown brands , surely China made could put a fuse material NOT accurate as in BIGGER to its rating. I seen such reports on China made MCB/breakers.


Before buzzer installed



.



.
With buzzer installed




If and when the DIY Load Box will be used for amperage reading assist






AA. Insert fuse at that black fuse terminal. For load higher than 10 amps ( DMM limit is 10amps ). Current clamp to be use in this setting. Clamp the fuse assy wire to read amperage.
BB. Connect DMM to the Wago 221 connector in amperage mode, for load under 10 amps. Fuse of AA not used. This is good for parasitic load test when using a DMM with 400 milliamps setting.
My Car at deep sleep mode only uses 6 milliamps.


To use DMM for voltage information while using DIY Load Box.
Connect the DMM in voltage mode to the Wago connectors prepared.


.



The big gold color and has plastic clear cover negative post is from a speaker connector.
It is to be used only when I need to clamp to something big as negative post and extra distance.
The extra big additional connection is only negative post, there is none positive post. Negative post is safer in our cars using car body as negative ground.

The extension wire for the big negative post has a fuse and a crocodile clip suitable for up to battery post size. It is the number #2 below.



Cable accessories 1A & 1B is to be used when sharp pointed test leads I have won't work and instead a mini crocodile clip required.
I find using Wago 221 connector to test lead a much more solid and stable connection compared to those slide-on-into-test-lead type mini crocodile clip with rubber boot,
which item 1A and 1B are exactly that slide-on type.

ALL WIRES to all crocodile clips are crimped and soldered, for all no 1 to 3 accesories.
Item no 2 and 3, due to being a bigger crocodile clip, the 2 sides of the clip's jaws are also soldered with a wire. So both side of jaws have equal performance in terms of electric power delivery.




.




The item no #1 wire accesories, simple jumper wire with 2 big crocodile clips suitable for battery post........... comes handy for this scenario :
Car computers have slept well. Now I need to remove battery negative wire while I do not want to wake up the computers from a power loss + re-connection.
With my DIY Load Box and #1 jumper, I can single handedly, loosened the battery terminal while using the sharp test lead/probe needle point....pressing to the battery post circular lead block,
undo the battery terminal 10mm nut, slide up the battery terminal and get the pre-prepared #1 jumper crocodile clip to bite the battery post circular lead block. DONE.
This save me 2 hours of waiting for computers to sleep again, if ever the car computer loose negative wire connection to battery.

I don't want to test parasitic load via B95 battery sensor, I always remove it completely from the battery post.
This battery sensor B95, when using battery tester Konnwei KW650, can produce 4% error for battery state of health or internal resistance.
That battery sensor is a shunt, and a shunt is a resistor.


The test lead is a separate buy and it is from Uni-T. Model UT-L73 Multimeter Probe. It is very slim sharp egde, suitable for my purpose.


END.

 

Awesome work… I’ve been using automotive bulbs as loads for years. Usually involves messing jumpers and pins. However your setup is more elegant.

 

... indeed....bulbs as load are helpful.