Wiring up a DCDC charger

[ErOsion9o]

Hi members,

Ive just installed a Supercheap Ridge Ryder 20a DCDC charger in the rear seat well
of my NT pajero.

I ran 4gauge 100amp cable from the main battery to the back, from there i used 4gauge to connect the aux battery to the dcdc charger and 6gauge 50amp for the negatives. All positive connections have a 100/50A fuses. The fuses are not blown.

Upon switching it on for the first time, the charger came on for about 5 seconds and hasnt been back on since. The main battery is outputting over 13.5 volts (12.8 is required for the unit to work).

The only thing i havent done is run a negative shared cable from the main battery to dcdc/aux battery. Is this required? I have a good solid earth connection for the charger and the aux battery.

[Keithyv]

You should not need separate negative feeds no - earthing to the chassis should be fine.

Where are you measuring the 13.5 volts? right at the main battery or at the input to the DC-DC charger? The only thing could be you are getting a severe voltage drop under load but even then the DC-DC charger SHOULD kick in and then kick straight back out again. Maybe it's just faulty?

You've tried all this with the vehicle running? that should bring the main battery voltage up to over 14 V

[ErOsion9o]

Where are you measuring the 13.5 volts? right at the main battery or at the input to the DC-DC charger? The only thing could be you are getting a severe voltage drop under load but even then the DC-DC charger SHOULD kick in and then kick straight back out again. Maybe it's just faulty?

I have just tested to voltage on the DCDC charger whilst the car was running. On the DC in+ and the negative output i was getting a reading of .04 V. On main battery it was reading over 14v.

[Keithyv]

.04? that's not good...

[ErOsion9o]

Does that mean possible faulty charger?

[nj swb]

If you're getting 0.04 V on the DC + input then you have a wiring problem. You need to chase back along your +ve supply until you find more volts, then figure out what stopped them getting through.

Unless I've misunderstood your post?

[ErOsion9o]

Ive used pre-existing 4g cable that was once connected to a stereo amp rated at 100a. My assumption would be that the cable is damaged.

I will re-wire with 6b&s under the chassis. Hopefully this fixes the problem.

The only reason i am skeptical of it being a wiring issue is that the charger did turn on for ~5 seconds the first time i tested it. Could it be internal damage?

**after troubleshooting at lunch, i found the fuse near the main battery to be blown - i will replace after work and report back**

[denmonkey]

Ive used pre-existing 4g cable that was once connected to a stereo amp rated at 100a. My assumption would be that the cable is damaged.

I will re-wire with 6b&s under the chassis. Hopefully this fixes the problem.

The only reason i am skeptical of it being a wiring issue is that the charger did turn on for ~5 seconds the first time i tested it. Could it be internal damage?

**after troubleshooting at lunch, i found the fuse near the main battery to be blown - i will replace after work and report back**

Check all your work before you go slapping another fuse in. Run over your wires to make sure you don't have a short somewhere.
It's possible you may have done it during the install

I stuck on in my carvan a few weeks back and have had no issues with it .
I can confirm it requires the 12.8v to become active and start charging

[Sparky3975]

As has already been mentioned, check the resistance/continuity and shorts to earth on the existing cable? It may be an easy repair rather than running more cabling. Just ensure you have fused the cables correctly too. I recently installed a BCDC and mine is protected with 40Amp fuses in/out.

[ErOsion9o]

So the issue was a faulty 100a fuse, no signs of it being damaged or broken however upon testing another fuse, all is working.

Cheers, hope this helps someone in the future.