DC to DC Convertor Low Voltage in Powerboost

[Ajzride]

This confuses me. If you are tied directly to the aux battery under the rear seat, and are still having issues, how could this be truck related? Unless your aux battery is going bad and the voltage is dipping under load?

I would try this same test with the battery isolated from the truck completely, or get a LifePo4 that can fit in the same spot and try it again. The lifepo4 will basically hold its voltage until it is dead, then the BMS should cut it off.

So your question prompted me to do some testing.

With the Aux battery connected to the truck, it's at 14.34v

With the Aux battery disconnected from the truck, it's at 12.94

I connected the starlink directly to the aux battery while disconnected from the truck. Fired up and worked perfect.

I then connected the aux back to the truck and connected the starlink to the positive and negative of the aux battery. it still work



What is different? Before, I connected my 12- to the post on the positive cable after the 125AMP fuse and the 12- to a seat bolt instead of directly to the battery.

The seat bolt ohm'ed to ground perfectly fine, so I don't know why it wouldn't work. Perhaps @Gros Ventre hit the nail on the head and I am missing something (I did it ohm it after his suggestion).

Next step is to add-a-fuse to the power port and see if it will power from that circuit while grounded straight to a battery.

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[Gros Ventre]

So your question prompted me to do some testing.

With the Aux battery connected to the truck, it's at 14.34v

With the Aux battery disconnected from the truck, it's at 12.94

I connected the starlink directly to the aux battery while disconnected from the truck. Fired up and worked perfect.

I then connected the aux back to the truck and connected the starlink to the positive and negative of the aux battery. it still work



What is different? Before, I connected my 12- to the post on the positive cable after the 125AMP fuse and the 12- to a seat bolt instead of directly to the battery.

The seat bolt ohm'ed to ground perfectly fine, so I don't know why it wouldn't work. Perhaps @Gros Ventre hit the nail on the head and I am missing something (I did it ohm it after his suggestion).

Next step is to add-a-fuse to the power port and see if it will power from that circuit while grounded straight to a battery.

You'd be surprised at the stuff that can make a ground connection resistive. Sometimes all you can do is get out the sandpaper and clean it up anyway... some corrosion products don't look like they're resistive...

 

[Ajzride]

Device powered up fine when I connected it to the accessory fuse in the engine panel and grounded to the main battery. Looks like they don't make an add-a-fuse for those M-Case fuses, so I'll have to get creative.

 

[HammaMan]

Aux batt grounds through the cab, when I installed my amp I used both the cab ground and the frame ground the PPOB inverter uses via grommet/hole in the cab that Y into a distribution block. No noise. The DC/DC could have some noise that other voltage converters don't like, exacerbated via the method they spot weld/glue the cab together. Everything in the truck steps down voltage whereas you're trying to step up.

 

[Ajzride]

the frame ground the PPOB inverter uses via grommet/hole in the cab that Y into a distribution block.

Any tips on where that is?

 

[HammaMan]

Any tips on where that is?

Under the truck -- should be obvious to find the PPOB inverter under RH rear floor, can't miss the ground bolted to the frame. Very little grounds to the frame so it's pretty much good to go

 

[Ajzride]

Under the truck -- should be obvious to find the PPOB inverter under RH rear floor, can't miss the ground bolted to the frame. Very little grounds to the frame so it's pretty much good to go

Thanks, I have cases of grommets, I'll add a ground there.

 

[HammaMan]

Here's the hole I made, ends up being underneath the C pillar plastic. Made a tiny pilot hole to make sure it wasn't too close to features underneath.

 

[Ajzride]

Here's the hole I made, ends up being underneath the C pillar plastic. Made a tiny pilot hole to make sure it wasn't too close to features underneath.

For testing I just unscrewed one bolt from the tire jack mount and dropped the wire through there, it didnt' make a difference being grounded to the frame.

 

[Ajzride]

Finally got it working.

1. Pull power and ground directly from the auxiliary battery
2. power and ground from the auxiliary battery into 30amp relay
3. trigger for 30 amp relay from power-port fuse under hood.
4. Power from relay into a Meanwell SD-100A-24 power conditioner and converter
5. 12 gauge wire from the Meanwell to the starlink

Now it comes on and off with the USB ports no problem.

https://www.meanwell-web.com/en-gb/dc-dc-enclosed-converter-input-9-5-18vdc-output-sd--100a--24

Forgot to take a picture after I rerouted the wires and put on some loom.

 

[HammaMan]

Finally got it working.

1. Pull power and ground directly from the auxiliary battery
2. power and ground from the auxiliary battery into 30amp relay
3. trigger for 30 amp relay from power-port fuse under hood.
4. Power from relay into a Meanwell SD-100A-24 power conditioner and converter
5. 12 gauge wire from the Meanwell to the starlink

Now it comes on and off with the USB ports no problem.

https://www.meanwell-web.com/en-gb/dc-dc-enclosed-converter-input-9-5-18vdc-output-sd--100a--24

Forgot to take a picture after I rerouted the wires and put on some loom.

First time you tried the meanwell or were you trying it all along?

 

[Ajzride]

First time you tried the meanwell or were you trying it all along?

The meanwell just came in today.

 

[HammaMan]

They're pretty decent PSUs so I suspect it has better filtering on it. Most consumer 3D printers use them - they know what they're doing.

 

[Ajzride]

Yea, meanwell's stuff is top notch. They make a 12v to 12v version as well, which would be perfect is someone is having trouble getting 12v accessories to work with the powerboost fickle electrical system.

 

[ReverendQ]

Finally got it working.

1. Pull power and ground directly from the auxiliary battery
2. power and ground from the auxiliary battery into 30amp relay
3. trigger for 30 amp relay from power-port fuse under hood.
4. Power from relay into a Meanwell SD-100A-24 power conditioner and converter
5. 12 gauge wire from the Meanwell to the starlink

Now it comes on and off with the USB ports no problem.

https://www.meanwell-web.com/en-gb/dc-dc-enclosed-converter-input-9-5-18vdc-output-sd--100a--24

Forgot to take a picture after I rerouted the wires and put on some loom.

Nice.
Adding in some solar might get you some more Ah if your use case(s) warrant it.
I assume you upped the auxiliary battery also?

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