MPP Solar Inverter Whine only when driving at 40-48mph

[2muchwhine2littlewine]

I have built out a Ram Promaster van and have a house battery setup using a 200AH LiFePO4 PowerUrus battery, 12v fuse box for lights, fridge, fan, USB chargers, 2*200W rich solar panels in series, and a MPP solar inverter (1000w 12v 110vac MPP Solar off grid Inverter 40A MPPT solar charger 1012LV MS). I installed the battery, MPP solar inverter, fuse blocks and all my 12V appliances a few months ago with no issues. After connecting up my solar panels I now get a high pitch whine coming from the mpp solar inverter only when I am at driving at a certain speed. It starts pretty quietly around 40MPH gets louder and then reduces in volume until it goes away at ~48mph. If I drive at 45 it stays on loudly at a constant volume. Accelerating and decelerating, bumpy vs smooth road, windy verses calm, driving in the sun verses no sun has no effect on the noise. It has been like this for a few weeks now and I have checked all my connections are tight. I also have disabled the alarm beep on the unit though it still beeps when the sun turns it on and off and this noise sounds just like the alarm though the beeps though the beeps always start and stop and don't gradually fade in and out. Also, the unit still is charging my battery while this sound is going on and I don't have any USB device plugged into the coms port. Anyone have any ideas on what I could try to get rid of this noise?

 

[sunshine_eggo]

Disconnect PV from inverter. Noise still present?

 

[Symbioquine]

Disconnect PV from inverter. Noise still present?

Similar question; Does the noise happen if you turn off the inverter entirely?

 

[2muchwhine2littlewine]

Similar question; Does the noise happen if you turn off the inverter entirely?

The inverter is off - I have not tried driving with it on yet.

 

[2muchwhine2littlewine]

Disconnect PV from inverter. Noise still present?

I will try later today and update

 

[2muchwhine2littlewine]

Disconnect PV from inverter. Noise still present?

I disconnected the PV entirely and the noise is still present... now I am really baffled.

 

[newbostonconst]

Alternator whine?.....you need some cheese....

 

[Adam De Lay]

We’re the panels on the van before the noise started happening?

 

[CoolWill]

It's dirty alternator power. Experiment with some bypass capacitors at the inverter and/or alternator.

 

[Tomthumb62]

Do you have any alternator charging?

If not, perhaps isolate your solar system from the van’s ground/chassis will help. If all your 12v items are connected to the chassis or other common ground, then you have a long job ahead of you.

Not saying this is the solution, but it might be.

 

[2muchwhine2littlewine]

We’re the panels on the van before the noise started happening?

No they were not... if it is the panels any way to get it to stop?

 

[2muchwhine2littlewine]

Do you have any alternator charging?

If not, perhaps isolate your solar system from the van’s ground/chassis will help. If all your 12v items are connected to the chassis or other common ground, then you have a long job ahead of you.

Not saying this is the solution, but it might be.

No alternator charging for the house battery / 12v fuse box. I currently have no chassis grounding - the house system is floating and I have everything tied back to the battery terminals.

 

[Adam De Lay]

No they were not... if it is the panels and way to get it to stop?

I'm just spit-balling, but I'm wondering if you're getting the noise from the wind running over/under the panels and vibrating.

 

[2muchwhine2littlewine]

It's dirty alternator power. Experiment with some bypass capacitors at the inverter and/or alternator.

my system is disconnected from the car alternator and my understanding alternator whine is that comes through in line with acceleration which this noise is not in line with. house inverter is off and turning it on has no effect on the sound.

 

[2muchwhine2littlewine]

I'm just spit-balling, but I'm wondering if you're getting the noise from the wind running over/under the panels and vibrating.

I have thought of that and feel like wind, bumps, and rain on the panels would affect the sound volume and pitch and they dont seem to have any effect I can ascertain

 

[Adam De Lay]

I have thought of that and feel like wind, bumps, and rain on the panels would affect the sound volume and pitch and they dont seem to have any effect I can ascertain

Maybe check and make sure all your roof connections, including cables are all tightened down? Maybe it's the cables under the panels and the sound is traveling down the cables and that's why it sounds like it's coming from the inverter?

 

[Adam De Lay]

Not sure where everything is stored, any possibility of having someone else drive so you can try and listen to different areas?

 

[mikefitz]

With a metal body van, the house battery negative and inverter case earth point need bonded to the metalwork for safety.

Have you considered there is a mechanical resonant frequency of the inverter case or a internal part, in sympathy with vehicle vibrations.
You may have faults on the vehicle, wheel inbalance or failing wheel bearings, ( common on your vehicle).

 

[2muchwhine2littlewine]

With a metal body van, the house battery negative and inverter case earth point need bonded to the metalwork for safety.

Have you considered there is a mechanical resonant frequency of the inverter case or a internal part, in sympathy with vehicle vibrations.
You may have faults on the vehicle, wheel inbalance or failing wheel bearings, ( common on your vehicle).

the entire inverter was installed (without grounding to the car metal) without any noise. Can you elaborate on why I need it grounded to the car metal? I worry that that might lead to issues with the vehicles electrical system and lead to more noise linking the two systems. Also Will Prowse does not call out the system to be earth grounded for vans: https://www.mobile-solarpower.com/the-minimalist-great-for-small-vans-and-cars.html

 

[mikefitz]

Can you elaborate on why I need it grounded to the car metal

Safety, prevention of fire and electrocution.

The inverter has a metal case. Any internal failure, DC or AC, could result in that voltage on the casing.

There are distributed cables, DC and AC in the van. Faults could develop that caused van metal to have a DC positive or AC voltage.

By having van metal bonded to DC negative and AC protective earth, overcurrent protection would activate.

In my country, as a professional installer, there is a need to comply with standards that require the grounding, DC negative, AC protective earth, to vehicle body, frame, chassis.
In many installations where battery to battery chargers are used, both the house and vehicle battery are in effect connected to van metal . The AC protective earth is always connected to van metal, and would fail inspection if this was omitted.