Sound Insulation for Battery Charger Against Bulkhead

[Warby12]

Hi there. I have a great spot for my battery charger, screwed to a bulkhead but the trouble is the other side of the bulkhead is the galley.

When the fan on the charger is running the noise seems to resonate through the bulkhead like it's attached to the base of a guitar!

I can't see this kind of music catching on

It's a great spot for the charger but can anyone suggest a way I can deaden/absorb the vibration?

[nimblemotors]

I recently took in/out a few times a air injection pump, and it has these nice little rubber isolators that have nuts in them, so the attached pump is isolated by the rubber from the vehicle frame. Grainger has these for $2 each..

[model 10]

Mount it on some rubber grommets and add a little insulation.

[Warby12]

Hi there! Yeah I should have said I did try that in a homemade bushing kind of way. I need more it's a real sounding board. I guess I could glue another piece of ply on their to thicken it but I really want quiet it completely. Maybe I could put a bit of lead sheeting behind it. I know noise has to be absorbed and lead is good for that. Plus if I ever install a nuclear power plant part of the shielding will be done!

[Terra Nova]

Take it off the bulkhead.

[model 10]

Double mount it. Mount it to a piece of ply with the rubber and the ply with more rubber (and lead and insulation.) I've used lead as a sound insulation but not to stop vibration. I also think there needs to be a decoupler
(foam) when you use lead to break up the sound.

[nimblemotors]

I could ask why a battery charger would be making vibrations and noise?
Might start there.

[Warby12]

"Double mount it!" You're right! I was just about to use Terra Nova's advice but instead do a variation and remove the bulkhead.

You saved me from it Guy

I'll try: Charger attached to a piece of thin ply with grommets, with sheet of lead on the back and that ply attached to the bulkhead with more grommets. I will take a photo so the design will be recorded for posterity

[Warby12]

Originally Posted by nimblemotors

I could ask why a battery charger would be making vibrations and noise?
Might start there.

It's one of these: M 300 Incl. STARTER
It's not that bad the fan noise and it's only when under heavy load but it seems perfectly matched to the harmonics of the bulkhead! The spot where I want to put it is too perfect to ignore, close to the batteries, away from the engine, good airflow, safe from salt etc. There is a little sub panel for the solar controller, wind gen switch etc. It's in a cavernous cockpit locker that I'm turning into a little workshop.

[colemj]

It does seem strange that it would vibrate so much that a bulkhead would resonate with it. Is it a thin bulkhead? Have you tried gluing a wood support on it to change its resonance frequency? The plywood you mention might do that too.

Mark

[Warby12]

Thanks Mark! Yes it is definitely a resonance thing. I sure don't want to sound like I understand harmonics etc because that is one complex area

If I sit the charger down on a bench, It makes hardly any noise but if I place it against the centre of the bulkhead you can hear it all through the saloon!

Probably just changing the characteristics of the bulkhead by gluing another plywood square on will take off 90% of the noise but I want to fix the problem completely. I've ordered the grommets Nimblemoters has suggested and I'm pretty confident this will work in combination.

I hope people don't think I'm being too finicky about this I've put a lot of thought into positioning these bits of equipment and half the fun of having a boat is the interesting problems they throw up!

[jeepbluetj]

I'd use dynamat instead of lead. Available at all car stereo shops

[Terra Nova]

Originally Posted by Warby12

...Probably just changing the characteristics of the bulkhead by gluing another plywood square on will take off 90% of the noise...

Dreaming.

[nimblemotors]

I can only assume it has a fan which makes the noise and vibration.
Change the speed of the fan, or isolate the fan itself mounting to the charger,
or replace the fan with another better one.

Originally Posted by Warby12

Thanks Mark! Yes it is definitely a resonance thing. I sure don't want to sound like I understand harmonics etc because that is one complex area

If I sit the charger down on a bench, It makes hardly any noise but if I place it against the centre of the bulkhead you can hear it all through the saloon!

Probably just changing the characteristics of the bulkhead by gluing another plywood square on will take off 90% of the noise but I want to fix the problem completely. I've ordered the grommets Nimblemoters has suggested and I'm pretty confident this will work in combination.

I hope people don't think I'm being too finicky about this I've put a lot of thought into positioning these bits of equipment and half the fun of having a boat is the interesting problems they throw up!

[Ex-Calif]

Sounds like you've attached a small vibration to a large sub-woofer cum amplifier.

This unless you can stop the transmission of the vibration through the mounting bolts you have to stop the bulkhead from vibrating.

Amplitude & frequency. You can't change the frequency (easily) so you have to deaden the amplitude.

You have to change the resonant characteristics of what I am guessing is a thin bulkhead - plywood double - bigger than you think. You need to stop the bulkhead from vibrating.