whining noise after dual batteries installed

[Jc12]

Hey guys, i just wrapped up my dual battery setup yesterday and almost immediately noticed a whining noise. I will outline everything i can - also this a two parter as i have one other question unrelated to the noise

-most noticeable when in 'drive' but idling
-increases as i accelerate then disappears
-not noticeable in park or highway speeds
-sounds the loudest on the driver side when inside the cabin

i tried to duplicate it and stand at my engine but i couldn't really pick up on it as i couldn't leave the car in drive. I am guessing it is the alternator, my gauge is giving me completely normal charging readings and it doesn't seem to have any issues charging both batteries (i used the TMAX kit with the isolator).

The second item is how i mounted the plate which holds both batteries. I used fairly thick steel and noticed there was a slot just above the alternator where i could extend the plate into to help support the weight. Thinking about it now it might not be a good idea as it will limit how much the alternator can travel this limiting how much the engine block can travel on the mounts. I revved it up in park and noticed it has some play but i couldn't tell if it is the same as when the battery platform wasn't mounted. Any thoughts? (ill include a photo)

Thanks!

Here is the plate resting on top in the gap above the alternator

<a href="http://s1188.photobucket.com/user/jeffconnell12/media/dual%20battery/7182F1F7-4BEB-43B4-84C4-0C9317BAAF0B_zps3ur5mwxh.jpg.html" target="_blank"><img src="http://i1188.photobucket.com/albums/z419/jeffconnell12/dual%20battery/7182F1F7-4BEB-43B4-84C4-0C9317BAAF0B_zps3ur5mwxh.jpg" border="0" alt=" photo 7182F1F7-4BEB-43B4-84C4-0C9317BAAF0B_zps3ur5mwxh.jpg"/></a>

<a href="http://s1188.photobucket.com/user/jeffconnell12/media/dual%20battery/CFC98CAF-7B9D-439F-9007-DD02B9219296_zpsptgyssf4.jpg.html" target="_blank"><img src="http://i1188.photobucket.com/albums/z419/jeffconnell12/dual%20battery/CFC98CAF-7B9D-439F-9007-DD02B9219296_zpsptgyssf4.jpg" border="0" alt=" photo CFC98CAF-7B9D-439F-9007-DD02B9219296_zpsptgyssf4.jpg"/></a>

<a href="http://s1188.photobucket.com/user/jeffconnell12/media/dual%20battery/2F595619-DE07-4E0D-AF8F-778BE6360F79_zpshxjkrcpc.jpg.html" target="_blank"><img src="http://i1188.photobucket.com/albums/z419/jeffconnell12/dual%20battery/2F595619-DE07-4E0D-AF8F-778BE6360F79_zpshxjkrcpc.jpg" border="0" alt=" photo 2F595619-DE07-4E0D-AF8F-778BE6360F79_zpshxjkrcpc.jpg"/></a>

 

[IBallEngineer]

I'll address the 2nd issue, NOTHING mounted on the body should EVER touch anything on the motor unless it's a wire or cable. You've created a vibration/noise source at best, a broken part at worst.

Now assuming the bracket does NOT touch the alternator, the noise is probably the alternator working. When it is outputting high amperage it will whistle, or whine. But as the batteries charge that should diminish.

 

[BrianSD_42]

Is the whine coming from your speakers?

 

[Jc12]

okay thanks, i will cut it off and maybe add a second piece of steel to reinforce the plate.

I can drown the whine out with the stereo so is it safe to assume it would get louder if i increased the volume? It definitely seems more like it is coming through the firewall.

 

[nevada]

I'll address the 2nd issue, NOTHING mounted on the body should EVER touch anything on the motor unless it's a wire or cable. You've created a vibration/noise source at best, a broken part at worst.

Now assuming the bracket does NOT touch the alternator, the noise is probably the alternator working. When it is outputting high amperage it will whistle, or whine. But as the batteries charge that should diminish.

agreed.

occasionally when wheeling, if someone kills a battery, I will lend them my 2nd, since I have a high output, I will charge their battery. the alt whines very loudly, until the charge level comes up a bit.



OP, did you install a discharged battery? if so, that is very bad for the alternator. put it a trickle charger over night.

 

[Jc12]

the battery (AGM deep cycle) came charged and sat one week in my garage before i installed it so i believe it was up around 12.6v.

 

[burnoil]

When I did the dual setup on my FJ a couple years ago the alt whined a lot if the secondary was depleted a bit. Noticed it almost right away..."doubt-induced amplification" is what happens when you wrap up a project and then start "hearing" things. I have it BAD...real bad

 

[Jc12]

When I did the dual setup on my FJ a couple years ago the alt whined a lot if the secondary was depleted a bit. Noticed it almost right away..."doubt-induced amplification" is what happens when you wrap up a project and then start "hearing" things. I have it BAD...real bad

Oh this is only one of the 100 new sounds i swear i'm hearing hahaha. thanks for the feedback guys!

 

[98OzarksRunner]

I'll address the 2nd issue, NOTHING mounted on the body should EVER touch anything on the motor unless it's a wire or cable. You've created a vibration/noise source at best, a broken part at worst.

Now assuming the bracket does NOT touch the alternator, the noise is probably the alternator working. When it is outputting high amperage it will whistle, or whine. But as the batteries charge that should diminish.

Correct. The motor mounts (with rubber bushings) allow the motor to move slightly to reduce vibration and noise. The body is also isolated from the frame with rubber mounts, so you have movement of the body on the frame, and movement of the motor on the frame - lots of things have to move. As the motor moves (or the body moves), it will probably break your bracket and your batteries will be hanging in the air.

 

[19963.4lsr5]

My alt whined on the 97 when I first got it. Got worse as the load increased. I put the spare alt from the 96 and the noise and vibration went away.

 

[Jc12]

i've been looking into an alternator upgrade in the near future but cant get over the fact i just installed all of this using 4 gauge wire (very short distances) which is fine for my current setup but i fear undersized for a 130-150 amp alternator.