Dual batteries - different question

[KidHauler]

I've searched the site and the internet, but nothing seams to fit this type of setup.

I've been helping a buddy wire a project into his '07 Silvy. It's a great big 'ol "Q" siren.
Yes, a Q siren. Yes, the BIG, shiny, fire truck siren. I know, but he loves it.

That said, I'm looking for a little guideance on the wiring so as not to blow the truck up. We have wired the switch to a constant duty solenoid using the aux post at the fuse panel - no luck. This thing pulls about 100a at start up, and about 50-75a at peak run time.

We then considered wiring direct to the battery, per the instructions, but don't want to compromise the rest of the electrical system when this monster fires up.

Now, we are considering adding the second battery for just the siren, using the CDS to control charging.

So my question breaks down to this; 1) Does the 07 Silvy already have a setup for dual batteries? The 2nd tray is there. 2) What's the proper way to use the CDS to maintain both batteries? 3) Would it be easier/safer to NOT hook the 2nd battery to the rest of the truck, but attach a trickle charger and just maintain it that way?

I hope someone can help. We've been at this for about a week, and I'm really leaning towards option 3 at this point.

Thanks for your input,

Dusty

[bill190]

Wire it direct to the battery like the instructions say.

Use the proper gauge wire for the amperage. Table...
http://www.offroaders.com/tech/12-volt-wire-gauge-amps.htm

[TRPLXL2]

Direct to the battery would be fine, BUT what size alternator does that truck have?? 100 amps additional draw is a lot on the stock alternator, on my last truck I had invested in a 245 amp alternator from Painless Wiring and I was glad I did.

[Kaiser-Wave]

if you want to add a second battery its simple, just use the ground and ground it somewhere near by and run the constant along the fire wall to the other constant post, this WILL not do anything to the electrical system or hurt the battery's, the only time i have ever seen this turn into amess is when you use two different battery's just make sure they are the same model and exact same specs and it will be fine, i've always ran dual battery's that way in all the cars i have built including my own and never had a problem. But if you it really draws that many amps you probably should rewind the factory alternator to higher amperage, and if you are afraid of hooking up the wire str8 to the battery put a fuse in between that and the horn that way if anything happens it will pop the fuse not fry the horn (you will probably need like an 80 amp fuse to be safe or even 100 amp circuit breaker)

[KidHauler]

Thanks to all for your help.

bill190 - thanks for the link, it's in my favorites.

TRPLXL2 - The owner is researching the alternator. I'm sure it won't handle the load.

Kaiser-Wave - I'm not against following the directions. They call for an in-line 300a fuse, but I just don't think the rest of the electrical system will handle the initial draw. We'll try the dual battery setup, but I think isolating the siren from the rest of the truck is probably the way I'm gonna go.

Thanks again, I'll get some pictures up when we get this thing figured out.

D

[Oscarvan]

I am drawing on boat electrical knowledge. Multiple battery banks are a common situation there.

I your case you could wire the second battery, completely in parallel with the battery that's in there. But, I would install an battery cutoff switch in the hot lead between the two.

I doubt this siren would run for more than a few seconds at a time. When you run it, disconnect it's battery from the truck battery (open the switch). If you have a 200A second battery you can do a parade and run the thing for a 20 second spurt quite a few times. Any more and you will get a serious headache. :gasp:

Then, when you're done and go driving for a while, turn on the switch and let the alternator re-charge the second battery.

[KidHauler]

I'm diggin' it, Oscarvan. That was kind of my thought for attaching the trickle charger - wind it up a few times, then plug it in.

Thanks, oh, and welcome to the site!

D

[Shooter]

I would go with the switch to isolate the second battery as well. I have seen them sold in three diff configurations..the first one you have to pop the hood and turn it by hand to reconnect it to the charging system once it draws the battery into the low voltage range where it may not start the vehicle with the original battery. The second one you can do from a switch inside the vehicle without lifting the hood, and the third is fully automatic. I dont remember the link for the store that sold them, but I saw them on a forum someplace. It could have been on here in fact, you may want to run a search on just adding a second battery to the silverado. I believe that is how I found it the first time.
I would also put in a min of a 100 amp breaker in the circuit, and rewind the alternater. Better to blow the breaker more often than to fry something else in the system anyway.
Good luck with your project. :great:

[KidHauler]

Just an update: The system has been in for about two weeks, and no fires yet!

We went with the second, marine battery. Hot is wired to a 150a circiut breaker, then to the CDS, down to the siren. Ground was run to the alternator bracket, but we might move that to the frame. My buddy also picked up a trickle charger with changeable ends, so that he can use it on different vehicles as well. So, it's in the truck, but not wired to it.

He said that he's done a few full winds on the siren, and the battery hasn't needed charging yet. I've told him to stop by some time so that I can get pictures.

Thanks to all for your input.

Dusty