Deep Cycle Battery

[60eldo]

   Does anyone know if its OK to use a deep cycle battery in our cars. Why I ask. I just put a stereo and amp in my car, and with car off and running the stereo, battery went dead in about an hr.

[TJ Hopland]

Deep cycle doesn't have anything to do with how long a battery will last at a given load like your example of running the stereo.   It has to do with maintaining that capacity over time when you constantly significantly discharge it then recharge it.   A typical starting battery you pull some power out when you start but recover it fairly quickly so it tends to be charged most of the time.  Deep cycle is used for things that use power for extended periods without being charged like say an electric golf cart or a camper boat RV sort of thing.

If you constantly significantly discharge a standard battery its capacity will be reduced over time.   No real harm in having a deep cycle and not significantly discharging it but in your case I don't think is or will solve the current issue. 

If you plan to run the stereo for extended periods regularly then a deep cycle would be a good idea but you would also have the secondary issue of not having the capacity to start the car again.  If that is how you want to use the car the you would want to do a dual battery setup with an isolater like you would use in an RV.   The isolater is a one way valve sort of thing that will let the 'house' battery that is running the stereo charge off the cars main system but won't let it use any power from the starting battery. 

[Bobby B]

   Does anyone know if its OK to use a deep cycle battery in our cars.

You can use anything you want, but ask why wouldn't they come from the factory with them. First off, they offer lower CCA for the same size battery. So if you live in a colder climate, you usually have to increase the size of the battery by 20% or so.  Also, Typically automotive systems put out a lot of current and quickly bring the system up to 13.8 (temp corrected) and just keep it there. Sort of like going from Bulk straight to Float. There's really no Absorb stage, and the more expensive, less-suitable-for-the-application deep cycle battery will have its life shortened as a result. Read up on why a deep cycle battery is needed, mostly in the marine world.......
                                                                                        Bobby

[60eldo]

  So what I want to do is ie I go to a car show in the summer, cars parked and off. I play the stereo for an hour or so, go to start the car, batteries dead. Any suggestions, maybe put another battery in trunk, and just run the stereo off that one.

[rajeevx7]

Brother, I don’t think it’s possible to play an amplified audio system at significant volume independently for 1 hour without murdering your battery.

Go buy a lithium-ion Bluetooth boom-box and stream feed it from your phone.

[TJ Hopland]

Does a 60 have an accessory position for the ignition?  Just wondering if there are things running that you don't need.  Stock radio or a modest aftermarket one?   An hour seems like a very short period to kill a battery. 

For a car show I would think you could come up with something with its own batteries.   Maybe something like this?

https://www.detroitdiecast.com/product-p/amplified-bluetooth-rca.htm

And run it off one of those jump start packs that has a power jack on it?

[Cape Cod Fleetwood]

  So what I want to do is ie I go to a car show in the summer, cars parked and off. I play the stereo for an hour or so, go to start the car, batteries dead. Any suggestions, maybe put another battery in trunk, and just run the stereo off that one.

When I take The Ark to car shows, I have a battery operated CD player on the ground, under the engine, playing all the top songs of 1970. Keeps the crowd around the car not only because they like, but they can't tell where the music is coming from, LOL!

\m/
Laurie

[fishnjim]

Must be one heck of a big amp?   TURN THE VOLUME DOWN! 
We use them in boats for that reason, and they make dual purpose deep/start these days.

[TJ Hopland]

One of the biggest design differences in a deep cycle is they leave more room at the bottom for crud to build up.  At the moment I can't remember the actual name of the crud.  The deeper cycling creates more of this crud stuff which in itself degrades the battery but what kills them even faster is when that crud builds up at the bottom and shorts across the plates.  Simply leaving room at the bottom so the build up doesn't touch the plates as soon helps that part of the problem.  Changing the ratio of fluid to plate changes the capacity as well as capacity vs physical space is why they don't just leave that space at the bottom of every battery. 

In this specific case my questions are:

-What is the capacity / size of the current battery?   And when tested how close does it currently come to that original spec?   Maybe its just time for a new battery.

-Is the current charging system working to its original specs?  If it is under optimum engine speeds how long would it take to recover say 40% of the batteries charge?   How about idle?    Are you then using the car enough that it can fully recover?  If any of these items are lacking a larger capacity battery won't help.   You would possibly need a larger or second alternator to support a bigger battery(s).   If that isn't the direction you want to go then maybe a second stand alone system that you plug in to charge at home would be the way to go.

Up sizing the existing alternator / generator isn't a simple process either to do properly.  You either need to limit the power going into the original wires or upgrade/replace them.  Limiting is possible but more complicated (and expensive) than you would think.  Upgrading has its own complexity and really needs to be carefully thought out.  That is were basically a secondary independent system for the stuff you are adding to an old car starts to make sense especially if you start talking about a significant amount of electric stuff like a mega stereo or hydraulics or whatever.     

If some sort of a secondary system is what you are thinking there is plenty of information on that sort of thing in the marine RV world.   Bigger boats and RV's almost always have 2 battery systems.  One for starting the engine and the other to run everything else.  They have all sorts of options and gadgets to control, monitor, and isolate those systems.               

[T J Lankes]

Below is a link for a short video on AGM batteries from Johnson Controls which manufactures most of the car batteries.  They make the batteries under many brand names like Delco, Champion, Duralast, NAPA, Optima, etc.

As has been indicated, the big advantage of AGM batteries is that they can withstand the fully discharge and recharge cycle (deep cycle) better than wet flooded batteries and thereby last longer before becoming sulfated (shorted across plates).

I put one of the flat plate models in my '79 de Ville last year and it works great.  (Champion branded from Pep Boys).

https://www.youtube.com/watch?v=nL9hArPnWYM

[60eldo]

Lots of great ideas thanks. But now after installing the stereo and amp and playing it for about 2 wks in the garage not running, I decided to take the car out yesterday, nice day. So I started it and drove about 1 mile and started hearing loud scratches coming out of the speakers, and when I tryed to turn the stereo off it wouldnt. Came home, the amp is fryed, Oh great, I get to do this all over again.

[Bobby B]

Came home, the amp is fried.......

What happened? Takes a lot to fry modern day amps. They're usually protected, and most likely stable down to 2-4 ohms. I'd be checking what's going on before you hook up another one. You sure it's not the amp that fried the Speakers?
                                                                                        Bobby

[TJ Hopland]

I think its time to do a careful check of your charging system.  Among other things I would at least temporally install a volt meter to monitor what is going on.   I wonder if maybe you have an over volt issue?    Maybe starting with a partially discharged or weak battery is causing the charging system to run too high of a voltage?

[cadillacmike68]

When I take The Ark to car shows, I have a battery operated CD player on the ground, under the engine, playing all the top songs of 1970. Keeps the crowd around the car not only because they like, but they can't tell where the music is coming from, LOL!

\m/
Laurie

I use a Bose Acoustic Wave. The optional power case uses 10 D size batteries. You can take over an entire care show, or a beach, with one of them!

I do have a 4 channel and single channel pair of kickers in the trunk of the convertible along with a kicker sub (also in the trunk), but that's strictly for driving. It would likely drain both batteries after less than 1 hour running with the car off.

To keep the batts charged while driving I have a chrome PowerMaster 150 alternator built from the Delco 12SI alternator. So far, so good. I just bought an XM plug-in for the Kenwood receiver.

[60eldo]

   WOW,,,thats alot of tech talk that I dont understand. So I bought another amp sounds OK but not impressed. Just see what happens, no sub woofer just 4 4hm speakers in boxes sitting on the back seat.

[cadillacmike68]

Johnny,

I would check the power wires to the amp and the wires to the speakers to ensure they are not frayed or possibly grounded somewhere. Also, the speakers should not bounce around too much. They should be fixed in place. If the voice coils move a lot over bumps, etc. while playing, this can cause a large shift in impedance which can short out an amp on no time.