Power for engine off demos

Car currently just has the stock oem battery. I don't want to add another battery to the vehicle.
System consists of Alpine DD headunit, MiniDSP 8x12, and two Arc Audio 4150xxk amps with all channels @ 4ohms. So not looking for window shaking volumes, just SQ demos and for being judged at indoor competitions.

I use a Battery Tender Jr, which caps out at 500ma output, while tuning in the garage. That seems to work fine for that but after a couple hours the voltage started to get low. So I need something more - something that will last at a 2 day indoor event (SVR) where the engine must remain off.

I'm looking to use some things I already have to accomplish this.

I currently have an old Optima Blue Top (deep discharge + starting) battery that is in very good condition. I also have a industrial brand 12vdc/12a power supply with adjustable output voltage (11-16vdc).

So, I was thinking of just connecting the optima battery and the power supply in parallel to my vehicles battery. I could use 4ga cables to connect it all up.

Would this set up work? I'm not sure where I should set the output voltage on the PS?

Maybe 120 v plug and a converter ?

You've got the right idea, but that tender just doesn't put out the amperage you need. Something like this is what a lot of guys use https://www.amazon.com/IOTA-Engineer...0030GA42A?th=1

Quote:

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Originally Posted by BigAl205

You've got the right idea, but that tender just doesn't put out the amperage you need. Something like this is what a lot of guys use https://www.amazon.com/IOTA-Engineer...0030GA42A?th=1

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Thanks for the info on that. But I was hoping to just use what I have on hand. Do you think the 12vdc/12a power supply would work?
It's a Lambda industrial controls power supply. I'm going to hook it up in the garage this weekend to verify it doesn't add any noise to the system.
Just need to figure out where to set the output voltage :hmm:

Basically, I'm thinking using the stock battery and the optima blue battery juice for demos and the power supply can just keep them topped off...

I see what you're saying...and to be totally honest, I don't know for sure without doing a current test. The second battery would extend your reserve time, but it also means you have two batteries that the charger is trying to keep up with. IOW, a second battery would give you longer individual demo times, but you would have a longer recovery time for the charger to bring both batteries back up to full charge.


If you want to go for hours (or days) without cranking your car, you're going to need a power supply (charger) that could cover the entire continuous current draw of audio, dome lights going on and off, or anything else.

Quote:

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Originally Posted by BigAl205

You've got the right idea, but that tender just doesn't put out the amperage you need. Something like this is what a lot of guys use https://www.amazon.com/IOTA-Engineer...0030GA42A?th=1

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That be the "ticket" ,nice Al ! ^^^^^

Any other input on this?

Someone has had to try using a regular power supply for this purpose at some point.

I use the Iota DLS-55. If you use the power supply you have, adjust the output to like 13.5 - 14V. Be careful of leaving the supply on for long periods when you are not Demo'ing/tuning.

Edit: Most don't use a power supply like this because of the warning I gave above. If you leave it on the battery for long periods, it will overcharge and ruin the battery.

Thanks PaulD... That was my concern about overcharging but I think I can be careful enough for that not to happen.

Not too concerned about the PS being able to supply current at higher voltages as my amps have fully regulated power supplies. So I think my small 12a PS with properly adjusted output voltage should work perfect for what I'm trying to accomplish - just keep the two batteries topped off.

Suppose I should at least fuse the positive cable at the secondary battery to be safe - I believe I have an old fuse holder laying around somewhere for that.

Reading some of the posts in this thread has confirmed my current PS should do what I need: https://www.diymobileaudio.com/forum...le-tuning.html

If your extra battery is in the back, you need two fuses inline with the power...one near the front battery, but also one on the same power cable near the rear battery. If the power cable were to get shorted out , the front fuse would protect the main electrical system, but it would do nothing to keep the rear battery from discharging forward.

Temporary Second battery will be under the vehicle with the power supply next to it all connected in parallel with the main vehicle battery.