[zygadr]

Hi guys, my apologies as this does not directly relate to R.W.A. (sorry Vinnie ).

Just a couple of simple questions : I have a class d amp module which I have briefly tried with two 2ah SLA video camera batteries wired in series. The sound just blew me away!

Question is : can I use car batteries?(yes I know the risks). Are they of low enough impedance compared to SLA's?

Any help is much appreciated!
Cheers,
Rob.

[srb]

I would only use AGM (Absorbent Glass Mat) type auto batteries similar to the Optima, which have lower internal resistance than regular wet cell types (typically < .003 ohm).  They are "sealed", but do have safety valves to vent if overcharged, so proper voltage regulated battery charging is essential to prevent venting of hydrogen gas.
 
I would not under any circumstances use a standard wet cell auto battery.
 
Steve

[zygadr]

Thanks for that info Steve.
Looks like I'm up for quite a bit of money for 2 AGM batteries?

[zygadr]

Without getting in to a debate on whether car batteries are safe to use in a home environment with an amplifier that under normal use would require minimal charge times, it appears that others HAVE used car batteries quite successfully.

There are a number of posts on other forums/websites that indicate that a car battery can be used providing adequate room ventilation is provide in the charging cycle.

Anyone else care to comment on the possibilities of this?

I recall visiting a large specialist battery store where I noticed that they were charging a normal flooded cell inside the shop.
Further to that, some of the so called sealed batteries showed signs of fluid leakage.

[Vinnie R.]

Hi guys, my apologies as this does not directly relate to R.W.A. (sorry Vinnie ).

Just a couple of simple questions : I have a class d amp module which I have briefly tried with two 2ah SLA video camera batteries wired in series. The sound just blew me away!

Question is : can I use car batteries?(yes I know the risks).

Any help is much appreciated!
Cheers,
Rob.

Hi Rob,

I am going to move this post to the lab, as it does not pertain to Red Wine Audio equipment - but I still would like to respond and hopefully you will find this helpful:

I agree with srb - use sealed lead acid batteries (AGM) like the Optima - do not use typical automotive car batteries (if you shake them and hear liquid sloshing inside, I do NOT recommend them because they can leak in your home  )

Are they of low enough impedance compared to SLA's?

A big car battery sized SLA (e.g. Optima) has ultra-low impedance and HUGE output current.  Be VERY careful not to short the outputs.  These can literally output hundreds of amps! 

IMHO, you do not need such a large battery unless your power amp draws a lot of continuous current (e.g. Class A, and/or uses tubes), or you are looking to play for a very long time between charges, or both. 

here are a number of posts on other forums/websites that indicate that a car battery can be used providing adequate room ventilation is provide in the charging cycle.

Anyone else care to comment on the possibilities of this?

Do not put them in an air-tight enclosure, and make sure you properly charge them (do not over charge them) and you'll be fine.  You need to pick an SLA automatic charger (I recommend a 2 stage charger that has a "bulk charge" stage, and then a "trickle charge" stage) whose output current is correct for the size (capacity, measured in Amp-hours, or AH) of the battery you are charging. 

I recall visiting a large specialist battery store where I noticed that they were charging a normal flooded cell inside the shop.
Further to that, some of the so called sealed batteries showed signs of fluid leakage.

Then those were either not well-made batteries, were abused (perhaps wickedly overcharged, dropped hard...), etc. 

Hope this helps,

Vinnie

[Danny Richie]

I have to agree with Vinnie's comments.

They are really not that expensive when you have to consider that a pair of these big 100 amp hour AGM's are about the same price as a good power cable.

I will at some point build a nice looking little box for these so if they ever do leak then that might catch it before it is a problem. I don't see these leaking for any reason though.

My demand on them is very light and my charger is more of a trickle charge so it doesn't stress the batteries either. This one goes through four different charging cycles and will not over charge. That is very important.

[Vinnie R.]

Hi Danny,

Those big 12V, 100Ah Power Sonic SLAs are the real deal! 

http://www.powersonic.com/site/doc/prod/103.pdf

Looks like you have two in parallel (200Ah).  That's a lot of juice!   

My demand on them is very light and my charger is more of a trickle charge so it doesn't stress the batteries either.

Even if you charge at 0.1C (0.1 x 200Ah) = 20A, that won't stress them at all.  How strong of a charger really depends on how much current you are consuming, and if you are leaving the charger always connected, or disconnected when playing 

Best regards,

Vinnie

[Danny Richie]

I can play all day with just my 15 watt tube amp on it and at the end of the day be down to about 12.45 volts. 

I will eventually be powering my buffer (tube pre-amp) and a small pair of 30 watt tube mono blocks on those two batteries. It should actually be good for about 2 days of being on all the time.

If I listen all day long then it takes all night long on this charger to bring them back to just over 13 volts. So the whole system seems to work pretty well.

And I do have to disconnect when listening.

When I get a box built for these then I will run the charger through a light switch mounted on the front of the box. I think those are rated at 15 amps or so. So I can just through the switch on or off quickly and easily to turn the charger on and off. This will keep me from having to pull the quick disconnect in and out (as if that is any trouble).

[Speedskater]

You can also think about UPS batteries and marine batteries (West Marine or US Boat may still have a white paper about these batteries).  Both types of batteries are often times used in close proximity to humans. These are both deep cycle designs for continuous use, which are better than auto batteries that are designed for starting engines.

[donreitz]

This is a fascinating topic. I've heard of the advantages of powering audio equipment with batteries but never thought about doing it with auto batteries. What equipment is required to take an audio system off grid? In my case I have a a tube preamp and tube monoblocs. I already power my Mac and Musicstreamer+ through my Mac's battery.
Thanks,
Don

[srb]

This is a fascinating topic. I've heard of the advantages of powering audio equipment with batteries but never thought about doing it with auto batteries. What equipment is required to take an audio system off grid? In my case I have a a tube preamp and tube monoblocs. I already power my Mac and Musicstreamer+ through my Mac's battery.
Thanks,
Don

If you are powering components that already run off of external 12VDC power supplies, it becomes a matter of getting the right DC connection plug, correct polarity and a suitable charging system.
 
If you are trying to power AC components, it becomes more difficult.  You would also need a DC to AC pure sine wave inverter to supply the required 120VAC. The most efficient inverters are about 85% to 90+% efficient.  That loss combined with the relative inefficiency of the tube amp's power supply as well, is probably going to result in a multi-battery setup to get significant runtime.  A good pure sine wave inverter can run upwards of $250 - $500 in the 300W - 600W range, and significantly more if you need more clean AC power.
 
It obviously would be cheaper and more practical to run your tube preamplifier on batteries than your tube amplifiers.
 
In comparison, the Gary Dodd Battery Powered Amplifier is designed from the ground up to run on batteries, and uses an efficient switching type power supply internally.
 
Steve

[Danny Richie]

For off the grid products, there are digital amp offerings from Vinnie: http://www.redwineaudio.com/ Looks like has has a new tube pre-amp as well.

You can also run the Virtue Audio amps on batteries: http://store.virtueaudio.com/ And I think he will have a new batch of these amps available soon. I'll be selling them again as soon as I can get stock on them. I like them and my customers appreciate the great value they offer.

For tube amps off the grid and know for having one of the best sounding pre-amps in the industry (also off the grid) is Dodd Audio: http://doddaudio.com/default.aspx

Dodd Audio has several new products all running on batteries. I used an almost all off the grid system in my room at RMAF with his new stuff and it was a real advantage.

He is also working on some new 30 watt mono-blocks. Actually they have been ready for a while and sound incredible, but Gary needs to still take care of one issue that they have involving the unsynchronized power converters feeding back with some pre-amps. I think he will solve it as soon as he has some time to get back on them.

Cool looking amps huh?

[jtwrace]

What's the cost of them?

[EDS_]

Without getting in to a debate on whether car batteries are safe to use in a home environment with an amplifier that under normal use would require minimal charge times, it appears that others HAVE used car batteries quite successfully.

There are a number of posts on other forums/websites that indicate that a car battery can be used providing adequate room ventilation is provide in the charging cycle.

Anyone else care to comment on the possibilities of this?

I recall visiting a large specialist battery store where I noticed that they were charging a normal flooded cell inside the shop.
Further to that, some of the so called sealed batteries showed signs of fluid leakage.

I used to be in the battery business.

Places like Lowes and Home Depot use battery powered order pickers and reach trucks whose batteries are charged inside.

Every cold storage warehouse in the US and most other places uses a fleet of battery powered electric forklifts - often with two batteries per forklift.  I'll skip the details but these batteries are huge often weighing thousands of pounds each and they are charged inside by chargers the size of suitcases.

[zygadr]

Yes, thanks to all once again.

I think that there are some urban myths blending with actual facts here?

Don't get me wrong..........I'm not trying to upset the apple cart! .......it's just that I know where EDS is coming from.
People I have spoken to in the industry, after they realize that you're only after some factual/personal information only, will admit that that deadly gases, explosions, acid leaks etc. are overblown terror spreading rumors.........who knows