[dunlapk]

Seth,

How long will the M901 run on the  Dodd Audio, 7Ah, 28v Battery Kit?

[virtue]

Theoretically forever since you would never unplug it and you'd never run it long enough to deplete it fully.  It might actually be net-charging during normal use. That's my understanding.  If you unplugged the charger, may 7-8 hours with normal listening.

[cynan]

Net charging? I can't say that I've noticed that happening with my M901/battery setup (see DIY batter thread). But then I've not monitored it very scientifically - I just can't ever recall the charger light turning green during use (not that I normally sit and stare at the charger when I listen to music    ).

The Dodd setup is using the Powerstream switching charger @ 1.8A correct? (which I have)

Interesting. I'll have to take some voltage measurements the next time I listen for an extended period...

[virtue]

If the average current draw is less than 1.8A... the charger should be able to top it off continuously, right?  Gary?

[gld]

I am pretty sure that it's less than 1.8 amps. I will find some time this evening and measure it. I have a M451, pretty much the same amp. I'll let you know in a bit.
gary

[gld]

Ok, I have taken the time to measure the current draw of the M451 I have.
I was using one of the new battery supplies made by myself. I was also using a 5 AH pack and the batteries were right out of the box, 25.9 volts.
The amp was connected to the speakers in my lab, approx 89 db and 8 ohms.
In standby mode it consumes 520 milliamps all the time. In play mode it used 550 milliamps and I had to play it louder than 1/2 volume to get it to 600 milliamps! It is quite energy effeicient! I would imagine that on a 5AH pack it will play on average 7-8 hours at normal listening levels. On a 7AH pack I could see 10-12 hours at the same levels. Actually with the chargers that are supplied with each kit you can leave it connected and plugged in all the time without any sonic or any other kind of problems.
Gary

[wsturner]

Those are interesting numbers. It may be best to just leave the unit on, and turn the volume all the way down, when not listening.

[robgreen]

Hi Seth,

I would really appreciate it if you can post a pic of this battery kit. With dimensions too if possible. I need to know whether it will fit into my cabinet before ordering one from you. Of course the tidier it looks, the less negative comments I will receive from the spouse....Thanks.

Rob

[virtue]

Here are the specs on the 7Ah:

http://www.batteryplex.com/sheets/PS%2D1272%20F1.pdf

There are two in a unit as you see below.  Gary had some trouble with the white heat-shrink tape we hoped to put around the unit so they'll probably go out "as-is".  It's not in a box and it ain't got the elegance of a Black Lightening (if you can afford it, buy one!), but the connectors are perfect and it's  mostly a "finished" product.  We had some logistics issues with the ABT charger (cheap) so these first few are actually shipping with Soneil. 



Seth

[jtwrace]

It's not in a box and it ain't got the elegance of a Black Lightening (if you can afford it, buy one
Seth

You design the circuit to make it automatic and I'll make the case.   

[virtue]

Rock 'n' Roll. 

For those less inclined to do so, we want our customers to support our friends at RWA.  Vinnie makes a great product - and he charges enough to keep the lights on, which I respect. 

Very best,

Seth

[jtwrace]

Rock 'n' Roll. 

For those less inclined to do so, we want our customers to support our friends at RWA.  Vinnie makes a great product - and he charges enough to keep the lights on, which I respect. 

Very best,

Seth

 

[virtue]

Here's what Vinnie told me about why the SMART circuit is still relevant when we can leave Gary's charger plugged in... 

Yes, you can leave the charger connected to the SLA batteries - but the problem is that the charger gets "tricked" into thinking that the batteries still need to be charged in the "bulk charge state", which is 14.75V per battery, while they might already be fully charged.  So this will premature age the battery.  The reason is that the charger sees the load of the amp, and is tricked into thinking the batteries are not fully charged when they are.  Leaving them charging in the "bulk charge" state of 14.75V per battery will dry them out.  If a trickle charger was used instead of a two stage charger (with no greater than 13.8V per battery, this should not hurt the batteries).

Also, without a SMART board, when the batteries go bad (when running off the grid with no charger connected), the voltage drops and drops without the customer knowing, so you lose power and performance and the customer never knows it - until finally the voltage gets so low that the amp does not run correctly and shuts off.  So it is good that the customer knows when the voltage is getting too low and does not play below a minimum voltage, as performance is lost.

Also, if you run with the charger connected at the same time, it is not off the grid and the charger noise is coupled onto the battery power (you can see the HF noise with a scope).  In this mode, the batteries are acting like huge storage capacitors and they do clean up the sound, but it is not as clean as running w/o the charger, and like I mention, the batteries get beat up.