Battery power experiment

As I mentioned on another thread recently, I'm experimenting with running my hifi from a battery - the theory being to remove any possible effects of poor mains quality.

Project has kicked off in earnest today - I've managed to get the battery (all 65kg of it!) upstairs and in position without slipping a disc and I've hooked everything up with a table lamp to prove that it will at least work in theory without blowing anything up!

The battery is a 200Ah AGM battery. I chose AGM primarily for its safety aspects - spill proof and very low gas emissions on recharge. The inverter/charger is a Powermaster 3kw model acquired second hand on eBay.

Output from the inverter is routed to a consumer unit (no RCD, but house mains earth is utilised) and each component will run off its own 6A MCB. Wiring is Supra LoRad 2.5 apart from the wire running from the mains to the inverter which is Belden 83802.

By my calculations, I will get at least 2 hours (probably more like 3) of listening on a 50% charge. That should do me for most listening sessions, but if I want to carry on listening I can simply switch the wall socket on and the inverter will automatically switch to charging mode and pass through the mains to the equipment.

Hopefully I'll get the hifi rigged up tomorrow and I'll post an update. In the meantime some pics of progress so far:

Step 1: Trash room



Battery and inverter in situ



Consumer unit wired to inverter output

 

Hmmm.......

I''ll be intererested to know what you discover.

 

Sounds like a really interesting experiment. You could really go very "green" and charge the battery with wind or solar. Looking forward to reading the outcomes. Keep us informed.

 

Now this is intereting..looking forward to how this turns out.

NB since this is a separately-derived supply (ie battery-powered) you really don't have to tie to the mains earth at any point (it buys you no extra protection) You even wish to try not doing so.

 

I think the quality will depend upon the design/quality of your invertor, and especially when it's under load.

Wouldn't have thought that standard invertors give too pure a mains signal (the waveform coming out of a generator, for example, is dire)

What's available from hifi mains generator kit that can be persuaded to work from a 12V DC supply?

 

That's true enough. And most 'modified sine' inverters simply have an extended delay between half-cycles of the square wave - which equates to massive crossover distortion!

Nonetheles, I would like to read what the OP makes of this approach

 

Hi Felix. That's interesting - I'm no expert, just done quite a bit of web research before starting this, so interested in alternate ideas. My thinking was that, especially as I have not installed an RCD on the AC side of the inverter (that decision largely driven by something read on Russ Andrews' site for right or wrong), I should have an earth to provide some protection against equipment faults. Does that make sense?

Absolutely. Most inverters on the market are modified sine inverters which would probably be much worse than using the mains. However, the Powermaster is a pure sine wave inverter (specified at <2% THD), so should be fine (hopefully much better than fine, but we shall see!) - should have mentioned that originally.

Pure sine wave inverters are generally marketed for running inductive loads (which don't take kindly to modified sine waves) or for the yacht fraternity, as modified sine waves can cause visible effects on TVs. They're much larger, heavier and expensive than modified sine wave inverters - hence why I've waited until I could bag one at a decent price on eBay

 

I should preface this by declaring I'm not an electrician...

Yes, but it may actually make things worse, too.

Look at this way. If the inverter/battery system has integral overcurrent shutdown, that should covers the fire risk from faults in the supply side. As a bare minimum the battery/inverter requires such protection.

Now you have a powerful battery-backed system capable of delivering lethal currents at high voltage:

if you tie that system to Mains earth, it is capable of delivering a lethal shock to a person at 'mains earth' potential - ie a person with a leakage path to 'earth'... barefoot on a concrete floor, or touching a rad, or almost anything, really...

But if the new system is not tied to mains earth, there exists no shock-to-Earth hazard. You'd have to be exposed to both L and N in the new system to be at risk. See what I'm getting at..? It's like 'double insulated' equipment; the risk of 't earth' shocks (the more-common route) is greatly reduced, and your system gains independance from common-mode noise depending on the 'Earth' tie.

Undoubtedly there will be other considerations in this approach, and either way you are right to be cautious: this is serious stuff. I'll see if I can have a word on good practice with a tame EE I know...

 

Thanks Felix, that's good food for thought. Please let me know what your EE thinks if you have a chance to discuss...

I'd like to think this one through, but my gut feel is that not having any earth is a no go (ultimately, priority 1 is safety not sound quality) so if this idea works out well, I guess I'll be looking at a dedicated earth spike. That's do-able but probably only if and when I decide the battery system is a keeper.

 

Wow! There's me powering just my Dac via a 12V sealed acc from Maplin
I have very good mains here. So good I can only just hear a slight improvement on the acc with phones on, on most critical music.

I have tried various expensive mains leads and silencers - none of which have made much difference - guess I am lucky.

 

Please don't do this until you know the full electrical implications.

 

Early impressions

So, I got everything hooked up this afternoon and had a little listen. Only managed about 30 mins before the battery was reading at 50% discharge - I think this is because it is a brand new battery that has stood in a warehouse slowly discharging for god knows how long. It's on charge now, so we'll see how I fare on a full charge.

On balance, my first impressions are that this is simply outstanding. I'm a bit excited at the moment, but this feels like the biggest step forward since I bought my speakers. It's not all upside though.

The brief listening I have done has been with battery power and no earth. Briefly compared A/B to standard AC mains and compared in memory to how I've been listening for a couple of years - AC mains through Kemp filters. Only used CD as a source.

On the positive

I was hearing low level detail and sublety that really wasn't even hinted at before. Listening to L'arpeggiata the instrumental timbre, fingering and venue ambience was breathtaking. David Bromberg equally so. Listening to a slice of Tony Allen, I literally heard rhythms that I had no idea were there before and the level of detail and discrimination was way beyond what I have heard before.

On the negative

- There was some slight but noticeable hum from the subwoofers of my speakers. This is not unique to the battery; I have had this problem since day 1 but it has been tamed since the Kemp units were in place. Let's say it's a "design feature" of Avantgarde speakers. It's not noticeable when the music is playing but I will try routing the power to the subs from the battery through the Kemp filters to see what effect that has. I know from past experience with a "Noise Sniffer" that the amps on the subwoofers do chuck quite a bit of crap back onto the mains so the filters are probably a good idea in any event.

- At the end of the listening, there was some very slight distortion noticeable. I suspect this was due to voltage drop at the battery and should be resolved by a good charge.

- I'm unsure about the effect on dynamics at the moment and need to listen further. I think this will have to be done on vinyl as there is an obvious effect on the speed of the CD player when switching between mains and battery power which makes direct comparison very difficult. My CD player is specified for a 230V input, which matches the inverter output. My mains is generally in the 248-251V range. It's not something I'd specifically noted before, but listening to the two power sources back to back it is obvious that the CD player runs fast on mains power.

More (and more considered) views to come in due course...

 

Interesting stuff look forward to reading more

 

I've been put off with demo many years ago by pink triangle ..maybe at on of the bolton shows ...

they hooked up a battery lead acid [not gel] no music signal turned up the volume to hear not snap cracle and pop but something akin to a fizzy drink ......this was attributed to bubbles forming and breaking on the plates in the battery.

I can remember if the demo was to sell there better batteries or what ......

could the noise your hear be associated with the chemical actio in the battery ?

I've been playing with a solar panel to power regulator thing then to 2300ah 12v sealed batt ..this feeds an inverter to a plug block where I hook up all my rechargeable gadgets ....

I find the invert left on will gobble most of the bat power ie outgoing power exceeds the solar incoming power ....on the average day .....have you noticed this ?



I've not considered trying to hook the hifi up to this ...but may well try a few simple experiments now you got me thinking about it ..

 

Hi. I don't think so - it's a faint low-pitch constant hum and it's always been present to some extent with my subwoofers, whether on mains or battery. I turned the woofers off last night and the noise completely went, so I'm fairly sure that the issue is my perennial issue rather than anything attributable directly to the battery - I'm sure it's just pretty badly designed subwoofer amps! It's only audible with no music playing so not a major issue, but I'll reintroduce power filters just for the subs as this sorted the issue before.

Definitely noticed that the inverter uses a fair bit of power, yes! I run mine into the mains though so there's plenty of juice on tap.

Give it a go! You don't mention whether your inverter is a modified sine or pure sine - if it is the former, I'm not sure how much success you'll have, but it's definitely worth a go. I wouldn't recommend running a motor (i.e. turntable) off a modified wave inverter though.

Have fun

 

Why the double conversion (12v-240v-low charging voltage)why not just use a 12v charging circuit

 

yes did think about it ...but each unit comes with a handy charger ..but at 230v what you save o the swings you loss on the roundabouts !

but your not wrong!

 

more considered views (aka after the boyish excitement)

OK, so done a lot of listening now and have a good handle on the impact. For reasons not connected with the battery, almost all my listening has been CD, so comments are not necessarily applicable to vinyl replay at this stage.

There is greater space and air around the instruments and you can hear the floor of the recording venue very clearly. Overall, there is far greater PRaT and the system has a better sense of flow and musicality arising from an inky black background. OK, I'm taking the piss...

In reality, there is a subtle but worthwhile improvement. I can identify (at least some of) the "hi-fi" improvements, but the overall effect is one of more realistic and enjoyable music. The main factor that seems to be influencing this is that individual instruments are more clearly delineated, both tonally and particularly spatially, making the interaction between the various threads of music more apparent and enjoyable. There is also a subtle improvement in the solidity of the imaging.

Someone else describe the effects of their battery experiments as creating a "calmer" sound, and I think that's also a fair assessment.

I'm sticking with it in any case.

 

I agree with Penance here but also from a legal point of view. What happens if this thing does start to burn and sets your house on fire? There is a good chance your house insurance won't pay out

 

An interesting experiment but IMHO a bit of a sledgehammer to crack a nut (65kg is a big sledgehammer).

As an alternative, wouldn't a good mains conditioner be better and then modify the more 'sensitive' components (DAC, Pre-amp) to run directly from DC?