Is there such a thing as a battery power center?

[DualFuel]

I am wondering if there is a thing that you can hook up to the battery bank that tells you the voltage at a glance, sounds an alarm when the bank reaches preset numbers. I started out thinking about a permanent digital voltage meter but, then realized why not shoot for the everything in a bundle?

 Tell me what you know....

Thanks,

DF

[dnix71]

Be careful what you ask for. The old Harbor Freight "controllers" with id10t lights instead of a digital display had a really annoying alarm that would sound if the battery voltage got out of range, high or low. They weren't adjustable, though.

Why do you need the addon? If you have a decent contoller, it will divert any excess and cutout at low voltage.

I'm sure GHurd has a kit that would work for your setup.

[DualFuel]

In a way, I have low voltage cut out through the inverter. The high voltage cut out comes from the controller for the panels. What I want is to walk through by the battery room, and glance at a display that tells me what my voltage is to the hundreth of a volt. I bought and dedicated a Walmart DVOM to the task. Its sorta a PITA because it has to be turned on each time. Or the 9volt goes dead. I suppose I could put a power resistor on it and use bank voltage to power it.

 Thing is if Im cutting wood or washing clothes or something heavy like the aircompressor, I'd like to know before the inverter shuts down, that its time to pull the rope on the yanmar.

DF

[TomW]

DF;

If yopu try to power the DVOM with the battery you are reading you will more than likely release all that carefully encapsulated magic smoke.

Bad Mojo.

Tom

[zap]

Would this work for you?  $25 but you also get a record of ah in/ah out.

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=10080

Videos of the unit can be found on YouTube.

http://www.youtube.com/watch?v=4RkldBzc-Vs

[bob golding]

not sure if  knowing the voltage will help much. i have a 1 kw short term load on my system. the voltage drop when it turns on gets near to the shut off point of the inverter even though the voltage looks fine before it switches on. as soon as the load is removed the voltage goes backs up again. it drops the voltage by around  1 volt which can be enough to trip the inverter if the batteries are low. i have 800 amp hours split into 2 400 banks so i can keep them  charged.

[tanner0441]

Hi

I don't understand why you want to be able to read the voltage to 100th of a volt

But to be able to just look at a meter any time, I would go for a large scale analoge meter, only pulls microamps, so no load to speak of.

Or look on ebay there are digital meters that have a 1.5 volt cell and run for weeks.

Brian

[DualFuel]

Gosh, I think that would be fine.

I tried an analog meter that read in the hundreths, but it got stuck in place, so I didn't think it was meant for continous duty.

 Basically, if I can watch the hundreths scale fluctuate, I can tell at a glance whether the bank is charging or discharging, and the rate of change.

 Thanks Zap.

DF

[zap]

DF, I'm now thinking I'm wrong about ah in/ah out.  I thought for sure I'd read that the Turnigy read power both ways... seems it doesn't.

This is a long read but it has some good points.  I hope the "ah in" wasn't important to you.

http://endless-sphere.com/forums/viewtopic.php?f=3&t=13607

If you end up getting it, let us know how it works?

[ghurd]

With a semi-stable load, and semi-stable solar, I still see fluctuations.

Or with no load, the battery voltage will start to drop when the charging amps are reduced... but still charging.  Meaning the voltage can go down even when charging.

Not sure a 1/100th Volt voltage change will tell what you want to know with any accuracy at all.

If you just want a beeper to sound when the voltage drops below a certain threshold, that's pretty easy.

For the meter- Could series 10 AA nicds or a 7AH SLA, charged from a 1.5W HF PV, 7809 voltage regulator, to a $3 HF meter.  It works 24/7.  Simple.  Fairly cheap.

G-

[DualFuel]

Hi,

Its kind of funny that two people have responded with "not sure if 100th of a volt will..." and twice I've said what I've wanted...was 100th of a volt display.

 I do like the link with the digital meter. That'll probably do it. Then I realized that I could buy a lot of 9 volt batteries for $25. Seeing as I go through about two a year, well.... you get the picture.

 I am going to try and explain why 100th of a volt means a lot. First my bank never goes below 12.00vdc. If its 12.20 its low. 12.45 seems to be resting voltage after dark and the surface charge has worn down. So if we throw out the 12 we're left with .4 something. What I like seeing is the RATE of change that only a digital meter can show me. When I am discharging heavily the 100ths flash faster and faster the heavier the load. Same with charging. Its the pace of the 100ths numbers that tell me how much wind or solar I am getting. I never even read the numbers, just watch them flash.

 Now that we are nearing the equinox it isn't as critical because the solar will be excessive and the controller will kick everything out at 15vdc anyway. During the winter solstice time, I watch the meter much more ferverently, unless its a howling blizzard, then the wind is blowing 40s and I have plenty of power.

 So thats why I like watching 100ths, for the 'tween times when you have to monitor your consumption very carefully OR pull the rope on the Yanmar.

DF