Author Topic: voltage meter  (Read 2215 times)

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thirteen

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voltage meter
« on: April 01, 2009, 03:40:58 PM »
I have made a bank of three 12v batteries. Is there an inline meter that I can leave in place between each battery to monitor the voltage from one to the next. These were used but free batteries from large equipement only two years old. They were totaly discharged for over 5 months and they just replaced them. All I had to do was haul them off. It took me three weeks to get them charged and they tested out ok. So they are big batteries (referred to as 8D) but not that good for deep cycle usage. But free. I think these will be good for about 3 years then I will have my other micro hydro system in place along with my solar system. I only have good water for 8 months out of the year then I will use solar. I cannot use solar in the winter because there is not much sunlight maybe 3 hours a day at best. For I am in a valley with high mountians all around.
« Last Edit: April 01, 2009, 03:40:58 PM by (unknown) »
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imsmooth

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Re: voltage meter
« Reply #1 on: April 01, 2009, 10:30:29 AM »
and the question is...?
« Last Edit: April 01, 2009, 10:30:29 AM by (unknown) »

TomW

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Re: voltage meter
« Reply #2 on: April 01, 2009, 10:56:03 AM »
Maybe he meant for it to be a Diary and just an update? I don't see a question in there, either.


Tom

« Last Edit: April 01, 2009, 10:56:03 AM by (unknown) »

ghurd

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Re: voltage meter
« Reply #3 on: April 01, 2009, 11:16:57 AM »
"Is there an inline meter that I can leave in place between each battery to monitor the voltage from one to the next".


I am having trouble with inline and between.  Sounds like a 36V series question, but it seems strange to make 36V in this day and age.


If it is a 12V system, and all 3 are connected, then they will all have the same voltage.  Even the bad one, if there is a bad one.

G-

« Last Edit: April 01, 2009, 11:16:57 AM by (unknown) »
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Flux

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Re: voltage meter
« Reply #4 on: April 01, 2009, 11:40:02 AM »
The only in line meter is an ammeter and that doesn't measure voltage. If this is a parallel battery bank you can only measure the combined bank voltage. If these are individual cells then you can read each cell voltage but unless you can get at the cell links you will have to disconnect the banks to measure each string.


If they are flooded cells and you can measure sg then that will give a good indication that all 3 strings are ok. A duff cell will mess up the voltage and the sg will go funny on the dodgy string.


Flux

« Last Edit: April 01, 2009, 11:40:02 AM by (unknown) »

thirteen

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Re: voltage meter
« Reply #5 on: April 01, 2009, 12:45:17 PM »
Yes I did not put a ? mark instead of a period on the second line. My mistake.  A little more detail might help. I would like to follow the voltage between each battery. Each battery has cetain things tied to it for power with its own inverter and are still tied all together for the major power usage. One battery is 10 ft from the other two. This is not the best system but it works.
« Last Edit: April 01, 2009, 12:45:17 PM by (unknown) »
MntMnROY 13

thirteen

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Re: voltage meter
« Reply #6 on: April 01, 2009, 12:51:09 PM »
My system is different but it only needs to be operational for about 2 1/3 years then it all changes to a better system and a building just for the system it's self. Two batteries are in on place the other is about 10 ft away.  

That helps me thank you.
« Last Edit: April 01, 2009, 12:51:09 PM by (unknown) »
MntMnROY 13

jaskiainen

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Re: voltage meter
« Reply #7 on: April 01, 2009, 01:16:56 PM »
HI G


I disagree a bit with the same voltage part.

My friend is going to make same kind of set up for his boat.

3x2 batteries, 3 different loads after them.

The trick is to separate them with diodes.

So they all will charge when the boat is running, but only specific ones

will discharge when using power.


I'm not sure is this the case here, but just got that feeling...

« Last Edit: April 01, 2009, 01:16:56 PM by (unknown) »

dnix71

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Re: voltage meter
« Reply #8 on: April 01, 2009, 04:03:56 PM »
Them is big batteries. 8D means 8 times a U1 I think. The ones I see online if AGM'S or gel, are about $700 each, and the Exide brand, flooded/calcium-lead are $200 each MSRP.


You need to tell us which they are: sealed or not, and if they are "marine" grade or intended for auto/truck use. The make model of the battery would tell us what they are.


http://www.keenzo.com/showproduct.asp?M=K-TOOL&ID=1435205&ref=GB

is a standard hydrometer sold at almost any auto parts store. If your battery has removeable caps, then for about $6 you can quickly check each cell.


http://www.customdynamics.com/LED_battery_gauge.htm#Kuryakyn_LED_Battery_Gauges_and_Chargers_


is a stick-on motorcycle gauge (a little pricy for home use, $35 plus shipping) but is portable and flashes red when your battery voltage is high or low.

« Last Edit: April 01, 2009, 04:03:56 PM by (unknown) »

ghurd

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Re: voltage meter
« Reply #9 on: April 01, 2009, 04:09:21 PM »
I originally had the feeling if he understood how to separate a single charging system into 3 battery banks, he would know how to connect a voltmeter.


"Each battery has cetain things tied to it for power with its own inverter and are still tied all together for the major power usage" makes me wonder.

G-

« Last Edit: April 01, 2009, 04:09:21 PM by (unknown) »
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Ungrounded Lightning Rod

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Re: voltage meter
« Reply #10 on: April 01, 2009, 04:14:53 PM »
When they're tied in parallel the voltage is forced to be the same.  You have to disconnect them to read different voltages.


What you probably want to be looking at is STATE OF CHARGE.  You can do that by measuring the specific gravity of the banks.  (Unfortunately that isn't a "hook up a meter" job.  Fortunately you don't have to do it very often - monthly might be about right - to detect a problem before it gets bad.)


You could also compare the currents in the wires to the individual banks.  But you have to be careful with how you do that, because very small differences in resistance in the wiring and instrumentation can massively unbalance the currents between the segments of the bank.


Also:  Measuring current is an expensive proposition because you have to buy and install a shunt in each branch where you want to measure current.  And the current differences from battery pathologies tends to be small compared to the operating current - until a pathology gets so bad that the only thing to do is pull out the ruined cells and replace them.


So I'd recommend that you go with periodic specific gravity measurement and leave it at that.  Much cheaper, gives you an earlier warning, and you can combine it with the periodic check of the water level.

« Last Edit: April 01, 2009, 04:14:53 PM by (unknown) »

Goahead

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Re: voltage meter
« Reply #11 on: April 06, 2009, 06:01:05 AM »
Or you could make your own...





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Keep it cool

Goahead

« Last Edit: April 06, 2009, 06:01:05 AM by (unknown) »