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mz-Blue

Battery Isolation

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mz-Blue    0

Hi

I have a solar panel sysyem and I recently upgraded the panel so am producing more power, So I purchased additional batteries (6x75 Amp hr) . I have an older bank of batteries (about 3 years old thet are still good) . Any suggestions of how I can isolate the baterries , perhaps using a switch and isolater and then being able to switch off to the inverter to provide power.

 

So to summarize. Having an option at to switch battery banks to charge ( or can I charge at the same time using a battery isolater. And then selecting the battery bank ( bank A or B to feed the inverter.

 

What I am trying to avoid is using different vintages of batteries as they will diminish the quality of the good batteriries

 

Cheers

 

Mike

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BEngo    84

Busbars.

One busbar for each battery bank.  Connections to each battery bank going via an isolator, and fuse if needed.    Connect the busbars together with another  isolator.

Connect the solar to the busbars  via an SPDT contactor ( AKA BIG relay like  www.waytekwire.com/item/75581/White-Rodgers-586-102111-Power-Relay-Contactor/) so that either but only one of the busbars is connected to it.  Depending on your solar controller as to whether it will be OK with a momentary open circuit, you may need a make before break contactor.  If you want to solar charge both at the same time make the link isolator.

Connect the inverter input to both busbars via another SPDT contactor so that you can invert of either.

Connect all the negatives together- probably via another busbar.

N

 

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WotEver    628
1 hour ago, BEngo said:

Depending on your solar controller as to whether it will be OK with a momentary open circuit, you may need a make before break contactor.

This bit is important. :)

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Tony Brooks    593
14 hours ago, mz-Blue said:

Hi

I have a solar panel sysyem and I recently upgraded the panel so am producing more power, So I purchased additional batteries (6x75 Amp hr) . I have an older bank of batteries (about 3 years old thet are still good) . Any suggestions of how I can isolate the baterries , perhaps using a switch and isolater and then being able to switch off to the inverter to provide power.

 

So to summarize. Having an option at to switch battery banks to charge ( or can I charge at the same time using a battery isolater. And then selecting the battery bank ( bank A or B to feed the inverter.

 

What I am trying to avoid is using different vintages of batteries as they will diminish the quality of the good batteriries

 

Cheers

 

Mike

 

No they will not as long as you keep a close eye on them. There is nothing wrong with an end user mixing old and new batteries as long as they do it from a position of knowledge and act accordingly.  If a professional did it then they would in my view be asking for a bad name because customers can be very forgetful when it suits them. The idea that it is bad to mix new and old batteries that are in good condition comes from that.

Mixing new batteries with even a single old one with an internal short is bad and it will cause the new batteries to discharge and probably sulphate. Mixing new batteries with a sulphated (but not shorting) old battery will be fine. each battery in a bank will take the charge it wants from whatever charge is available.

If you do mix just make sure you are right on top of your battery monitoring so at teh first sign of excess self discharge you can pull the offending battery from the bank.

 

  • Greenie 1

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WotEver    628
1 hour ago, mz-Blue said:

How would one determine when a battery needed to be removed from the bank 

If it warms up more than the others or bubbles the electrolyte more or requires more frequent topping up. Separating the batteries and checking the voltage of each one would be another way. 

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mz-Blue    0

Hi WotEver

So to separate the batteries , how would I do that ? do you mean to unhook them from the others and the inputs and draws and then measure the voltage. How long should they be unhooked and what would be considered a bad voltage.

For example my batteries (my new  ones)

were charged a week ago and the are not hooked up to anything, so the have been at rest for a week as I have not yet installed them. Three of the batteries read 13.07 volts, one is 13.04 and one reads 12.96. Would the 12.96 volts be considered bad.

 

Also regarding the mixing of batteries In this case I could not mix them as my old bank is "wet" and my new batch is a gel type, so I believe that they would not work well together as they have different settings on the charge controller.

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Tony Brooks    593

In addition to the above the first indication you often get is a lower than normal voltage first thing in the morning. If you do not know a good reason its a fair bet a battery is self discharging. Then as WotEver says.

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WotEver    628
18 minutes ago, mz-Blue said:

Three of the batteries read 13.07 volts, one is 13.04 and one reads 12.96. Would the 12.96 volts be considered bad.

Nope. 12.6V would leave me suspicious though, with the others still sitting with surface charge. By low voltage I meant say <11.5V 

19 minutes ago, Tony Brooks said:

In addition to the above the first indication you often get is a lower than normal voltage first thing in the morning. If you do not know a good reason its a fair bet a battery is self discharging.

Yup - once you've noted this it's time to see which one's causing the problem. 

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Mikexx    4

All of the above!!

However, a less intrusive way is to measure current withone of these:

  http://www.ebay.co.uk/itm/LCD-Digital-Electronic-AC-DC-Clamp-Voltage-Multimeter-Current-Volt-Tester-Meter-/232288839877

I have one and its a handy way of making sure that a charging current isn't being taken by just one battery, or where a battery has minimal capacity and taking none. Depending on setup and how the batteries are connected a little arithmetic might be required.

I would connect the batteries together. As long as one doesn't take the others down, both discharge and charge currents will be lower and kinder to the batteries.

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Loddon    216
10 hours ago, Mikexx said:

All of the above!!

However, a less intrusive way is to measure current withone of these:

  http://www.ebay.co.uk/itm/LCD-Digital-Electronic-AC-DC-Clamp-Voltage-Multimeter-Current-Volt-Tester-Meter-/232288839877

I have one and its a handy way of making sure that a charging current isn't being taken by just one battery, or where a battery has minimal capacity and taking none. Depending on setup and how the batteries are connected a little arithmetic might be required.

I would connect the batteries together. As long as one doesn't take the others down, both discharge and charge currents will be lower and kinder to the batteries.

That one seems to only do ac current! 

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cuthound Contributor    325
6 hours ago, mz-Blue said:

good idea , i will buy one. How exactly do you use them?

You set the range on the dial,  according to what you want to measure, current, ac voltage, dc voltage or resistance.

Then if it current you clamp the jaws around a single cable and take the reading from the display.

If you want to measure voltage or resistance, you use the probes.

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Tony Brooks    593

Note what Loddon said above - If you follow the instructions from Cuthound any reading you get for current on that meter will be garbage.

Get one that is probably rather more ex[pensive that states it measures DC amps and then the instructions are correct - well they are correct anyway but you will not be able to set the range for DC amps on the one linked to because it does not have one.  It is not clear that you know the symbols used to signify AC and DC.

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Chewbacka    151

The UNI-T UT203 meter seems to be a common choice because it is a clamp meter that does DC currect for about thirty quid on ebay.  Less if you get it from a far east supplier and are happy to wait a month for it to wend it's way through the post............

They are a little unstable on DC current as they work by using a hall sensor and so are sensitive to residual magnetism and nearby fields.  But select the DC current range, leave to settle for a few seconds, then open and close the jaws a few times and with the jaws closed press the delta button just before you fix it around the cable, then it is pretty good.  Even if you don't bother to faff about with it it is still accurate to under an amp.

If you want accurate readings under a few amps an 'in circuit' meter is better, but for general fault finding, checking solar and inverters it is perfect.

  • Greenie 1

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Robbo    172
6 minutes ago, Chewbacka said:

The UNI-T UT203 meter seems to be a common choice because it is a clamp meter that does DC currect for about thirty quid on ebay.  Less if you get it from a far east supplier and are happy to wait a month for it to wend it's way through the post...........

Uni-t meters are also available from stores like Maplins which is prob another reason why it’s popular.

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Mikexx    4
5 hours ago, Loddon said:

That one seems to only do ac current! 

Spot on and apologies. There is this one:

  http://www.ebay.co.uk/itm/Handheld-Digital-Clamp-Multimeter-AC-DC-Volt-Amp-Meter-Tester-/262861536981

which I have a little more confidence about and is posted within the UK although it is from a Thai company!

It is worrying when in some descriptions you see: DCA:6V/60V/600V And few now seem to do DC current.

This is the one I bought, though at less than half the price 7 years ago:

  http://www.ebay.co.uk/itm/UNI-T-UT203-Digital-Handheld-Clamp-Multimeter-Tester-Meter-DMM-CE-AC-DC-Volt-Amp-/232050132333

Another thing is to make sure the meter clamp can hold the size of cable in use. The one I bought can do 90sqmm with a heat-shrink thin colour sleeve.

 

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cuthound Contributor    325
4 hours ago, Tony Brooks said:

Note what Loddon said above - If you follow the instructions from Cuthound any reading you get for current on that meter will be garbage.

Get one that is probably rather more ex[pensive that states it measures DC amps and then the instructions are correct - well they are correct anyway but you will not be able to set the range for DC amps on the one linked to because it does not have one.  It is not clear that you know the symbols used to signify AC and DC.

Only because the meter shown is ac only. The instruction I gave are generic for tong tester type meters, whether they read ac or dc.

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WotEver    628
32 minutes ago, cuthound said:

Only because the meter shown is ac only. The instruction I gave are generic for tong tester type meters, whether they read ac or dc.

I believe that was Tony's point, not that there was anything wrong with your generic advice. 

Edited by WotEver
Autowrong

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cuthound Contributor    325
Just now, WotEver said:

I believe that was Tony's point, not that there was anything wrong with your genetic advice. 

But I didn't give any advice on genetics, only on how to use a meter :D

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WotEver    628
1 minute ago, cuthound said:

But I didn't give any advice on genetics, only on how to use a meter :D

Don'cha lurve autocorrect?

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