Victron Inverters

[SylwerDragon]

NC - Mean normal close
NO mean normal open.

usually it is referred to contact of relay

[cortijo]

Very simple. Donate your batteries to a Fisherman as a Boat Anchor.

Very funny.

It seems that running dual battery banks is more popular on boats because one battery will start the engine and the other to run the rest of the boat.

Dual Battery Bank Controllers do exist
They charge 2 battery banks without connecting them.


There would have to be some sort of switch which would change the connection to the inverter according to the master battery voltage,
once the cut off point on the main battery is reached it would change over to the backup battery when necessary.

There must be a lot of people out there who would like to have a system with 2 battery banks.
For example if the main battery starts to show signs of age and you want to get some new ones but the old ones still have some life.
Someone gives you some batteries etc.

Someone ought to market this.

I still have my original batteries: 2 large lorry batteries connected to 20 watt panel with a cheap charge controller.
They supply lighting to an outside area for having beers in the summer.
I don't like throwing stuff away that is still useful.

[inetdog]

In the late 1700s, Charles-Augustin de Coulomb ruled that a battery that receives a charge current of one ampere (1A) passes one coulomb (1C) of charge every second. In 10 seconds, 10 coulombs pass into the battery, and so on. On discharge, the process reverses. Today, the battery industry uses C-rate to scale the charge and discharge current of a battery.

Most portable batteries are rated at 1C, meaning that a 1,000mAh battery that is discharged at 1C rate should under ideal conditions provide a current of 1,000mA for one hour. The same battery discharging at 0.5C would provide 500mA for two hours, and at 2C, the 1,000mAh battery would deliver 2,000mA for 30 minutes. 1C is also known as a one-hour discharge; a 0.5C is a two-hour, and a 2C is a half-hour discharge.

Interesting collection of factoids.
1. The Coulomb reference seems totally irrelevant.
2. The 1C symbol you use in the first sentence is more commonly written as C with a subscript 1, or for the graphically challenged typists, C1. The symbol 1C commonly refers to the current which corresponds to the C rate, but does not tell us what time period (one hour, twenty hours, one hundred hours) was used to determine C in the first place. Peukert's Law as applied to Lead Acid batteries tells us that the C1, C20 and C100 figures will be very different. You then switch to using the same symbol to represent current in the second part of the paragraph.
3. I do not agree that most portable batteries are rated based on C1. The more common, AFAIK, is C20, and some batteries are rated by their manufacturer using C100, which tends to make them look better. . Starting/cranking batteries are rated in Reserve Minutes, which is more closely related to the C1 rate. But anybody who uses a starting/cranking battery for PV is making a large mistake.

[Beanyboy57]

C Rate

I need a tutorial that explains what C/8 means.
How many amps would C/8 be in this case?

You say that I need a 50 amp charger but my 30 amp charger never uses it's full charging capacity.
I don't understand?

In the late 1700s, Charles-Augustin de Coulomb ruled that a battery that receives a charge current of one ampere (1A) passes one coulomb (1C) of charge every second. In 10 seconds, 10 coulombs pass into the battery, and so on. On discharge, the process reverses. Today, the battery industry uses C-rate to scale the charge and discharge current of a battery.

Most portable batteries are rated at 1C, meaning that a 1,000mAh battery that is discharged at 1C rate should under ideal conditions provide a current of 1,000mA for one hour. The same battery discharging at 0.5C would provide 500mA for two hours, and at 2C, the 1,000mAh battery would deliver 2,000mA for 30 minutes. 1C is also known as a one-hour discharge; a 0.5C is a two-hour, and a 2C is a half-hour discharge.

[Sunking]

It looks like I can get 650 AH for about 2500 euros.
How can I combine them with the 380Ah batteries I already have to get the system I ought to have?

Very simple. Donate your batteries to a Fisherman as a Boat Anchor.

[cortijo]

<quote>YOu have outgrown your system</quote>

So in your opinion I have just about enough panels but maybe half the amount of battery capacity I need.

What is the solution?

Can I buy more batteries to solve the problem?
Obviously I don't want to throw away my existing batteries because they still have a lot of life left.

Can I combine old batteries with new ones somehow?

It looks like I can get 650 AH for about 2500 euros.
How can I combine them with the 380Ah batteries I already have to get the system I ought to have?

[cortijo]

This tells me you have never gotten your batteries fully charged.

I would wait for the sun to properly charge the batteries. If I am using the battery charger it is just to stop the batteries getting too low. I wouldn't waste the petrol on using the charger to fully charge them.

[cortijo]

It is very easy.

C= the rated battery capacity in Amp Hours at the 20 hour rate. 8 is the 8 hour discharge rate. Now it is just simple factoring out what we need. Amps = AH / H. So your battery is 380 AH right?

So C/8 = 380/8=47.5
C/10 = 380/10 = 38

380 AH / 8 Hours = 47.5 amps. So to charge your battery in the shortest amount of time which is 8 hours you would need a 50 amp charger.

If I have a 30 amp charger that only wants to charge at less than 17 amps.
Why would I want to get a charger of 50 amps when it is not even using the capacity of my 30amp charger?

[Sunking]

In reality what actually happens when I use the charger is the following:

At the start, the charger charges at around 23amps
Then after about 5 minutes it goes down to around 17amps
After about an hour it will be charging at about 12amps.
The lowest I have ever see is 9 amps.

This tells me you have never gotten your batteries fully charged. During the Charge process the current starts high like you have noticed. Then it tapers down to 0 amps some hours later, then switches to FLOAT which will also be 0 amps assuming you have no load on the batteries.

[Sunking]

I need a tutorial that explains what C/8 means.
How many amps would C/8 be in this case?

It is very easy.

C= the rated battery capacity in Amp Hours at the 20 hour rate. 8 is the 8 hour discharge rate. Now it is just simple factoring out what we need. Amps = AH / H. So your battery is 380 AH right?

So C/8 = 380/8=47.5
C/10 = 380/10 = 38

380 AH / 8 Hours = 47.5 amps. So to charge your battery in the shortest amount of time which is 8 hours you would need a 50 amp charger.

[cortijo]

<quote>YOu have outgrown your system</quote>

So in your opinion I have just about enough panels but maybe half the amount of battery capacity I need.

What is the solution?

Can I buy more batteries to solve the problem?
Obviously I don't want to throw away my existing batteries because they still have a lot of life left.

Can I combine old batteries with new ones somehow?

[cortijo]

For the generator needs to be sized to provide a C/8 charge rate for FLA batteries to minimize fuel burn and minimize charge efficiency. So if you were to say have a 24 volt 380 AH battery, you are looking at about a 2 Kva genset and a 24 volt 50 amp charger.

I have a tudor battery charger I think it is rated at 30amps (I am not at home at the moment)

I have 2 generators:
One is about 2500 watts the other is 450 or 900 (dual).

The charger has an indicator panel on the front which I think refers to BULK - ABSORPTION - FLOAT.

In reality what actually happens when I use the charger is the following:

At the start, the charger charges at around 23amps
Then after about 5 minutes it goes down to around 17amps
After about an hour it will be charging at about 12amps.
The lowest I have ever see is 9 amps.

It makes no difference if I am using the 450 900 or 2500 watt generator. (except the 450 one does not like 23amps)

I have always considered that the Tudor battery charger was a good make and it avoids overcharging even if a lot more power is available.
I always use the 450 or 900 watt generator because it seems that using the 2500 watt generator is just a waste.
Once the charging rate is down to below 12 amps the 450 watts the generator is very happy to power the house and charge the batteries at the same time.

I need a tutorial that explains what C/8 means.
How many amps would C/8 be in this case?

You say that I need a 50 amp charger but my 30 amp charger never uses it's full charging capacity.
I don't understand?

[Beanyboy57]

I have a 24 volt system
I have 12 of the following batteries

Classic 5 OPzS 380 2v Solar Liquid Cell
Voltage: 2V
Capacity: 380Ah @ c120

I just checked out your battery specs...Long life flooded tubular plate batteries
Design life: >20 years at 20ºC, >10 years at 30ºC, >5 years at 40ºC.
Cycling expectancy of up to 1500 cycles at 80% depth of discharge.
Manufactured according to DIN 40736, EN 60896 and IEC 896-1.

Low maintenance
Under normal operating conditions and 20ºC, distilled water has to be added every 2 – 3 years.
It seems like you have great batteries that will serve you well if you look after them. I am envious...hahaha

[Sunking]

This is my case:
When I bought my batteries my mountain house was only used for weekends.
I like it so much up here that I now spend a lot of time here. From March - November this year I have been here permanently, 100% off grid.

The choice of batteries was made by an installer.
At this time I did not understand anything about batteries or solar systems so I had to go along with what my "expert" thought best.
It probably was the right amount of battery for my usage at the time.

YOu have outgrown your system

The big difference between my conception of a good system and other people on this thread and also books I have read is that other people believe that
the batteries should be able to withstand 5 days of no sun whereas I would be happy with 1 day.

Here is the part you do not understand yet. You never ever want to discharge your battery more than 50%. If the batteries are sized for 5 day reserve capacity only gives you 2.5 days for cloudy spell. At that poin tyou have to shut down or start running the generator. For the generator needs to be sized to provide a C/8 charge rate for FLA batteries to minimize fuel burn and minimize charge efficiency. So if you were to say have a 24 volt 380 AH battery, you are looking at about a 2 Kva genset and a 24 volt 50 amp charger.

If your batteries are as you claim 24 volts @ 380 AH gives you a total capacity of 24 x 380 = 9.1 Kwh of reserve capacity at a 20 hour discharge rate (19 amps). As I have tried to say before I will bet you money you discharge at a higher rate that 19 amps. That being the case you have to derate the batteries which means they are actually less than 9.1 Kwh.

You claim you are using 4.5 to 5 Kwh each day and I believe you. That means you are discharging your batteries more than 50% each day. Your battery voltages are indicating you are doing just that.

[Sunking]

The CC s are PWM


I now have 2 charge controllers.
One with 250 watts of panels the other has 950 watts.

You need 1 MPPT unless you have different size panels. Just replacing the CC will boost your daily harvest some 20 to 30 % without adding a single panel.