Conflicting info on whether the controller and inverter come off the same battery terminals.

[Russelljw]

So I need a battery bank to run our stationary rv.
I bought four 170ah dekas. Got them from a reputable battery/solar dealer in Denver. The batteries seem to be good, he said they had 95% life left. Got them wired for 24v bank. Have a make sky blue 40amp controller.
Batteries hit 29v no problem, problem comes when about 10pm they are down in the 23.7 range( too low). I only need them to power the furnace fan and some led lights each night. My old batteries did this without a problem.
So I called the guy back up and told him batteries were not preforming well. He said he had no complaints on them and would switch them for another type if I wanted. He asked how I had them hooked up and I said the controller and inverter were coming off the battery 1 and 4 ( same terminals ). He said no the controller goes to battery 2 and 3 and the inverter goes to bats 1 and 4. I had never heard this.
This is what I want to figure out. What terminals exactly to come off of for the controller and inverter.
Thank you

 

[John Frum]

By controller do you mean solar charge controller?
Do you have a shunt based battery monitor?

Please post a picture(s) of your system layout.

 

[MurphyGuy]

So I need a battery bank to run our stationary rv.
I bought four 170ah dekas. Got them from a reputable battery/solar dealer in Denver. The batteries seem to be good, he said they had 95% life left. Got them wired for 24v bank. Have a make sky blue 40amp controller.
Batteries hit 29v no problem, problem comes when about 10pm they are down in the 23.7 range( too low). I only need them to power the furnace fan and some led lights each night. My old batteries did this without a problem.
So I called the guy back up and told him batteries were not preforming well. He said he had no complaints on them and would switch them for another type if I wanted. He asked how I had them hooked up and I said the controller and inverter were coming off the battery 1 and 4 ( same terminals ). He said no the controller goes to battery 2 and 3 and the inverter goes to bats 1 and 4. I had never heard this.
This is what I want to figure out. What terminals exactly to come off of for the controller and inverter.
Thank you

You bought used batteries? That's probably your problem.

There is no such thing as a "refurbished" battery.. unless you count polishing the outside of it as being refurbished. The market is filled with these "refurbished battery" sellers and every one of them is a scam.. You might get lucky, you might not.. but one thing that is known is that they are selling you a battery with unknown life left.

 

[Tecnodave]

If your batteries are 6 volt, and all in series for a 24 volt system the inverter and charge controller wire to the most negative terminal and the most positive terminal.

Im thinking that your dealer is under the impression that you have a 12 volt system.

 

[rmaddy]

Wiring everything up with bus bars would be a much better approach.

 

[upnorthandpersonal]

Should just be something like this, assuming each battery is 12V. Two batteries in series to get 24V, then two sets of those in parallel.

 

[Russelljw]

You bought used batteries? That's probably your problem.

There is no such thing as a "refurbished" battery.. unless you count polishing the outside of it as being refurbished. The market is filled with these "refurbished battery" sellers and every one of them is a scam.. You might get lucky, you might not.. but one thing that is known is that they are selling you a battery with unknown life left.

I have got great batteries from these people before in the past. They apparently have contracts with big companies that have solar back up banks. And the batteries have never been discharged past a certain percentage, in this case they were never used only kept charged,

 

[Russelljw]

Should just be something like this, assuming each battery is 12V. Two batteries in series to get 24V, then two sets of those in parallel.

View attachment 75510

Yes this is what I have, but the guy said, the inventor should come off bats. (1 and 4)and the controller should be hooked to batteries 2 and 3.
And through me for a loop.
So just as above the inverter and controller can both come off the same terminals, correct?

 

[MurphyGuy]

I have got great batteries from these people before in the past. They apparently have contracts with big companies that have solar back up banks. And the batteries have never been discharged past a certain percentage, in this case they were never used only kept charged,

You got lucky.. it does happen.

 

[MurphyGuy]

Yes this is what I have, but the guy said, the inventor should come off bats. (1 and 4)and the controller should be hooked to batteries 2 and 3.
And through me for a loop.
So just as above the inverter and controller can both come off the same terminals, correct?

He's full of donkey doo doo..

UpNorthAndPersonal is correct...

Here's my guess.. Charge up each battery individually and load test each one.. I bet at least one is bad, probably two..

You did check water level right?

 

[Russelljw]

Pics

 

[rmaddy]

Yes this is what I have, but the guy said, the inventor should come off bats. (1 and 4)and the controller should be hooked to batteries 2 and 3.
And through me for a loop.
So just as above the inverter and controller can both come off the same terminals, correct?

No. Neither the inverter nor the charge controller should be connected to the batteries at all. Add bus bars. Connect them to the batteries. Then connect the invert and the charge controller to the bus bars.

There are good and bad ways to wire up batteries in 2S2P. There are good and bad ways to connect those batteries to the bus bars. The diagram in post #6 is one of the good ways.

 

[Russelljw]

He's full of donkey doo doo..

UpNorthAndPersonal is correct...

Here's my guess.. Charge up each battery individually and load test each one.. I bet at least one is bad, probably two..

You did check water level right?

I separately charges all batteries today. They are all showing good, go up to about 14v and settle at 12.8 to 13.1v. And they hold there.

 

[Russelljw]

No. Neither the inverter nor the charge controller should be connected to the batteries at all. Add bus bars. Connect them to the batteries. Then connect the invert and the charge controller to the bus bars.

There are good and bad ways to wire up batteries in 2S2P. There are good and bad ways to connect those batteries to the bus bars. The diagram in post #6 is one of the good ways.

I have bars coming in the mail.

 

[Russelljw]

He's full of donkey doo doo..

UpNorthAndPersonal is correct...

Here's my guess.. Charge up each battery individually and load test each one.. I bet at least one is bad, probably two..

You did check water level right?

Have not checked water level.

 

[Russelljw]

By controller do you mean solar charge controller?
Do you have a shunt based battery monitor?

Please post a picture(s) of your system layout.

Yes solar charge controller
No I don’t have a shunt monitor
I posted pics below

 

[John Frum]

Have not checked water level.

Those look like sealed batteries, confirm?
The interconnects between the batteries look correct and the connections to your loads and charge sources should come off the most positive and most negative terminals.
But...
The wires to the rest of the system are way too small.
I don't see any over-current protection.
No busbars.
No means of disconnect.
And finally no shunt based battery monitor.

The thin wires and lack of over-current protection are safety issues.
The busbars, disconnect and shunt are secondary issues.

 

[rmaddy]

The thin wires and lack of over-current protection are safety issues.

With a 2500W inverter on a 24V system you want 2AWG wire or larger for all battery and inverter wires. The inverter should have a 150A fuse. When you get the bus bars you will want a 150A fuse at the battery as well.

The wires from the batteries to the charge controller depend on the max output current of the charge controller. There should be a fuse there too.

 

[Russelljw]

Those look like sealed batteries, confirm?
The interconnects between the batteries look correct and the connections to your loads and charge sources should come off the most positive and most negative terminals.
But...
The wires to the rest of the system are way too small.
I don't see any over-current protection.
No busbars.
No means of disconnect.
And finally no shunt based battery monitor.

The thin wires and lack of over-current protection are safety issues.
The busbars, disconnect and shunt are secondary issues.

I know those wires are too small, and I am ordering the fuses for between controller and bats and inverter and bats.

Please explain, ( most positive and negative terminals)

 

[Russelljw]

I

With a 2500W inverter on a 24V system you want 2AWG wire or larger for all battery and inverter wires. The inverter should have a 150A fuse. When you get the bus bars you will want a 150A fuse at the battery as well.

The wires from the batteries to the charge controller depend on the max output current of the charge controller. There should be a fuse there too.

I thought the controller to battery gets a 80 amp fuse and the bats to inverter got a 150?

 

[Russelljw]

Those look like sealed batteries, confirm?
The interconnects between the batteries look correct and the connections to your loads and charge sources should come off the most positive and most negative terminals.
But...
The wires to the rest of the system are way too small.
I don't see any over-current protection.
No busbars.
No means of disconnect.
And finally no shunt based battery monitor.

The thin wires and lack of over-current protection are safety issues.
The busbars, disconnect and shunt are secondary issues.

The batterys are called maintenance free, but they appear to have little slots for a flat head to maybe check fluid.

 

[rmaddy]

I thought the controller to battery gets a 80 amp fuse and the bats to inverter got a 150?

The battery gets a fuse. The wires to the inverter get a fuse. The wires to the charge controller get a fuse.

The battery and inverter fuses should both be 150A to go with the 2AWG wires.

Since you never stated what charge controller you have and what its output current is, I can't say what wire and fuse you need there.

Remember, you size the wire to the load then you size the fuse to the wire so the fuse is the weak link. The fuse size is typically about 1.25 times the load but most importantly it must be less than the chosen wire is capable of carrying.

 

[Tecnodave]

There are several maintaince free lead acid battery types, these are AGM, Adsorbed Glass Mat.

 

[Russelljw]

The battery gets a fuse. The wires to the inverter get a fuse. The wires to the charge controller get a fuse.

The battery and inverter fuses should both be 150A to go with the 2AWG wires.

Since you never stated what charge controller you have and what its output current is, I can't say what wire and fuse you need there.

Remember, you size the wire to the load then you size the fuse to the wire so the fuse is the weak link. The fuse size is typically about 1.25 times the load but most importantly it must be less than the chosen wire is capable of carrying.

I have a make sky blue 40amp mppt controller. Will be replacing it with a epever.
Thank you so much for this info!

 

[Russelljw]

There are several maintaince free lead acid battery types, these are AGM, Adsorbed Glass Mat.

They are not AGM batteries. I know that.