Battery monitor and a/c charger

[LennyM]

Good morning everyone I have a question I hope can be answered about charging. I have put together a simple backup power system consisting of four 100 amp hour AGM batteries in parallel I just installed a Renogy battery monitor. I am using a 55 AM PowerMax AC charger. I am not using a charge controller since my solar panels are connected to the grid. And this battery system is purely for grid down situations. If the grid goes down I will simply plug the charger inTo one of my sun power inverters which has 120 V AC output. My question is why do I not see That the system is charging in my battery monitor, it is constantly reading discharge. My inverter is on drawing 7 W but I have no loads connected to the inverter but yet the battery meter is still reading discharge. Is my power max charger too small or is the voltage too low I am currently reading 13.7 V in the system again with no loads connected other than the inverter powered on.

 

[mopat]

I do not understand your system(s). "my solar panels are connected to the grid"...how is this happening?

 

[Zil]

Need a simple wiring diagram. Can't tell shit how things are connected without.

 

[LennyM]

I do not understand your system(s). "my solar panels are connected to the grid"...how is this happening?

I have a grid attached system, my solar panels are powering two inverters and that is feeding back to the grid. I don't use the power directly. The battery's are being used only for emergency power and I feed my house though a transfer switch. My back up system gets charged from a 55 amp charger that plugs into house power. Now if the house power goes out I can plug that charger into my inverter that is attached to my PV. It uses "Sunny Boy" Inverters with have a 120V ac output if the grid goes down.

 

[LennyM]

You know this just occurred to me, Im using a three stage 55amp charger. Im not using a charge controller. The charger is hooked directly to the batteries. Im relying on the charger to sense voltage in order to charge or float. Do I need a charge controller ?

 

[Bob142]

Your Powermax is a charge controller if switch A is set in three stage charging mode. Read your manual for details. It might be in the 13.2V maintenance portion of the charge cycle.

Your battery monitor says 97% so you seem to have charged it at some point. If you discharge your battery bank to something like 80% and then try to charge it with the Powermax, what happens?

 

[LennyM]

Thanks Bob I’ll let you know

 

[LennyM]

Ok Bob you see what I m drawing still 12.5 volts fan is on on the charger it’s getting warm but still has not kicked into the 14.7 volt charge

 

[Bob142]

Is your Powermax negative wire connected to the same shunt terminal as your inverter? Unless you have it connected to the shunt the battery monitor doesn't know about it.

If you have it connected directly to the battery bank, move the connection to the shunt, then just turn on the Powermax (no loads on the system) and watch the monitor. You should see it charging.

 

[LennyM]

I have the negatives connected on a bus . ok so your saying connect the charger negative the P- terminal. Ok will report back to you. Thanks so much for your interest and time. ??

 

[LennyM]

BOB!!!!!!!! It worked !!!! Thank you so much