Need help with my solar setup please..

waywaynorcal

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How is your MPPT configured to charge the batteries? Is it for a lead acid profile? What is your bulk / float settings? Do you have a battery charger for the bank when there is grid power?
Those are some of the issues I am trying to figure out. The profile is set for GEL and is correct for the batteries I am using. The bulk float settings I have not set manually and I am not entirely sure what is optimal for the setup I have.
I do not have a battery charger as of yet. I plan on getting one soon.
 

Kdkool

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The physical wiring of your system looks to be fine. I think your problem can be one of two things.

1) A defective battery
2) An incorrect charging profile

For scenario #1, it's possible that you could have a defective battery that's pulling down on the other battery that's in parallel. Have you ever severely depleted the banks? I'd try removing one of them out of parallel configuration and let the system charge one battery at a time and see if one of them behaves significantly different from the other.

For scenario #2, are you using the EPEVER configuration tool? There is a bluetooth to RS485 to Bluetooth (Phone) and USB to RS485 (PC) configurator that you can use to configure those settings. It may just be that the default gel profile is not in agreement with what the Renogy batteries want. I would double check this. I would contact Renogy and ask what they recommend for the bulk and float points are as well as their their recommended low voltage cut off.

Ideally, your inverter and other DC loads should not significantly deplete your batteries. Those types of batteries should not be depleted more than 50% for maximum life.
 

waywaynorcal

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I talked with Renogy tech support this morning and they gave me the numbers I need.
It looks like my setup is correct by the number.
Boost absorption is 14.2, Float is 13.8, Bulk/Boost return is 13.2
Next step is to test the batteries. I don't have a battery tester so I am going to take them into Les Schwab and have them tested. I live in a pretty rural area and Schwab is the closest to me that has a battery tester.
For the future can someone recommend a battery tester for these batteries? One not too expensive that I can use to see if the battery is bad or good?
 

Hedges

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Most stores test batteries for cranking amps (and may call it "cold cranking amps", which it isn't.)
That's one indication, but capacity is another, more important for this application.

What I did was put a loan (oil filled radiator heater) on an inverter and let it run until low-voltage disconnect.
I spot-checked battery voltage and current, and measured load resistance.
I estimate I got 35 Ah to ~ 80% DoD from 12 year old 104 Ah batteries.

Inverter driving heater would be constant watts. Load directly on battery could be constant resistance. Light bulbs (like some automotive headlamps) could work, but resistance varies with temperature so not constant as voltage drops. Resistance hot is about 10x resistance cold, so you can't rely on an ohmmeter, need ammeter to measure.

Instead of capacity test, first thing to do would be disconnect all loads and let PV fully charge battery. Disconnect and let sit a few hours. Measure resting voltage and compare to specs.
 

waywaynorcal

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Renogy suggested taking the batteries to an auto parts store to measure the internal resistance and to take a photo of the numbers should there be a warranty issue. The problem is I live in the middle of nowhere and I don't know how capable the shop in town is. What is the resting voltage on one of these batteries? Specs are in the image below.
 

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Kdkool

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Renogy suggested taking the batteries to an auto parts store to measure the internal resistance and to take a photo of the numbers should there be a warranty issue. The problem is I live in the middle of nowhere and I don't know how capable the shop in town is. What is the resting voltage on one of these batteries? Specs are in the image below.
I suggest that you disconnect one battery and let the remaining one charge up to capacity. Your profile will charge the batteries to 14.2V and then stop. It will then switch to "charge" the batteries at 13.8V. Should the batteries drop below 13.8V, it will bulk charge it back to 14.2V. You can do a self dissipation test by letting the batteries charge up to 14.2V and then disconnecting it. Verify after a few days that the one battery is still relatively charge (13.6V+). A bad battery will generally self dissipate faster.

You can also alternatively do a full capacity test. Once the MPPT has charged the batteries to 14.2 or somewhere in between 13.6V to 14.2V, do a capacity test by loading your inverter with a known power draw (hair dryer / heat gun / etc) and verify that the one battery can run said power draw for the calculated amount of time the battery the battery is rated for (200aH).

Then repeat the same test with the other battery.
 

Hedges

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Renogy suggested taking the batteries to an auto parts store to measure the internal resistance and to take a photo of the numbers should there be a warranty issue. The problem is I live in the middle of nowhere and I don't know how capable the shop in town is. What is the resting voltage on one of these batteries? Specs are in the image below.

Page 35 gives resting voltage for my SunXtender.
Yours will differ somewhat, need to find similar documentation for it.

 

Kdkool

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Have you been abusing your renogy batteries by drawing more than 50% of it's rating? That'd cause accelerated wear on lead acid batteries. That's the real advantage of switching to the lithium batteries. A 200aH lead acid battery would have ~half the capacity (assume similar voltage between the two) of a 200aH of the lithium battery because it generally does not like being more than 50% depleted. You should consider a load disconnect or alarm when the batteries approach 50% capacity.
 

waywaynorcal

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I hope i havent been abusing them. I assume the system cuts off anything that goes below 50 percent in order to not damage the battery. I believe I set it in the charge controller or I remember it being set.
 

Kdkool

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I hope i havent been abusing them. I assume the system cuts off anything that goes below 50 percent in order to not damage the battery. I believe I set it in the charge controller or I remember it being set.
I don’t see how it cuts off as you don’t have a cut off relay / switch / FET. Your particular mppt doesn’t appear to have a load terminal.
 

Hedges

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Inverter may have a low-battery cutout. But, it could be too low a voltage to protect the battery (at least at low discharge rate).
At high discharge rate, battery voltage is lower even before SoC gets low, but springs back when load is removed.
It probably takes a more sophisticated state of charge monitor algorithm to make a good SoC based cutout.
 

Supervstech

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I hope i havent been abusing them. I assume the system cuts off anything that goes below 50 percent in order to not damage the battery. I believe I set it in the charge controller or I remember it being set.
Your inverter is directly connected to the batteries… no possible setting in the charge controller could protect them from too low a discharge… the protection must be in the load… if the inverter has protection, that could work, but most inverters will run until you shut them off… or the battery voltage drops to zero percent SOC…
 

Hedges

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Cut off of discharge?
Most convenient would be if inverter monitors SoC and has setting to shut down.
If inverter has remote enable, wire to a monitor, possibly SCC if it has SoC controlled relay.
There are breakers with remote trip (Midnight has some), but probably not high enough amperage for inverter battery current.
Could disconnect AC loads with relay or remote trip breaker. Then still have inverter idle load. If it has standby/search setting, that would further reduce draw.
There are relays for battery current (Gigavac, etc), such as used with BMS of lithium battery. You want low hold current, and "economizer". And it has to be rated for continuous operation, not like an automotive starter relay.
You can control relay with a battery monitor, maybe just battery voltage but it needs a delay to allow surges. And voltage will give poorer measure of SoC, depends on both current and temperature.

Controlling loads so heavy loads are only operated with higher SoC would help avoid draining battery to cutoff. Or just enabling them when there is sunlight, by sensor or timer.
 
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