Need Solar Guru Help!

[campermama]

This is my system...

570w solar panels (parallel)
?2 100ah BB lithium (parallel) (12v)
Victron smartsar 100/50 controller
Renogy battery monitor
Renogy 2000w inverter

Victron goes through bulk mode until it reaches absorption V, then goes to absorption mode for 1 hr (recommended by BB), (highest V I have seen on the monitor during absorption mode is 13.5, while mppt reads 14.4)then it goes to float (mppt reads 13.6v, monitor reads 13.4v), the amps never go down to 0, it sticks around at 2-4 amps. So to me it seems batteries are never "fully" charged?

V always drops to 13.2(something) v when it gets dark. According to charts I have seen that is only 70%!
ALSO, discharging amps at night seem really low....TV, inverter on, led lights on, it shows - 1.8 amps, how can that be?

Here is a "drawing" of my set up....

My 12v System

[CA_Traveler]

campermama wrote:
Meanwhile, mppt just went to float 13.6v, monitor says 13.4v and ~+4.5 amps, it will stay like this all day, I'm at a loss.

Renogy monitor or MPPT monitor? Renogy monitor should show battery amps ONLY and MPPT shows solar amps to the RV with includes RV loads and any battery charging.

I'm suspicious that there could be additional wiring involved. Turn off shore, gen, solar, turn on lights, does the Renology show - amps?

[campermama]

I have 3 go power panels in parallel, batteries are connected as you stated above.

[CA_Traveler]

What panels do you have? Wondering if they could be connected in series to produce more power. If your voltage readings are accurate then you have 14.4-13.5 = 0.9V wiring loss which is high and should be corrected.

Also not sure of the current wiring but balanced wiring on the batteries is best for a variety of reasons including battery life. Connect all + battery wires to battery 2, connect the shunt to battery 1 - post and all negative wires to the shunt. This is in addition to the + to + and - to - wires between the 2 batteries.

Can your Renogy battery monitor display the battery SOC? Mine can display % SOC which is based on actual power (amps and voltage) available rather than inaccurate voltage as noted in a prior post. Don't want to get technical but SOC is about available power (watts or AH) and using just voltage is often misleading.

Guessing you want to do some amount of boon docking and having accurate input can enhance your power usage and understanding.

[campermama]

Meanwhile, mppt just went to float 13.6v, monitor says 13.4v and ~+4.5 amps, it will stay like this all day, I'm at a loss.

[2oldman]

otrfun wrote:
lifepo4's not needing absorption---that was the lifepo4 charging philosophy a 2-3 years ago when nearly all lifepo4 converters/chargers were single-stage 14.6v (no absorption or float stage).

Also interesting is the 48v Dakota charger appears to have bulk only, so perhaps it depends on the kind of Li battery. But, I'm getting off the subject.

[campermama]

Many 12v lifepo4 voltage/SOC charts show 13.20v (resting voltage) as equivalent to 70% SOC. The key here is "resting voltage".


Ok so the 13.2 is not really "resting", then would the actual "resting" voltage show a higher voltage or less?

[2oldman]

otrfun wrote:
As for 2oldman's comment about lifepo4's not needing absorption---that was the lifepo4 charging philosophy a 2-3 years ago when nearly all lifepo4 converters/chargers were single-stage 14.6v (no absorption or float stage).

Okay, I guess things have changed. My 5yo 48v pack only has bulk and float, but the specs for 12v Battleborns do specify an absorb voltage. I adjusted my solar controller's absorb to almost nothing.

[otrfun]

campermama wrote:

2oldman wrote:
The 1.8 amps sounds more like the 120v side. 13.2 is more than 70% on any chart I've seen. I did not know any Li battery needed absorption.

Can you please post a chart that shows 13.2v is not 70% for Lithium batteries? If it's not 70% what is it? . . .

Many 12v lifepo4 voltage/SOC charts show 13.20v (resting voltage) as equivalent to 70% SOC. The key here is "resting voltage".

If you're going to use a lifepo4 voltage/SOC chart to determine SOC, you must have zero charge/discharge current (ideally by disconnecting the battery entirely). Then you must let the voltage stabilize to a final resting voltage before taking a voltage reading. Depending on the situation, it can take anywhere from a few minutes to a few days to reach the final resting voltage.

As for 2oldman's comment about lifepo4's not needing absorption---that was the lifepo4 charging philosophy a 2-3 years ago when nearly all lifepo4 converters/chargers were single-stage 14.6v (no absorption or float stage). These days it's common knowledge you can damage a lifepo4 subjecting it to a 14.6v bulk mode indefinitely. Thus, the need for an absorption voltage. Many recommend 13.2v - 13.6v. There are still a lot of single-stage 14.6v lifepo4 converter/chargers on the market. Highly recommend purchasing a 2-3 stage converter/charger instead.

[campermama]

2oldman wrote:
13.3 to 13.4 is 100%, so I guess 13.2 could be 70%, but that does surprise me.

Yup, can't figure out why it's that low!

[2oldman]

13.3 to 13.4 is 100%, so I guess 13.2 could be 70%, but that does surprise me.

[campermama]

2oldman wrote:
The 1.8 amps sounds more like the 120v side. 13.2 is more than 70% on any chart I've seen. I did not know any Li battery needed absorption.

Can you please post a chart that shows 13.2v is not 70% for Lithium batteries? If it's not 70% what is it?

See my post above this one, I found/fixed an issue that should fix the amps issue.

[campermama]

So there was one connection wrong that was affecting the amps reading....the Neg of the inverter was not on the shunt! I have now switched them.
Now it's just the charge issue, I think.

[otrfun]

I'd suggest checking/verifying load/discharge (-) and charge (+) current separately by measuring current on the appropriate wires/cables with a DC clamp-on ammeter (during the day and at night). Your battery monitor only provides the sum total of both, which doesn't give you a clear picture of what's going on. It's also possible your battery monitor is inaccurate or mis-calibrated. A DC clamp-on ammeter would help confirm the accuracy of the battery monitor's current readings.

[Boon_Docker]

Rotated OP's 12v system link.

[2oldman]

The 1.8 amps sounds more like the 120v side. 13.2 is more than 70% on any chart I've seen. I did not know any Li battery needed absorption.