
	Already a member? Login here. If not, Register Today! \| Help

Newest | Active | Popular | RVing FAQ

Forum Rules | Forum Posting Help and Support | Contact

Open Roads Forum > Tech Issues

This Topic Is Closed | Print Topic | Post New Topic |

Sponsored By:

campermama

Here and There

Senior Member

Joined: 11/16/2003

View Profile

Good Sam RV Club Member

Offline

Posted: 04/12/23 10:14am

Link | Print | Notify Moderator

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

2018 Dodge Ram 3500 Laramie,SRW,CTD,4x4,Long bed
2020 Jayco eagle ht 274ckds

My Adventure Blog:
https://roaddivaontheroad.blogspot.com/2020/03/getting-ready.html

2oldman

Senior Member

Joined: 04/15/2001

View Profile

Offline

Posted: 04/12/23 10:58am

Link | Print | Notify Moderator

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.

Boon Docker

Mountain Foothills of Southern Alberta

Senior Member

Joined: 10/30/2015

View Profile

Posted: 04/12/23 11:04am

Link | Print | Notify Moderator

Rotated OP's 12v system link.

[image]

otrfun

On The Road

Senior Member

Joined: 09/08/2012

View Profile

Good Sam RV Club Member

Posted: 04/12/23 11:34am

Link | Print | Notify Moderator

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.

campermama

Here and There

Senior Member

Joined: 11/16/2003

View Profile

Good Sam RV Club Member

Offline

Posted: 04/12/23 11:41am

Link | Print | Notify Moderator

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.

campermama

Here and There

Senior Member

Joined: 11/16/2003

View Profile

Good Sam RV Club Member

Offline

Posted: 04/12/23 11:44am

Link | Print | Notify Moderator

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.

2oldman

Senior Member

Joined: 04/15/2001

View Profile

Offline

Posted: 04/12/23 12:45pm

Link | Print | Notify Moderator

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

campermama

Here and There

Senior Member

Joined: 11/16/2003

View Profile

Good Sam RV Club Member

Offline

Posted: 04/12/23 01:00pm

Link | Print | Notify Moderator

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!

otrfun

On The Road

Senior Member

Joined: 09/08/2012

View Profile

Good Sam RV Club Member

Posted: 04/12/23 01:03pm

Link | Print | Notify Moderator

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.

2oldman

Senior Member

Joined: 04/15/2001

View Profile

Offline

Posted: 04/12/23 01:24pm

Link | Print | Notify Moderator

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.