Solar charging in longer daylight hours. (1 Viewer)

[Jimbohorlicks]

OK. So we have a victron controller 100/30 with 200watts of solar charging a 100ah lithium.
So today fully charged.100% on battery app and battery on standby. Ie not charging or discharging.
The victron history shows bulk charged for just over 5hrs and absorption for 7 hrs and now in float mode with minimal charge.
So run the microwave and reduce soc to 75%. Battery still showing as on standby and victron on float charge o.2 amps input.
Pulled the fuse between solar and victron and reinserted . Now charging on bulk.
Can someone explain why the victron does this.

 

[Raul]

OK. So we have a victron controller 100/30 with 200watts of solar charging a 100ah lithium.
So today fully charged.100% on battery app and battery on standby. Ie not charging or discharging.
The victron history shows bulk charged for just over 5hrs and absorption for 7 hrs and now in float mode with minimal charge.
So run the microwave and reduce soc to 75%. Battery still showing as on standby and victron on float charge o.2 amps input.
Pulled the fuse between solar and victron and reinserted . Now charging on bulk.
Can someone explain why the victron does this.

Why you absorb for 7hrs with lithium? If you bulk at 14.4v no absorb needed, max 5 minutes. If you bulk at 14v, you need 30 mins absorb. And at 14.6v needs 0 seconds absorb. Your settings are bad. Switch to lifepo4 presets, that atleast reduces absorb to 2 hrs and bulk to 14.2v.

 

[Jimbohorlicks]

Why you absorb for 7hrs with lithium? If you bulk at 14.4v no absorb needed, max 5 minutes. If you bulk at 14v, you need 30 mins absorb. And at 14.6v needs 0 seconds absorb. Your settings are bad. Switch to lifepo4 presets, that atleast reduces absorb to 2 hrs and bulk to 14.2v.

I have done that this morning and the battery is at 73% but on a float charge. The history this morning shows bulk on for 2hrs 48 min. abs 2hrs 23min and then on float at 0.4amps with battery on standby.
Changing the absorb to 6hrs starts a charge regime of 1.5amps.ie takes the charge off float to absorb stage with more amps.

 

[monzer]

Not going to attempt the maths but how long was the microwave on to suck out 25% capacity of the battery?

 

[Raul]

DC

I have done that this morning and the battery is at 73% but on a float charge. The history this morning shows bulk on for 2hrs 48 min. abs 2hrs 23min and then on float at 0.4amps with battery on standby.
Changing the absorb to 6hrs starts a charge regime of 1.5amps.ie takes the charge off float to absorb stage with more amps.

What's telling you the SOC capacity? My immediate guess, whatever it is, its out of sync or settings not right, or both.

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[Jimbohorlicks]

The SOC is on my battery app

 

[headlight]

The SOC is on my battery app

So that's from the BMS.
BMS 's can't detect draws below 1amp, 1.5amps with my BMS.
That means that small drains are not recorded and the app SOC can be well off.
I have an app for my LifePo4 and a Victron shunt.
The SOC shown on my app and shunt can be very different eg the other week my app showed 98% SOC and my shunt 78% SOC.
The shunt is the correct reading.
I would get a shunt.

 

[Raul]

Not going to attempt the maths but how long was the microwave on to suck out 25% capacity of the battery?

It seems we don't get the full picture, and info its coming in drabs. If microwave is 800w plus, its possible that the battery got hammered with 1C plus discharge. That will affect the SOC reading for sure.

 

[Jimbohorlicks]

The soc was showing at 100 % so boiled a kettle of water (700w) and soc down to 93%.
Microwave is 800w and was on for 8 maybe 10 mins in 3 stages. We heated a 2min rice bag and a microwave pot of chilli we prepped yesterday. .
Batter app indicated 90 plus amps being drawn. Battery is a 100ah ecotree with Bluetooth..
So expecting at 5pmish that I could get some charge back into the battery before the sun went down. But victron controller on float charge .minimal amps and batteryvapp showing battery on standby ie not charging up and not discharging.
I thought that if the battery was at70% soc that the victron would change from flaotvto a bulk or abs charge but didnt until I pulled the fuse and reinserted it and the charge went from float at o.2 amps to abs at 1.5 amps(6 .30 pm).

 

[Jimbohorlicks]

Just to add a little further. OK so thecsoc may be inaccurate from the battery app or bms. But I had taken a substantial load out of the battery using the kettle and microwave. So why would the victron controller stay on a flaot charge until I pulled the fuse reinserted it and immediately the amps increase to the battery.?

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[Raul]

Just to add a little further. OK so thecsoc may be inaccurate from the battery app or bms. But I had taken a substantial load out of the battery using the kettle and microwave. So why would the victron controller stay on a flaot charge until I pulled the fuse reinserted it and immediately the amps increase to the battery.?

Yes got that, the controller should of switched to bulk as soon as the voltage dipped below the float voltage ( with the load), by 0.2v ish.
Can you post the solar controller settings? There is a setting for the re bulk, 0.10v to allow re bulk more than once in the same day.

 

[JockandRita]

Raul, he's about 15 x meters at ten o'clock from you. Maybe when Jim comes back from town, he could pop the kettle on and pour you a coffee, so that you can monitor things live.

Just a thought Jim.

Jock.

 

[Raul]

Raul, he's about 15 x meters at ten o'clock from you. Maybe when Jim comes back from town, he could pop the kettle on and pour you a coffee, so that you can monitor things live.

Just a thought Jim.

Jock.

Thank you, I wasn’t aware, I will give it few minutes till he returns.

 

[DavidG58]

Think I am glad I stuck to gels

 

[Jimbohorlicks]

Thanks to Raul we now have some more insight as to what's going on. He suggested the existing cables to the battery from the controller were the problem being undersized. A voltage check at the controller 14.2v and at the battery 13.4 v showed that I was losing voltage because of the cable size. My app and plug in gauge I have were reading the battery correctly but the victron controller was seeing 14.2v as the solar output side hence going into float.
I am due to change the solar panels to 360w and the batteries to 200ah when weather and time permits So will invest in some heavier Duty cables as well.
Thanks again Raul.

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[Raul]

You are welcome Jim, at-least you know all works as it should, less the cable from controller to the battery. The multimeter readings clarified what’s happening.

 

[AdrianChen]

Ah a simple result! - thought the controller might have been set for a gel battery at some point with long absorption and re-bulk at 0.4v, as always I'm overthinking!

 

[Raul]

Ah a simple result! - thought the controller might have been set for a gel battery at some point with long absorption and re-bulk at 0.4v, as always I'm overthinking!

That’s what I thought at first as well, but, the controller is set right, and it reaches the set absorb value on the terminals, checked with the multimeter. And with same multimeter, at battery end, the terminals read much lower, the cable needs upgrading.
The fact that it had a previous charge helped by EHU to 100% added to the confusion. At least the ehu charger can do 100%,, but not the solar.

 

[AdrianChen]

That’s what I thought at first as well, but, the controller is set right, and it reaches the set absorb value on the terminals, checked with the multimeter. And with same multimeter, at battery end, the terminals read much lower, the cable needs upgrading.
The fact that it had a previous charge helped by EHU to 100% added to the confusion. At least the ehu charger can do 100%,, but not the solar.

Ah no battery voltage sensing. I have a spare smart sense somewhere....

 

[Raul]

Ah no battery voltage sensing. I have a spare smart sense somewhere....

No batt sense and no shunt either, I was looking if anything could be networked to share data, but it’s only a victron controller in the system. Surprisingly the eco tree bms it is reading small amps in, that’s a plus.

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[AdrianChen]

No batt sense and no shunt either, I was looking if anything could be networked to share data, but it’s only a victron controller in the system. Surprisingly the eco tree bms it is reading small amps in, that’s a plus.

SmartSense will give the controller batt volts (and temp) if its a BT version of controller, but not the other benefits of a shunt.