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Old 08-28-2021, 01:07 PM   #1
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Lithium battery charging

Recently had 2 Battleborn batteries installed along with a Victron Blue Solar charge controller 150/35 for the 180 watts of solar on the roof. I also have 2 Zamp portable suitcases of 140 watts each.
The portable solar is what I'm confused about. They're connected directly with the Airstream installed port on the tongue so they're not going thru the Blue Solar charge controller. When the Victron BMV-712 shows I'm charged to around the 80% level (this level varies) one of the portable panels will show "ful" and quit sending power to the batteries. It's doing it right now and the voltage on the batteries according to the BMV-712 is 13.4 volts.
The controllers on the portable panels are 10 amp controllers (Zamp assured me two controllers would work together nicely).
I was under the impression that the lithium batteries would accept lots of power up until they got close to full charge, and I'm hoping 80% is not close to full charge.
Is this normal behavior?

Thanks.
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Old 08-28-2021, 03:05 PM   #2
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Hi

Welcome to multiple controllers fighting with each other. What you see is *very* normal for a multi controller setup. The only answer is to go with networked controllers that all understand the "big picture".

Bob
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Old 08-28-2021, 04:34 PM   #3
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You might also want to make sure the suitcase panels are set to the lithium's voltages. If they are set for lead then they will think they are done early.
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Old 08-29-2021, 06:51 AM   #4
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Originally Posted by wareaglewalt View Post
Is this normal behavior?

Thanks.
Yes...pretty much.
You are charging thru an independent system which some say is not possible. It's worked fine for us for 4 Seasons now.

We also use 2 Zamp 180w portables charging thru the the 7-pin umbilical.

I've found when setting up if I connect both panels to their Y connector and then attach to the the 7-pin it helps, as they both start at the same time.
But one panel will always drop as the charge reaches float stage. They don't charge above the absorption rate using the panel controllers.

POI...it's NOT a $6-10k system....a 3k MacGyver DIY.

Bob
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Old 08-30-2021, 07:01 AM   #5
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Hi

What happens with multiple controllers *is* that one shuts down early. You get *some* charging out of them all, but you don't get full charging out of all of them. To keep things balanced as you get towards full charge (and very small voltage changes) the controllers need to each know what the other one is doing. Then they will all stay "on line" right to the end of the charge cycle.

Bob
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Old 08-30-2021, 07:23 AM   #6
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When does the "charge cycle" end...when the sun goes down?

I'm not concerned about cycling, as long as the BB's stay above 12.5v.
I do not use an integrated charge system, the Zamps are stand alone.

I may not have the largest brain pocket, but what I do have has served me well.
So far.

Bob
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Old 08-31-2021, 07:51 AM   #7
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Originally Posted by ROBERT CROSS View Post
When does the "charge cycle" end...when the sun goes down?

I'm not concerned about cycling, as long as the BB's stay above 12.5v.
I do not use an integrated charge system, the Zamps are stand alone.

I may not have the largest brain pocket, but what I do have has served me well.
So far.

Bob
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Hi

Ok, since you asked for more details ....

As the battery is charged (any battery) the voltage goes up. That's just how the chemistry works. At some point they get to a voltage that signals this or that to the controller. In the case of lithiums the signal says "we're full". In the case of lead acids the signal says "don't jack the voltage up any more, but no, we aren't full ... see, we're still pulling lots of current ...."

On a lead acid, the point that the voltage stops going up is roughly the 80% charge level. You run from 50% to 100% so this is just barely past "half way" in terms of usable capacity. Lead acids can spend a lot of hours in this range before they are fully charged. Four hours is not at all uncommon.

Both batteries charge cycle is "complete" when they are fully charged. The charger voltage then drops back to a lower level and just sits there. On an RV this may be problematic due to the loads on the battery. (The charger *assumes* current goes to a very low level ...).

With multiple solar controllers one of them spikes or drops. A decision is made by one of them due to the current change that the battery is now "full". It drops back to a low output voltage. Since the other one is still chugging along, there is now no current out of that controller and it says to it's self "hey, I made the right decision". It says in low voltage mode.

Can another blip come along? Sure it can. They can swap places. It depends on loads in the trailer and light to the panels driving the controllers. It also depends a bit on just how the controllers firmware has been written.

So will fighting controllers put current into your batteries? Sure they will. Will you get any use at all out of one of the other controller once they start fighting? No, you won't get any benefit from that other controller. If the 100W portable just shut off the 400W on the roof, it will be a while before the batteries get charged.....

Bob
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Old 08-31-2021, 08:08 AM   #8
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Originally Posted by uncle_bob View Post
Hi

Ok, since you asked for more details ....

As the battery is charged (any battery) the voltage goes up. That's just how the chemistry works. At some point they get to a voltage that signals this or that to the controller. In the case of lithiums the signal says "we're full". In the case of lead acids the signal says "don't jack the voltage up any more, but no, we aren't full ... see, we're still pulling lots of current ...."

On a lead acid, the point that the voltage stops going up is roughly the 80% charge level. You run from 50% to 100% so this is just barely past "half way" in terms of usable capacity. Lead acids can spend a lot of hours in this range before they are fully charged. Four hours is not at all uncommon.

Both batteries charge cycle is "complete" when they are fully charged. The charger voltage then drops back to a lower level and just sits there. On an RV this may be problematic due to the loads on the battery. (The charger *assumes* current goes to a very low level ...).

With multiple solar controllers one of them spikes or drops. A decision is made by one of them due to the current change that the battery is now "full". It drops back to a low output voltage. Since the other one is still chugging along, there is now no current out of that controller and it says to it's self "hey, I made the right decision". It says in low voltage mode.

Can another blip come along? Sure it can. They can swap places. It depends on loads in the trailer and light to the panels driving the controllers. It also depends a bit on just how the controllers firmware has been written.

So will fighting controllers put current into your batteries? Sure they will. Will you get any use at all out of one of the other controller once they start fighting? No, you won't get any benefit from that other controller. If the 100W portable just shut off the 400W on the roof, it will be a while before the batteries get charged.....

Bob
Sorry,this is one thing I don't have a photo of...BUT.

I have had one Zamp portable panel controller shut down and the second will continue charging. Just lucky I suppose.
Disclaimer.....I have NOTHING on the roof.
With all my posts on my system I thought that was clear....my bad.

Bob
🇺🇸

Myth?
BTW I don't believe he's in an AS.

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Old 08-31-2021, 08:51 AM   #9
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Quote:
Originally Posted by ROBERT CROSS View Post
Sorry,this is one thing I don't have a photo of...BUT.

I have had one Zamp portable panel controller shut down and the second will continue charging. Just lucky I suppose.
Disclaimer.....I have NOTHING on the roof.
With all my posts on my system I thought that was clear....my bad.

Bob
🇺🇸

Myth?
BTW I don't believe he's in an AS.

Well I do have rooftop panels as well as portable. Right now I'm at 65% charge on the batteries, the rooftop panels controlled by the Blue Solar are kicking in 4-5 amps of the total 9 amps going into the batteries according to the BMV-712 and state of charge is 13.39 volts. The portable panels are doing 4-5 amps but only one suitcase is participating. The other says Full. Zamp Support says they understand Battleborn batteries to be fully charged at 13.4 volts which is somewhat true, butt I'm still in the bulk charging phase which I'm thinking the batteries should be taking anything they can get. One other note is the Blue Solar is MPPT and the Zamp portable is PWM.
If this behavior from the portables is the way it's going to be then I'll accept it. Not happy with it though. I was hoping the charging algorithm/profile on the portable's controller would be better suited. When I bought them and told Zamp Support my exact setup they said it would work. I guess it does, technically.
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Old 08-31-2021, 09:45 AM   #10
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Quote:
Originally Posted by wareaglewalt View Post
Well I do have rooftop panels as well as portable. Right now I'm at 65% charge on the batteries, the rooftop panels controlled by the Blue Solar are kicking in 4-5 amps of the total 9 amps going into the batteries according to the BMV-712 and state of charge is 13.39 volts. The portable panels are doing 4-5 amps but only one suitcase is participating. The other says Full. Zamp Support says they understand Battleborn batteries to be fully charged at 13.4 volts which is somewhat true, butt I'm still in the bulk charging phase which I'm thinking the batteries should be taking anything they can get. One other note is the Blue Solar is MPPT and the Zamp portable is PWM.
If this behavior from the portables is the way it's going to be then I'll accept it. Not happy with it though. I was hoping the charging algorithm/profile on the portable's controller would be better suited. When I bought them and told Zamp Support my exact setup they said it would work. I guess it does, technically.
Why not happy?...your BB's are charged to 13.4 ?(FULL)
Do you want more?
I use our Zamp portable 'solar' to charge when needed.
To maintain is a whole 'nuther matter.

FWIW when we first started with the Zamps I had a 140 & a 180 they still 'played' well together.

Bob
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Old 08-31-2021, 10:12 AM   #11
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[QUOTE=ROBERT CROSS;2532847]Sorry,this is one thing I don't have a photo of...BUT.

I have had one Zamp portable panel controller shut down and the second will continue charging. Just lucky I suppose.
Disclaimer.....I have NOTHING on the roof.
With all my posts on my system I thought that was clear....my bad.

Bob
����

Myth?
BTW I don't believe he's in an AS.


Hi

Yup, one wins the fight and the other one looses the fight. The winner keeps charging and the other one goes to sleep. If they both are equal capacity, you now get half as much charging horsepower.

Bob
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Old 08-31-2021, 10:55 AM   #12
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Quote:
Originally Posted by ROBERT CROSS View Post
Sorry,this is one thing I don't have a photo of...BUT.



I have had one Zamp portable panel controller shut down and the second will continue charging. Just lucky I suppose.

Disclaimer.....I have NOTHING on the roof.

With all my posts on my system I thought that was clear....my bad.



Bob





Myth?

BTW I don't believe he's in an AS.





This video was very informative. I feel educated on the subject.
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Old 08-31-2021, 10:56 AM   #13
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[QUOTE=uncle_bob;2532889]
Quote:
Originally Posted by ROBERT CROSS View Post
Sorry,this is one thing I don't have a photo of...BUT.

I have had one Zamp portable panel controller shut down and the second will continue charging. Just lucky I suppose.
Disclaimer.....I have NOTHING on the roof.
With all my posts on my system I thought that was clear....my bad.

Bob
����

Myth?
BTW I don't believe he's in an AS.


Hi

Yup, one wins the fight and the other one looses the fight. The winner keeps charging and the other one goes to sleep. If they both are equal capacity, you now get half as much charging horsepower.

Bob
But what does that matter I'm charged to 13.4 and I usually just fold 'em up for three or four daze 'til I need to charge again?
I couldn't care less about 'maintaining' a set number.

I should live in Austin Tex I guess. 🤔

Bob
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Old 08-31-2021, 01:45 PM   #14
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Lithium battery charging

I have been told that the Battleborn batteries will limit the incoming charge to float status as it approaches a full state of charge regardless of output of panels.
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Old 09-01-2021, 07:24 AM   #15
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Originally Posted by ROBERT CROSS View Post
Why not happy?...your BB's are charged to 13.4 ?(FULL)
Do you want more?
I use our Zamp portable 'solar' to charge when needed.
To maintain is a whole 'nuther matter.

FWIW when we first started with the Zamps I had a 140 & a 180 they still 'played' well together.

Bob
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If you'll go back and re-read the post you'll see I said the BMV is reporting state of charge in the 60% range, voltage is 13.4. Something's weird here.
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Old 09-01-2021, 07:38 AM   #16
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I have been told that the Battleborn batteries will limit the incoming charge to float status as it approaches a full state of charge regardless of output of panels.
Hi

Lithium batteries will not "boil off / dry out" if held at high voltage the way lead acid's will. They still are not happy if kept at max voltage all the time. AFIK, none of the BMS's drop the voltage to the batteries. If you put in 14.X, the battery is either connected or it's shut off. Shutoff happens above 14.6V.

Bob
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Old 09-01-2021, 07:46 AM   #17
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If you'll go back and re-read the post you'll see I said the BMV is reporting state of charge in the 60% range, voltage is 13.4. Something's weird here.
Ok got it...
POI....It took me 5 tries at adjusting the settings to correctly approximate the SOC...it can be a moving target.

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Mine, may not apply to yours...
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Old 09-01-2021, 08:34 AM   #18
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Todays read-out.

Bob
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Old 09-02-2021, 08:05 AM   #19
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Todays read-out.

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Hi

Looks like it may be time for another tweak on the settings ....

All of these shunt based gizmos are playing math games to work out what's what. That works, but only to a degree. One of the magic settings is the "I'm full now, let's call this 100%" setting. If you hit this on a daily ( or even every few days) basis, the math errors don't pile up. Run on Solar for a few weeks and never quite hit the "full" point and the minor math errors pile up.

Bottom line, you still do watch voltages. 13V on a lithium is in the vicinity of 30% to 40% charged rather than 86%.

Bob
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Old 09-02-2021, 03:23 PM   #20
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[QUOTE=uncle_bob;2533498]Hi

Looks like it may be time for another tweak on the settings ....

All of these shunt based gizmos are playing math games to work out what's what. That works, but only to a degree. One of the magic settings is the "I'm full now, let's call this 100%" setting. If you hit this on a daily ( or even every few days) basis, the math errors don't pile up. Run on Solar for a few weeks and never quite hit the "full" point and the minor math errors pile up.

Bottom line, you still do watch voltages. 13V on a lithium is in the vicinity of 30% to 40% charged rather than 86%.

Bob[/QUOT

No thanks, we be happy where we are...
At 200 we we stop at 20.
It's an approximate no matter the dartboard parameters. 🤔

Bob
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