MPPT Solar and Lithium Question

[wulfraat]

Yes I looked hard at the Venus vs CCGX and went back and forth. In the end the CCGX also provides me with remote console access once I added the WiFi dongle - so it had all the same capabilities hardware and software-wise. Added bonus of the dedicated screen and physical buttons.

The built in screen was more $$ but in the end for my install it was more convenient for a quick glance at how the system is running / performing / etc.. anyone in the trailer can quickly see what the deal is. also - using remote console via a web browser is slightly more clunky than using the physical buttons in the CCGX.

It was a close call though. [emoji4] as the victron hardware evolves I’m sure I’ll move to the latest and greatest when the next version comes out [emoji4] victron integrated stack is pretty awesome and well engineered. Especially the multiplus - great piece of equipment with dynamically adjustable power assist capabilities.

If you have a web-enabled trailer, the system will
also push data to the victron remote management cloud which is pretty awesome as well - I really like the ability to check in and see how things are going in real time when I’m away from the trailer - IE gain real-time access to the control panel output, menus, data, etc.... via your phone, tablet, laptop, what have you

[uncle_bob]

Originally Posted by daleyocum

I do indeed have some gaps in my understanding. I find it very weird the BMV712 shows, for example, a negative current drain of 8A on a sunny day (lights and fans) with zero amps coming from the solar charge controller. Even weirder is I can crank the solar float voltage up to 14.5 and still not see that negative current change.

I’m an electrical/SW engineer so it’s quite possible I’m overthinking all this and I should just let these magic black boxes do their thing :-)

Hi

Under pretty much exactly the same conditions, my MPPT is putting as much current as it possibly can into the system.

1) What does the "solar voltage" read when you see nothing out of the MPPT? (should be up above 20V in the sun)

2) What does the MPPT output voltage read? (should be 14.4 when set to 14.4)

3) What does the BMV-712 voltage read? (should be same as MPPT)

4) Do you have a Victron BatteryProtect in the mix? (I do and it would produce odd results if it cut in)

5) Is the little short jumper still in the plug on the MPPT? ( it should be there ...)

6) When you look at history on the MPPT what does it show for max power? (mine shows 95% of max array power )

7) Do the currents add up? ( you sort of need to know the load current to do this. Mine do add up correctly)

Since my system runs as it should and yours seems to be funky, I'm guessing the issue is *not* the lack of further smarts in the system. My MPPT and BMV-712 don't know anything about each other.

Bob

[daleyocum]

Originally Posted by uncle_bob

Hi

Under pretty much exactly the same conditions, my MPPT is putting as much current as it possibly can into the system.

1) What does the "solar voltage" read when you see nothing out of the MPPT? (should be up above 20V in the sun)

2) What does the MPPT output voltage read? (should be 14.4 when set to 14.4)

3) What does the BMV-712 voltage read? (should be same as MPPT)

4) Do you have a Victron BatteryProtect in the mix? (I do and it would produce odd results if it cut in)

5) Is the little short jumper still in the plug on the MPPT? ( it should be there ...)

6) When you look at history on the MPPT what does it show for max power? (mine shows 95% of max array power )

7) Do the currents add up? ( you sort of need to know the load current to do this. Mine do add up correctly)

Since my system runs as it should and yours seems to be funky, I'm guessing the issue is *not* the lack of further smarts in the system. My MPPT and BMV-712 don't know anything about each other.

Bob

Thanks for hanging in there on this. The trailer is in the storage yard currently but I can answer some of your questions.

1) Solar voltage reads 19-20v

2) MPPT voltage reads whatever I set the float voltage to more or less.

3) BMV712 voltage was unexpected. I wired its little positive lead down stream of the use/store relay so it wouldn’t run when we weren’t in the trailer. I’ll be changing this when the Venus arrives. Surprisingly it reads something like 13.2. Is there a regulator in there somewhere? I’ve removed the AS stock converter/charger.

4) No Victron battery protect since it’s built into the Battleborns.

5) Jumper is still in.

6/7 I’ll have to check when I’m in the trailer.

[daleyocum]

Just got this response from Victron:

“The MPPT will charge the battery based on voltage/absorbtion time unless they are controlled by something external like a CCGX or Venus.
It will not talk to the BMV for these controls.
If that CCGX "knows" what load/charge/feedin criteria should be used (for this DVCC/ESS is needed) ,it can control the MPPT.
With ESS the MPPT can be controlled to feed the load when the battery is already full.”

I take this to mean with Lithum a CCGX or Venus is pretty important in a Victron system for maximum performance, certainly worth the $300 for a Venus. This is a fairly new feature for the CCGX/Venus and so you’ll need the latest firmware in those (v2.12 or later) and enable it. Check the firmware versions on your Battery monitor and Multiplus inverter (if present) to make sure they are current.

As I understand it, without that central controller in a Victron system there are three choices.

1) Turn off all this magic and have the solar array constantly pumping energy into the batteries and rely on the battery management of the batteries (Battleborn, etc) or the Victron Battery Protect to keep them from being harmed. That will help with load support.

2) Let the MPPT controller guess based on your voltage and absorption time settings what it should do. That means until the voltage drops critically low you won’t get load support, just an initial charge in the morning. For some that may be fine. For those with fantasies of the solar helping your generator with AC (hybrid inverter required) or driving other heavy loads while the sun is up you may only be getting a fraction of the energy your solar array is able to provide.

3) YOU can be the intelligent controller and charge your MPPT controller’s setting on the fly depending on loads in the trailer. You could force it into charge mode when you need load support and remember to turn it back when you don’t.

Battleborn themselves wants separate settings for bulk and float (14.5 and 13.5) so I don’t think they are fans of relying on the internal battery management if you can avoid it.

This story is still unfolding so I’ll report back when I get my Venus installed next week.

[uncle_bob]

Originally Posted by daleyocum

Just got this response from Victron:

“The MPPT will charge the battery based on voltage/absorbtion time unless they are controlled by something external like a CCGX or Venus.
It will not talk to the BMV for these controls.
If that CCGX "knows" what load/charge/feedin criteria should be used (for this DVCC/ESS is needed) ,it can control the MPPT.
With ESS the MPPT can be controlled to feed the load when the battery is already full.”

I take this to mean with Lithum a CCGX or Venus is pretty important in a Victron system for maximum performance, certainly worth the $300 for a Venus. This is a fairly new feature for the CCGX/Venus and so you’ll need the latest firmware in those (v2.12 or later) and enable it. Check the firmware versions on your Battery monitor and Multiplus inverter (if present) to make sure they are current.

As I understand it, without that central controller in a Victron system there are three choices.

1) Turn off all this magic and have the solar array constantly pumping energy into the batteries and rely on the battery management of the batteries (Battleborn, etc) or the Victron Battery Protect to keep them from being harmed. That will help with load support.

2) Let the MPPT controller guess based on your voltage and absorption time settings what it should do. That means until the voltage drops critically low you won’t get load support, just an initial charge in the morning. For some that may be fine. For those with fantasies of the solar helping your generator with AC (hybrid inverter required) or driving other heavy loads while the sun is up you may only be getting a fraction of the energy your solar array is able to provide.

3) YOU can be the intelligent controller and charge your MPPT controller’s setting on the fly depending on loads in the trailer. You could force it into charge mode when you need load support and remember to turn it back when you don’t.

Battleborn themselves wants separate settings for bulk and float (14.5 and 13.5) so I don’t think they are fans of relying on the internal battery management if you can avoid it.

This story is still unfolding so I’ll report back when I get my Venus installed next week.

Hi

Welll ... Battle Born has said multiple things at various times about what the batteries need to. / want to / are willing to see. When they are talking up the fact that a lead acid charge controller will work with the Battle Born's they talk about 14.5 and 13.5. That's fine and they make is a selling point of the batteries. It's the first thing they will tell you if you ask so it eliminates the "buy a new charger" from the conversation.

Poke or push a little ( check the threads here on the forum for instance ) and they talk about using a normal lithium converter. Push a little on the charge / discharge process associated with a lead acid profile and indeed more information comes up. If you use a lead acid profile, you will have to manually force it into high voltage mode to get the batteries fully charged. Run high(er) voltage 14.2 vs 13.5 and you don't have to do that .....

So no, it's not a one size fits all sort of thing.

One gotcha with the magic controller hubs: They pull current. Store the trailer or park in in the shade for a long time, parasitic current can be an issue. Any idea how much the Venus pulls when it's just idling?

Bob

[SilverHouseDreams]

The only issue is if your “float” voltage is too high and the BMS has to actively bleed the excess voltage. However that shouldn’t apply unless you exceed 3.6V per cell (14.4V). I am not sure why they would suggest a “float” voltage or 13.5, that just seems unnecessary for LFP. That forces your batteries to cycle, perhaps if you are on shore power 90% of the time this would be better than leaving at 100% SOC permanently...however if you are truly cycling via normal use then you are just adding extra wear.

I would just let the battery “rest” with no real load for a few hours after charging...check the voltage and set the “float” to that voltage or just slightly below.

If your battery is “resting” at >13.5V at 100% SOC then your system is entirely operating as it is programmed to. Even with more brains that may not change...no doubt ESS is impressive, but likely added complexity with minimal value.

I just noticed you are in Portland, as am I...we could always meet and chat a bit and give you a second set of eyes. We are taking the AS to Sunriver next weekend, but am around during the week.

[uncle_bob]

Hi

The wording in the Battle Born manual is "our batteries do not need to float". That is after they talk about bulk and absorption both being set to an ideal voltage of 14.2 to 14.6V. So what they really are saying on float is "we don't care". They get the 13.5V number from the resting voltage of the battery. A bit further on they mention that a "self protect" voltage of 14.7V to 15V "will not allow current into the battery". On the label sticker on the battery it's self, they state "charging voltage 14.4V".

To the extent that "to much voltage" gets the BMS going .... you are running a fraction of an amp through a pass device that is set up to handle 200A for short periods and 100A continuous. Since that's charge, discharge, and disconnect current, the BMS *is* dealing with it. The reliability of the solid state gizmos in the BMS is *not* going down the drain from handling a quarter amp ....

Bob

[uncle_bob]

Hi

Sorry for the double reply ... I got pulled away for a dog emergency

Part of the problem here is the term "float". If you have a battery hooked to nothing but the charger that has a meaning. In an RV with parasitic loads all over the place ... not so much. With just the charger hooked to the battery, set it to 13.5V and no current flows. On an RV, set the charger to 13.5V and your parasitic loads suck the battery down to that voltage ( = current very much *does* flow ). Overnight with pretty much nothing turned on, my 400AH setup sucks down well below 13.5V. In the morning the solar wakes up and blasts it back up to the bulk voltage.

The charger hooked just to the battery meets Battle Born's definition of "float not required". You set the charger to < 13.5 ( like to 12V ) and no current flows. It's no different than disconnecting the charger from the battery. Since there is zero current, the battery does not cycle. There is no wear and tear. If you have them sitting on a shelf in the garage, this is the ideal.

These guys have only been doing this for at most a year. They are doing an amazing job. Not quite having every little bit of their messaging worked out is not at all surprising. I suspect that this is not a "cast of thousands" operation ...

Bob

[daleyocum]

I've asked Batttleborn (battlebornli) to weigh in on this thread. We'll see what they say.

[pdavitt]

Have been following this, and other related, threads with interest. There seems to be a trend toward the use of Victron equipment for upgrading electrical systems. I agree, Victron started by providing equipment to the marine market, which makes them a logical choice for a mobile environment.


Victron batteries do not seem high on the list. What I am about to say is not a dig on Battleborn or other manufacturers. They are trying to provide a seamless Lithium, alternative to Flooded Cell/AGM batteries and doing a good job.


However, there is a reason to purchase a completely homogeneous system.

Victron recently incorporated CanBus BMS control of their battery charging devices, MPPT Charge Controllers and the Quattro/Multiplus Inverter Chargers into their CCGX/Venus GX PLCs. The battery BMS now controls the charging directly.


Below is an excerpt from the latest CCGX Manual noting the availability for DVCC (Distributed Voltage and Current Control) for their systems.


3 DVCC - Distributed Voltage and Current Control

3.2 Generic features
Below features apply to all types of systems, and all types of batteries. Both lead batteries andbatteries with a CAN-bus BMS.

1. Add a user-configurable maximum charge current setting. This is available in the Venus GUI and works across the whole system. MPPTs are automatically prioritized over the mains. In case a CANBUS-BMS is connected and the BMS requests a maximum charge current that is different from the user-configurable setting, the lower of the two will be used.

2. Add shared voltage sense (SVS) for VE.Bus devices and VE.Direct Solar Chargers.
a. The system automatically selects the best available voltage measurement. It will use the voltage from the BMS or a BMV battery monitor, if possible, otherwise it will use the battery voltage reported by the VE.Bus system.

b. The voltage displayed on the GUI reflects the same voltage measurement.

c. Shared Voltage Sense (SVS) is by default enabled when DVCC is enabled. It can be disabled with a switch in the Settings/System Setup menu.

3.3 Features for systems using a CAN-bus BMS systems


These features apply to all types of systems (ESS and not ESS), that have a CAN-bus BMS connected battery.

1. CAN-bus BMS control is no longer tied into ESS. It now works for other systems as well, including Off-grid and plain backup systems. It is not longer necessary to wire allow-to-charge and allow-to-discharge connections to the AUX inputs on a Multi or a Quattro.

2. VE.Direct MPPT Solar Chargers are now also controlled with the max charge current, just like Multis and Quattros already were.

3. When inverting, ie in Island mode, Multis and Quattros will shut down when the max discharge current is zero. They will automatically start again as soon as either AC mains returns, or when BMS increases the max discharge current again.

4. New for Off-grid systems only (for ESS systems this was already happening): setting up charge voltages in VEConfigure is no longer necessary: the Multis, Quattros and also MPPT Solar Chargers will charge with the voltage as received via CAN-bus from the battery.

Pat

[daleyocum]

I chose the Battleborn batteries mainly because of their lower price and to avoid having to buy/mount a separate battery management unit. Depending on what the Venus let’s me do that may or may not have been an error. I didn’t realize the Victron’s had an advantage other than being blue!

[pdavitt]

Originally Posted by daleyocum

I chose the Battleborn batteries mainly because of their lower price and to avoid having to buy/mount a separate battery management unit. Depending on what the Venus let’s me do that may or may not have been an error. I didn’t realize the Victron’s had an advantage other than being blue!

That's one of the main reasons I chose Victron equipment. It's about time a manufacturer provided for direct charging control from the batteries rather than relying on a "guess" of what the batteries need.


I'm a little embarrassed but below is my list of Victron equipment I have received, or have ordered for a 48V battery system. This is going into an RV with 1,400 Watts of solar.


Victron BlueSolar MPPT 150/45-tr (12/24/36/48V)
Victron Quattro 48/5000/70-100/100 120V
Victron Color Control GX
Victron Lynx Ion BMS 1000 w/2 MEGA 58V 200A Fuses
2Ea. Victron Lithium-ion HE NMC 24V 200Ah 5.0kWh Batteries


Pat

[daleyocum]

Originally Posted by pdavitt

That's one of the main reasons I chose Victron equipment. It's about time a manufacturer provided for direct charging control from the batteries rather than relying on a "guess" of what the batteries need.


I'm a little embarrassed but below is my list of Victron equipment I have received, or have ordered for a 48V battery system. This is going into an RV with 1,400 Watts of solar.


Victron BlueSolar MPPT 150/45-tr (12/24/36/48V)
Victron Quattro 48/5000/70-100/100 120V
Victron Color Control GX
Victron Lynx Ion BMS 1000 w/2 MEGA 58V 200A Fuses
2Ea. Victron Lithium-ion HE NMC 24V 200Ah 5.0kWh Batteries


Pat

That's a pretty amazing system. Never apologize for awesomeness!

[kenfconnor]

Let me start by confessing to having a degree in physics (but many years in the past). So I love technology and have made a career based upon electronics. I own 3 vintage airstreams which we use frequently for many trips. As I read through this thread I am amazed about the complexity and cost of these battery/solar upgrades. We rarely boondock but when we do we dont seem to need a lot of juice so I have settled on a single 230 watt panel carried on my truck to top off 2 Costco deep cycle batteries. My wife would not be happy if we did not get to an RV park at least after 4-5 days anyway but the one panel seems to work fine (for mostly west coast camping). Just curious if those who are making these major investments really use the capacity or is it more of just a desire to see what the technology can do? I am not judging but beyond a few amps for the basics like lighting and water pump and perhaps a small inverter for occasional AC power like a microwave where is all this reserve capacity used?

[SilverHouseDreams]

Originally Posted by kenfconnor

Let me start by confessing to having a degree in physics (but many years in the past). So I love technology and have made a career based upon electronics. I own 3 vintage airstreams which we use frequently for many trips. As I read through this thread I am amazed about the complexity and cost of these battery/solar upgrades. We rarely boondock but when we do we dont seem to need a lot of juice so I have settled on a single 230 watt panel carried on my truck to top off 2 Costco deep cycle batteries. My wife would not be happy if we did not get to an RV park at least after 4-5 days anyway but the one panel seems to work fine (for mostly west coast camping). Just curious if those who are making these major investments really use the capacity or is it more of just a desire to see what the technology can do? I am not judging but beyond a few amps for the basics like lighting and water pump and perhaps a small inverter for occasional AC power like a microwave where is all this reserve capacity used?

I’m certain that some are path finding and showing what the future could look like. Not needing a generator to have a “normal” lifestyle on the road. I find the idea of 5kwh of battery and enough solar to maintain it fascinating and intriguing, though if I had the space/weight capacity for such I’d probably source batteries via different method (eg second life for EV/PHEV packs).

In my case I only have 100Ah useable currently, and I could surely have bought a lot of Pb batteries for the $1800 (guesstimate) I have into it...but, to get me to the 200Ah of useable capacity that I will arrive at would have required a new trailer and TV...which absolutely would cost far more than my new DC power setup has. And I think outside of rare hot days that don’t cool off quickly enough, that we can likely be pretty comfortable (and quiet) while off grid. My current weight savings over Pb would allow for me to carry a generator and have the same net weight and tongue weight as before (if I don’t add the next 100Ah battery)...and use my existing TV. This summer is the live with and learn to decide which fork I take (or if I do both, gen and more battery). I’m constrained on space with a 22FB, but won’t be by functionality.

[daleyocum]

Originally Posted by kenfconnor

Let me start by confessing to having a degree in physics (but many years in the past). So I love technology and have made a career based upon electronics. I own 3 vintage airstreams which we use frequently for many trips. As I read through this thread I am amazed about the complexity and cost of these battery/solar upgrades. We rarely boondock but when we do we dont seem to need a lot of juice so I have settled on a single 230 watt panel carried on my truck to top off 2 Costco deep cycle batteries. My wife would not be happy if we did not get to an RV park at least after 4-5 days anyway but the one panel seems to work fine (for mostly west coast camping). Just curious if those who are making these major investments really use the capacity or is it more of just a desire to see what the technology can do? I am not judging but beyond a few amps for the basics like lighting and water pump and perhaps a small inverter for occasional AC power like a microwave where is all this reserve capacity used?

We do most of our camping off the grid but are also pretty used to the luxuries of a microwave, induction cooktop, hairdryers, slow cooker, computers, TV, AC, etc. From a cost effectiveness standpoint it would be cheaper to just use the generator but we’d rather enjoy the peace and quiet.

You are right that logic doesn’t have much to do with this at the end of the day, though!

[uncle_bob]

Originally Posted by daleyocum

.......

3) BMV712 voltage was unexpected. I wired its little positive lead down stream of the use/store relay so it wouldn’t run when we weren’t in the trailer. I’ll be changing this when the Venus arrives. Surprisingly it reads something like 13.2. Is there a regulator in there somewhere? I’ve removed the AS stock converter/charger.

.......

Hi

Ok something is very wrong there. The BMV712 should always be reading same / same as the MPPT ( and a multimeter for that matter ). If it's not, then either there is a wiring error or it's broke.

What the Venus and other Victron smart boxes do is get their BMS system running. Without a central brain, their batteries don't have the full set of smarts to do the job. That's not a knock on Victron, it's simply a design decision they made. Their batteries have been out on the market for a while now. Whatever they did does work.

I have yet to see anybody ( from Battle Born or otherwise ) explain why cycling the batteries a lot is better than keeping them up around 14V. In fact, when pressed on the point, their response seems to be "yup, that works fine".

So yes, this is a bit murky.

Bob

[pdavitt]

Originally Posted by SilverHouseDreams

I’m certain that some are path finding and showing what the future could look like. Not needing a generator to have a “normal” lifestyle on the road. I find the idea of 5kwh of battery and enough solar to maintain it fascinating and intriguing, though if I had the space/weight capacity for such I’d probably source batteries via different method (eg second life for EV/PHEV packs).

That's exactly why I am doing this. I want to find out the upper limit of what is possible with today's technology, not what is economically practical. Oh, and those Victron Lithium-ion HE NMC 24V 200Ah 5.0kWh batteries, I've got two of them coming. The amazing thing is that they only weigh 63lbs. each and are only 14"x14"x7.5". They are not LiFePO4 but LiNiMnCoO2 (Lithium Nickle Manganese Cobalt Oxide), are about $1,000.00 each cheaper than Victrons similarly sized LiFePO4 batteries, and weigh about half as much.


Pat

[wulfraat]

Originally Posted by kenfconnor

Let me start by confessing to having a degree in physics (but many years in the past). So I love technology and have made a career based upon electronics. I own 3 vintage airstreams which we use frequently for many trips. As I read through this thread I am amazed about the complexity and cost of these battery/solar upgrades. We rarely boondock but when we do we dont seem to need a lot of juice so I have settled on a single 230 watt panel carried on my truck to top off 2 Costco deep cycle batteries. My wife would not be happy if we did not get to an RV park at least after 4-5 days anyway but the one panel seems to work fine (for mostly west coast camping). Just curious if those who are making these major investments really use the capacity or is it more of just a desire to see what the technology can do? I am not judging but beyond a few amps for the basics like lighting and water pump and perhaps a small inverter for occasional AC power like a microwave where is all this reserve capacity used?

Well I’m there with you as an applied mathematician with background in software engineering.

For me it was both - wanted ability to proceed as normal with life as if plugged in (no reliance on the grid) and I enjoy being on the leading / bleeding edge. The big capacity hog is the air conditioner plain and simple.

The decision to go big on solar capacity for me was that I was going through the effort and expense to chuck panels up top, so why not load it up if the space is available. With installation costs the $$ to go from 4 to 6 or 6 to 8 is not that much in the overall budget. On my last trailer I installed solar in two waves once I figured out I didn’t have enough first time around and it was not ideal as I had to use mix-matched panels, non-optimal layout, etc.

The decision to go big on battery was two fold:

(1) I want to be able to run the AC without a generator as I use my trailer as a mobile office from time to time. I don’t like big generators or the noise they generate so I have the choice for non at all, or use a tiny one and supplement with batteries via the power assist feature of the hybrid inverter. It’s not “camping” by any means but when it’s hotter than Haiti outside you can’t work in the trailer without AC. When I go camping I throw on a backpack and use my feet - the airstream for us is really a second tiny home / mobile office that we travel with.

(2) longevity - plan to keep this unit 10+ years (kept the last one 8 and we needed more space so moved to a 30’). 600ah allows one to managed to 50% DoD most of the time so I am hoping to see 5,000 cycles on these and not have to touch the batteries for the next 10+ years.

I enjoy system design. Our tiny house airstream trailer is a bit of a dry run of sorts as we are kicking around the idea of building off grid potentially. So it is good to see real world performance of this equipment over time before we make a larger investment in a permanente installation.

30% tax credit of the install cost for the 2018 tax year also helps bring down the expense.

[AlinCal]

Sorry for the highjack...A few weeks back we had an awesome campsite on the beach and in the next site over was a 40'+ high $$$ bus. I was petrified that they would be running their onboard generator endlessly, they never ran it once and when we got to higher ground on a walk I saw it had 8 solar panels on the roof! wished I had asked to see the battery bank.
Halleluja!