EPEVER MPPT Solar Charge Controller 40A wattage

12VoltInstalls

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hose of electrons into a pail it will only flow if there is a complete circuit
True; I wasn’t trying cover my entire knowledge base, just the idea of electricity related to a supposed capacity. Water just runs over at capacity of a receptacle, electricity just… stops at capacity. Capacitors aside ;)
 

DerpsyDoodler

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True; I wasn’t trying cover my entire knowledge base, just the idea of electricity related to a supposed capacity. Water just runs over at capacity of a receptacle, electricity just… stops at capacity. Capacitors aside ;)
The bold is incorrect. Electricity doesn't just stop because "capacity" is reached.

Imagine the water is contained in a sealed system. It stops when there's either an open circuit (no where to flow) or when pressure prevents it from flowing. If I'm pumping the water at 40psi, once the pressure in the pipe is the same, i can no longer push anymore water without increasing the psi. In the case of a capacitor, back pressure prevents current from flowing once it is charged to the source voltage.

12v source charges capacitor, capacitor reaches src voltage and begins pushing back with the same amount of electrical pressure. If you up the voltage, the capacitor will continue to charge until it either fails spectacularly or once again reaches the source voltage.
 

12VoltInstalls

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The bold is incorrect. Electricity doesn't just stop because "capacity" is reached.
If you read back you’ll notice I stated that what I wrote was a not very good analogy of differentiating between water that has a physical volume and electricity, but not a scientifically sound description. Just an imperfect banal ‘visual’ to contrast the difference from water.
You are taking this far too seriously. :)
 

DerpsyDoodler

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If you read back you’ll notice I stated that what I wrote was a not very good analogy of differentiating between water that has a physical volume and electricity, but not a scientifically sound description. Just an imperfect banal ‘visual’ to contrast the difference from water.
You are taking this far too seriously. :)
I was trying to help you in your search for a good analogy. That's what you said you'd been looking for, right? Hope I helped. If not, feel free to ignore my post.
 

Tecnodave

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Its very hard to teach basic concepts to someone who is just getting into an area of study. I started doing radio before i was a teen, by now its been 55 years.....tinkering endlessly and following up with a career in all facets of electricity from DC to microwave. cant sum that up very easily.

@DerpsyDoodler very good analogy, heard that many years ago.....still valid
 

ProfitBroseph

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I hope this is kosher, cause I made a post elsewhere bc I’ve got some questions…
But I found this thread after posting and you guys are SO CLOSE to helping me that I’m gonna post my questions here and post a link to my post.
Maybe y’all can help me out, TIA!

I have 6x 250w SanTan panels on the roof of my bus.
I have 2x EPEver BN 40a 150v MPPT.
I have 3S2P setup on panels, with 3 on each side of my bus that I can tilt, thus 2 MPPTs for voltage/sunlight differential, which I believe is necessary.
I have 15x 3.2v 400ah cells connected 3P5S for an 18v battery.
I am hoping to charge my battery bank with these EPEvers to ~18v.
Will I have to put the MPPTs into 24v charging mode?
Epever Manual shows 9-17v parameter -says “please use double value in 24v” charging, but will the MPPT recognize my battery as a 24v version if voltage runs from 15.5v-18v?)
OR in custom battery mode can I set these parameters to whatever I want between 8v-32v as stated elsewhere in manual without worrying abt “24v mode?”

What do y’all think of this setup anyway?
I’m wondering if I’m actually oversized on panels; I believe this 150v unit is rated for 780W of panels on 12v systems or 1560W on a 24v system, just wondering what this means for my setup.
Am I correct that the MPPT’s rated charge power of 520W (for 12v) is much lower than MPPT max PV rating of 780W, meaning I’m potentially leaving some current at the panels, but not leaving much bc panels are 5+ years old?
Can I safely assume these MPPTs will charge my batteries in full sun to 18v at 28.8a? Or is my math inaccurate?

Final question: is my 150v MPPT at risk of over-voltage from 3x ~40v panels in cold/sunny weather wired in series? I count just 120v max input but I can’t find precise values for how high the input might get in some conditions.
Panel sticker shown below for anyone interested.

Here is my original post if cluttering this post isn’t helpful:
Thread 'EPEver BN 40a MPPT Battery is 3S5P'
https://diysolarforum.com/threads/epever-bn-40a-mppt-battery-is-3s5p.36590/
 

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DerpsyDoodler

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I hope this is kosher, cause I made a post elsewhere bc I’ve got some questions…
But I found this thread after posting and you guys are SO CLOSE to helping me that I’m gonna post my questions here and post a link to my post.
Maybe y’all can help me out, TIA!

I have 6x 250w SanTan panels on the roof of my bus.
I have 2x EPEver BN 40a 150v MPPT.
I have 3S2P setup on panels, with 3 on each side of my bus that I can tilt, thus 2 MPPTs for voltage/sunlight differential, which I believe is necessary.
I have 15x 3.2v 400ah cells connected 3P5S for an 18v battery.
I am hoping to charge my battery bank with these EPEvers to ~18v.
Will I have to put the MPPTs into 24v charging mode?
Epever Manual shows 9-17v parameter -says “please use double value in 24v” charging, but will the MPPT recognize my battery as a 24v version if voltage runs from 15.5v-18v?)
OR in custom battery mode can I set these parameters to whatever I want between 8v-32v as stated elsewhere in manual without worrying abt “24v mode?”

What do y’all think of this setup anyway?
I’m wondering if I’m actually oversized on panels; I believe this 150v unit is rated for 780W of panels on 12v systems or 1560W on a 24v system, just wondering what this means for my setup.
Am I correct that the MPPT’s rated charge power of 520W (for 12v) is much lower than MPPT max PV rating of 780W, meaning I’m potentially leaving some current at the panels, but not leaving much bc panels are 5+ years old?
Can I safely assume these MPPTs will charge my batteries in full sun to 18v at 28.8a? Or is my math inaccurate?

Final question: is my 150v MPPT at risk of over-voltage from 3x ~40v panels in cold/sunny weather wired in series? I count just 120v max input but I can’t find precise values for how high the input might get in some conditions.
Panel sticker shown below for anyone interested.

Here is my original post if cluttering this post isn’t helpful:
Thread 'EPEver BN 40a MPPT Battery is 3S5P'
https://diysolarforum.com/threads/epever-bn-40a-mppt-battery-is-3s5p.36590/
First, that would be a 16v nominal battery, with a charge setting of ~18v. This is odd. Why are you configuring your battery bank this way?

Second, The EPEVER works in 12 or 24v mode. That said there is a range that you can configure charge settings in. However, I don't think it can be made to work safely (in a way that won't try to destroy your batteries) like this.

Finally, asking this question again, because this is really where we need to start. Why are you configuring your battery bank this way? You could create 1x 24v battery (8 cells) and have 7 spare or 3x 12v battery (12 cells) and have 3 spare.

What is your intended load for the batteries? Do you have a BMS?
 

ProfitBroseph

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First, that would be a 16v nominal battery, with a charge setting of ~18v. This is odd. Why are you configuring your battery bank this way?

Second, The EPEVER works in 12 or 24v mode. That said there is a range that you can configure charge settings in. However, I don't think it can be made to work safely (in a way that won't try to destroy your batteries) like this.

Finally, asking this question again, because this is really where we need to start. Why are you configuring your battery bank this way? You could create 1x 24v battery (8 cells) and have 7 spare or 3x 12v battery (12 cells) and have 3 spare.

What is your intended load for the batteries? Do you have a BMS?
I had a bad experience with a Chargery and 500a Daly BMS, and now I own 10 overdischarged 3.2v, <400ah cells.
I’ve capacity tested via charge/discharge cycles and matched them 1/10, 2/9, 3/8, 4/7, 5/6 with a cumulative capacity for these paired cells of ~700ah.
I have 5 new (3.2v 400ah) cells arriving from Guangdong in the next 30 days (I hope.)

I intend to pair these cells to make a 3P5S 16-18v battery bc all of my RV components are rated from 12-18v and I have the cells.
My solar array should be sized for me to soon wish I had extra battery capacity, whereas previously I ran my generator every other day regardless.
I can’t imagine why I would wish to have extra cells, at any rate.

For BMS I intend to purchase an electrodacus as soon as production resumes in May but I’m open to alternatives that aren’t Daly BS using fet system that will not pass 150a much less the 500a it is rated for.

I have a Xantrex XC Pro 3000W inverter/charger that I’m hoping to use to charge my 3P5S battery as it is also rated sufficiently.
 

12VoltInstalls

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all of my RV components are rated from 12-18v and I have the cells.
An “18V” nominal battery is 19.2V “fully charged nominal.” Not a good plan. I’ve had expensive “10-18V” LEDs and cheapo of similar ratings. I’ll tell you for free they will tolerate 15+ volts for a while but any extended time at 16V+ and they will wink out. 13.8V to 14.2V is a nice target for nominal 12V top end. 16V seems sketchy.

I’m reasonably sure the SCC is gonna wig out and wreck those cells. It ain’t made for that.

IMHO you should build a 12V battery. Buy additional cells and make a second one.
Final question: is my 150v MPPT at risk of over-voltage from 3x ~40v panels in cold/sunny weather wired in series?
It’s less than 120VDC so that’s sufficient headroom for 3S. 3S2P for the array
have 3S2P setup on panels, with 3 on each side of my bus that I can tilt, thus 2 MPPTs for voltage/sunlight differential, which I believe is necessary.
One 40A with panels facing two directions would work. Are you saying 780W is a hard limit for that SCC?
Two small controllers does solve all this. Or one 50- or 60-amp controller.
 

ProfitBroseph

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An “18V” nominal battery is 19.2V “fully charged nominal.” Not a good plan. I’ve had expensive “10-18V” LEDs and cheapo of similar ratings. I’ll tell you for free they will tolerate 15+ volts for a while but any extended time at 16V+ and they will wink out. 13.8V to 14.2V is a nice target for nominal 12V top end. 16V seems sketchy.

I’m reasonably sure the SCC is gonna wig out and wreck those cells. It ain’t made for that.

IMHO you should build a 12V battery. Buy additional cells and make a second one.

It’s less than 120VDC so that’s sufficient headroom for 3S. 3S2P for the array

One 40A with panels facing two directions would work. Are you saying 780W is a hard limit for that SCC?
Two small controllers does solve all this. Or one 50- or 60-amp controller.
I wouldn’t charge this battery to >18v.
Bulk charging would be set to 17.5v then float at 18v. I understand I’ll be sacrificing some top end capacity but for the extra 1100ah I figured it was a good trade off.

I have had a 12v battery for the last 2 years of full time off-grid living, I charge my LiFePO4 battery to 13.6v Bulk/13.8vAbsorption and I would never charge it to 15+ volts…you’re using different values than I would…maybe just bc I want to be cautious with my (already damaged) cells. But I also haven’t heard if charging cells like these >14.4v.

And all of my LED lights are dimmer-compatible so I was hoping they were (honestly) rated for a wide range of voltages. My LED pucks def weren’t the cheapest at $12ea but I’d love to hear more abt your experience. Really gonna wrench my plans if this is the case 😡

The EPEever MPPTs have a pretty good reputation, but you’re saying you do not believe the BN 40a 150v version will do what it’s rated for and charge my battery to whatever parameters (18v vmax) I set?

I’m still learning but I’m also trying to use all my cells. It’s a lot (for me) to spend >$2000, then to buy more cells due to BMS failure. I have 700ah of a 16v battery currently and another 400ah of a 16v battery en route, can you clarify your suggestion that I buy more cells to make another 12v battery? My battery size isn’t the issue, is it?

RE: a single MPPT, I have two 40A MPPTs bc I will have two different orientation of panels. I believe this is necessary bc otherwise my array will split the voltage between the two panels, not maximize my tracking. These panels will not be 3S2P, they will be two separate strings of 3S panels with individual MPPTs, sorry for the confusion.
 
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DerpsyDoodler

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all of my RV components are rated from 12-18v and I have the cells.
Because they're rated to 18v doesn't imply you should create an odd battery bank to accomodate. Components (rated for 12v nominal) can handle a higher voltage. Its a sign of quality.

I can’t imagine why I would wish to have extra cells, at any rate.
As spares.

With a more fleshed out plan you might not be seeking this discussion. Also, if you plan on buting more cells in the future, then consider the 3 spares as part of the future growth plans.

For BMS I intend to purchase an electrodacus as soon as production resumes in May but I’m open to alternatives that aren’t Daly BS using fet system that will not pass 150a much less the 500a it is rated for.

I have a Xantrex XC Pro 3000W inverter/charger that I’m hoping to use to charge my 3P5S battery as it is also rated sufficiently.
And what input voltage is the xantrex rated for? (presumably 12v). 3kw is pushing the top end of recommended use for a 12v battery bank.

If it's a 24v inverter, then you'll need a 24v nominal bank (8s with 7 spares for future growth).

I'm not interested in beating my head against a wall. No one can stop you from doing what you want, but considering I'm not the only person telling you this, hopefully it will give you pause for thought.

Your reasons for not wanting a fet-based BMS are understandable, especially with the current you will need to push for a 3kw inverter @ 12v. That said, 3x 12v batteries in parallel wired to share the load equally will mean less than 120a per 12v nominal battery. If you'll open your mind to re-planning around the components you have, the people on this forum will help get you up and running with a safe system that won't destroy your batteries or your RV.

Strongly suggest you stop work, put the tools down, listen to what youre being told, and start asking questions based on that.

I'm going over to the thread you linked where we can hopefully continue this conversation.
 

12VoltInstalls

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you’re saying you do not believe the BN 40a 150v version will do what it’s rated for and charge my battery to whatever parameters (18v vmax) I set?
I don’t know if it would actually. It might.
have two 40A MPPTs bc I will have two different orientation of panels. I believe this is necessary bc otherwise my array will split the voltage between the two panels, not maximize my tracking.
I have 400W facing SE and 400W facing SW on one AN50. 4S2P
The parallel arrays (if matched) do not have any downsides in practical terms.
Bulk charging would be set to 17.5v then float at 18v.
That seems odd. With LiFePo I’d think you’d float a whisker under boost/absorption- though I suspect LiFePo settings probably don’t have an absorption setting. Not in my experience set so uncertain. But it’s weird to float above boost and the software may not allow it.
 

ianganderton

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Question regarding over panelling Epever SCCs

Can the controller output 40A to the battery and 40A to the load at the same time potentially therefore using the excess PV available?
 
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DerpsyDoodler

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Question regarding over panelling Epever SCCs

Can the controller output 40A to the battery and 40A to the load at the same time potentially therefore using the excess PV available?
Load is limited to 20a iirc. Maybe even 10 (I don't recall off the top of my head because I don't use it). That said, I believe the total output is 40a regardless of where the power is going.
 

ianganderton

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Load is limited to 20a iirc. Maybe even 10 (I don't recall off the top of my head because I don't use it). That said, I believe the total output is 40a regardless of where the power is going.
Ahhh of course the OP has a BN controller. I have the AN version and the load capacity is 40A

I’m not over panelling at 480W so it’s just an academic question really

I guess the conversion from PV to battery nominal happens in the MPPT phase of the controller and the output is 40A where ever it’s going

On the epever devices is the load voltage regulated in anyway or is it the same as the MPPT output
 

DerpsyDoodler

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Ahhh of course the OP has a BN controller. I have the AN version and the load capacity is 40A

I’m not over panelling at 480W so it’s just an academic question really

I guess the conversion from PV to battery nominal happens in the MPPT phase of the controller and the output is 40A where ever it’s going

On the epever devices is the load voltage regulated anyway or is it the same as the MPPT output
Not sure what the circuitry looks like, though it must have some form of regulation. Maybe @Will Prowse would do a teardown on one. Could make for an interesting video.
 

Browneye

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I don’t know if it would actually. It might.

I have 400W facing SE and 400W facing SW on one AN50. 4S2P
The parallel arrays (if matched) do not have any downsides in practical terms.

That seems odd. With LiFePo I’d think you’d float a whisker under boost/absorption- though I suspect LiFePo settings probably don’t have an absorption setting. Not in my experience set so uncertain. But it’s weird to float above boost and the software may not allow it.

It won't allow you to put wonky values in. Values have to graduate up/down per the installation manual on parameters setting.
 

12VoltInstalls

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Question regarding over panelling Epever SCCs

Can the controller output 40A to the battery and 40A to the load at the same time potentially therefore using the excess PV available?
Barring the amp limits as mentioned in the other posts- assuming 40A output capacity and the controller is connected to a busbar as are loads- busbar then goes to batteries- I’ll give an example from the other day on my AN50:
Coffeemaker (about 760W) was brewing; AN50 was outputting 43A+ at 13.x volts and the batteries were delivering 13A to the busbar. So like 56A to the load between the two. So yes, the solar can power the load.

If you meant the load outputs of the SCC I doubt they’re rated at 40A. I think mine is 30A? I don’t use them. But they are pass through so a 40A controller with maybe 30 “load” connection shouldn’t be asked to make 80A. Bad things to come of that.

I would NOT use the load outputs myself
 
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