Little help choosing mppt

[Tiagoo]

Now this is interesting. I was just about to order the victron 100/50 but decided to have a quick look here first.

I should say that our batteries are the cheapest possible leisure I could find on fleabay, and therefore they’re likely to be just starter batteries, at £80 a piece. They were ordered in a rush just to get us through the first few weeks of moving in.

That said, I don’t think lithium on a canal boat is a good idea.. they’re very peculiar about temperature, from what I understand. And temperatures on a steel boat’s bilge are not particularly friendly.

Now, I’m starting to question myself as to why I’m willing to spend £500 on a victron controller (with the accessories), when I couldn’t care less about if the batteries last or not.

I think mainly it’s because I’d like to buy once only, on the solar side. I bought decent panels, and would like to buy a decent controller. And I would like it to be scalable, and I would like it to work.
Those are my only requirements, scalable and that works. Meaning I don’t want a charger that’s not suitable or breaks in a couple months, and also don’t want to be restricted by it in the future.

so, with the new information from @wholybee, I’m wondering if something cheap that can be parallel connected in the future solves the scalability problem, and if it works, it solves the other one..

I’m still unsure about the 12v vs 24v, but that’s another story.. I’m only worried about the efficiency of the buck converter and how I may have to get multiple ones. But I’ll be researching that soon..

 

[Tiagoo]

Ok folks, quick update. I found a victron 100/50 on fleabay for £220 so I bought it.
Most other brands were a good bit over £100 for 40A so this one makes sense..
Speaking of sense, I also got the smart sense for another £30.

So now I’m not sure I need that shunt thing or not. It’s a bit expensive so I’d like to avoid it, and with cheap batteries, do I need it?

 

[wholybee]

No doubt you will be very happy with the Victron. I don't think anyone every regrets going that route. I have several of them on my boat, with the shunt/BMV. I will be updating my shore charger to Victron soon. But not too soon because I live off of solar and don't really need a charger.

The shunt will provide more information. Some of that will overlap with what you get with the Victron MPPT. You will be able to track how much energy you use each day, what time the battery was fully charged, and how many charge cycles. Maybe the most important is that you will know how deeply you are discharging. With Lead Acid you should only use 50% or less of the battery. Sometimes that is hard to know how much you are using. If you want your batteries to last as long as possible, it's worth the money to get a shunt or BMV (the BMV is a shunt but has a display so you don't need to use the phone app. If you are less concerned about getting the longest life, you can certainly make do with just the information the MPPT will give you(which is very good)

What kind of temps do you see in your boat? Lithium is fine between 32F-80F (0C to 27C). It can go higher with a slightly reduced life. (and for those of us that cruise the tropics often goes much higher!), and it is usually simple enough to put them on a small heating mat if your temps are below freezing. The general rule is that if it is a comfortable temperature for you, it's good for the LFP.

 

[RV8R]

Ok folks, quick update. I found a victron 100/50 on fleabay for £220 so I bought it.
Most other brands were a good bit over £100 for 40A so this one makes sense..
Speaking of sense, I also got the smart sense for another £30.

So now I’m not sure I need that shunt thing or not. It’s a bit expensive so I’d like to avoid it, and with cheap batteries, do I need it?

Since you have cheap batteries, skip the shunt. Your V 100 | 50 smart will record a lot of information. You can set up the charge profile & guess at the battery temperature & adjust the w yourself. If you ever do go to Lithium, they don’t n’t use temperature compensating setting - so you might get by without one.


Here is a screenshot of my Cabin V 100 | 50 ,,, lots of information for you recorded or real time.




Good Luck with your installation ? !!

 

[Tomthumb62]

Renogy is fine. It's cheap, and you get what you pay for, but it works and does the job.

If were to do it over and I didnt need an inverter powered on 24/7, I would’ve kept our 2000W Renogy inverter but replaced the 30A Renogy charge controller with a 30A Victron one. The inverter was fine except for the high idle draw (our new Victron inverter uses 97% less idle draw on eco mode) but the charge controller is a bit wonky, such as it usually reads the voltage too high but it’s not consistent. Wish they would fix that, but it’s a you get what you pay for deal.

 

[Tomthumb62]

So now I’m not sure I need that shunt thing or not. It’s a bit expensive so I’d like to avoid it, and with cheap batteries, do I need it?

You’d love it but it’s not needed. I’d love one but have decided it’s not worth the cost.

What I did instead was to buy the Powerurus 200Ah lithium battery with Bluetooth. It has a built SOC reading that does measure amps in and amps out (what the smart shunt does), it’s just not as accurate as a true columb shunt. But it’s close enough. Haven’t had it long enough to tell accurate it is with much conviction, but so far it seems to be within 5% accuracy.

FYI, it sounds like you may have gotten some bad info about cold and lithium. You’re on a boat in a canal. How often does it get below freezing? And if it does, exactly how cold does it get, or has gotten in the past 75 years? Because lithium does fine discharging in the cold, down to about 0F and most are rated down to -20F. Where you have to watch it is charging below freezing. If you do, it can permanent damage the battery. But not a problem, you just be sure to get a lithium battery with “low temperature protection”, which will not allow the battery to receive a charge below a certain preset temperature (usually 32-40F). And if you simply insulate the battery, such as encasing it in a camping cooler, you can keep it warmer than the surrounding air. Or just keep the battery inside your living quarters where you’re going to naturally keep the temperature human comfortable.

 

[DIYrich]

I was not aware of this! Does it apply only to charge or also discharge? Leisure batteries are meant to be less peak amp than car batteries, I think. Would that mean a large amount of amps being discharged very quickly could damage the batteries?

They can discharge a lot faster than they can charge. Think about the current a starter motor takes.

Assuming the charge rate is what the battery is capable of “taking”. I presume the same should apply to discharge.

So if I understand correctly, to charge the 260ah I can pump 65amp to them. Which would probably mean that if my charger is max 50amp, would take just under three hours at half discharge. Seems fine to me.

But if they were in series they could only take 32.5amp charge?

Yes, but 32.5 amps at 24v. Same number of watts. Also each battery is getting 32.5 amps, whereas in parallel, each battery gets 1/2 of the 65 amps.

 

[RV8R]

If were to do it over and I didnt need an inverter powered on 24/7, I would’ve kept our 2000W Renogy inverter but replaced the 30A Renogy charge controller with a 30A Victron one. The inverter was fine except for the high idle draw (our new Victron inverter uses 97% less idle draw on eco mode) but the charge controller is a bit wonky, such as it usually reads the voltage too high but it’s not consistent. Wish they would fix that, but it’s a you get what you pay for deal.

At my Cabin; I am @ a crossroad regarding my 12vdc & inverter.

I have a Victron Multi 12 | 3000 | 120 I purchased in 2018 for a van project & decided not to install it in my van. So I have never installed it & now I am considering putting it in the Cabin.




The standby ( no load ) is 20 W ,,, the max efficiency is 93% but that is max ,,, I do not expect that ( after decades of reading performance specs when I see the word max I just read I will never see that 93% efficiency & more like 85% ,,, just because I am not that lucky ,,, kinda like vehicle gas mileage - I never hit those numbers either ).

The crossroad; Our current fridge ARB 50QT specs @ 0.87 amps ( 24/7 average ) ,,, or about 240Wh per day. We want a bigger fridge. Will probably stay with 12vdc @ $2,000 to $3,000 ?.

Why ? ,,, No need for an Inverter turned on 24/7 ,,, even though I have an inverter ( no cost ).

The inverter @ 20 W is 480 Wh per day stand by or almost 200% energy use just on standby of our current fridge.

If I did buy a 120vac fridge, it would cost I assume around $300 to $1,000.

IMO in 12vdc, simplicity & conservation makes my life easier. I have had zero issues with my Cabin 12vdc almost 100% Solar charged electrical system ( gas generator charging if the sun will not cooperate).



edit; Design - One Thing Pushes Another.

So my 250Ah AGMs @ 12vdc are Rolls ,,, Here are the specs ( 2 - 6V in series if that info isn’t apparent);



Make your own conclusions, but on the sides of the actual batteries it states max charge @ 80 something amps ,,, these specs state max charge @ 75 amps & recommend @ 50 amps.

Discharge specs listed as well.

Why am I posting this? ?‍ ,,, The OP can connect the dots to “inverter use”. If I wanted to use the 3000VA constant or 6000VA max inverter I have, I am gonna need a bigger boat ( movie Jaws reference ) ,,, cause I’m gonna need some batteries ???


@Tiagoo ,,, If this post of mine seems irrelevant to your thread here, I can understand that. Don’t be shy to ask if you have questions, but I posted this for your benefit & understanding. Electrical Design is created from the current (& possible future) loads back to the batteries & chargers. It isn’t rocket science, but if you are interested in such things it is best to learn & design ( start with a schematic as best you can ). That starts with identifying your “Loads”.

Design ,,, One Thing Drives Another.

 

[Tomthumb62]

At my Cabin; I am @ a crossroad regarding my 12vdc & inverter.

I have a Victron Multi 12 | 3000 | 120 I purchased in 2018 for a van project & decided not to install it in my van. So I have never installed it & now I am considering putting it in the Cabin.

View attachment 159611


The standby ( no load ) is 20 W ,,, the max efficiency is 93% but that is max ,,, I do not expect that ( after decades of reading performance specs when I see the word max I just read I will never see that 93% efficiency & more like 85% ,,, just because I am not that lucky ,,, kinda like vehicle gas mileage - I never hit those numbers either ).

The crossroad; Our current fridge ARB 50QT specs @ 0.87 amps ( 24/7 average ) ,,, or about 240Wh per day. We want a bigger fridge. Will probably stay with 12vdc @ $2,000 to $3,000 ?.

Why ? ,,, No need for an Inverter turned on 24/7 ,,, even though I have an inverter ( no cost ).

The inverter @ 20 W is 480 Wh per day stand by or almost 200% energy use just on standby of our current fridge.

If I did buy a 120vac fridge, it would cost I assume around $300 to $1,000.

IMO in 12vdc, simplicity & conservation makes my life easier. I have had zero issues with my Cabin 12vdc almost 100% Solar charged electrical system ( gas generator charging if the sun will not cooperate).



edit; Design - One Thing Pushes Another.

So my 250Ah AGMs @ 12vdc are Rolls ,,, Here are the specs ( 2 - 6V in series if that info isn’t apparent);

View attachment 159615

Make your own conclusions, but on the sides of the actual batteries it states max charge @ 80 something amps ,,, these specs state max charge @ 75 amps & recommend @ 50 amps.

Discharge specs listed as well.

Why am I posting this? ?‍ ,,, The OP can connect the dots to “inverter use”. If I wanted to use the 3000VA constant or 6000VA max inverter I have, I am gonna need a bigger boat ( movie Jaws reference ) ,,, cause I’m gonna need some batteries ???


@Tiagoo ,,, If this post of mine seems irrelevant to your thread here, I can understand that. Don’t be shy to ask if you have questions, but I posted this for your benefit & understanding. Electrical Design is created from the current (& possible future) loads back to the batteries & chargers. It isn’t rocket science, but if you are interested in such things it is best to learn & design ( start with a schematic as best you can ). That starts with identifying your “Loads”.

Design ,,, One Thing Drives Another.

Good questions. No one right answer for everyone. Depends upon your use case and what is already on hand.

Our 120v mid size fridge cost $275. Inverter $350. Could go to a smaller inverter $325. Idle draw is measured at an average of 2W, so 48Wh per day. No need here for a 3000W inverter, but our heating and cooking are propane. It’sa camp trailer. So seasonal needs not year round.

 

[RV8R]

Good questions. No one right answer for everyone. Depends upon your use case and what is already on hand.

Our 120v mid size fridge cost $275. Inverter $350. Could go to a smaller inverter $325. Idle draw is measured at an average of 2W, so 48Wh per day. No need here for a 3000W inverter, but our heating and cooking are propane. It’sa camp trailer. So seasonal needs not year round.

Thanks @Tomthumb62

48Wh per day is very acceptable to me for an inverter & even if just dedicated for a 120vac fridge. 2W standby & what is the efficiency ,,, you got a make, model, & spec?

I am a firm believer in “All Things Heat“ to be other energy than battery power for RVs & small Cabins. But like you said, depends upon our individual uses & interests.

Many solar panel installs on vans “burn more gas or diesel“ than charging by alternator (Aerodynamic Drag Penalty of the roof panel install) ,,, depends upon the install & vehicle of course.

 

[sunshine_eggo]

Thanks @Tomthumb62

48Wh per day is very acceptable to me for an inverter & even if just dedicated for a 120vac fridge. 2W standby & what is the efficiency ,,, you got a make, model, & spec?

And a horrifically unrealistic expectation. This is in low-power mode where the unit does not provide consistent AC output. It is basically turning itself on for 5 seconds and off for 10-15 seconds, so if you need to power something all the time, it won't work like this. It will burn 9W. Per @Tomthumb62 's description, running a single fridge reliably took a little tweaking of the settings to make it work. When it's powering the fridge, the inverter is burning 9W, not 2W. Assuming a 33% duty cycle on the fridge (about what mine does), the inverter idle consumption is 104Wh - 8 hours @ 9W and 16 hours at 2W.

 

[RV8R]

And a horrifically unrealistic expectation. This is in low-power mode where the unit does not provide consistent AC output. It is basically turning itself on for 5 seconds and off for 10-15 seconds, so if you need to power something all the time, it won't work like this. It will burn 9W. Per @Tomthumb62 's description, running a single fridge reliably took a little tweaking of the settings to make it work. When it's powering the fridge, the inverter is burning 9W, not 2W. Assuming a 33% duty cycle on the fridge (about what mine does), the inverter idle consumption is 104Wh - 8 hours @ 9W and 16 hours at 2W.

Thanks @sunshine_eggo ,,, I’m all about “Just The Facts / Specs” & “No Rock Un-Turned”

I don’t want to complete my install & find out I was blind to some “Silver Bullet Equipment”.

I like solid theory designs that require “zero or very little tweaking”. In a World where sometimes Manufacturers over state their equipment’s abilities I have become a bit of a skeptic / critic.

I can accept 100Wh to 200Wh per day for a dedicated fridge inverter, but I like simple(ish) & less time dealing with issues that might crop up. My Cabin 12vdc Solar Harvest system pretty much works flawlessly & I very rarely need to charge by gasoline generator.

I have procrastinated on buying a new 12vdc fridge ,,, the ARB 240Wh / day fridge is working for us, but we want bigger & not a chest fridge. Currently fence sitting as no clear answer seems to be apparent to my sometimes obtuse thinking.

Thanks for your reply post ?.

 

[Tomthumb62]

And a horrifically unrealistic expectation. This is in low-power mode where the unit does not provide consistent AC output. It is basically turning itself on for 5 seconds and off for 10-15 seconds, so if you need to power something all the time, it won't work like this. It will burn 9W. Per @Tomthumb62 's description, running a single fridge reliably took a little tweaking of the settings to make it work. When it's powering the fridge, the inverter is burning 9W, not 2W. Assuming a 33% duty cycle on the fridge (about what mine does), the inverter idle consumption is 104Wh - 8 hours @ 9W and 16 hours at 2W.

You make good points for sure. It’s a night and day difference in how much power the inverter uses and the eco mode is a big reason for this. For my use case, it’s perfect, but it wouldn’t be for everyone.

The power is consistent once it senses a load. I have mine set to 10W. Loads below that won’t wake up the inverter. I have no AC loads less than 10W, so I’m good there. The only inconvenience here is if the fridge isn’t running and the inverter would be in power saving cycle (every 15 seconds then powers for 5 seconds looking for a load), then the fridge light will be off. That’s it.

I think you’re making it out to be a major hassle and aggravation. I don’t find it that way. The settings took only a little tweaking. It actually works fine at almost anything other than the default eco settings.

The eco mode is THE main reason I bought the Victron. It’s regular idle draw actually isn’t so fantastic as you pointed out, but the eco mode is so user adjustable that it’s going to work in a lot more cases, you just need to make it work. It won’t work for something like a desktop computer that doesn’t have a UPS, or for fridges with a digital thermostat that require 24/7 power.

 

[sunshine_eggo]

I think you’re making it out to be a major hassle and aggravation. I don’t find it that way. The settings took only a little tweaking. It actually works fine at almost anything other than the default eco settings.

Didn't mean to come across that way. For a completely inexperienced user, it might be a bit much.

The ability to customize the ECO mode is a very nice feature. Most other units simply have one or two eco modes that behave in specific ways with two different levels of low power consumption. My 2X Quattro 5Ks that must supply loads 24/7 consume 1.3kWh/day.

The eco mode is THE main reason I bought the Victron. It’s regular idle draw actually isn’t so fantastic as you pointed out, but the eco mode is so use adjustable that it’s going to work in a lot more cases, you just need to make it work. It won’t work for something like a desktop computer that doesn’t have a UPS, or for fridges with a digital thermostat that require 24/7 power.

It is actually pretty fantastic when you compare to other inverter/chargers. The MP-II are pretty much leading the industry in low idle power consumption.

 

[Tomthumb62]

For a completely inexperienced user, it might be a bit much.

The ability to customize the ECO mode is a very nice feature.

I agree, for a complete newbie they might be overwhelmed. The ECO mode documentation is pretty thin. It's actually written in pretty plain English, but for some reason I wanted someone to hold my hand to tell me what it meant in even plainer English, lol. Then I just started messing with the settings and learning what each setting did (or what I thought it did, until my theory and the result lined up). The documentation for the ECO mode could be much expanded and it would be a very good thing. I think they assume that most of their customers (or installers) are all electrical engineers and already know what terms like "sensing a load" means.

I did a fair amount of research before buying the Victron Phoenix 12/1200VA inverter to try to learn more about the ECO mode and whether it would work with my fridge or not. I found the Victron Community forums and there were lots of questions like mine. One person flat out said that the ECO mode didn't work with his fridge and blamed Victron for misleading him. It took me a while to figure out that the guy was either an idiot or more likely, just inexperienced and unwilling to admit his ignorance. Another response came from one of the long-time stalwarts of the forum there (perhaps an off-duty Victron employee) and his reply was "Yes, the ECO mode will work with your fridge." That's all he wrote and his point was driven into me far enough that I was convinced the ECO mode would work just dandy with my mechanical-thermostat fridge. And it has worked just so.

After reading what I just wrote, I think I agree with you more so now...might be a bit much for someone inexperienced. Maybe I will try to produce an "Victron ECO Mode Tutorial". Maybe next winter...no time right now lol.

 

[RV8R]

It is good to obtain different opinions from different types of people; optimists / realists / pessimist. We all have our biases & sometimes we know what they are ,,, even how they are shaped.

Thanks @sunshine_eggo & @Tomthumb62 for your posts on this.

Team Blue BTW ain’t perfect. Don’t get me wrong as I love Victron, but they have their own issues. The Cyrix230 I installed in my Van came with paper instructions that were inconsistent with the internet instructions on their website. When I emailed them an inquiry, they pawned me off to the seller who did not have an answer. After I pushed for the answer The seller finally came back with an answer which was “it does not matter which lug you place the starter or house battery on” ?. If i doesn’t matter, then why doesn’t Victron state this on there installation diagrams ?

True Customer Support & clear documentation is part of it IMHO. I vote with my dollars.

 

[Tomthumb62]

True Customer Support & clear documentation is part of it IMHO. I vote with my dollars.

I agree with you a bit here. How Victron is set up as a business isn’t like many of the other off grid equipment manufacturers. At least not the ones popular on this sub. Victron doesn’t provide direct consumer service, they require the seller you bought from to provide that. That’s why you only buy from a reputable seller who can actually provide the support you need. However, Victron DOES provide some casual support on their Victron Community forum. There are some very knowledgeable people on there, including some Victron employees. And there’s idiots on there too, just like any free online forum.

All Posts - Victron Community

community.victronenergy.com

As for poor documentation, that truly is unfortunate. Personally I don’t tend to buy things that I don’t know how to install without any documentation. For example, my off grid system is very small and simple (12v, 400w solar, 200Ah battery) and to get it “right” it took me over two years of learning from this forum and YouTube videos how to do it. We’re I to try to install a 35kW grid tied system, at this point I’d say no way I’ll leave that to a professional or maybe spend another 6 months learning from this forum how to do it all except for the live hookup that an electrician would do.

I started with the Renogy brand because their brand message is one that feels like they will hold my hand; that anyone can do solar and our products are sexier looking than the Blue Blimps that come with no mfr-to-consumer direct support. Ya ever tried Renogy’s customer support? They’re very nice but support is slow. I think it’ss combination of a language barrier and their marketing is so hard hitting that their sales are massive and they make their money by providing just enough mediocre support so as not to totally trash their brand image. You get what you pay for.

Like any purchase, it’s wise to do your due diligence and find out from reviews or people you trust about 1) is this product good and worth the money? and 2) is this seller reputable and can provide help if I need it?

Lots of companies don’t deal directly with end users. Too much unpredictable overhead and engineers stereotypically are good at designing things and less good at dealing with impatient, angry and clueless customers. I mean look at the many self-professed engineers on this forum. Some of them are crazy smart on this electrical stuff but they’re not going to necessarily say it in a way you want to hear…you might need to look up some terms first before you can understand what they’re saying. But once I understand , I feel like I’ve been graced by the Midas touch. At least that’s been my experience lol.

 

[sunshine_eggo]

If you expect Victron to support you directly as an end user, you will always be disappointed. That's now how they're structured. It is the obligation of the Victron dealer to support you. If they don't support you, other dealers must. They even have a means of entering a support ticket through Victron to make sure dealers respond.

Their documentation has been targeted more towards installers than DIY, so it can be lacking, but it has improved substantially over the last couple of years. I have a GREAT dealer, who is responsive and supportive. If he doesn't know the answer, he reaches out to Victron, and I have an answer in the next couple of days.

 

[Tomthumb62]

If they don't support you, other dealers must.

I didn’t know that. Huh. Does this result in shady Victron sellers who won’t support their customers then passing the baton to our w sellers who didn’t make the sale?

 

[RV8R]

Thanks @Tomthumb62 & @sunshine_eggo

You are right !! I will always be disappointed ?.

The only bad thing I have to say about Victron is they do not directly support their customers. Other than that I love their stuff & I do not find it onerous to sort it out ,,, I do not like misleading or improper or lacking instructions or specifications.

I have had to hold plenty of P.Eng. & Architects feet’s to the fires in my 4 decade commercial construction career ,,, well versed in BS & have an extremely sensitive BS meter.

I have not & probably won’t ever buy Renogy.

Online Reviews ? ? ,,, Well the average IQ of a person is 100 ,,, par ,,, It depends upon their ability to post a non-bias review with their findings & their knowledge base. I like reviews from people I know or had some experience with & if they love the “thing” I want to hear about all the bad & ugly of it.

Many DIYers on forums, parrot what they have just learned last week. I can appreciate their enthusiasm, but scratch a little below the surface of knowledge & it starts falling apart. Same deal with the Seller if the Cyrix230 ,,, I knew more than the Seller ( sales guy ) I was dealing with ?.

A lot of it will depend upon the DIYers education background & life experiences.

BTW; I have received “Direct Support” from Victron before. Why was that ? The purchase was on Amazon & I can’t remember if it was a reseller or Victron itself. The Cyrix230 purchase was from a local marine shop I like.