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Little help choosing mppt

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Tiagoo

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Hi all, just posted this on the newbie forum but just realised there’s a marine forum that probably applies more to my circumstances being a houseboat.

I’m currently setting up a solar system on my houseboat and I’m stuck on the mppt charger.
We have two lead acid 130ah batteries and two 36v 260w panels to charge them.
Eventually we’re looking to get a couple more batteries but still use them as 12v, because it being a boat most of what we use is 12v (lights, pumps, etc)

Now, from my research, I think a Tracer BN 40amp is our best bet for the money. Discontinued but still available.
My problem is, 40amp at 12v is only 480w, which makes the system not scalable without either another mppt, or changing to 24v.
Is there a better solution that I’m not seeing?

Also, apparently renogy is a no go because it’s rubbish, I’m told.. victron is prohibitively pricey. And epever apparently is ok..
Are there other options that won’t catch fire and maybe allow me to get 60A or more for not too much money?

And last question. Is there such thing as a two in one inverter/mppt that can output 3000w ac but still charge 12v batteries? Because all I found was crazy high voltages, presumably for very large systems.

Thank you very much in advance!!
 
Tiagoo said:
Hi all, just posted this on the newbie forum but just realised there’s a marine forum that probably applies more to my circumstances being a houseboat.

I’m currently setting up a solar system on my houseboat and I’m stuck on the mppt charger.
We have two lead acid 130ah batteries and two 36v 260w panels to charge them.
Eventually we’re looking to get a couple more batteries but still use them as 12v, because it being a boat most of what we use is 12v (lights, pumps, etc)

Now, from my research, I think a Tracer BN 40amp is our best bet for the money. Discontinued but still available.
My problem is, 40amp at 12v is only 480w, which makes the system not scalable without either another mppt, or changing to 24v.
Is there a better solution that I’m not seeing?

Also, apparently renogy is a no go because it’s rubbish, I’m told.. victron is prohibitively pricey. And epever apparently is ok..
Are there other options that won’t catch fire and maybe allow me to get 60A or more for not too much money?

And last question. Is there such thing as a two in one inverter/mppt that can output 3000w ac but still charge 12v batteries? Because all I found was crazy high voltages, presumably for very large systems.

Thank you very much in advance!!
Click to expand...
While not my experience in Houseboats, I do have experience with the Epever/Tracer 4215BN 40AMP MPPT SCC. I use mine with 24VDC. Also a seperate 24VDC 3000 Watt Inverter. Very strong & reliable.
For 12VDC needs, I use a 24VDC - 12VDC Buck Converter. No issues for over 2 years of service.

24V - 12V Converter/Regulator 40Amp

Solar panels, I used 1400watts of PV, (4) 350 Watt panels. 2S2P
Without issue.
 
NCislander said:
While not my experience in Houseboats, I do have experience with the Epever/Tracer 4215BN 40AMP MPPT SCC. I use mine with 24VDC. Also a seperate 24VDC 3000 Watt Inverter. Very strong & reliable.
For 12VDC needs, I use a 24VDC - 12VDC Buck Converter. No issues for over 2 years of service.

24V - 12V Converter/Regulator 40Amp

Solar panels, I used 1400watts of PV, (4) 350 Watt panels. 2S2P
Without issue.
Click to expand...
Thanks for the reply!
Would that converter have decent efficiency? And would it be able to handle large amperage loads? Certain things in boats can use a large amount of amps.

I thought about maybe use one battery for those loads (still have it as a 24v battery bank but then use one of those connected to those specific high amp loads) but I think discharging only one battery will mess with the bank, no?
 
Tiagoo said:
Hi all. First post here.
I’m currently setting up a solar system on my houseboat and I’m stuck on the mppt charger.
We have two lead acid 130ah batteries and two 36v 260w panels to charge them.
Eventually we’re looking to get a couple more batteries but still use them as 12v, because it being a boat most of what we use is 12v (lights, pumps, etc)
Click to expand...

260Ah of 12V lead acid should be charged at about 26A, though you may be okay between 16A and 34A.

Best to check the recommended charge rate of your batteries. When not specified, 0.1C is regarded as ideal with an acceptable range typically 0.06-0.13C.

Tiagoo said:
Now, from my research, I think a Tracer BN 40amp is our best bet for the money. Discontinued but still available.
My problem is, 40amp at 12v is only 480w, which makes the system not scalable without either another mppt, or changing to 24v.
Is there a better solution that I’m not seeing?

Also, apparently renogy is a no go because it’s rubbish, I’m told.. victron is prohibitively pricey. And epever apparently is ok..
Are there other options that won’t catch fire and maybe allow me to get 60A or more for not too much money?
Click to expand...

IMHO, Epever is only marginally better than Renogy near the bottom of the barrel.

Tiagoo said:
And last question. Is there such thing as a two in one inverter/mppt that can output 3000w ac but still charge 12v batteries? Because all I found was crazy high voltages, presumably for very large systems.
Click to expand...

Not sure what you mean. There are 3000W inverter/chargers that run on 12V, BUT this results in VERY high DC current... 3000W/12V/.85 = 294A = BEEFY cables. Generally, 12V is best up to 2000W; 24V is best up to 4000W with 48V above 4000W.
 
Tiagoo said:
Thanks for the reply!
Would that converter have decent efficiency? And would it be able to handle large amperage loads? Certain things in boats can use a large amount of amps.

I thought about maybe use one battery for those loads (still have it as a 24v battery bank but then use one of those connected to those specific high amp loads) but I think discharging only one battery will mess with the bank, no?
Click to expand...
I'm not really sure. The 24v - 12v converter is rated at 40amps. Your performance may very. I have had great success in my Shop/Garage. But again using a 24vdc based setup.
Tiagoo said:
Thanks for the reply!
Would that converter have decent efficiency? And would it be able to handle large amperage loads? Certain things in boats can use a large amount of amps.

I thought about maybe use one battery for those loads (still have it as a 24v battery bank but then use one of those connected to those specific high amp loads) but I think discharging only one battery will mess with the bank, no?
Click to expand...
I have only maintained 24vdc banks. (2) 12vdc batteries = 24vdc
 
If I had a boat with mostly 12v powered stuff, I would stay 12v

A 4215BN will supply a maximum of 520w @ 12v, that will easily keep 2x 130ah lead acid batteries charged out at sea. Grab an MT50 meter as well for programming/monitoring.

I've never seen a 12v 3000w AIO unit.

A standalone 3000w inverter will work fine on 12v if setup correctly with short/fat cables, 99% of the time you wouldn't be using it to it's full capacity anyway :)
 
Last edited:
For expanding abilities, 12 volt now & maybe 24 volt later, Victron has some ( 100 | 50 ) that are both 12v ( 700 W ) & 24v capable ( 1400 W ).

Sometimes you pay a little more upfront for the future.

Just a thought.


I like my Victron MPPT 100 | 50 so much I purchased 2nd one to utilize as a portable Solar charger for batteries I have in remote areas;

P max 113 W outta 100 W panel ,, not bad ?

IMG_2096.png

71104332505__251D2D9E-1CE7-42E7-AF24-0E7E9F54A338.jpeg
 
Last edited:
sunshine_eggo said:
260Ah of 12V lead acid should be charged at about 26A, though you may be okay between 16A and 34A.

Best to check the recommended charge rate of your batteries. When not specified, 0.1C is regarded as ideal with an acceptable range typically 0.06-0.13C.



IMHO, Epever is only marginally better than Renogy near the bottom of the barrel.



Not sure what you mean. There are 3000W inverter/chargers that run on 12V, BUT this results in VERY high DC current... 3000W/12V/.85 = 294A = BEEFY cables. Generally, 12V is best up to 2000W; 24V is best up to 4000W with 48V above 4000W.
Click to expand...
Pardon my ignorance but I’m not sure what charge rate means and I’m interested in learning more about it. I shall do some research in the evening. Don’t think I’ve come across this before.

Yes, to be fully honest I hadn’t even thought about those 300A going to the inverter! But it will be so close to the batteries that I think it could be manageable, so long as I can fit such thick cable onto the inverter.. (that’s probably not gonna happen is it.)
 
RV8R said:
For expanding abilities, 12 volt now & maybe 24 volt later, Victron has some ( 100 | 50 ) that are both 12v ( 700 W ) & 24v capable ( 1400 W ).

Sometimes you pay a little more upfront for the future.

Just a thought.


I like my Victron MPPT 100 | 50 so much I purchased 2nd one to utilize as a portable Solar charger for batteries I have in remote areas;

P max 113 W outta 100 W panel ,, not bad ?

View attachment 159323

View attachment 159324
Click to expand...
It sounds good and I wouldn’t mind spending that much, but on will prowls video he mentions how you can’t fit very large gauge cable onto victrons, and that’s a real turn off to be honest..
I’m I worried about something I shouldn’t?
 
The power output terminals of the Victron 100/50 take 16mm2 cable, (AWG 6) . Volt drop at 50 amps over a 1meter cable run is 1%.
If volt drops are a worry, other useful Victron products, Victron Smart Shunt battery monitor and Victron Smart Battery Sence, can report actual battery voltage to the controller.



Any type of boat is a much more demanding environment than a static land based system and high quality units and instalation parts, (cables, terminations, over current protection fuses and breakers, buss bars), will result in a reliable system.

It's probable your boat needs to comply with the boat safety scheme,

part 3 - electrical installations | Boat Safety Scheme | Go Boating - Stay Safe

Faulty electrics, or poorly installed electrical systems, can be a real hazard and could place you and others at risk. The provisions of Part 3 in the 2002 BSS Standards are mandatory for non-private boats where applicable. This part of the...
www.boatsafetyscheme.org www.boatsafetyscheme.org

Also for insurance purposes there may be a need for the electrical system, both the 12 volt and the 230 volt AC to comply with standards .

More details on your intended use would be useful.

Do you have shore power, 230v AC.
A guess on your daily power needs, Ah at 12v, or watts .
Total panel watts to be installed. ( the more panels the better due to low winter yield)
Is the houseboat full time .
 
Tiagoo said:
Pardon my ignorance but I’m not sure what charge rate means and I’m interested in learning more about it. I shall do some research in the evening. Don’t think I’ve come across this before.

Yes, to be fully honest I hadn’t even thought about those 300A going to the inverter! But it will be so close to the batteries that I think it could be manageable, so long as I can fit such thick cable onto the inverter.. (that’s probably not gonna happen is it.)
Click to expand...
Charge rate is how fast the battery can be charged - how many amps input to the battery. "C" is the capacity of the battery.

For two 130ah batteries, that is 260ah capacity.
.25c for flooded lead acid, and .30 for AGM. So 65 amps should be ok.

If you are going to mix 12v and 24v, I recommend 24v batteries. You get more watts from the mppt (current limited), cheaper to down convert to 12v, smaller wires for lower amps required.

At 24v your two batteries are 130ah, so charge up to 33 amps. Same 800 watts max.
 
mikefitz said:
The power output terminals of the Victron 100/50 take 16mm2 cable, (AWG 6) . Volt drop at 50 amps over a 1meter cable run is 1%.
If volt drops are a worry, other useful Victron products, Victron Smart Shunt battery monitor and Victron Smart Battery Sence, can report actual battery voltage to the controller.



Any type of boat is a much more demanding environment than a static land based system and high quality units and instalation parts, (cables, terminations, over current protection fuses and breakers, buss bars), will result in a reliable system.

It's probable your boat needs to comply with the boat safety scheme,

part 3 - electrical installations | Boat Safety Scheme | Go Boating - Stay Safe

Faulty electrics, or poorly installed electrical systems, can be a real hazard and could place you and others at risk. The provisions of Part 3 in the 2002 BSS Standards are mandatory for non-private boats where applicable. This part of the...
www.boatsafetyscheme.org www.boatsafetyscheme.org

Also for insurance purposes there may be a need for the electrical system, both the 12 volt and the 230 volt AC to comply with standards .

More details on your intended use would be useful.

Do you have shore power, 230v AC.
A guess on your daily power needs, Ah at 12v, or watts .
Total panel watts to be installed. ( the more panels the better due to low winter yield)
Is the houseboat full time .
Click to expand...
Are we talking voltage drop from charger to battery or from panel to charger?
From panel to charger I wouldn’t think it’s very important because it’s 36v to 12v (about 5m away). If it’s charger to battery would be a little annoying but I can get it closer to the batteries if that’s the case.

I’m not sure what I would be using the ‘shunt’ for (is it just a monitor?), but the smart battery sense seems very necessary in my case with flooded lead batteries.
I’m assuming it will connect to the mppt and work together?

So, in short, I’m thinking if I get the smart sense plus a 100/50 victron, I can get the panels charging at 12v, and in the future I could double the panel wattage and get the batteries in series at 24v..? Maybe two banks of two (520ah total) at 24v.

Am I thinking this right?
 
DIYrich said:
Charge rate is how fast the battery can be charged - how many amps input to the battery. "C" is the capacity of the battery.

For two 130ah batteries, that is 260ah capacity.
.25c for flooded lead acid, and .30 for AGM. So 65 amps should be ok.

If you are going to mix 12v and 24v, I recommend 24v batteries. You get more watts from the mppt (current limited), cheaper to down convert to 12v, smaller wires for lower amps required.

At 24v your two batteries are 130ah, so charge up to 33 amps. Same 800 watts max.
Click to expand...
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?

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?
 
mikefitz said:
The power output terminals of the Victron 100/50 take 16mm2 cable, (AWG 6) . Volt drop at 50 amps over a 1meter cable run is 1%.
If volt drops are a worry, other useful Victron products, Victron Smart Shunt battery monitor and Victron Smart Battery Sence, can report actual battery voltage to the controller.



Any type of boat is a much more demanding environment than a static land based system and high quality units and instalation parts, (cables, terminations, over current protection fuses and breakers, buss bars), will result in a reliable system.

It's probable your boat needs to comply with the boat safety scheme,

part 3 - electrical installations | Boat Safety Scheme | Go Boating - Stay Safe

Faulty electrics, or poorly installed electrical systems, can be a real hazard and could place you and others at risk. The provisions of Part 3 in the 2002 BSS Standards are mandatory for non-private boats where applicable. This part of the...
www.boatsafetyscheme.org www.boatsafetyscheme.org

Also for insurance purposes there may be a need for the electrical system, both the 12 volt and the 230 volt AC to comply with standards .

More details on your intended use would be useful.

Do you have shore power, 230v AC.
A guess on your daily power needs, Ah at 12v, or watts .
Total panel watts to be installed. ( the more panels the better due to low winter yield)
Is the houseboat full time .
Click to expand...
Btw, good point on the boat safety. We just had it done with an empty shell, but in three years time I guess the electrics will need to look good!..

also: no shore power,
Daily needs are very minimal. Less than 150w. BUT, the girl does like some luxuries, so if we can afford them, we will have things like hairdryer and a fridge. Nothing silly like induction hob though!
It’s a full time home but cooking, heating and hot water is powered by gas/diesel/wood. We don’t watch tv, and we like dimmed lights and candles.
There’s not a whole lot of space for panels so possibly only two. Maybe more if we can fit them.


Completely off topic but: is there such thing as a turbine to utilise the current of the canal for power?
 
Hi @Tiagoo

I will attempt to give you my opinions to help with your houseboat project.

First, it is always best to produce a schematic drawing of your intentions. A picture is worth a 1000 words ,, or so they say.

Now onto the best I can do without your schematic;

I like designing electrical for my “current” needs & for possible future needs or an easy swap ,, thus the recommended on the Victron 100 | 50 Smart

Your concern about Will’s 6 gauge ,,, no problem ,,, keep the 12vdc side close to the batteries ,, as a beginner you will start to learn limitations about 12vdc / wire size / & wire length. Also if you do not want issues on a boat, do not cheap out on wire, connections, etc. I build all my stuff with marine grade ( or with my airplanes - aviation grade ) equipment & materials if available ,, never regretted it ,, and I do not own a boat.

Forgive me if I have not absorbed the info, however your battery manufacturer should have a charge profile for your batteries ,, what are they & what is the charge profile ?? This will answer your “Charge Rate”. The nice thing about the Victron 100 | 50 is you can probably set it up exactly to your needed “Charge Profile” as it is user programable easily from your phone or tablet (smart).

As you are using “lead” batteries, if you add a Victron BM 712 Smart with a temperature sensor wire, you can “network” & adjust your Victron 100 | 50 to compensate your battery charge for battery temperature.

I try to stick with equipment that can handle all battery chemistries & 12vdc & 24vdc.

Not sure about your battery comments, but if you parallel them you combine the amps & if you series them you combine the voltage. Hope that makes sense.

If you in the future go 24vdc with your batteries you can keep your 12vdc appliances & “buck” the voltage down to your 12vdc panel.

My Opinion with Inverters are they are a “Big Deal” 12vdc to 120vac. That is you need big & close wires battery 12vdc to the inverter. You also need batteries that can handle the amps. Here is a gross rule for 12vdc to 120vac inverters ,,, take your 120vac “Load” or “Appliance” in watts & knock a zero off the end of it & that will be the amps between your 12vdc batteries & your inverter ,,, so 3000W would be 300 amps ?. In my World 300 amps is a “Big Deal” ,,, Big Wire / Short Runs / Really Good Connections. Also, there is no free lunch inverting power. There is an efficient factor & standby energy penalty when ready but not being used. My current 12vdc cabin fridge uses less energy per day than the standby power ( no use ) that my inverter will use.

How do you use your boat “All Things Heat & AC”. For my Van, I use Propane. All Things Heat by 12vdc is huge ,,, 1 20lb Propane tank holds as much energy as 116 - 100Ahr Lithium batteries.

ABYC ,, Is the standard for Marine ( as far as I know ), if that sort of thing interests you.

Yes I have seen water turbines ,, not sure about how effective they are.

Have you thought about a DC2DC charger or an alternator charge circuit of some sort ( your boat has an engine/starter battery ? ). If this is a possibility then maybe something like a Kisae 1250 “dual” Solar / Alternator charger would be a possibility ? There are pros / cons to every design decision. Hence the schematic & current & future equipment specs ,, Kinda shooting in the dark trying to help without this info. I am more like @sunshine_eggo when posting ,,, I want all the info up front ,,, the easiest way for me to figure out what your intended design is in the form of a schematic.


If my notes above are confusing or overwhelming, start with obtaining your Battery Manufacturer’s specifications; charge profile ,, max discharge rate ,, etc
 
Last edited:
There would need to be a significant current flow in the canal for the turbine to work. I have used towed turbine generators on Atlantic crossing but you need over 4 knots of speed before any useful output. I assume you mean using a turbine whilst the boat is moored up, I don't think canal current is high enough.

With electrical power consumption it sounds quite low compared to many leasure requirements. Hairdryer and domestic modest AC fridge are easily powered by a 2000 watt, resionable quality Inverter on a 12v system.

Comments on charge rates. You don't state the type of batteries but some of the numbers discussed seem high for the lead acid batteries available in the UK. I would recomend for a 100 Ah battery, 10 to 15 amps for flooded or sealed and 20 amps for AGM. For AGM a charge current lower than recommend will reduce service life, its much less critical with other LA types.

Charge time for lead acid batteries is almost always much longer than expected to get to 100% state of charge. Once the battery reaches around 80% SOC , ( or lower with very high charge currents), the battery accepts a lower and lower charge current. At full, the current will be lower than 1 amp per 100 Ah. From 50% SOC to 100% SOC takes a minimum of 5 hours, regardless of charger power.

With solar, its not uncommon for a lack sufficient power yield in a day to fully charge the batteries. Without battery monitoring, ( such as provided by the Victron Smart Shunt), its difficult to know the battery true state.
Many leasure battery systems are thus undercharged and in turn over discharged, this results in reduced service life.

LA discharge current. Short term can be high without much impact on battery life. Medium term, say running a 2000 watt inverter for hairdrier/coffemaker, about 40 amps per 100Ah battery, so a 500 Ah for a 12 volt battery pack , long term 10 amps per 100 Ah.

The 12 or 24 volt decision has most effect on selection of inverter, either a 12v or 24 volt model, and what action is need for the existing 12v stuff.
If you decide to go for 24 volt system either a 24 to 12 DC to DC converter is needed or the 12v stuff replaced by 24 volt stuff.

Mike
 
Couple things. Renogy is fine. It's cheap, and you get what you pay for, but it works and does the job. Second, you can parallel controllers for more capacity. They don't even need to be the same brand. You can buy the Tracer now, and if you add more panels, can buy a new controller for the additional panels, and keep the Tracer on the old. If you are going to be cheap, that is a consideration.

I do highly recommend the Victron. But the advanced features are less important as long as you have lead acid batteries. The problem with lead acid batteries is that you ruin them if you don't fully charge them. How often they need fully charged depends on the battery, but figure at least once or twice per week(some need it every day) get them to fully charged, and have them float there for a few hours. Then, once in a while (semi-annually or annually) equalize them by overcharging them. I mention this, because if you do not have access to shore power and are relying on solar for your primary power, those to things are almost impossible. It can be done, but you would need a lot of solar. Much more than you would other wise need for your daily usage. As others mentioned, lead acid charging slows down dramatically once it gets to 80% charged, so to get them fully charged by sundown, you need to get them to 80% by mid to late morning.

With that said, if you do not have shore power, I would go cheap for now, and stash the savings toward an upgrade to LFP in the future. Given that an LFP battery will last 10-20 years, doesn't need to be fully charged regularly, and requires less solar total, the total cost of ownership 20 years is cheaper than lead acid. Lead is only cheap if you plan on selling the boat soon.
 
wholybee said:
But the advanced features are less important as long as you have lead acid batteries.
Click to expand...
I do not agree the advanced features are more important . Victron records history of the past 30 days and indicates the duration of absorbtion and float, and the maximum and minimum voltages. This allows the user to evaluate that the battery is being charged correctly , and if necessary alter the loading to Inprove charging. We agree that correctly charging a LA is critical to its health , Victron charger history gives you the information necessary.

Battery prices in the UK for a quality deep cycle LA are quite high. Most of the so called deep cycle leisure batteries are starter batteries that have a much lower cycle life than claimed. It's probable a 200 Ah lithium battery will meet the OP needs.

www.fogstar.co.uk

Lithium Leisure Battery - Fogstar Drift 12v 230Ah

230ah 12v Fogstar Drift Lithium Leisure Battery | Grade A LiFePO4 cells, JBD BMS, Bluetooth, Heating | Lowest Prices in the UK. 10 Year Warranty.
www.fogstar.co.uk www.fogstar.co.uk

The similar capacity AGM assuming a 50% discharge needs , 450 Ah, 3 off 150 in parallel


Lithium cost £720, AGM cost £600

Mike
 
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