MTTP Solar Charge Controllers

[goboatingnow]

that unit is badged under severe names, I don't believe the german translation is correct.
and common sense would it isn't as you say. ( since an absorption time of a few minutes would be a meaningless design idea)
Dave

[noelex 77]

Originally Posted by goboatingnow

that unit is badged under severe names, I don't believe the german translation is correct.
and common sense would it isn't as you say. ( since an absorption time of a few minutes would be a meaningless design idea)
Dave

The specifications I listed was from the Conrad web site you can read the German version from the same link. The specifications are easy to read and exactly the same in German so there is no translation problems.
Very short absorption times are used for standby applications which is what this regulator was obviosly designed for. It is not suitable for boats.

Hopefully there are other models of this regulator that are more suitable, but none are listed on the Conrad web site.

Goboatingnow where did you get the specifications you quoted in your post?

[goboatingnow]

http://www.sunpowerplus.co.nz/IVT%20...structions.pdf

[noelex 77]

The data comes from the New Zealand version which I think is an unlikely spot for the OP to buy from. At $339 New Zealand dollars ($254 us dollars) its expensive
Many of these regulators are sold in multiple versions with different software for different companies.
That version looks better, *but there are still some features that are not sensible and will reduce the power output




Description of functions.

1. Bulk charging phase
Up to a voltage of 14.7V, the battery is charged with maximum current.
2. Timer phase
The battery is held on a voltage of 14.7V for several minutes. The duration of the timer phase is determined by the type, age and quality of the battery up to 90 minutes
3. Float phase
In this phase, the solar charge applies pulses to the battery, thus loosening the generated sulphate layers
(desulfating function). In this process, the battery voltage is maintained on 13.7V
4. Standby phase
In this phase, there is no charging current. The voltage of the battery decreases slowly
5. Reactivation phase
After approx. 11 minutes (depending on the solar module) the solar controller is reactivated automatically. The solar controller can also be reactivated manually by pressing button 1.

Steps 4 and 5 are not sensible and have probably been designed to reduce the heat build up in the regulator. Better regulators have enough heatsinking to maintain the float voltage indefinitely .

The other concern is the low light shut off which only checks every 30 minute for sufficient light, this is probably a legacy of the regulators initial design as a design for standby rather than cyclic operation.

In summary the New Zealand version could be used on a boat, but there are much better regulators out there.

[goboatingnow]

Steps 4 and 5 are not sensible and have probably been designed to reduce the heat build up in the regulator. Better regulators have enough heatsinking to maintain the float voltage indefinitely .

The other concern is the low light shut off which only checks every 30 minute for sufficient light, this is probably a legacy of the regulators initial design as a design for standby rather than cyclic operation.

Im not sure your reading the manual properly.

Standby mode is activated when the panel output is lower then the regulators own operating current - Makes sense.

Your heat build up actually is nonsensical as the device is able to sustain bulk and absorption modes, float is a low power hence low heat mode anyway

The manual says standby mode is checked every 11 minutes.

I see no evidence that it was designed as a standby system. Its contains proper IUU charge sequence and a thread poster has said he has fitted 6 units with no problems

DAve

[noelex 77]

Originally Posted by goboatingnow

Im not sure your reading the manual properly.

Standby mode is activated when the panel output is lower then the regulators own operating current - Makes sense.

Your heat build up actually is nonsensical as the device is able to sustain bulk and absorption modes, float is a low power hence low heat mode anyway

The manual says standby mode is checked every 11 minutes.

I see no evidence that it was designed as a standby system. Its contains proper IUU charge sequence and a thread poster has said he has fitted 6 units with no problems

DAve

The low light standby is separate and disables the controller for 30 minutes, which is too long.
A quote from the installation manual.

"The stand-by switch checks in 30minute intervals if there is sufficient solar capacity. If the result is positive the solar controller automatically switches on and charges the battery. In this case one of the three battery status LEDs is on. The solar controller can also be switched on manually by pressing the button."


The regulator generates very little heat in bulk mode ( I you think about it's obvious all the power is going to the batteries at this stage. Heat would represent a great inefficiency.
During float typically lots of power is wasted with PWM. the rapid switching of the mosfets generates a good deal of heat. You can verify this yourself just by feeling any solar regulator it will be hottest during maximimum regulation.

If you look at the better solar regulators they have large heatsinks, metal cabinets, and often cooling fans. These things are expensive, so are often compromised in cheaper regulators. Consequently they often have to shut down to protect themselves when operating anywhere near their rated output. This regulator seems has anticipated the need to do that and shuts itself down as part of the charge algorithm.
This is good for long term reliability, given the minimal heatsinking, but not ideal for charging batteries as efficiently as possible.

You really need to look at these cheaper regulators very carefully. Many of the Chinese manufacturers have learnt that if it says MPPT, high current, and is cheap it will sell well. If it doesn't break down customers are happy. They don't realise the fixed an inapropiate voltage set points and inefficiency are shortening the life of an expensive battery bank.

[goboatingnow]

Hmmm doesn't make sense at float a PWM charger would only have a very low duty cycle. So little heat would e generated.

Anyway it doesn't say they are PWM chargers anyway.

Dave

[sy_gilana]

All I can say from experience is.
1 The panels are putting out 19% more than the old "normal" reg.
2 The reg also contains a desulphation zapper that you can hear and feel pinging away (dont ask how to feel it)
3 When the batteries are full they are full, it seems to go into an 11 minute wait and see mode, HOWEVER, if the fridge cycles on during this 11 minute idle phase, the reg immediately kicks in and supplies the power for the fridge.

I regularly watch this via the Link 2000r, I have the solar array wired through the second tap on the shunt ie. battery 2.

Volts at 28.4, solar reg in idle mode, zapping away. sun shining. switch to amps on link. hovering around +0.1, fridge starts, amps -4, about 5 seconds later, amps 0, then +14 for a few seconds, then back to +01~+0.5 for as long as the fridge runs, voltage at 28.4 again.

It seems as though it gives and matches exactly what is drawn when the batts are full.

Hope this helps...

Maybe if it was more expensive it would appear better...

[noelex 77]

Thanks for explaining how it works in practice. Unfortunatly that's just what the handbook suggested and it's far from ideal. Once the absorption phase is over the battery will not be full. The float voltage should be regulated to maintain a voltage of 13.8 ( it should be adjustable for different batteries) irrespective of the load ( providing the solar output is enough)so that the batteries slowly build up to 100% charge.

It soudnds like during the standby cycle ( there should not be a standby cycle at all when there is enough solar power )the battery is hitting the voltage return point and rentering an absorb cycle.
The 28.4 (14.2 for 12v) is too high for a float voltage. It would be much better for the batteries to maintain a constant lower voltage.

[NorthPacific]

I was facing the same dilemma which controller to use. I was pointed to this gentleman.
The RV Battery Charging Puzzle « HandyBob's Blog

Worth a look see. He recommends a Trimetric. His blog is very good with and answers many questions. Worth a look see. He will also answer email questions that are not explained on his blog.

[noelex 77]

Originally Posted by NorthPacific

I was facing the same dilemma which controller to use. I was pointed to this gentleman.
The RV Battery Charging Puzzle « HandyBob's Blog

Worth a look see. He recommends a Trimetric. His blog is very good with and answers many questions. Worth a look see. He will also answer email questions that are not explained on his blog.

I think trimetric only make battery monitors. Tristar are charge controllers made by Morningstar which I think is probably what you are thinking of.

[NorthPacific]

Ya Thanks for that Noelex. I had my wires crossed!!!!

From HandyBobs blog:
Here is an extract from his blog. I offer his advice since I am clueless:-)


I still believe that the Morningstar Tristar PWM with the optional temperature sensor at under $200 is the best bang for the buck in charge controllers. Consider MPPT only if you are going big, over 600 watts and then, if you can use the big 24V panels, buy them. Do not buy a cheap, “budget” MPPT controller. You get more energy late in the charge cycle with a smart PWM controller that stays in absorption mode than you get early in the day due to “boost”. People who have bought those things do not want hear this and of course the glossy marketing you read will also not agree. It takes a lot of thinking to understand it, but it is true. There really is not enough boost to measure late in the charge cycle and when the panels are hot. You need to realize that the conditions that supply extra amps do not last all day. You get the 25% boost when a system is not producing much anyway. It goes away as the sun gets higher and the panels get hot. Yes it works, but adding a panel costs less on small systems than buying an expensive controller. I still use a Tristar PWM with 600 watts on our rig and I have no plans to change it. (We bought a freezer, so I finally had to add panels.) I will be using 24V panels in series for higher voltage and MPPT on my shop building where it does makes sense. Which controller I will use is undecided. However, a few of the overly complicated, very expensive things have been ruled out.

-

I will not work on a system without installing a real battery monitor. On the surface this does not look like something a low budget guy would say and people with pop up trailers and pick-up campers can get by without one, but many people with those have thanked me later when they realize just how knowing what is going on with their batteries has allowed them to live instead of to worry. When somebody tells you that you can monitor your batteries with nothing but a volt meter, ask them if they would like to drive a car with a fuel pressure meter, but no fuel tank gauge. This is a very similar concept. You need to know how much fuel you have left if you are going to expect to be able to live decently on battery power. A volt meter or a charger remote will not do this. I like the Trimetric 2025 the best, with a 500 amp shunt. I do sell these, but I am not set up to ship anything yet. The Magnum BMK is easier to install and is self adjusting, requiring very little input from the installer. That is why dealers like it and I understand. However, IMHO the BMK is not as user friendly (just try to find it in the inverter remote by pushing buttons) and the self adjusting program is just not as accurate as I think it needs to be. I have installed Trimetrics on three systems that already had a BMK. But I do love Magnum inverters and am recommending them to everybody. I am now using one bought for my shop building to run construction tools from some 6 year old Trojans that were given to me.

[noelex 77]

Originally Posted by NorthPacific

Ya Thanks for that Noelex. I had my wires crossed!!!!
.

I always blame the spell checker

[sy_gilana]

Hi again. This is not a Chinese device. Take a look at the rest of the range of their stuff. its ivt-hirschau.de
I have written to the engineer who designed it and forwarded him the link to this thread via email. I have been in contact with him before. Lets see if he has anything to add, he might, its his job...

[sy_gilana]

Hello again. Well in the interests of checking my decisions because I don't know everything, I wrote to IVT and had a response today, actually two because I posed a question to them. DISCLAIMER, I have no ties with these guys except a good customer relationship even though I did not purchase directly from them, but through a mail order house called Conrad.de.

First reply....
"
Dear Mike,

First of all, I would like to thank you for the trust you placed into products. Your comments and feedback are very welcome to us.

After reading the postings it seems to me that there is some misunderstandings.
Some of the participants don’t seem to be quite sure about the way their MPPT functions. (Maybe we should help our customer Conrad to revise their manuals).

In the mean time (for about 2 years now) we offer a MPPT solar charger version specifically for AGM batteries. In this case the charging end voltage would be 14,7V which is normally best for the most AGM batteries. Yet, this also depends on the battery manufacturer. Some manufacturers (see battery data sheet) advise a max. charging end voltage of 14,4V .
In this case we always ask our customers to get all relevant information before choosing battery & solar charging system.
Our interest is not only to sell our charger to our customers but sell a charger which best suits his needs.


Anyway, since we found that AGM batteries were becoming more and more popular especially on boats we decided to make 2 different versions of the MPPTs.
ðRegular version : with charging end voltage at 14,1V
ðAGM version : with charging end voltage at 14,7V

Besides we are always trying to improve out products to the customer needs. Therefore we are working on a V2 version on which the efficiency of the MPPTs will be even better.

If you have any further question or comments, please let me know.

Thanks again.

Best regards
IVT-Technik
Elfie Cummings
"
Then my question to them based upon Noelex 77's points.


quote
"

Hello Elfie, und vielen dank fur deine email. Es tut mir leit mein Deutsch ist zehr schlecht...




What is your reason for the 11 minute wait time that one poster commented was a bad idea?

"

...and his reply

"
Dear Mike,

actually your deutsch doesn’t seem so bad at all.

Well briefly said the 11 minutes stand by phase (see below point 4 from the manual MPPT regular version) was meant to minimize the power consumption of the solar charger especially at night (when there will be no further solar voltage available for charging).

Basically after being fully charged (point 1), after the 90 minutes timer phase and the maintenance phase where the voltage will be kept at 13,7 V , the charger goes into this stand-by phase in order to save power. In this phase the charger requires only minimum power.
After 11 minutes it checks the voltage (both battery and solar voltage) and if necessary it starts charging.
At night of course there will be no solar voltage so the MPPT will go back to standy-by. This way you avoid drawing power from the battery which would leave you (possibly) with an empty battery in the morning.
As soon as there is sufficient solar voltage or the battery voltage is low enough it will start charging automatically.

Besides as mentioned under point 5 below, if a customer has any reason to by-pass this stand-by phase he can do it by pressing the according button.

We have given this a lot of thought and have tried to consider all eventualities when designing the MPPT Series. That’s why we decided to make the AGM version with the higher charging end voltage. We want to achieve good efficiency and preserve the (mostly) expensive batteries. A battery should be full, but not driven into gasing.
But we can not custom-make a solar charger for every individual customer.

Anyway, I hope this information is useful to you. If you have any further question, I’ll be glad to assist you.


1.Main charging phase
Up to a voltage of 14.1V, the battery is charged with maximum current.

2.Timer phase
The battery is held on a voltage of 14,1V for several minutes. The duration of the timer phase is determined by the type, age and quality of the battery.

3.Charge maintenance phase
In this phase, the solar charger applies pulses to the battery, thus loosening the generated sulfate layers (desulfation function). In this process, the battery voltage is maintained on 13.7V.

4.Standby phase
In this phase, there is no charging current.The voltage of the battery decreases slowly.

5.Reactivation phase
After approx. 11minutes (depending on the solar module) the solar controller is reactivated automatically.
The solar controller can also be reactivated manually by pressing button 1

Best regards

Elfie Cummings"


I hope this has shed some light on the subject for those who are interested.