Should my system be F MPTT at low power??

Freewilley · September 2013

Re: Should my system be F MPTT at low power??

Ok, maybe that has been my issue all along?????
Remember, what happens is that it goes to float and does not drop down to bulk again and merrily floats away but I never get the batteries to rise in juice (because it is floating)

What is confusing to me is that the MX has been completly rebooted several times in the last month and I have NEVER adjusted this (ever). So I would think that it is at default.

What is also funny is that you can only move that setting in whole volts....so I can not put it over 12...also, the next setting is END,,,,what should that be set at? It is now 0.

Cariboocoot · September 2013

Re: Should my system be F MPTT at low power??

I haven't got my OB book with me but ... Float ought to be a number around 13.8 and re-bulk should be the nearest whole number below that I think so set it to 13.

This would not cause a problem with day-to-day cycling where it is going to restart anyway, but it would cause a problem with trying to match gen function and keeping ahead of power use if the panels are not able to maintain Float level.

Where did you get this MX from? Was it used by any chance? That really low number is the sort of thing you might find on a turbine application where maintaining Float is not at all difficult. Maybe it was just preset wrong to begin with.

NorthGuy · September 2013

Re: Should my system be F MPTT at low power??

Cariboocoot wrote: »

I haven't got my OB book with me but ... Float ought to be a number around 13.8 and re-bulk should be the nearest whole number below that I think so set it to 13.

Is re-bulk the setting that say the controller to do bulk/absorption if the voltage drops below the set level? If so, wouldn't the high setting cause a second absorption for the day?

Cariboocoot · September 2013

Re: Should my system be F MPTT at low power??

NorthGuy wrote: »

Is re-bulk the setting that say the controller to do bulk/absorption if the voltage drops below the set level? If so, wouldn't the high setting cause a second absorption for the day?

Yes, but you won't make Bulk & Absorb twice in a day if the panels can't maintain Float. Overnight it will reset itself and start all over again the next day.

Freewilley · September 2013

Re: Should my system be F MPTT at low power??

Cariboocoot wrote: »

I haven't got my OB book with me but ... Float ought to be a number around 13.8 and re-bulk should be the nearest whole number below that I think so set it to 13.

This would not cause a problem with day-to-day cycling where it is going to restart anyway, but it would cause a problem with trying to match gen function and keeping ahead of power use if the panels are not able to maintain Float level.

Where did you get this MX from? Was it used by any chance? That really low number is the sort of thing you might find on a turbine application where maintaining Float is not at all difficult. Maybe it was just preset wrong to begin with.

Mx was brand new. Would a hard reset not have changed the settings? Hard to believe it has been wrong for this long....

So, today I started off much higher..12.2 and 240 SG. The generator has been running for 5 hours. After an initiial good go, the charging dropped way down to 100 watts for most of this time. Almost no sun.
Absorb setpoint is high at 14.9 for this get up the juice exercise. The SG came up to 1.245 after 3 hours and to 1.250 after 5 hours. Is that the kind of charging to expect???
So slow?

Blackcherry04 · September 2013

Re: Should my system be F MPTT at low power??

Freewilley wrote: »

Mx was brand new. Would a hard reset not have changed the settings? Hard to believe it has been wrong for this long....

So, today I started off much higher..12.2 and 240 SG. The generator has been running for 5 hours. After an initiial good go, the charging dropped way down to 100 watts for most of this time. Almost no sun.
Absorb setpoint is high at 14.9 for this get up the juice exercise. The SG came up to 1.245 after 3 hours and to 1.250 after 5 hours. Is that the kind of charging to expect???
So slow?

Yeah, that sounds about right because the batteries will only accept about 3-5 amps DC at this point without raising the Voltage level. You also have the recombining factor of the electrolyte that the higher the concentration the slower it goes. Another factor is all the surface sulfate is gone and the pores of the lead is being cleaned out. The whole process is where you the complete capacity of the battery is regained, if you stop now it will never finish and you'll be back where you started..

Freewilley · September 2013

Re: Should my system be F MPTT at low power??

But 3-5 amps DC should be 300-500 watts, not 100?

Cariboocoot · September 2013

Re: Should my system be F MPTT at low power??

Disconnecting power from an MX doesn't change its settings. You'd be amazed at how long you can leave one sitting around with no power on and it still remains set the same - until you change it.

Usually the Re-Bulk is set very low as it is unlikely to be needed. But during this heavy gen use it seems charging is getting confused between the two sources.

Where are you reading 100 Watts from?
5 Amps AC charging on the MATE with a 12 Volt system is equal to 50 Amps in DC or 600 Watts. With that much power coming in from the FX the MX will scale back and contribute very little.

5 Amps on the DC side is only about 60 Watts @ 12 Volts, or 75 Watts @ 14.9 Volts.

And yes the charging goes slower the closer it gets to fully charged. That's why running the gen to do the whole thing isn't very economical.

Blackcherry04 · September 2013

Re: Should my system be F MPTT at low power??

Freewilley wrote: »

But 3-5 amps DC should be 300-500 watts, not 100?

Put your clamp meter on the battery and check the amps going in, if your reading off a display it's can be off 200 watts or more.

Cariboocoot · September 2013

Re: Should my system be F MPTT at low power??

Blackcherry04 wrote: »

Put your clamp meter on the battery and check the amps going in, if your reading off a display it's can be off 200 watts or more.

Yes: displays on both charge controllers and inverters are notoriously inaccurate for some readings, particularly calculated ones like Watts. This is because they don't need to be accurate; they just need to work.

vtmaps · September 2013

Re: Should my system be F MPTT at low power??

Cariboocoot wrote: »

Where did you get this MX from? Was it used by any chance? That really low number is the sort of thing you might find on a turbine application where maintaining Float is not at all difficult. Maybe it was just preset wrong to begin with.

The default Rebulk on the outback FM (successor to the MX) is 6 volts. In other words, Rebulk is disabled. I think the MX is similar with a very low default rebulk voltage.

Its like end amps... the default end amps is 0, so therefore end amps charging is disabled by default.

--vtMaps

Vic · September 2013

Re: Should my system be F MPTT at low power??

The MX-60 is shipped with the Re-Bulk set very low, LIKE 9 V. This disables this function. It is possible that Re-Bulk could be used in trying to continue the Bulk/Absorption stage ...

The MX-60s here will STOP charging from PV when another charger brings Absorb V to or above the Vabs setting in the MX. When the other charge source terminates its charge, the MX exits to Float for the rest of the day, unless one Forces Bulk. So if there is still some/good sun for the PV to continue charging, and you shut off the generator, just Force Bulk, and see what the MX will do. Believe that running the generator to Absorb voltage is causing the MX-60 to go to Float (or F-MPPT). If the MX status screen shows Float, then a Force Bulk could get the MX back to work. Obviously, if it reads "F-MPPT, there is too little PV power available to even maintain Vfloat.

EDIT: Also believe that the MX status screen shows something like "Bad Abs" or similar when another charger has Absorption voltage near/above the Absorb voltage set or the MX. If Willey sees this for the MX's charge stage, then he will know that when the other charger (generator/FX) that is shut off, the MX will go to Bat Full, and then to Float (from memory).

Believe the "End" That Willey is seeing it the End Amp setting in the Misc menu. with 00 set, the EA function is disabled, which is probably good right now, when he needs a very LONG Absorb..

It is unclear just where the 5 A and 100 Watts is being seen that Willey has reported. Vic

Freewilley · September 2013

Re: Should my system be F MPTT at low power??

The 100 watts is off the Mate.

It is now 0 watts charging and the MX is still on absorb. only 34 watts solar, typical.
So almost no power is going in to the bank.....but at least the gen is powering the small house load right now.

Something seems wrong about this...

vtmaps · September 2013

Re: Should my system be F MPTT at low power??

Freewilley wrote: »

The 100 watts is off the Mate.

It is now 0 watts charging and the MX is still on absorb. only 34 watts solar, typical.
So almost no power is going in to the bank.....but at least the gen is powering the small house load right now.

Something seems wrong about this...

What is the voltage on the battery? Has the fx inverter gone into float?

--vtMaps

Freewilley · September 2013

Re: Should my system be F MPTT at low power??

Voltage on batt is 15.0
Yes, inverter may be floating, not sure how I would tell that....but if it is maintaining 15.0 I guess it is not in float..

vtmaps · September 2013

Re: Should my system be F MPTT at low power??

Freewilley wrote: »

Voltage on batt is 15.0
Yes, inverter may be floating, not sure how I would tell that....but if it is maintaining 15.0 I guess it is not in float..

if your inverter is holding the battery at 15, its not floating (unless you set the float voltage to 15). On your mate, the status screens can give you info on what charge mode the inverter is in.

Are the batteries bubbling vigorously at 15 volts?

--vtMaps

Freewilley · September 2013

Re: Should my system be F MPTT at low power??

They are bubbling, many small little pops, not sure if that is vigorous.
I made sure the inverter is bulk mode thru the mate.

Cariboocoot · September 2013

Re: Should my system be F MPTT at low power??

Freewilley wrote: »

The 100 watts is off the Mate.

It is now 0 watts charging and the MX is still on absorb. only 34 watts solar, typical.
So almost no power is going in to the bank.....but at least the gen is powering the small house load right now.

Something seems wrong about this...

The MATE normally does not display Watts, but Amps AC. Pic of main screen here, which is useful in telling how much power is coming in and where it is going to.

Freewilley · September 2013

Re: Should my system be F MPTT at low power??

That is not my Mate, and it sure is watts on my sum screen...

Freewilley · September 2013

Re: Should my system be F MPTT at low power??

But anyway, now the MX is reading BAT FULL and the genny is charging at 100 watts....

Blackcherry04 · September 2013

Re: Should my system be F MPTT at low power??

Freewilley wrote: »

But anyway, now the MX is reading BAT FULL and the genny is charging at 100 watts....

It sounds like you really don't have the equipment you need. At a minimum you need a way to access the temperature at the plate level, A accurate Digital Voltmeter, A clamp on amp meter.

A battery recovery expert has a water tank, a variable power supply and the know on how to alter the battery chemistry to do certain things and other procedures to make the plates shed. With a Battery charger or a charge controller you can hardly do that.

Where your batteries are new, all you need to do is check them for a SG rise every hour, ck the temperatures every 30 minutes. If you are getting around 110 deg F, stop and let them cool and keep on getting it.

Freewilley · September 2013

Re: Should my system be F MPTT at low power??

And you realize that these are brand new batteries? Not even in service a week....
But I had the same trouble with the last pair (tho not brand new, both stale)

I just forced the MX into bulk and it picked up a little more wattage from the solar because it went to absorb.

Blackcherry04 · September 2013

Re: Should my system be F MPTT at low power??

Freewilley wrote: »

And you realize that these are brand new batteries? Not even in service a week....
But I had the same trouble with the last pair (tho not brand new, both stale)

I just forced the MX into bulk and it picked up a little more wattage from the solar because it went to absorb.

Yeah , we know they are new.

Here is the point if you have no SG rise in 2 hours of EQ voltage charging, there is a chance that something is not right with the electrolyte, There is no way to know who filled them if they were dry shipped and how much they put in and how much water was added. The no way on here to tell you, all anyone can do is guess with the information supplied from you. How much was the last rise ?? what was the temperature ?? How many DC amps are they taking ??

Freewilley · September 2013

Re: Should my system be F MPTT at low power??

Temp is just below 80, my scale says DEDUCT 2 from sg reading.
They have been taking less than 1 amp for 3 hours I guess.
sg
7:30 am 1.240
1030 1.245
100pm 1.250
5pm !.250

I have put them on EQ mode now, they were absorbing.
Gonna get the SG as high as possible and see what happens tommorrow, it will be sunny.

Freewilley · September 2013

Re: Should my system be F MPTT at low power??

Well, you hardy souls that have been kind enough to read about my issues over the past week....I guess I have a summary....

It started when my Mate showed the system going into float when the batteries were actually 30% depleted...about halfway to 50% DOD line.
I have properly adjusted for voltage loss of .2 and equalized for 4 seperate short sessions for a total of more than 15 hours.
Yesterday I did run the system without EQ for most of the day, and it DID NOT revert to float, so the problem may have been solved with those two changes. BUT since it was only charging on FX, maybe it is not solved.
Today I am running the genny until I have good solar, then will switch to MX charging only and see what happens.

What has been the problem lately, as the batts have never come up to 100% they seem to plateau at 1.250...despite many hours of genny running ....so stay tuned....

Cariboocoot · September 2013

Re: Should my system be F MPTT at low power??

Are you not getting good sun? Because frankly an 880 Watt array on an MX60 ought to be able to charge those batteries all on its own in one day.

Freewilley · September 2013

Re: Should my system be F MPTT at low power??

Cariboocoot wrote: »

Are you not getting good sun? Because frankly an 880 Watt array on an MX60 ought to be able to charge those batteries all on its own in one day.

No, almost no sun for 2 days. I am now, finally, getting solar.
Not sure why they would not fully charge off the FX and genny...I am absorbing at a high point, 14.8...but that should not be affecting it?

Anyway, genny is now off, SG is 1.240 (up marginally from 1.235 in 4 hours of genny) and solar is more than enough to keep MX in absorbing and handle loads of cottage.

System has not reverted to FLOAT as it did last Sunday....and has previously.

Cariboocoot · September 2013

Re: Should my system be F MPTT at low power??

Freewilley wrote: »

No, almost no sun for 2 days. I am now, finally, getting solar.
Not sure why they would not fully charge off the FX and genny...I am absorbing at a high point, 14.8...but that should not be affecting it?

Anyway, genny is now off, SG is 1.240 (up marginally from 1.235 in 4 hours of genny) and solar is more than enough to keep MX in absorbing and handle loads of cottage.

System has not reverted to FLOAT as it did last Sunday....and has previously.

The differences in the two charge sources are minor. The FX should complete the Bulk stage faster, as it starts out at full current whereas the solar needs to come up over time as insolation improves. The FX does not have an End Amps function. Otherwise, if the Voltage and time settings are the same it will work just as well.

Freewilley · September 2013

Re: Should my system be F MPTT at low power??

There has GOT to be an issue with the brand new Surrettes, MEthinks....I have been absorbing with solar for a couple of hours, and the genny was absorbing before that....the Manual says they should absorb in 90 minutes and I have not seen any increase in SG...still at 1.240

Sulphation?

vtmaps · September 2013

Re: Should my system be F MPTT at low power??

Freewilley wrote: »

There has GOT to be an issue with the brand new Surrettes, MEthinks....I have been absorbing with solar for a couple of hours, and the genny was absorbing before that....the Manual says they should absorb in 90 minutes and I have not seen any increase in SG...still at 1.240

Sulphation?

Permanent hard sulfation is unlikely if the batteries have been recently manufactured. Someone earlier mentioned the possibility of having been filled improperly or perhaps having had a spill that someone compensated for with water.

Assuming that there is nothing wrog with the batteries, you really only have two choices when charging a battery: time and voltage. If you can't increase the time, try increasing the voltage by 0.2 volts.

There are many folks who increase their absorb voltage a bit seasonally, in the winter, to make up for less sunlight hours. Its harder on the battery, but easier on the generator.

--vtMaps

Should my system be F MPTT at low power??

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