Tristar TS-60 Temp Compensation +++

Re: Tristar TS-60 Temp Compensation +++

Glen,

I agree with Mike--An intimidating first post.

Muskoka wrote: »

My totally off grid system consists of:

1 - Rogue MPT-3024, maxed out, 30 amps charge current
2 - Morningstar Tristar TS-60, 25 amps charge current
3 - Morningstar Sunsaver Duo - 23 amps charge current
4 - Morningstar Suresine-300 Inverter
5 - (4) 6volt 420ah U.S. Battery L16HC XC, 840ah total @ 12 volts. Batteries are one month old.
6 - Honda eu2000i Generator

Good Hardware--Includes a Battery Monitor--I always like to see that.

Loads are small, small cabin, last week 4 days no real sun, my Trimetric TM-2025 went from 100% to 80%, television, computers, lights, cell phone charger....

By the way, is this a full time or part time cabin (summer/winter/etc.)?

1. I have temperature senors on all 3 controllers. The Tristar is 7deg f higher than the Sunsaver on all temperature readings. I tried switching the sensors around and still got the same variance. The controllers are 6 inches apart, and connected to the same lug on the battery bank. I'm sure this isn't helping things. The Rogue and Sunsaver are close in temperature. I don't understand how to set the Morningstar controllers for temperature compensation. In Msview there is a spot to input a voltage adjustment value, problem is it has a negative sign before the box, and I need to raise the voltage +.168 volts for every 10deg f below 80deg f (per email with settings from U.S. Battery). My battery room temperature is about 40deg f so I need to adjust by roughly +.672ish volts. How do I input this value when there is a negative sign before the input field? Or, do I not need to input anything in those fields when using the Remote Temperature Sensors?

General comments (my system is Grid Tied--and I do not sell/service solar stuff--I just play one on the Web:roll:).

The temperature sensors are not that accurate... a 7F spread is not going to hurt things. Some controllers have offsets you can program in to get things a bit closer. That you are using Remote Battery Temperature Sensors is a very good thing--Many times charge controllers get warm themselves, and do not do a good job of estimating battery temperatures.

The "-" sign is just the math. For example if 77F is the battery standard temperature and they are at 47F, then 47f-77F=-30F degreeF drop. Since the battery should be higher when cold they simply multiply by "-" XX mV/degreeF. "-"x"-" equals a positive increase.

Usually controllers have a default value in the field--but if 0/blank is entered, usually the voltage offset function is disabled.

Also watch out for units... Some are given in -XX mV/degree per cell and others are per 12 volt / 24 volt / 48 volt bank. So there may be a 2 volt per cell conversion depending on specifications and controller setup.

2. U.S. Battery is recommending a Bulk charge of 14.8 volts, Absorption of 15.5 volts for 2 hours, and a Float of 13.2 volts. How would I go about setting the Morningstar controllers for these values. I guess my problem is I don't understand how the temperature compensation value is being used, or even how to program it properly. The Rogue temperature compensation is controlled from within itself, not configurable, don't have to worry about that one.

Generally, you simply plug in the "battery specifications" which are assumed to be at ~77F / 25C... And the offset is applied based on temperature reading (as described above).

Morning Star -- You may have to purchase a separate display head to program non-default values for some of their controllers (or get a, not cheap, dongle to connect to a PC to program values).

3. Design question. My arrays are in three different locations due to space and shading issues and system growth over the years. The two arrays hooked up to the Morningstar controllers, are spaced equal distances from the battery room, same voltage, but receive sun at different times of the day. The shading is not drastic, 1/2 hour on one array and then 1/2 hour on the other, winter only. Would I be better off to take those two arrays and hook them up to the TS-60 (eliminate the Sunsaver Duo). How is the shading at different times going to affect charging if their hooked up to the same controller? I'll assume the shading does nothing, when one array is getting full sun I'll get full charge from it, and when the other is getting full sun, I'll get full charge from it? Just want to make sure.

Oh boy--There are lots of caveats with that question.

First, you have a mix of MPPT and PWM controllers. Basically, if you want to share several arrays on one MPPT controller--They should be facing the same direction/mechanical installation to collect optimum power. MPPT does not work as well with split arrays.

For PWM controllers--As far as I know--As long as the Vmp of the several arrays are correct (~17.6 volts for a 12 volt battery bank)--there is no issue with an East/West split array on a single PWM charge controller.

There is a whole bunch more hand waving I can do if you want to discuss this question in detail. MPPT and PWM controllers each have their own sets of requirements and limitations and it is a lot to swallow at one time.

4. Some numbers? I took an sg reading this afternoon and all cells were very close, just below 1.250 (no load, system still charging, barely). This is not temperature compensated, so I would need to subtract .004 for every 10deg f below 80deg f, so again at room temperature of 40 deg f, I would take off .016, giving a sg of 1.234.

Are the batteries "bubbling"? Have you written down the maximum S.G. from when the batteries where new/fully charged/fully equalized?

Different battery manufacturers (and sometimes at fill time by the distributor) use different SG electrolyte (by application, ambient temperatures, etc.).

How much water are you using? Do you have to refill every month or once a year? Checking every month and refilling every two months is probably "about right".

Now, at these readings, the Rogue said the batteries were full, and the Tristar was still charging in bulk mode. Absorb voltages are set at 15.2 volts because that's as high as the Rogue goes (U.S. Battery wants 15.5 for 2 hours), so I set the Morningstars to the same as the Rogue. Both controllers were reading 15.2 volts.

15.0+ volts for several hours is usually a "equalization charge" for most flooded cell battery banks. Something done a 1/2 dozen +/- times a year--not usually recommended every day (equalization and over use of equalization is hard on a battery in its own right--Equalization should only be done when cells are out of balance or to stir the electrolyte).

I guess the question is, 1.234 temperature compensated sg is not 100%, batteries are not full. I must not be doing something right in the math maybe, probably the temperature compensating?

In the end, it can be the battery initial fill, issues with your personal hydrometer, even DMM reading errors (calibration, weak battery, etc.) that can give confusing information.

The best place to start--fully charge the battery bank and log the readings for each cell. That will be your 100% for your bank with your tools. (15+ volt for two hours and low current flow certainly sounds like 100% state of charge).

How do I get these controllers coordinated, and set, to get the batteries to 100% in cold weather. The Sunsaver seems to do nothing when the Tristar is charging at full current. It's works fine on its own, because if I turn off the breakers for the other controllers, it (Sunsaver) will charge at full current.

Separate charge controllers on the same bank will never coordinate (unless they have a com-link between the controllers).

Things to check for first--Make sure you have heavy/short gauge wiring between the bank and each controller. Do not share one wire run with two or three charge controllers. You want as close as possible to zero volt drop between the controller and the battery bank (probably on the order of 0.010 volt drop at max current--and no more than 0.100 drop for a 12 volt battery bank).

Next, you can "tweak" controller voltage settings (perhaps raise one controller by a few tenths of a volt). Controller voltage readings are not always exact (just repeatable--a different issue). And charge controller current readings can easily be off by 5 even 30% (not very accurate).

I hope this helps.

-Bill

I forgot to add--This web page on how to properly wire parallel connected batteries for proper current sharing.

Re: Tristar TS-60 Temp Compensation +++

Not a problem--We do have a 5,000 character limit per post--And, on occasion, I have been known to hit that limit with multi-part questions. :roll:

Muskoka wrote: »

Bill, I still don't understand the temperature compensation input field. Here is a picture of the (default) screen from MsView. At current temperatures I need to put +.672 volts in that field, but don't understand how with that negative sign there.

I think you are just getting yourself confused here... Look at the problem as "when temperature rises, battery charging voltage falls"... So there is "-" sign between temperature and charging voltage. The software guy just plugged "-" in there to say that he has accounted for the "slope" of the compensation and all you need to do is enter the numbers.

Second, you may have some unit confusion... Assuming your Battery bank is a 12 volt bank--then you should not be entering 0.672 or .672 in the Bat Temp Compensation field...

First, the US Battery table says that is 0.672 per 10C for a 48 volt battery bank (forget the +/- sign--that is just telling to add if below 80F or subtract if over 80F battery temperature).

Assuming 12 volt bank, the "right number" is 0.168 volts per 10C...

However the controller is asking for Volts per C -- So the real number you should be entering is 0.0168 volts per C (leading 0. may or may not matter--characters and leading zeros in input fields have been killing Quality Testers for decades).

The batteries do get bubbling pretty good. I have only had them for a little over a month. They don't seem to be loosing any liquid yet. To be quite honest it doesn't seem to take very long to get them in the high 90%, I just don't see the Tristar go to float.

Lead Acid Batteries are nearly 100% efficient in the 0-85% charge/discharge range... If you take out 25 AH to power a load, then putting back in 25 AH will restore the battery to its last state of charge. (note: this is not power efficiency, a battery may discharge at 12.0 volts and recharge at 14.0 volts--P=V*I--so the power out is less than the power needed to recharge a battery).

The higher you go above ~85-90%, the more "AH" Losses you will have (those lost AH are turned into bubbling hydrogen/oxygen gasses). Roughly, for a Flooded Cell Battery, if you pull out 100 AH, it will take ~120 AH to bring it back to near 100% charge.

You have a battery monitor--Assuming it is programed and working correctly--You should see the AH out vs AH in tracking pretty well.

The Sunsaver seems to sit there and do nothing when the others are charging. The Rogue goes to full mode which is good, but the sg readings don't add to (indicate) a full battery. We are not having very clear weather right now, I need to monitor some more. I have never had the batteries below 80%, so I haven't really had a chance to see how everyone works together when the sun is nice and bright and the batteries are low enough to draw considerable current.

Most problems seem to revolve around:

1. deficit charging (simply never replacing all current/power back into the battery every few days)
2. not using distilled (low mineral) water and/or leaving the plates exposed (not checking levels once a month or so)
3. cycling batteries below 20% state of charge (cycling them dead)
4. insufficient charging current/energy
5. letting batteries set below ~75% state of charge for days/weeks/months (sulphation)

If you are not drawing the batteries much below 85-90%--they will probably not accept full current.

I would monitor the battery voltage with a DMM and see how it tracks when charging, floating, loading, and resting--And see that they are working correctly.

If you need power out of the Dual charger--Other than reprogramming its voltage (which I don't think you can)--you probably have to accept it as is, replace it with another programmable controller, or program the other controllers with lower bulk charging voltage (but that is going to slow down the charging of the batteries by doing that--so what would be the point).

The US Batteries have pretty high charging voltage set points... Watch your water usage and bubbling--I would not have a problem bringing those voltages down a bit if the water level is excessive (fill once every two months is good, filling every 2-4 weeks is probably too much water usage).

Also, you can confuse the Float/Aborb/Bulk calculations on the charge controllers if you draw significant loads during the day (makes the batteries look like they are requiring more charging current than they really are--so controllers do not go into float). But, that is probably not a huge problem with solar (with grid power, you have 24x7 charging power and can fairly quickly boil batteries dry).

I have 2 different hydrometers, same readings on both, and a new refractometer is on it's way.

The old engineering dilemma... 1 meter--always correct. 2 meters--which one is correct. 3 meters--engineering is not supposed to be a voting democracy--pick one meter and put the other two in a drawer.

Making any sense yet?

-Bill