Solar taking forever to charge batteries, power disappearing

[Spaceman Spiff]

Ok...are you sure that the Trimetric monitor is set for AGM? I assume it can be programmed for AGM setpoints . . . 

Trimetric is not programable for AGM but the MT Tracer is programmed for Sealed. Trimetric is set to call the batteries charged at 14.3V and it is saying 98% full...has been since I got back at 2:30pm. Currently pulling in 38.5v and 1.8 A at 4pm from solar panels to controller. Batteries read 13.9V and 2.7 A according to Tracer meter. No output as everything is off.

Flashing lights on controller which supposedly mean batteries are full but Trimetric disagrees.

Bogart makes a battery monitor called TM-2030 which is an amp counter.  It is independent of battery type.  All it does is record the amps in/amps out, voltage across the kelvin terminals and make some simple calculations on and stores this data.  You need to tell it when your battery is full when first setting it up and whenever your battery bank profile changes (batteries age).  Unless you do this, its reporting of 100% (full battery) will be incorrect.

The two ways I know to determine a full AGM battery is:

• When the absorption amps reach 1 amp per 100AH of battery the battery can be concidered fully charged.
• Voltage across the terminals after the battery has been fully charged and has rested (no input or loads) for 8+ hours.  A good 12V battery should read 12.7V.  If you measure the battery voltage before the surface charge has had a chance to infiltrate the lead your voltage reading will be high.

Bogart also makes a charge controller called SC-2030 that works with the TM-2030, which I know nothing about.

As Sternwake used to say: blinking lights on controllers lie.

 

[tx2sturgis]

 Unless you do this, its reporting of 100% (full battery) will be incorrect.

{snip}

As Sternwake used to say: blinking lights on controllers lie.

Thanks for this, and it follows that lesser charge readings (in percentage) will be incorrect also.

Sternwake, you ain't lyin!

 

[jonsun]

set your tracer program at least for flooded. but really you need to set it up in user for trojans specs which are absorption setpoint of 14.8v. that will likely require you to punch in higher equalization and high voltage disconnect numbers. in the manual it gives a flow chart for doing this.

 

[John61CT]

Trimetric is not programable for AGM but the MT Tracer is programmed for Sealed. Trimetric is set to call the batteries charged at 14.3V

There is no need for a batt type setting.

Trimetric is fully programmable, 14.3V is just a default. You should set it to the Absorb voltage recommended by the batt mfg, also matching all your charge source regulators.

When the "% of C" trailing amps is reached, as acceptance falls, that's when TM says Full. By default 2% of AH capacity, which must also be programmed correctly.

I would change this to .5% , as long as the charge sources could be programmed to hit this before dropping to Float, which they should.

http://www.bogartengineering.com/support/manuals/

Currently pulling in 38.5v and 1.8 A at 4pm from solar panels to controller. Batteries read 13.9V and 2.7 A according to Tracer meter.

Forget panel volts and amps, focus on what is going into the bank, and only look at stats from the Trimetric unless only available elsewhere or say a calibrated Fluke pro-level DMM.

Flashing lights on controller which supposedly mean batteries are full but Trimetric disagrees.

No, that light means "controller has gone to Float", in this case too early.

Whole point of having a good BM is you use it to calibrate everything else, keep tweaking all the charge sources until they reliably stay on Absorb V (not go to Float V) automatically every cycle until the TM says the bank is Full.

Using SC-2030 gives Trimetric that full level of control over the solar charging algorithms.

 

[John61CT]

So what is wrong with the controller I have? I wanted an MPPT controller so I could enlarge the array if necessary and manke best use of all available sun and power

It is a cheapie, part of an IMO overpriced kit. IMO, others say it's fine.

The cheapest quality MPPT SC I would buy is Victron 75/15, only $100, very flexible, cheap enough you just buy another once you get past ~250w

But meantime let's work with what yo got. You need to get the mfg specs for Absorb V and trailing Amps to program your charger(s).

Not Trojans, not generic, from the docs or tech support from these guys.

Batteries are 12V Mighty Max AGM

In the meantime use the Trimetric default of 14.3V, set all your charge sources to that, they might call it Bulk setpoint, proper term is Absorb, some have both set them the same. Leave Float as is until you get batt mfg specs.

 

[jonyjoe303]

whats the most amps you have seen coming out of your panels? with 400 watts you should see at least 20 amps when the sun is overhead, do you ever see that many amps? 

The voltage doesnt matter as much as the amps, you should aim at 14.4 volts, but the amps is what matters. Recently I found out you need to get the voltage reading directly from the battery, because of voltage drop. My mppt controller will read 14.4 volts but the battery reads 13.9 volts. It always reads that which meant I been undercharging my battery for years. I have to raise the bulk/absorb voltage to 15 volts to get the battery to read 14.4 volts. Maybe you have a similar situation because your battery is reading 13.9 volts. At 13.9 volts the battery will never get a full charge as recommended by the battery mfg. With lead acid it makes a big difference to fully charge every day.

One thing I found out is the higher you raise the absorb voltage the more amps go to your battery. If you don't think your getting your batteries fully charge also raise the float voltage to 14.4 volts, keep it there all day. The controller should bulk until it reaches 14.4 volts, then switch to absorb (at 14.4 volts) for several hours, then to float. If your controller is skipping the absorb and going straight to float, then you are undercharging your batteries because it reaches 90 percent then stops charging (which is what float does). By increasing the float to 14.4 volts, you force the controller to absorb your battery.

 

[John61CT]

Bogart makes a battery monitor called TM-2030 which is an amp counter.

AKA Trimetric, this is what she's got, manual linked above

You need to tell it when your battery is full when first setting it up and whenever your battery bank profile changes (batteries age).  Unless you do this, its reporting of 100% (full battery) will be incorrect.

You tell it how to measure Full in the initial setup, once in use should reset itself when the conditions are met, assuming charge sources are programmed to get the bank there.

Part of that is an accurate assessment of AH capacity, when new some just enter rated AH, but if the bank isn't broken it's in probably lower.

And will get lower again, very quickly if the bank isn't coddled.

When capacity is 75-80%, should be replaced.

Only way to know capacity is a 20-hour load test. Very similar to the initial breaking in process.

As Sternwake used to say: blinking lights on controllers lie.

Well it is up to us to buy devices that are properly adjustable, and program them correctly.

 

[jonsun]

Trimetric is not programable for AGM but the MT Tracer is programmed for Sealed. Trimetric is set to call the batteries charged at 14.3V and it is saying 98% full...has been since I got back at 2:30pm. Currently pulling in 38.5v and 1.8 A at 4pm from solar panels to controller. Batteries read 13.9V and 2.7 A according to Tracer meter. No output as everything is off.

Flashing lights on controller which supposedly mean batteries are full but Trimetric disagrees.

Jim you want to tell her what's really wrong?

jonyjoe303
whats the most amps you have seen coming out of your panels? with 400 watts you should see at least 20 amps when the sun is overhead, do you ever see that many amps?

they're hooked up in 2 series 2 parallel almost certainly from the CRVL experts advice....hence why it's getting 38.5v. and doing it with 400ah. So never getting more than 5A. 
Another one down another down another one bites the dust.

 

[John61CT]

set your tracer program at least for flooded. but really you need to set it up in user for trojans specs which are absorption setpoint of 14.8v. that will likely require you to punch in higher equalization and high voltage disconnect numbers. in the manual it gives a flow chart for doing this.

This is incorrect, likely way off base, and confusing to the OP

And bringing up equalization in this context is confusing. It is part of the breaking in process, always done manually, usually using shore power, but not part of normal automated usage.

Same with voltage disconnect, let's not muddy the waters, stick to fixing the OP's problem.

 

[John61CT]

whats the most amps you have seen coming out of your panels? with 400 watts you should see at least 20 amps when the sun is overhead, do you ever see that many amps? 

Can be much less with everything fine, depends on lots of variables.

> you should aim at 14.4 volts

should be set to what mfg recommends

Yes read at the battery, SC should be right there, if V drops installed wrong.

> By increasing the float to 14.4 volts, you force the controller to absorb your battery.

Last resort workaround, to be used only if all else fails, and then only temporarily until the real issue is fixed

 

[jonsun]

when you're done pulling your hair out with internet advice, consult the manual.
https://www.renogy.com/template/files/Manuals/CTRL-CMD20-40.pdf

Bulk Charge: This algorithm is used for day to day charging. It uses 100% of available
solar power to recharge the battery and is equivalent to constant current. In this stage the
battery voltage has not yet reached constant voltage (Equalize or Boost), the controller
operates in constant current mode, delivering its maximum current to the batteries (MPPT
Charging)
Constant Charging: When the battery reaches the constant voltage set point, the
controller will start to operate in constant charging mode, where it is no longer MPPT
charging. The current will drop gradually. This has two stages, equalize and boost and
they are not carried out constantly in a full charge process to avoid too much gas
precipitation or overheating of the battery.
 Boost Charge: Boost stage maintains a charge for 2 hours by default. The user
can adjust the constant time and preset value of boost per their demand.
Float Charge: After the constant voltage stage, the controller will reduce the battery
voltage to a float voltage set point. Once the battery is fully charged, there will be no more
chemical reactions and all the charge current would turn into heat or gas. Because of this,
the charge controller will reduce the voltage charge to smaller quantity, while lightly
charging the battery. The purpose for this is to offset the power consumption while
maintaining a full battery storage capacity. In the event that a load drawn from the battery
exceeds the charge current, the controller will no longer be able to maintain the battery
to a Float set point and the controller will end the float charge stage and refer back to bulk
charging.
Equalization: Is carried out every 28 days of the month. It is intentional overcharging
of the battery for a controlled period of time. Certain types of batteries benefit from
periodic equalizing charge, which can stir the electrolyte, balance battery voltage and
complete chemical reaction. Equalizing charge increases the battery voltage, higher than
the standard complement voltage, which gasifies the battery electrolyte.
WARNING: Once equalization is active in the battery charging, it will not exit this
stage unless there is adequate charging current from the solar panel. There should
be NO load on the batteries when in equalization charging stage.
WARNING: Over-charging and excessive gas precipitation may damage the battery
plates and activate material shedding on them. Too high of equalizing charge or for
too long may cause damage. Please carefully review the specific requirements of
the battery used in the system.
WARNING: Equalization may increase battery voltage to a level damaging to
sensitive DC loads. Ensure that all load allowable input voltages are greater than
the equalizing charging set point voltage.

Battery Charging Parameters

Battery GEL SEALED FLOODED
High Voltage Disconnect 16 V 16 V 16 V
Charging Limit Voltage 15 V 15 V 15 V
Over Voltage Reconnect 15 V 15 V 15 V
Equalization Voltage ----- 14.6 V 14.8 V
Boost Voltage 14.2 V 14.4 V 14.6 V
Float Voltage 13.8 V 13.8 V 13.8 V
Boost Return Voltage 13.2 V 13.2 V 13.2 V
Low Voltage Reconnect 12.6 V 12.6 V 12.6 V
Under Voltage Recover 12.2 V 12.2 V 12.2 V
Under Voltage Warning 12 V 12 V 12 V
Low Voltage Disconnect 11.1 V 11.1 V 11.1 V
Discharging Limit
Voltage
10.6 V 10.6 V 10.6 V
Equalization Duration ----- 2 hours 2 hours
Boost Duration 2 hours 2 hours 2 hours
_____________________________________________________________________________________________________________________

see the paragraph in bold? that's why you're not charging very much. you have a huge bank and are trying to run a system at 38.5v and MPPT does not work for you with that big of a bank. So instead charging at 20amps you're charging at 5 amps.

 

[akrvbob]

they're hooked up in 2 series 2 parallel almost certainly from the CRVL experts advice....hence why it's getting 38.5v. and doing it with 400ah. So never getting more than 5A. 

This is not true at all. If her MPPT is working correctly it is stepping down the voltage and stepping up the amps--that's the very definition of an MPPT controller. She should be getting much more than 5 amps in at absorption and if she is not then her controller is broken and she should seek warranty replacement.

 

[jonsun]

here's trojans voltages http://www.trojanbattery.com/pdf/TrojanBattery_UsersGuide.pdf

your batts probably cant tell you or wont list it, most dont. your controllers preset for sealed is 14.4v, but wet cells are 14.6v which is a bit closer to where you need to be. So climb up on the roof and re-wire the panels in parallel (positive to positive, negative to negative) and use the wet cell preset on the controller. See what that gets you.

 

[jonsun]

This is not true at all. If her MPPT is working correctly it is stepping down the voltage and stepping up the amps--that's the very definition of an MPPT controller. She should be getting much more than 5 amps in at absorption and if she is not then her controller is broken and she should seek warranty replacement.

read the manual, especially in bold, right above your post. It doesn't function in MPPT outside bulk. with 400ah it's rarely getting down there. 200w/38.5v = 5a


this thread is gotdamn poetic lol

 

[John61CT]

you have a huge bank and are trying to run a system at 38.5v and MPPT does not work for you with that big of a bank. So instead charging at 20amps you're charging at 5 amps.

That makes no sense.

A 200AH bank depleted 50% or a 1000 AH bank depleted 10%, both need ~105+ AH to get back to 100%, the same panels and SC will do the same job equally well.

The bank never sees what's happening between the panels and the SC, only the SC output matters.

The power of the panels needs to replace power **used**, plus a bit.

Nothing to do with the size of the bank, nor MPPT vs other type of SC.

Where do you get this stuff?

 

[John61CT]

To the OP: never let a charge source do Equalization for you automatically, disable that feature.

What your SC is calling "Boost" is really Absorb in standard industry terminology, just substitute above.

Your goal is to set the SC boost/absorb Voltage and lengthen the time spent there, until Trimetric says 100%, after the TM has been programmed as specified above, both in sync with each other.

Then when you are on shore power do the same with mains charger.

 

[John61CT]

It doesn't function in MPPT outside bulk. with 400ah it's rarely getting down there. 200w/38.5v = 5A

You just keep repeating the same incorrect information in thread after thread!

MPPT function is one thing, Buck DC-DC conversion is another, you are taking the flaw with PWM controllers, which have no DCDC conversion, and keep writing as if MPPT has the same flaw!

The converter component takes the higher panel voltage, and **converts** it (transforms it if you like) to the lower output voltage, **keeping** 99% of the wattage (power).

So the 5A at 39V becomes say 15A at the output voltage.

Please study these last two sentences, go do some 101 googling and figure it out.

We don't need you to come back and eat crow, but do **please stop** wasting evetyone's time with your misunderstanding! !

 

[akrvbob]

when you're done pulling your hair out with internet advice, consult the manual.
https://www.renogy.com/template/files/Manuals/CTRL-CMD20-40.pdf
___________________________________________________________________________________________________________________

see the paragraph in bold? that's why you're not charging very much. you have a huge bank and are trying to run a system at 38.5v and MPPT does not work for you with that big of a bank. So instead charging at 20amps you're charging at 5 amps.

NO!! You are mistaken and have chosen the most confusing section of the manual to try to confuse things. Here is another part of the manual where it very clearly states the main job of MPPT is to reduce the voltage of the solar panel down to what the battery can accept, AND AT THE SAME TIME INCREASE THE AMPS!!!! Here is the quote from the manual:

"The voltage generated at the solar module needs to be stepped down to a rate that could charge the battery in a stable fashion by which the amperage is boosted accordingly to the drop. It is entirely possible to have a solar module generate 8 amps going into the charge controller and likewise have the charge controller send 10 amps to the battery bank. This is the essence of the MPPT charge controllers and their advantage over traditional charge controllers. In traditional charge controllers, that stepped down voltage amount is wasted because the controller algorithm can only dissipate it as heat" Page 5 of the manual

Very simply stated, it drops the voltage and increases the amps. It's just remarkably simple. That is the essence of MPPT. Of course, it only does it in bulk charging, that's the only time the battery can take that much power. 

Let me repeat what the manual said:

"the amperage is boosted accordingly to the drop."

If your controller is not increasing the amps during bulk charging, then your controller is broken and is the source of the problem. So, to stay on topic, monitor the amps going in during bulk charging and if it is not high enough call Renogy and ask them about it. The MPPT may not be working properly.

But, before you do that, just like everyone else has said, find out the specific requirements of your specific batteries and set the controller to meet them.

Most likely you are crippling the controller with too low a voltage at absorption and so the power you're creating is being wasted and not allowed to go into the battery. As hard to believe as it is, a lot of batteries want up to 14.8 volts.  

I also noticed that your controller is only set to hold absorption for two hours, the manufacturer may recommend three hours or more to hold absoprtion. You should find that out also. If they recommend 4 hours, you are drastically cutting down on the charge your batteries want.

 

[John61CT]

Actually, try to get the trailing amps spec, much more reliable under different load conditions than using an "egg timer" approach.

Yes, the charge source may only do egg timer, but since a Trimetric is "supervising" using the better protocol, keep tweaking the charge sources under normal usage conditions, until the TM almost always says 100% Full before the SC drops to float.

Going a bit over once in a while (lower loads) is NP compared to habitually going to Float too early.

 

[tx2sturgis]

I think that when all the dust settles here, the problem is that the system is not calibrated to the proper voltage level vs the charge percentage displayed. After all, the percentage indications are the only problem...so far.

Dune, when you did the initial calibration, did you rush things and possibly get a higher voltage reading, without letting the battery bank 'rest'?

BTW, I think the 'gel' setting might be what I referred to as the AGM setting...