Need help with hqst 40 amp controller

[chipster]

Here goes. I've googled the hell out of this. And searched.

My system consists of 4 100 watt hqst panels, a 40 amp hqst mppt controller and a 300 amp hour chins battery with a shunt meter attached. I've tried all kinds of parameters photo is of the current settings.

I'm getting 22.5 volts at 14 amps from my panels on a good day. The controller is only putting out 5 to 6 amps at 14.4 volts with that input. My battery soc can be from 60% to 90% and it's the same situation. By my math, I should be getting about 20 amps at 14.4 volts.

Are my expectations wrong? If not, what should I look at to troubleshoot.

 

[sunshine_eggo]

Here goes. I've googled the hell out of this. And searched.

My system consists of 4 100 watt hqst panels, a 40 amp hqst mppt controller and a 300 amp hour chins battery with a shunt meter attached. I've tried all kinds of parameters photo is of the current settings.

I'm getting 22.5 volts at 14 amps from my panels on a good day. The controller is only putting out 5 to 6 amps at 14.4 volts with that input. My battery soc can be from 60% to 90% and it's the same situation. By my math, I should be getting about 20 amps at 14.4 volts.

Are my expectations wrong? If not, what should I look at to troubleshoot.

Well, if you're at 14.4V, you're in absorption (boost), so the charge is voltage limited. If more amps are available, they can't be fed into the battery without increasing the voltage. At 14.4V, you're actually 0.2V over your set point.

400W/14.4V = 27.8A max. This assumes PERFECT conditions:

High noon
Crystal clear skies
Zero shading of any kind
50°F ambient
Sun directly overhead at your latitude.
Panels pointed perfectly perpendicular to the sun.
1000W/m^2 is actually hitting the panel
Battery sufficiently low SoC to accept the full current.

If you don't meet all of the above, you're not going to get max. To your point, 80% is a much more realistic expectation; however, that's not year round. If you're in the Northern hemisphere with panels flat on a roof, during Winter, you're lucky to get 10-12A.

If you're hitting 14.4V when the battery is at 60% as indicated by the shunt, this strongly suggests you have a connection problem.

Triple check that all crimps are of high quality and all threaded connections are properly torqued.

Next time you're at < 80% SoC and indicating 14.4V, record the Amps and check voltage AT the MPPT battery terminals and then at the battery terminals.

 

[chipster]

IDK.

My multimeter says the panels are producing 14 amps at 22 volts. Not all day, but mid afternoon in Corpus Christi Texas. That is me actually putting the leads on the ter inals. 14 x 22 is 308 watts. It's my understanding that the purpose of the controller is to take that 300ish watts and send it to my battery at the specified voltage ie. 14.4 or whatever the parameters say. I understand there will be some loss. 300 watts ÷ 14.4 volts is 20.8 amps. Not 5 or 6. At 60% soc my battery should take everything its given. When on an ac converter it takes 24 amps according to my shunt until it hits about 90%.

 

[sunshine_eggo]

IDK.

My multimeter says the panels are producing 14 amps at 22 volts. Not all day, but mid afternoon in Corpus Christi Texas. That is me actually putting the leads on the ter inals. 14 x 22 is 308 watts. It's my understanding that the purpose of the controller is to take that 300ish watts and send it to my battery at the specified voltage ie. 14.4 or whatever the parameters say. I understand there will be some loss. 300 watts ÷ 14.4 volts is 20.8 amps. Not 5 or 6. At 60% soc my battery should take everything its given. When on an ac converter it takes 24 amps according to my shunt until it hits about 90%.

14A * 22V = 308W. Pretty reasonable for Corpus if the sun can actually get through that heavy moisture laden air (used to visit Port Aransas as a kid in the summer... damn chewy air).

The other thing I left out is loads. The shunt is only going to show the NET going into the battery. If you're MPPT is saying the panels are producing 14A @ 22V = 308W, and you're only getting 6A * 14.4V = 86W, you're using 308W-86W = 222W in power.

 

[chipster]

I'm going off what the controller says for amp output. My battery shunt shows the same minus the load.

 

[sunshine_eggo]

I'm going off what the controller says for amp output. My battery shunt shows the same minus the load.

Then that makes no sense. It's not possible for the controller to have dramatically different input and output power.

 

[Bud Martin]

IDK.

My multimeter says the panels are producing 14 amps at 22 volts. Not all day, but mid afternoon in Corpus Christi Texas. That is me actually putting the leads on the ter inals. 14 x 22 is 308 watts. It's my understanding that the purpose of the controller is to take that 300ish watts and send it to my battery at the specified voltage ie. 14.4 or whatever the parameters say. I understand there will be some loss. 300 watts ÷ 14.4 volts is 20.8 amps. Not 5 or 6. At 60% soc my battery should take everything its given. When on an ac converter it takes 24 amps according to my shunt until it hits about 90%.

It is Clamp-on DC Amp meter that you are using since most Multi-meter has 10A max current reading? How did you perform current reading, pictures of the meter display?
The unaccounted (about 200W) power not going into the battery has to go some where and producing heat.
Measurement error? Do you have any loads running at the same time as the battery being charged?

 

[chipster]

It is Clamp-on DC Amp meter that you are using since most Multi-meter has 10A max current reading? How did you perform current reading, pictures of the meter display?
The unaccounted (about 200W) power not going into the battery has to go some where and producing heat.
Measurement error? Do you have any loads running at the same time as the battery being charged?

My meter doesn't like it , but will give me a reading. I've blown one fuse already. I just can't keep it on there long. I went to the roof to check panels because I had some travel damage. I checked each panel individually. One of five was bad. I got 3 and a bit from 4 panels and 1 amp from the fifth one. Checked all 5 in parallel and got 14 amps. Got same reading at terminals of controller. It doesn't seem hot.

I'm measuring what goes into the controller, and observing what the controller reports. I can verify the controller with my shunt meter, based on known load present reading. I'm competent with a multimeter, but this isn't what I'm trained to do. I'm by myself here. Can't get a picture.

 

[Bud Martin]

There is no way that you can have 22V @14A (308W) feeding the Solar charge controller and only getting 14.4V @6A (86W) to the battery, the rest of that much power, 222W, had to go somewhere.
BTW, fuse in your meter is only rated at 10A for 10A scale, correct?

 

[chipster]

There is no way that you can have 22V @14A (308W) feeding the Solar charge controller and only getting 14.4V @6A (86W) to the battery, the rest of that much power, 222W, had to go somewhere.
BTW, fuse in your meter is only rated at 10A for 10A scale, correct?

Yes on the fuse. I have two meters. The one I am using is no fuse. Because I blew the other. It does scale out though. Right now. 22v at 4amp input 14.2v at 1.4 amp output. 22x4 is 88. 14.2x 1.4 is 19.88. Roughly 23% now and 28% mid afternoon.

 

[Bud Martin]

Yes on the fuse. I have two meters. The one I am using is no fuse. Because I blew the other. It does scale out though. Right now. 22v at 4amp input 14.2v at 1.4 amp output. 22x4 is 88. 14.2x 1.4 is 19.88. Roughly 23% now and 28% mid afternoon.

That is big power loss, that power went somewhere else.

 

[chipster]

My uneducated theory is the controller is blocking it somehow. The led flashes slow indicating float.

 

[sunshine_eggo]

My uneducated theory is the controller is blocking it somehow. The led flashes slow indicating float.

It can't work like this. Period. The MPPT is a load to the solar panels. The load is in the form of the MPPT output. It's impossible for the unit to have substantially different input and output power beyond what is lost in inefficiency (5-10%). Either this is user error or measurement error by the unit itself. Too many impossibilities claimed for it to be otherwise.

Back to the perceived problem.

Again, if you're battery is at the 14.2V absorption/boost voltage, it will only receive whatever current is needed to maintain 14.2V. If more current is added, voltage will rise. You may have much more available, but it can't use it. In other words, if battery is at 14.2V, the battery is limiting the power.

Recommend you get a clamp DC ammeter that simply clamps over the wires to measure current.

Triple check that all crimps are of high quality and all threaded connections are properly torqued.

Next time you're at < 80% SoC and indicating 14.4V, record the Amps and check voltage AT the MPPT battery terminals and then at the battery terminals.

In addition to the above, confirm that your wires are of sufficient gauge.

Lastly, I've been assuming that the % SoC you've been using has been the SoC reported by the shunt. If the MPPT has a % reading, it's completely inaccurate and should be ignored.

 

[chipster]

It can't work like this. Period. The MPPT is a load to the solar panels. The load is in the form of the MPPT output. It's impossible for the unit to have substantially different input and output power beyond what is lost in inefficiency (5-10%). Either this is user error or measurement error by the unit itself. Too many impossibilities claimed for it to be otherwise.

Back to the perceived problem.

Again, if you're battery is at the 14.2V absorption/boost voltage, it will only receive whatever current is needed to maintain 14.2V. If more current is added, voltage will rise. You may have much more available, but it can't use it. In other words, if battery is at 14.2V, the battery is limiting the power.

Recommend you get a clamp DC ammeter that simply clamps over the wires to measure current.



In addition to the above, confirm that your wires are of sufficient gauge.

Lastly, I've been assuming that the % SoC you've been using has been the SoC reported by the shunt. If the MPPT has a % reading, it's completely inaccurate and should be ignored.

I will get the clamp meter. Voltages at controller are correct. Shunt shows voltage. I'm reporting amps from the controller and shunt agrees. Wires are good. 10 Guage stranded. I have a 30 amp hour lifepo4 battery i could hook up to see if that end of it is problem. (That sounds like an excellent idea.) I agree that soc from controller is completely unreliable. Soc is observed from shunt.

I understand what float means. I think. Does the bms in my battery decide this or the controller? The controller seems to be deciding this based upon the output current. Ie... I'm registering 14.2 volts because that's my output... so I should float at 4 to 6 amps.

BTW. Thank you. I appreciate your time helping me with this problem. It is important to me.

 

[sunshine_eggo]

I will get the clamp meter. Voltages at controller are correct. Shunt shows voltage. I'm reporting amps from the controller and shunt agrees. Wires are good. 10 Guage stranded. I have a 30 amp hour lifepo4 battery i could hook up to see if that end of it is problem. (That sounds like an excellent idea.) I agree that soc from controller is completely unreliable. Soc is observed from shunt.

I understand what float means. I think. Does the bms in my battery decide this or the controller? The controller seems to be deciding this based upon the output current. Ie... I'm registering 14.2 volts because that's my output... so I should float at 4 to 6 amps.

BTW. Thank you. I appreciate your time helping me with this problem. It is important to me.

Controller decides float. Once boost voltage is hit, that controller holds boost for the set Boost time. Then it drops to float. There may be a point where it drops to float earlier based on the current dropping below some threshold.

10awg is marginal for the max potential from the controller, but if the wires aren't long, it should be fine. Definitely worth checking that every connection is tight and nothing like shrink wrap is caught between the terminal faces.

 

[chipster]

So is

Controller decides float. Once boost voltage is hit, that controller holds boost for the set Boost time. Then it drops to float. There may be a point where it drops to float earlier based on the current dropping below some threshold.

10awg is marginal for the max potential from the controller, but if the wires aren't long, it should be fine. Definitely worth checking that every connection is tight and nothing like shrink wrap is caught between the terminal faces.

So is it likely that the controller is making bad decisions?

 

[sunshine_eggo]

So is

So is it likely that the controller is making bad decisions?

No. Again, if the battery is at the boost voltage, the controller can't put out any more current than the battery will accept.

 

[chipster]

No. Again, if the battery is at the boost voltage, the controller can't put out any more current than the battery will accept.

On solar. Just now. Panels input 22.5 volts at 10 amps. Easy math. Output was 14.2 at 3 amps. The shunt is showing .6 amp loss. I flipped the breaker for the ac converter. 20 amps. I need to figure out a way to drain my 30 amp boat battery.

 

[sunshine_eggo]

On solar. Just now. Panels input 22.5 volts at 10 amps. Easy math. Output was 14.2 at 3 amps. The shunt is showing .6 amp loss. I flipped the breaker for the ac converter. 20 amps. I need to figure out a way to drain my 30 amp boat battery.

Have you confirmed voltage readings with a separate meter?

When controller is at 14.2V, what is votlage at the MPPT battery terminals and what is the voltage AT the battery terminals?

 

[chipster]

Have you confirmed voltage readings with a separate meter?

When controller is at 14.2V, what is votlage at the MPPT battery terminals and what is the voltage AT the battery terminals?

Controller says 13.8. Meter says 13.8 at terminals. Battery is 13.3 at terminals and shunt. Both meters agree.