Solar panels putting out 54% more amps than rated?

djcote

New member
Hello everyone!

I just finished hooking up 4 100W HQST panels on my Arctic Fox 865. They are rated at 18V and 5.94 amps each. I ran my own 4 gauge wire to a Bogart Engineering charger and monitor.

It was about 3pm in the afternoon here in northern california, the panels are slanted down the cabover portion of the camper and the truck was parked away from the sun. Not even close to direct light.

Once i turned on the controller and the panels the battery monitor was registering over 37 amps :Wow1: going into the batteries. Rounding the panels up to 6 amps each, the rated power should be 24 amps. I'm having a hard time believing they are putting out 13 more amps than rated late in the afternoon in October. Is this possible?

The Bogart controller is only rated for 30 amps. The yellow light started flashing and it dropped the amps down to 31-32. It says over current isnt an issue so I'm not to worried about that. Just a little baffled how this is generating 54% than the rated power.

Also, how many amps does a fantastic fan usually pull? The meter was showing 20 amps on the highest setting. Seems high for a fan right? I'm wondering if the monitor is not reading correctly but the instructions state the zero draw on a system be close to zero and .3-.4 amps with the controller and monitor running. Mine was showing .4 with just the controller and monitor on. This tells me its monitoring correctly.


Any thoughts would be appreciated.
 

djcote

New member
Check the shunt values you used and you have the correct shunt.

Joe I was not aware there was a shunt setting in the controller. I'm 88% sure its hooked up correctly. I've got an email to Bogart also. The instructions on the controller aren't the best. I'll see if I can find a shunt setting.

Thank you
 

No Ma

Wonderer
If it's a Bogart TM-2030 then program mode number 11 selects the value for the shunt. There are two settings: Sh.H = 500A/50mV shunt and Sh.L = 100A/100mV shunt. Those are the two supported shunt types.

The Bogart controller and SC-2030 charger are very programmable. The documentation covers all the settings, but it is very detailed.
 

No Ma

Wonderer
Oh yeah... our fantastic fan draws a bit over 3 amps on high. The overall system in the teardrop shows a drain of 0.2 amps when nothing is running.

.1 amp is going to the ARB 82qt fridge, and .1 amp is going to the Propex heater. When I pull the fuse for the heater and unplug the DC connection for the fridge, the TM-2030 shows a drain of 0.0 amps. There is a little bit of a drain, but I'm using the 500A/50mV shunt, so the monitor resolution is only to .1 amp.

In another installation for a Jeep house battery with the TM-2030/SC-2030 and the 100A/100mV shunt, when there is nothing hooked up and nothing running, the drain shown on the monitor is 0.02 amp.
 

djcote

New member
No Ma thank you. I've just found the TM-2030 technical manual on their website. This was not included with the charger or controller. Kinda silly. It goes into great detail!

Hoping this 100 amp shunt will be ok with my system. Has anyone had one overheat? Bogart says its only good for about 70 amps before it gets too hot. I've got a 700 watt inverter that peaks at 1600 and can do 900w for 5 min. Will a shunt over heat and be ruined? If I pull a 10 amp load AC the inverter will be pulling over 100 DC amps out of the batteries. Any idea how long it would last at that?

Thank you for the help everyone.
 

Herbie

Rendezvous Conspirator
Hello everyone!

I just finished hooking up 4 100W HQST panels on my Arctic Fox 865. They are rated at 18V and 5.94 amps each.

Where is your reading of 37A being taken? Is that at the panel in-feed, or at the out-feed to the battery?

That rating sounded weird for a nominal "12V" panel, so I went at looked at their spec sheets. Not sure which exact model you have, but they have several that are listed at 17.9 to 18.9v and 5.29A to 5.7A. Yes, that multiples out to ~100w, but remember that your controller is then stepping that down to something closer to the nominal 12v of the system. (Depending on the charge algorithm, it might be as high as 14.7V for bulk charging, or closer to 13v if it doesn't do high-Volt charging.) Watts are watts, so even with a little bit of inefficiency, ~6A at 18V would be close to 9A at 12V.

If you're measuring at the battery-side, after the voltage has been stepped down, then that could explain the extra amperage.
 

ajmaudio

Adventurer
Where is your reading of 37A being taken? Is that at the panel in-feed, or at the out-feed to the battery?

That rating sounded weird for a nominal "12V" panel, so I went at looked at their spec sheets. Not sure which exact model you have, but they have several that are listed at 17.9 to 18.9v and 5.29A to 5.7A. Yes, that multiples out to ~100w, but remember that your controller is then stepping that down to something closer to the nominal 12v of the system. (Depending on the charge algorithm, it might be as high as 14.7V for bulk charging, or closer to 13v if it doesn't do high-Volt charging.) Watts are watts, so even with a little bit of inefficiency, ~6A at 18V would be close to 9A at 12V.

If you're measuring at the battery-side, after the voltage has been stepped down, then that could explain the extra amperage.

This does not apply here as the charger in question is is PWM. As far as the op question I also suspect you have the wrong shunt setting.. Your panels werent making that much... and a fantastic fan does not draw anywhere near 20 amps. Have you tried switching the shunt setting yet?
 

djcote

New member
Yes yes it was the shunt setting. Apologies for the lag in response. They need to include this expanded manual with every new controller. Values are now correct, fan pulling 3A on high.

Very happy with the setup so far. The wife turned on her hair dryer on high and tripped the 100A breaker I have on the inverter. Told her low only! Thats what its there for I guess. This is the highest draw item we have so anything else should be cake.

Went to New Brighton State Park over the weekend. No hookups. Batteries were full by 11AM under lots of shade. I was able to charge a laptop, a tablet and two phones at the same time and still put power back in. Amazing. Also took our little rice cooker, worked great off the inverter, fresh rice during the day or at night with plenty of battery left.

Now to get back my 1 MPG. The panels are too far forward on the cabover and catching wind. Going to need to put a little deflector up there some how.
 

ajmaudio

Adventurer
Glad you got that figured out. What kind of battery setup are you running? Did I miss that elsewhere in the thread?
 

djcote

New member
Hey John, I would love to go that route but the camper has a slide out tray that is pretty limited. I've thought about taking the tray out, that would give me a couple extra inches for a 6V pair but then taking them out or topping off would be a real pain. One big AGM might be a good option down the road. Spendy though.

Group 27 or 31 looks to be the only thing that will fit with easy access. If you have a secret, easy way of checking and adding water with an inch to spare on top I'm all ears!
 

ajmaudio

Adventurer
There are battery watering systems out there... they fit in the cap holes... I've seen one that automatically closes a cell off from the watering tube when full... but I cant remember the brand. You mentioned one big battery.. would a 4d or 8d fit?
 

djcote

New member
Yea a big Ole 8d would fit. Would be sweet but dang they want all the money for them. Remove the tray, slide in a big 8d agm, that would be ideal.
 

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