Charging a pair of USB2000 golf carts with the Rogue MPPT 3048.US battery says the absorb voltage should be 14.7V (for 2 GC2 in series) held for 2-3 hrs, with charge terminated by max time or when dV/dt = 4mv/cell/hr. But I don't understand the dV/dt criterion since supposedly the absorb voltage is to be held at 14.7V ???And anyway the Rogue doesn't allow such a criterion, it uses time, as set by FLOTM setpoint, or current as set by the FLOTR setpoint. It's default FLOTR is 0.01 of the battery capacity, or about 2 amps in my case. So that's what I'm using.But I'm worried that the batteries are not being fully charged with these conditions. And I don't have a decent Sp.Gr. tool to check. The 2A FLOTR setpoint seems to always happen before the 2hr FLOTM setpoint. Perhaps I should reduce the FLOTR a lot (to 0.5A?) and try to get the 2hr FLOTM setpoint to kick in more often? Think I've resolved the other issue I had with the Rogue. When in storage I set the float voltage to 13.1V as recommended by US Battery. But then the Rogue waits until the battery voltage drops to 0.5V less (or 12.6V) before going into MPPT mode. When actually using the trailer camping I want it to start MPPT sooner than that, to get the batteries as fully charged as possible before the sun goes down, so now I set float to 13.6V when camping, and then return it to 13.1V when in storage.

What are you getting for voltage at the terminals for Bulk charging rate, when close to topped off, but before going into maintenance charge mode? It should be 14.8 to 15.0V.

My GC2s are doing well with solar while camping where the controller takes them to 14.8, then drops to float (with no absorption time at 14.8) of 14.4 for the rest of the day (except for times at loaded voltages when using DC stuff). The SG gets to baseline by dark if the time at 14.4 is from mid-afternoon or before.So IMO don't sweat the details of the Rogue so much, the batts will do ok as long as they are getting "something like that." 13.6 for float while camping is too low IMO. You need as much time in the 14s as you can get. The voltage drops overnight, so that is your actual "float/take a break" time for the batts.Storage is different from camping. Now you don't want a prolonged time in the 14s daily.Your decent SG tool is a $6.00 hydrometer--the glass tube with the bobber showing green white red and numbers, not the useless plastic flat bulb with the sideways needle type.

NinerBikes wrote:What are you getting for voltage at the terminals for Bulk charging rate, when close to topped off, but before going into maintenance charge mode? It should be 14.8 to 15.0V.The Rogue has a voltage sense wire that I ran to the battery, and I suppose that is what it displays. It also has a battery temperature sensor that it uses to modify the set voltages.Once MPPT (bulk) mode gets to 14.7V at (at 20-25C?, it varies according to temperature, currently it's at 14.8), it switches to absorb mode and holds that voltage for the time specified (FLOTM) or until the current the battery is taking drops to the set current (FLOTR). Then it stops and eventually goes into maintenance mode.

BFL13 wrote:My GC2s are doing well with solar while camping where the controller takes them to 14.8, then drops to float (with no absorption time at 14.8) of 14.4 for the rest of the day (except for times at loaded voltages when using DC stuff). The SG gets to baseline by dark if the time at 14.4 is from mid-afternoon or before.So IMO don't sweat the details of the Rogue so much, the batts will do ok as long as they are getting "something like that." 13.6 for float while camping is too low IMO. You need as much time in the 14s as you can get. The voltage drops overnight, so that is your actual "float/take a break" time for the batts.Storage is different from camping. Now you don't want a prolonged time in the 14s daily.Your decent SG tool is a $6.00 hydrometer--the glass tube with the bobber showing green white red and numbers, not the useless plastic flat bulb with the sideways needle type.So you've eliminated the absorb step, and raised the float to 14.4V, when camping anyway. I can see the advantage to that. With the Rogue, if the voltage then dropped to 13.9V (14.4 minus 0.5), it would switch to MPPT and optimally bring the batts up to 14.7 or 14.8V.I dunno. It's so different from the USBattery recommended routines.With so little time at 14.7 or 14.8 (none really), don't the batteries take a lot longer to get fully charged?

I would like to have a period of 14.8 but the controller(Eco-Worthy 20a MPPT) won't do it--goes to Float right away, so I jacked up the adjustable Float voltage as high as it will go to 14.4 ( I would have chosen 14.8 if it would do that)I am surprised that the batts get to baseline SG anyway, doing it this way. I don't know how long at 14.4 it takes exactly but a few hours for sure, say most of an afternoon? Last year I had a no-adjustment controller that went to 14.6 and stayed there for two hours then dropped to 13.8 for the rest of the day. That did not work to get the batts to baseline SG and I had to do a run to 15+v every so often to get that done.So it seems this 14.8/14.4 routine is getting the job done and no need to hit 15s every so often. I am "just sayin" that this means you could likely get similar results with "something like that" not that an exact copy is the way or only way to go.

Charging GC2 with Rogue MPPT Solar | Good Sam Community

brulaz
Explorer
Jul 09, 2014
Almot wrote:
Well, Ontario isn't exactly Arizona. With 30A controller and ~450W you'll get 20-40 AH on a dark day, depends how "dark". It's still possible to get to Absorb, if - I hope BFL13 doesn't read this :) - you are trying to conserve energy. LED lights, efficient TV set. No 110V devices other than TV - at least, on a day like this. I hope you've maxed your solar up and didn't install a small 200-280W array.

Temperature default point is 25C, not 20C. It starts reducing the voltage when temps are higher than 25C.

Mostly everything is VDC (including the TV, but we haven't been using it), except my morning coffee grind. Lights are LED. Biggest draw is probably the 12VDC internet antenna amp ... it gets hot, and the computers. My wife is still working, so this is a "working holiday".

The panels are 2x195W in parallel (Voc 44V). Maybe we'll have more someday. There's a lot of energy up there just going to waste.:)
Almot
Explorer III
Jul 09, 2014
BFL13 wrote:
Panel temp 25C, not ambient.

In this topic it was a battery temp.
BFL13
Explorer II
Jul 09, 2014
Panel temp 25C, not ambient. At 25C ambient panel will be at least 45C
Almot
Explorer III
Jul 09, 2014
Well, Ontario isn't exactly Arizona. With 30A controller and ~450W you'll get 20-40 AH on a dark day, depends how "dark". It's still possible to get to Absorb, if - I hope BFL13 doesn't read this :) - you are trying to conserve energy. LED lights, efficient TV set. No 110V devices other than TV - at least, on a day like this. I hope you've maxed your solar up and didn't install a small 200-280W array.

Temperature default point is 25C, not 20C. It starts reducing the voltage when temps are higher than 25C.
brulaz
Explorer
Jul 08, 2014
Almot wrote:
brulaz wrote:

now I've been convinced to boost my float even higher when camping.

Either this, or leave it slightly below the recommended 1%C. When you are "camping", rather than just "charging", there is always some load even when you've turned off everything you could. Fridge, LP sensor, and self-discharge alone can draw 0.8-1.5A. So if you set FLOTR to 0.5A, it will never drop that low, and then timer function FLOTM will run 2 hours just like you wanted.
...

I've been trying to play with it today but it's been grey and rainy. So we've been inside using a lot of electricity and I don't think it's ever made it out of MPPT. This may be the first day the batteries haven't been fully charged at nightfall since I got the solar system installed.

Currently set to 14.7V@20C Absorb, for either 2 hr (FLOTM) or 1A (FLOTR) with float V set up to 14.4V, when camping.

But I will also try reducing FLOTR to 0.5A and/or increasing float V to 14.7V when camping one of these days. Going home tomorrow though ...
Almot
Explorer III
Jul 08, 2014
brulaz wrote:

now I've been convinced to boost my float even higher when camping.

Either this, or leave it slightly below the recommended 1%C. When you are "camping", rather than just "charging", there is always some load even when you've turned off everything you could. Fridge, LP sensor, and self-discharge alone can draw 0.8-1.5A. So if you set FLOTR to 0.5A, it will never drop that low, and then timer function FLOTM will run 2 hours just like you wanted.

This controller has probably more adjustable parameters than any other MPPT, and they are easy to play with because of built-in interface.

The ultimate choice will depend on the SG results. I can't measure it in my AGM, so I'm relying on battery specs and rested voltage in the morning. But you can.
brulaz
Explorer
Jul 08, 2014
Almot wrote:
brulaz wrote:
When in storage I set the float voltage to 13.1V as recommended by US Battery. But then the Rogue waits until the battery voltage drops to 0.5V less (or 12.6V) before going into MPPT mode.

I didn't notice this to happen, and I don't think this is supposed to happen with any controller in the way you describe it.

When there is none or very little loads (you said "storage", right?) - then Rogue maintains this Float 13.1 as long as there is any sun in the sky. There is always self-discharge current and some minor loads like LP detector, so in daytime the Rogue is always running, supplying enough current to maintain 13.1V.

Rogue will only let the battery voltage drop below Float 13.1 when there isn't enough sun to maintain 13.1 (or whatever Float you've set).
...

My bad. I didn't word that very well. This is what I meant:
brulaz wrote:
When in storage I set the float voltage to 13.1V as recommended by US Battery. But this doesn't work very well when out camping, as the Rogue waits until the battery voltage drops to 0.5V less (or 12.6V) before going into MPPT mode.

So I boosted float to 13.6V when camping, when there are more loads.
The only time the trailer sees mppt and absorb modes in storage is first thing in the morning as I have not completely isolated the batteries.

But now I've been convinced to boost my float even higher when camping.

EDIT: Folks, I really appreciate all this advice.
brulaz
Explorer
Jul 08, 2014
landyacht318 wrote:

...
Now I have it set at 1 amp, and 14.9ABsv or 2.5 hours at Absv, and once it requires less than 1.3 amps( 130 amp hour USBattery group 31), to maintain 14.9v or 2.5 hours have passed, then it goes to float mode, which I have set at 15.3v.

But I cycle my batteries daily and I consider the "float" stage as a 'finishing' charge stage, and even with a few hours at 15.3v a day, the SG does not return to baseline on this particular petulant 12v USbattery after 7+ cycles. For storage, not cycling, I would set float to 13.1v as recommended by USbattery.

Does USbattery give a specific charging algorithm for their GC-2's?
I've been going with this PDF from USbattery, and 15.3v is mentioned more than once.
http://www.usbattery.com/usb_images/charging_instruction_2011_3.pdf

I think US Battery has the same protocol for all its batteries. The 2 stage has the absorb as I described with a 13.1V float. The 3 stage includes a finishing step up to 15.3V as you are doing. Equalization is 15.3 for 1-3hrs, which I do every few weeks. My Rogue does not allow the float to be higher than the absorb, so can't really use it to "finish". Sounds like a nice feature to have.
Almot
Explorer III
Jul 08, 2014
brulaz wrote:
But I'm worried that the batteries are not being fully charged with these conditions. And I don't have a decent Sp.Gr. tool to check. The 2A FLOTR setpoint seems to always happen before the 2hr FLOTM setpoint.

Perhaps I should reduce the FLOTR a lot (to 0.5A?) and try to get the 2hr FLOTM setpoint to kick in more often?

Yeah, try and reduce FLOTR. I wouldn't worry about it though. Without loads it will probably switch to Float way before 2 hours. And I think this is how it should be. In my system it always switched to Float after spending some minutes in Abs - not hours. Especially when there are no loads other than LP fridge. Cheaper/simpler controllers keep it at Abs for 1 hour, regardless of the current. Which isn't good either, 'cause there is a risk of overcharging.

And get that SG gizmo since your batteries allow that.
Almot
Explorer III
Jul 08, 2014
12thgenusa wrote:
In Absorb it only takes a .2 volt drop below set point to revert to MPPT.

The OP was talking about controller letting voltage drop by 0.5V and reverting to MPPT while in "storage" and in Float, not in Absorb. Unless there are high loads, I don't see how this can happen. I understand "storage" as "everything off", there are no loads other than battery self-discharge.

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