Should my MPPT controller drop to 0 amps coming in, from solar panels only, for a few seconds before building back up to 16 amps or so, depending on the sun, stay there for a minute or so & then drop back to 0 amps for a few seconds again & repeat this cycle?
Is this normal behaviour?
I have a 60A Mppt Controller; 550W Solar Panels; 780Ah (6 x 130A) batteries.
I only started watching what happens because I'm not getting fully charged batteries recently. The batteries have always been fully charged when running fridge & freezer 24/7 until recently. I have disconnected the freezer last week & fridge today to try & isolate the fault.
I'm pretty sure it's not the controller as I just bought a new one because the previous Mppt controller did the same but worse - it was 40A & not big enough.
I've pulled all the batteries out to check individually & they all have exactly the same voltage.
I'll be checking what amps the fridge is drawing next week & checking if something is remaining "on" that shouldn't.
It's got me beat!!
TIA
Larry
Sounds like you may have a battery in the bank not playing ball. If you can isolate 5 of the batteries from the bank and only run on one battery and see what happens then. I would also have all the batteries individually load tested. I also have six batteries in my house bank with individual isolators on each battery. Several times a year each batteries is individually charged by a multi stage charger so as each battery is bought up to fully charge without the influence of another battery which could have a different internal resistance which does change as the battery get older.
Hi Lazzz,
A DC Clamp meter is invaluable for measuring DC currents. With a clamp meter, you simply close the clamp around a wire to read what current is flowing in it - no need to disconnect wires as with other types of current measuring meters.
Here's an example http://www.jaycar.com.au/400a-ac-dc-clampmeter/p/QM1563.
regards,
Allan
Another possibility is it could be a bad connection somewhere. The suspect connection might be good enough to give the MPPT a voltage reading but goes high resistance under load (high current). The MPPT wouldn't think it connected to a battery then and shut down.
I have also seen batteries with higher internal impedance than they should have do something similar to chargers. When the battery is sitting there with no current going through it it looks fine. Once you start to charge the battery, it results in a higher terminal voltage due the higher internal impedance. (V=IR) and the charger sees this as a charged battery and reduces the charge current.
good luck.
Dropping the charging current to 0 and measuring the float voltage is common for charging NiMH batteries, but not Lead Acid as far as I know. Which model MPPT controller is it?
Its not necessarily faulty at all!
MPPT chargers need to find the point at which they get the most power out of a solar panel at a given time by varying the load.
Its common to use a PWM internal regulator that repeatedly loads the panel lightly (feeding its power output to the battery) then ramps the load up until the power being taken out from the panel starts to dip (ie past the MPPT point) then set the load at that level for a period of time at that.
(Example - if a solar panel is putting out 30V with a 4A load on it (120W) when you increase the load to 5A the output voltage might not dip (now up to 150W). ie. Panel can handle it. But increase the load to 6A might make the panel voltage collapse down to 15V. Too much. Power is now only 90W, we are past the MPPT point so use the software to go back and find the load that gets us 150W which is the maximum power point in this case.)
The designs of all solar regulators are different like boats. The big criteria is are the batteries charged and staying charged.
Quick update:
I took all the batteries home to charge them separately.
I bit the bullet & bought a new Ozcharge 9 stage battery charger - www.ozcharge.com.au/collections/12-volt-battery-chargers/products/12-volt-12-amp-pro-series-battery-charger-and-maintainer - great bit of gear & good insurance for the batteries!!
This charger has a setting to "rejuvinate" the batteries which I hit all 6 batteries with & it worked well. It also has an equalisation setting as well which I didn't need at this stage.
All batteries came up great & are back in the boat & staying fully charged with the fridge etc running 24/7.
The controller still goes back to 0 amps very briefly, to check, & then climbs back up to whatever the sun is supplying.
Thanks for your help :)
I have the exact same problem with the same esmart3 charge controller. I certainly do not think this is normal at all. I have 1000W panels on a 600Ah bank (150ah/12 x 4 - Series/parallel combo). You are wasting half of the energy as the controller dips down to 0A then back up on about a 50% duty cycle. Pulling my hair out with this!
My Chinese-cheapie Tracer MPPT does this zero thing occasionally. The first time I saw it got fussed and disconnected/reconnected it, and it went back to normal but now I ignore it. For over 6 years it has done a sterling job (no pun intended) of keeping the house battery charged.
Every now and one of the too-cheap-to-be-any-good eBay buys turns out to be a bargain, and this was one of those. Sort of makes up for all the other pos's.
Cheers, Graeme