question

I've got a 12v 320Ah Narada Lead Carbon battery bank, a Multiplus 1200/12/50 and 3 SmartSolar MPPT 75/15's connected to 3 separate solar panels.

The problem I'm having is the MPPT controllers tripping over each other going into float WAY too early. So on the daily chart I'll have one controller yielding as much as 1300Wh while the other two will yield as little as 200Wh each. At the end of the day the battery is not fully charged either.

The dominant controller can be any of the controllers on any given day. The wiring and settings are the same for all three controllers. I guess it just a software race condition which one detects the 1A float first. As soon as is does that 1A load goes to the remain controllers.

Is it possible to have them share better. Does the BMV or Smart Sense Synchronise them at all. As it is they are operating at about 30% efficiency once two drop out.

Seems that only one MPPT controller can be the only charge source in the circuit. Otherwise once any one hits the 1A float threshold it go to sleep and doesn't wake up again. Leaving just one controller to do all the work and the battery no where near charged.

The situation is exacerbated when the generator is fired up. All the MPPT go to sleep because the generator is providing all the charge current. Then when it is turned off often only one charge controller comes back to charge and the other two stay on float even though the battery might only be 30% charged.

These MPPT charge controllers do not play at all well with other charge sources. Including their own kind. Is there any way to have them act as a simple power supply? That is just providing a voltage to battery and allowing the battery to simply absorb what it can? Or maybe get rid of the 1A threshold or have a timer that checks periodically if the battery can now accept greater than 1A and go back to absorption.

Basically modify the algorithm somehow so they're get back to work when they can. At the moment it's like having an employee that gets things done in the morning then goes to sleep and doesn't bother checking if more work has arrived because the other bloke is doing it all by himself and struggling at it as a result.

Seems theses things are too smart for their own goodand as a result are constantly tripping over each other. After which they don't get up and back to work again for the rest of the day! If it was an employee you'd fire them for not being team players! Lol

So when you say in the reply above "not enough difference to worry about" I'd love to know how you get there with this tech. :-)

Any solution would be appreciated.

Cheers,

Troy

I only have experience with lithium batteries, so there the BMS controls all the charge sources, couldn't the same be done somehow with lead-acid? Like DVCC controlled by bmv?