Equalizing over winter absence?

Re: Equalizing over winter absence?

vtmaps wrote: »

First of all, you cannot use end amps on your system with any loads, unless you have Outback's flexnet DC.

This is not true.
If it were, the End Amps function would not have been included with the MX controllers which existed before the FNDC.
It is a bit trickier with loads as a load allowance has to be made, but it can be done and does work.

In any case it is not relevant here because there will be no loads.

End Amps is typically 2% of the Amp hour capacity.

The problem with doing unattended EQ is that there's no one there to make sure nothing has gone wrong. EQ is at higher Voltage: it stresses batteries and increases water loss. It is therefor not a good idea to do it unless you know it is needed and the batteries are able to undergo the process (i.e. fully charged and with sufficient water in them).

As it is batteries that are fully charged when disconnected will probably not suffer enough self-discharge over half a year to go below the point where they really start to sulphate. They are not going to lose 25% of capacity in that time unless they are already old and suffering (like me).

Re: Equalizing over winter absence?

Freewilley wrote: »

So I have 4 S550 at 12 volts, 400ah at 20 hr, so I set at 16 amps?
That seems high?

On the loose caps, all I know is the EQ instructions say loosen the caps when EQing....that said, I have forgotten to loosen them, at least once, and nothing happened...

S550 is a 6 Volt 428 Amp hour battery I think? Four would be 856 Amp hours @ 12 Volts. 2% would be 17 Amps in fact.

Should I ask why this isn't a 24 Volt system? It would work much better.

Re: Equalizing over winter absence?

Actually the MX does have that function, it's just harder to find. But you wouldn't need it on both if the MX is a 'minor contributor' to charging (although it may try to stay in Absorb past the End Amps point on the FM; if unable to maintain the higher Voltage it will drop back to Bulk, otherwise it could keep Absorb going despite the FM's discontinuation).

What End Amps does is terminate Absorb stage when the output current of the controller falls below the set point. In this case EA = 17, so if current <17 Amps Absorb stops regardless of time settings.

You can experiment to find the best setting by running long Absorb time and observing the current to see where it plateaus - the point where the battery has done all the Absorbing it is like to do. Check against SG if possible to see if the battery truly is charged. This is a necessary procedure when running a controller without any battery monitor, especially with concurrent loads.

Running over your sig description I see 1050 Watts of PV. On a 12 Volt system that is about 67 Amps of current. Yet you have it divided between two 60 Amp controllers. Different spec panels?

Given that, you are going to have trouble with that much battery as the peak current available is too low. Frankly your system needs some serious re-designing. It needs more PV for one thing. You should consider some possible changes such as using an FM80 or Classic 150 to replace the two controllers you have now (if PV will allow) and selling off the others. Or selling the 12 Volt inverter and getting a 24 Volt one, thus eliminating one controller as well (if possible). As it is the batteries are inevitably going to suffer without regular gen run time.

Re: Equalizing over winter absence?

Freewilley wrote: »

Thanks, good advice.
I have two controllers because it is too much PV for one....800 watts is the max recomended on 12 volts bank. When I added a panel I was told, after the fact, that I was over and should add another CC. And yes, I have two different arrays, one of 2 240 watt panels fixed on the roof facing WSW, and the other 3 that pivot (on the ground).

Who told you that? 800 Watts on a 12 Volt system might make 52 Amps. A 60 Amp controller can handle around 900 Watts, but not 1050.

Two different arrays isn't as much of a problem as two different array specs: i.e. Voltage not the same between them.

I have already decided that I need to add more PV, and will add 2 240 watt panels next spring.

You need about 1340 Watts minimum for that battery bank so another 480 Watts would be good.

Any idea where to find the end amps on the MX? I went through the ADVANCED tab, which is where it was on the FM

Which is not where it is on the MX. It is under the miscellaneous screen, page 3.

Note that where you have two controllers supplying enough current each to exceed the desired End Amps setting you should divide it between the two: 8 Amps from one a 9 Amps from the other. You will still have to watch it for a cycle or two to see how it behaves. Ideally both will drop Absorb at about the same time, but it really depends on how the current is divided up between the two. If more comes from the MX when charging then its End Amps setting needs to be the higher portion of the total.

I hope that's not too confusing.
At least is shows why the MidNite Classic has the "Follow Me" function and WhizBang Jr. - makes things much easier for multiple controllers!