24V & 12V Solar Battery Hospital

[Scruff]

I built this a few weeks ago.



It's a hands-free battery recovery device. I tend to have a lottov orphans or idle batts hanging around and MorningStar are simply the best chargers I have seen.



The Shunt does nothing, it was for a meter. The meter was junk so I e-wasted the meter and left it there.
There's no loads attached. Usually, most batteries come out tippy-top after a month or so.
There's some damaged thin film panels on thuther end. They're not very good/good enough.




My truck battery was the first patient. Parasitic load left it 0V after a month... ...turns out that janky isolator I didn't approve of is there for a reason.
That's back in the truck now.



I had some gels in on the SunSaver LVD terminals with dawn - dusk lighting control isolation.



Complete with a electro-mechanical centre-tap fuse (breaks or blows)

The SunSaver is auto voltage detecting but there's a queue around the door of oddball 12V jobbers wanting to get in.
It just dawned on me to make it 12V & 24V instead of 12V or 24V.
I'm gonna put a PWM controller on the MPPT controller load terminals...I'll keep yee posted.

[Scruff]

I have a tendancy to get carried away with these things. 
The battery hospital is now Solar / Mains, 24V/12V & 12V with metering (that shunt was partially vapourised...if you have to ask...)

The PWM controller on the MPPT LVD terminals notion didn't work.
It was causing circuit breaker chatter. I had PWM Voltage but no current.
As I listened to it singing in torment wondering what to do next, I thought about asking MorningStar's advice and then I knew they'd just say no, don't do that. I thought some more and that maybe there was something to that...
I took a moment to reflect on my new no more blowing up expensive hardware resolution and recalled I had tried this before with a Mains charger and a PWM Controller...the mains charger lost.



I scrapped that this morning and reworked it.
Hehe...wiring planks in houses, too easy! So fast!
I'm used to 3D boxes in the nethers of a barge with an elbow in my armpit.
Cases/enclosures are great craic too.  Add a piece of hardware, see if the lid closes, open it, move hardware 5mm, see if lid closes...everything is metal, drill, hole, tap hole, keep fillings outtov hardware...

The My answer is MPPT twins because current limiting input.



Commissioned this evening. She's a bonnie! If I charge a battery on anything else, then stick it in here and low...there's still charging to be done...heaven's to Betsy! Almost like you can't buy anything this good!



The Remote Meter is on the Primary/Master/24V

The TriStar Meter is on the Slave/12V

If you ask me the TriStar meter works better because I get all the info without having to press buttons.

So what's in the secret sauce?



There's a 28V Meanwell 200W PSU coupled to a 20A Ebay Boost regulator set to 32V...because I didn't have a >28V power supply. This is my "utility solar panel".

The rotary cam switch switches the PSU on and changes the input to the Master Susaver between Mains & Solar.
That feeds a DC Switch-Disconnect.
That Feeds the Solar In terminals on the Master SS MPPT.
That charges one 24V battery.
I can put a second 24V battery on the Load Terminals.

I have Load LVD set to 27V
Low voltage Reconnect 27.2V

The Load terminals of the Master SS drives a relay (complete with a flyback diode).
The Relay takes a feed from the 24V battery and sends it to the Solar In of the Slave SS MPPT.
This charges a 12V Battery.
I can charge a second 12V battery on the Load Terminals.

What if there's no 24V battery that day?
Put 12V on the Master and turn off the Slave!


The unit is for maintaining idle & single use batteries. I take them in, charge them up on mains, then switch over to solar after first float.

The Ctek is a B-rate charger. It's there to charge my son's EV.



and demountable if I want to stick it on a car. I don't use conventional mains chargers. Ctek is the best I've found and they only ok and not 24V.

[Scruff]

New and Improved! We are on the Mk-V

So that boost reg. had three trimpots and no manual to be had.
It was misbehaving and I faddled with it until it towed the line. About 30mins later it fired up it's fan...that was the last straw. Out the window it went!

I made a new boost reg; this one delivers Morah Powah and higher efficiency.



Double Stacked Meanwell Twins in series.



400W and solid-state. 

!

Both are dialled up to max; 28V for more power and less component stress.

While the SS MPPT has current limiting, it's 15A non-adjustable. Twins are better. One alone was relying on the janky boost reg to bottleneck the system.
It's now 100% duty capable....that's my thing...I'm a little uncompromising about it sometimes...even when I try not to be.

The patients are packing in.



I've added a Diode Splitter to prevent sustained absorp-voltage of the Aux 24V battery (accidental feature).
The main reason for the diode was to prevent the second 24V battery powering the slave SS MPPT relay coil after the Master had isolated it (batteries both sides). Yes...that is overkill, quite...I'm actually impressed I found a use for one.
I can now have three independent 24V batteries (spare leg on the Diode Splitter) and 2 independent 12volts.


I earned myself a new trophy.



Don't wire things live! (I will probably not be listening to my own advice...or at most only when it suits me)
My €35 resistor is now a terminal block.

 

[Artful Bodger]

Double Stacked Meanwell Twins in series.

You can most likely tweak the voltage ref/ change feedback resistors on the meanwell to get 32V out. Be careful to check for a crowbar on the output side and tweak that up too.

[Scruff]

Thanks bodger I'll keep that in mind. I'm pretty happy with the twinset. In the interest of upholding my not blowing up more hardware policy the PSU output needs to be higher than the MPPT current limit.

[SparWeb]

Howdy,
There's a lot to take in all at once.  Looks like 3 major steps along the path to a flexible 12v/24v charger/desulfator for pairs or single sealed batteries.

I still don't get what the Remote Meter is showing.

Do I understand you correctly that there's a PV panel overhead somewhere?

Didn't you know: the User's Manual only exists to reassure you that it can be safely ignored.  Without that insurance you can't trust the little black box that comes with it.

Cool piece of kit there!

[Scruff]

Hi Sparweb,

I like it. Floating batteries on mains is an expensive occupation with low load charger efficiency, I try to minimise base load where I can, it comes from being a vehicle dweller.

There is a let's callit 100W solar panel thrown on the lawn compromising of 3 x 77W defective thin film freecycled panels. There's a pic in the proto-teach thread.

The remote meter is showing PSU (solar) input 28V + 28V series = 56V
Also showing watts depicted as VA in MorningStar language because they didn't have a spare W for the LCD.
 

[SparWeb]

The W and the Q cost extra.

Those panels deserve a safe spot out of the grass, don't they?

If I read it right, you're in Ireland.  There's a fellow down the road from you with an old tracking mount for you:

[Scruff]

That's certainly my kindov engineering alright. If it was auctioned as broken I'd be all over it.

Those panels nah...they're not long for the world and they're 7% efficiency when they're not broken. Outtov the 12 I stored for 2 years 5 have rated VOC.

I'll get a palette of 30 cell monos when I decide to up-spec.