PV panels/charge controller issues

I'm sure I know this answer, but can always hope I'm wrong lol

If I switch to a 48v battery system, what would happen if I hooked my 12v inverter to just one battery in it?

I'm.guessing it's going to really imbalance the charge through the whole system, if it works at all?

So apparently the disconnect between my charge cont6and batteries was faulty. Not sure how long it's been going, but I'm guessing it was at least a while.

While waiting for the Ys to come in I just have 2 panels hooked in. Getting around 175 to 180 watts in full sun.

This morning I'm sitting here and I hear the low power alarm on the inverter start. Check the batteries, they are at 9.9 volts. 4 watts coming in. I go check the panels and wires from them to the controller, change to a different two panels. Go back in and the charge controller is dark. Like zero functioning.

I start checking the wires going from the controller to the batteries. The disconnect it hot, like hot enough that the insulation on the wires going in and out of it have started to melt. The controller flashes on and off chaotically as I'm checking it out.

So I took it out and just bypass it (for now, we're ordering new, better disconnects).

Charge controller comes on perfectly fine and the two panels are putting out 325 to 330 watts.

So we'll be replacing all our disconnects... I'd gladly take suggestions keeping in mind we're broke lol

So,

1 - suggestions for disconnect switches that will handle this

2 - all the wires I have are too large for the contact points on the controller. Is there some type of screw-on or crimp-on end that will change large wires to tabs that will properly fit?

3 - separate but related, if I switch to a 48 volt battery bank, can I pull 12v off by hooking to just one battery in the bank?

Crinstam Camp wrote:
Charge controller comes on perfectly fine and the two panels are putting out 325 to 330 watts.

That's more like it! 83-84% efficiency.

Crinstam Camp wrote:

So we'll be replacing all our disconnects... I'd gladly take suggestions keeping in mind we're broke lol

So,

1 - suggestions for disconnect switches that will handle this

2 - all the wires I have are too large for the contact points on the controller. Is there some type of screw-on or crimp-on end that will change large wires to tabs that will properly fit?

3 - separate but related, if I switch to a 48 volt battery bank, can I pull 12v off by hooking to just one battery in the bank?

1. Were your previous disconnects rated for DC? AC goes to 0v 50 or 60 times per second. This makes it much easier to break an arc that forms between the contact points. [ur=https://www.mouser.com/blog/which-switch-who-cares-if-its-ac-or-dcl]More info[/url]. Going to 2s2p might make it easier to find disconnects. I don't know anything about US suppliers.

2. Probably but supplies will be local specific.

3. Yes, but. This will put more strain on that 4th battery and so probably reduce its life. There are 48V inverters but I think that gets expensive.

It was a DC disconnect 60amp (I think? Lol)

How about Canadian suppliers since I'm Canadian?

Oh as for local. The closest 'local' place to get anything is an hours drive away (2 to return).

Most of our stuff is sourced from amazon.ca although we try to use it just to find what we're looking for then order it direct from the manufacturer/seller.

For disconnecting a 12v system, the cheapest is an automotive battery disconnect.

I use two sets of 10g wires for my battery to solar controller. I don't know if 8g will fit. Also bought from my auto parts store.

The big wire from the disconnect should connect to a bus bar (or fused distribution center) and then you have your multiple small wires connected to that.

Alex Ronan wrote:For disconnecting a 12v system, the cheapest is an automotive battery disconnect.

I use two sets of 10g wires for my battery to solar controller. I don't know if 8g will fit. Also bought from my auto parts store.

The big wire from the disconnect should connect to a bus bar (or fused distribution center) and then you have your multiple small wires connected to that.

We have 4g connecting the 6 batteries together parallel with 4g to the inverter, coming off opposite ends of the bank. From the battery to the charge controller and from it to the panels is 10g. The 10g doesn't properly fit in the charge controller contacts, I trimmed a bit of the 10g off to make it work. That's why I was wondering about a proper end for them. If I could, I'd like to have 4g for it all but the end issue is the limiting factor.

As for the 12v vs 48  inverter cost... It's the main reason I don't want to switch to a 48v bank. We also have a 12v pump, car style 12v radio, 12v router and the power to the tracking mount controller is 12v.

How do I power all that stuff off a 48v bank?

Crinstam Camp wrote:

We have 4g connecting the 6 batteries together parallel with 4g to the inverter, coming off opposite ends of the bank. From the battery to the charge controller and from it to the panels is 10g. The 10g doesn't properly fit in the charge controller contacts, I trimmed a bit of the 10g off to make it work. That's why I was wondering about a proper end for them. If I could, I'd like to have 4g for it all but the end issue is the limiting factor.

You could run 4g for most of the run and crimp a ring connector onto it. For the last couple of inches, take the largest wire that will fit in the charge controller, crimp a ring terminal on to it, bolt them together and cover in heatshrink.

Crinstam Camp wrote:
As for the 12v vs 48  inverter cost... It's the main reason I don't want to switch to a 48v bank. We also have a 12v pump, car style 12v radio, 12v router and the power to the tracking mount controller is 12v.

How do I power all that stuff off a 48v bank?

Kinda depends on your power use. If it's an even split between ac and 12v, you could run a 24v system. Have half the bank power the inverter and half power the 12v stuff.


Sorry about getting your country wrong. My fault for firing off a quick comment in between jobs.

"Have half the bank power the inverter and half power the 12v stuff"

In a word, no. It's tempting to just tap 12V off of a 24V system, but if you do that, it will unbalance the batteries. Even if you put similar loads on the "high" and "low" halves of the 24V system, the loads will never be identical and the batteries will still get unbalanced.  When I bought the county's old brush truck some years ago, they told me that it kept eating batteries. It was a 24V military truck (M211/M135 GMC deuce) but they had added a 12V radio to it, and just connected it to the "low" battery. When you do that, the "high" battery constantly over-charges. Unfortunately the truck had bigger issues (the hydramatic transmission was blown), so I never have been able to use it.

The only time you can get away with hooking a 12V load directly to half of a 24V battery string is if you hook identical loads to both halves and have them both on at exactly the same time. About the only thing that qualities is light bulbs. mo

For everything else, you're better off getting a DC/DC switching (buck) converter. They used to be expensive and hard to find but now they're very cheap from China. Also, if you're running a 24V system, look at what's available in military surplus. There are lots of 24V motors and generators available for military equipment. Some are connected to pumps, blowers, fans, and other useful things.

Crinstam Camp wrote:I've tried editing my original post twice now and failed. Likely due to a really crappy connection on our end.

The controller is a Powmr HHJ-60A mppt.

These cheap controllers work, I have a couple myself for backups. BUT do NOT trust the displayed numbers they are usually off by a fair amount. Use a multimeter for the true numbers.

Crinstam Camp wrote:

3 - separate but related, if I switch to a 48 volt battery bank, can I pull 12v off by hooking to just one battery in the bank?

If you have a 48V system, the golf cart world is ready to bestow upon you inexpensive 48V -> 12V DC/DC step-down conversion.  Just search Amazon.ca for many offerings under $30.  Most appear to be rated at ~ 20A.  Hope this helps!

The Y connectors came in today. We have clouds but there's some nice breaks in them that let full sun through for a few minutes here and there.

According to the charge controller, having the panels hooked up 2x2 is giving between 780 and 790 watts in full sun with swings as high as 825 watts.

Now that that is solved let's get back to the 48v convo ..

If we have a 48v bank we could have 2800 watts at 76 to 160v coming in?

We'd need to get 2 more batteries, a 48v charger for the backup generator, and a 48v inverter. It does suck, but it not like having another 200Ahr of storage would be bad.

The other 12v stuff I was mentioning I think can all remain coming off the load terminals on the controller. However that's based on assumptions that I can't find mentioned in the manual.  

The first being is that those terminals always put out 12v. Is that right, or would it match the battery voltage?

The 2nd is that I can pull 15 amps off them. I have no clue why I think that as I dont see it anywhere in the manual.

Edited to add: I found it in the manual. The load output voltage matches the battery bank so it solves nothing, I'll still need the 48 to 12 converters. The other is that it's 5 amps max.

James Alun wrote:

You could run 4g for most of the run and crimp a ring connector onto it. For the last couple of inches, take the largest wire that will fit in the charge controller, crimp a ring terminal on to it, bolt them together and cover in heatshrink.

Can you show me a picture of what you mean by a ring connector?

Would wrapping the 10g wire around the 4g end and putting a couple of hose clamps on it work?

I'm just now thinking that if you've got a disconnect on that line already, use that to change wire size.

So the setup would look like [controller]-[short section of 10g]-[disconnect]-[4g]-[battery array].

Are you going to use fuses in the links between the batteries in the array?

I'm not comfortable with the thought of hose clamps. What sorts of cable are you using? Copper, aluminium, CCA? Stranded or flexible?

Omg... It took me WAY too long to figure out what you're talking about lol

That is much simpler than what my mind originally thought you were talking about.

Thanks lol

Oh and it's all stranded I use. The 4g is copper the rest is aluminum.

Just in case anyone else has the same brain fart as I did on reading James Alun's description to connect two different wire gauges together lol

Yep, just remember to use the protective goop stuff on the aluminium cables to prevent corrosion.

Crinstam Camp wrote:

James Alun wrote:

You could run 4g for most of the run and crimp a ring connector onto it. For the last couple of inches, take the largest wire that will fit in the charge controller, crimp a ring terminal on to it, bolt them together and cover in heatshrink.

Can you show me a picture of what you mean by a ring connector?

Would wrapping the 10g wire around the 4g end and putting a couple of hose clamps on it work?

I like using something like this for bigger wires to smaller connection pins usually I use the crimp on variety though:
https://www.amazon.ca/Conext-Link-GAD48-Gauge-Reducer/dp/B01K1INH82/ref=sr_1_6?dib=eyJ2IjoiMSJ9.gvTMlSgZN4lPRo5hl2o6_Gg1cLyTdMg3uayH9n8yB0nZWqc9x9UDAMOCHun9WGYUss0w0HNCW7EPfx7ruihm4M3Yd7QYpJXeQOicOfWEL5wVAlL6ApPOCDSp4FpqjNrmxDISenCcQ6pA9osmzIzrEcQlRbI4N2gRxXXwjoaGOFHYxVGlqn-TbvEXIjrRnBSohMpb60Xq584qoyTofxyNrcT1G3-HufHDFKQL4ocevCkjZBuF9Cr6Gc4YFXryHBFj5khVcdt23K-h1jLcQE__xq5m52DyHeSO9tCuK8GkA-U.F90rhhRMw-VrCCWQBG0LDNToIejcsuTnRdF2cxJe4G4&dib_tag=se&keywords=crimp+on+wire+reducer+terminal+4&qid=1753298231&sr=8-6

Those are exactly what I was looking for to start with. Why would you prefer crimp on ones over reusable ones?

Crinstam Camp wrote:Those are exactly what I was looking for to start with. Why would you prefer crimp on ones over reusable ones?

torqued on ones did not pass inspection here (ontario) but that is up to interpretation the theory was that a fine braided cable being torqued in could come loose or not engage the whole cable. Try to find the copper ones if possible. digikey has them, grainger will order them in. I use the bigger ones for 4/00 cables going into the Lux 10 and 12K inverters.