12/24v Solar Controller --> 6v Batteries

[RICH807]

Background: Purchased a used coach, came with a solar panel/controller setup that's connected to Two 6-volt house batteries. I got no paperwork for any of it but scouring the interwebs I at least found out what kind of controller is in place (a Chinese brand w/little info in the online manual). Literature describes it as a 12/24v unit.

I'm FAR from an electrical expert but it seems like the batteries are getting heavily charged during the day (boiling or near boiling the fluid... can audibly hear them peculating louder than what I'd expect. Seems like something's not right with the system but again, I'm not an electrical guy & never had any solar home or RV equipment before now.

Question: Can using a 12/24v solar controller lashed up to a solar panel send too much voltage to 6v batteries effectively killing them prematurely?

Pretty sure I need to replace these 2 house batteries but I don't know if I should go back to the OEM setup of Group-24 12v types or stay with 2 6v types.

Thanks much for any assistance you guys can offer!

[MEXICOWANDERER]

Just point the steering wheel straight and punch it. We have a solar CONTROLLER, not a voltage regulator.

[Airdaile]

I had an issue with solar overcharging that ended up being caused by someone connecting the charger wrong. You need to connect the batteries first, then the panels.

[BFL13]

Boon Docker wrote:

BFL13 wrote:
Ignore everything to do with lights and loads. Only thing to set for you is the max voltage it lets the battery get to. (Whatever they are calling that)

On the Solar30 they call it "cease charging" but all it means is that is when the controller starts controlling--ie stops the battery voltage from going any higher.

I do believe the battery charge settings are preset and can not be changed.

---It looks like a Solar30, but is not the same for how it works, so ignore what I said that does not apply to this one.---

It does say they have a four stage charging profile, so if no adjustable voltage, just set it to "Flooded" batts (vs AGM) and good to go.

EG, EP Solar has their standard profile of 14.6 for Absorb with fixed two hours at that once it gets that high, then drops to 13.6 Float. A good profile for many scenarios.

[Boon_Docker]

BFL13 wrote:
Ignore everything to do with lights and loads. Only thing to set for you is the max voltage it lets the battery get to. (Whatever they are calling that)

On the Solar30 they call it "cease charging" but all it means is that is when the controller starts controlling--ie stops the battery voltage from going any higher.

I do believe the battery charge settings are preset and can not be changed.

[CA_Traveler]

RICH807 wrote:
So I got a hold of & used a hydrometer on the batteries last night. 1 battery = almost every cell quite weak; tested out at 5-point-something volts about an hour after sunset. The other battery was in better shape but not by a whole bunch. Will be swapping them both out. Low hydrometer readings can mean the battery is not fully charged or needs to be equalized. ie It does not just mean that the battery has failed.

Have the batteries load tested which will fully charge then first, then you'll know.

ETA: I found out these batteries were put in sometime around the beginning of 2016 (when the previous owner had the solar put in).They should last 3+ years if not abused or were used a lot.

What you've posted MAY point to bad batteries but I'm not sure the batteries were fully charged (ie 14.8V bulk then absorb) let alone equalized.

For your panel: 12V panels are usually a 4x9 array of cells, easy to verify. 36 cells at 0.5V so 18V. Disconnect the controller input wires and measure to confirm. You may also be able to use a mirror to see a label.

[BFL13]

Ignore everything to do with lights and loads. Only thing to set for you is the max voltage it lets the battery get to. (Whatever they are calling that)

On the Solar30 they call it "cease charging" but all it means is that is when the controller starts controlling--ie stops the battery voltage from going any higher.

[RICH807]

Sure appreciate that.

Wondering if you guys could decipher some of this Greek I'm seeing in the controller manual? Between my lack of knowledge with these systems & their English as secondary (at best) language technical writing style it's tough sledding. 8-)


Per the manual: "The settable parameters of controller include load control mode, light-control timing, 3 time section duration
setting, 3time section power percentage, battery low-voltage
protection value, battery low-voltage return value, battery overvoltage value, and so on".

In addition to the above, I'm not sure what most of these modes do & when/if ever I should be setting the controller to operate in them:

Pure light-operated mode (L mode)
Light & timing mode (LT mode)
3 Light-control stages (3L mode)
Manual mode (H mode)
Normal open mode (24H mode)
Charge mode (Ch mode)

[BFL13]

The hydrometer will help you with the new 6s too. Voltages can be misleading, but the hydrometer tells the truth.

Solar is not enough to do it all. You should follow this guide for whatever brand of 6s you get.

https://www.trojanbattery.com/pdf/TrojanBattery_UsersGuide.pdf

I found it necessary to also have an adjustable voltage charger that can meet the higher voltage battery specs, which an ordinary "three-stage" RV converter cannot do.

This is a good one, but you have to operate it. It is not a hands free deal but nearly is, once you do the voltage setting. Easy. See the user's manual for it linked in this link.

A 60 amper is the size to get for a pair of 6s and it can be run by a 2000w gen. (the 75 amper needs more gen even though the pair of 6s could take the 75)

https://powermaxconverters.com/product/pm3-12v-series/

[RICH807]

So I got a hold of & used a hydrometer on the batteries last night. 1 battery = almost every cell quite weak; tested out at 5-point-something volts about an hour after sunset. The other battery was in better shape but not by a whole bunch. Will be swapping them both out.

ETA: I found out these batteries were put in sometime around the beginning of 2016 (when the previous owner had the solar put in).

[RICH807]

wa8yxm wrote:

First Though I now when you take 'em out and put 'em on the bench or in the back of the truck to haul to the battery store they are 6 Volt Golf Car batteries.. WHEN they are properly installed (See below) in the RV they are two halves of a single 12 volt battery.. Think of them that way

.

Good way to think about it, thanks.

[wa8yxm]

RICH807 wrote:
Question: Can using a 12/24v solar controller lashed up to a solar panel send too much voltage to 6v batteries effectively killing them prematurely?

First Though I now when you take 'em out and put 'em on the bench or in the back of the truck to haul to the battery store they are 6 Volt Golf Car batteries.. WHEN they are properly installed (See below) in the RV they are two halves of a single 12 volt battery.. Think of them that way and many questions self ansere

Proper (wires are represented by the equals sign)

Frame ====-(6v)+===-(6v)+==== 12 volt to RV

Second to answer the question quoted. ANY Charge controller or system has failure modes

One mode is : It does not do anything
One mode It never goes into "Bulk" or fast mode
One mode It never comes out of fast charge
one mode. it never switches to FLOAT

And that is ONE possible problem you have (The last fail mode not going to float)

IT is also possible the battery (one of the halves) has a shorted cell,

[BFL13]

You can disconnect the solar with a switch on one of the two wires going to the "Array" or "Solar" (whatever they are marked as) terminals of the controller. Leave the "Battery" terminals connected. Ignore the "load" terminals entirely.

You have 12v panels with your 12v battery system (two 6s in series is 12v) so all is well. If you had big 24v panels, you would have an MPPT controller.

Check the settings on the controller with the buttons for that to see what the voltage is set for. Mid-14s is good. Once it says the batteries are at that 14.x voltage, check what the real voltage is using your DMM. On my Solar30, it overshoots by 0.3v, so to get my 14.8, I have to set 14.5.

If yours is overshooting and getting the batts to 15.x, that would also explain the bubbling.

[RICH807]

Any issue with putting a disconnect switch of some sort between the solar panel & batteries? If so, would that go before or after the controller?

Thanks again everyone, I REALLY appreciate the assistance/education.

[RICH807]

BFL13 wrote:
That is a decent controller, similar to my Solar30, which is an older version of that one. It has an adjustable voltage feature. No reason not to use it with a pair of 6s. ( I did)

BFL13 wrote:
Note that this PWM controller is for 12v panels on 12v battery banks or 24 on 24. You cannot use it with 24v panels and 12v battery bank. (You need MPPT for that.

I have no idea what type of panel is on my roof, would I have to take it off the coach to figure that out?

https://www.amazon.com/dp/B018N01GWO/ref=cm_sw_r_em_api_i_c_9pwsDbFSZC9GY

BFL13 wrote:
Bubbling 6s at 13.x voltage as reported, does sound like the batteries are about shot. Confirm with an hydrometer if they are in the red or green.

Copy that, this stuff is a huge help to me.