Ok solar gurus - I am experiencing low voltage with my PV solar system. The charging voltage will not go above 12.8V. I'm using a Morningstar SS-6L-12V SunSaver controller (2nd gen) with 4 new Crown 6V 220 AH batteries wired series/parallel for a 440 AH 12V system, and a single 95 watt PV panel (astroenergy). The measured open circuit voltage from the panel is 20.3V. The SS-6L-12V should be charging at 14.4 volts for flooded batteries. The green charging light is on. I’m using a TriMetric TM-2025-RV battery monitor and I do get positive current flow (5A) but I’m going to end up stratifying my batteries if I don’t get the voltage up. I also have measured the voltage at the terminals of the controller and also see 12.8V there. (at rest battery voltage is 12.5V.) This is a new system (so all connections are new and clean, with dielectric grease and proper torque) but the components have been used before… over a year ago so my memory is hazy but I’m pretty sure I saw 14.4V before. I’m not too concerned about any wiring being undersized, I went overkill to avoid that possibility.So I have an email in to Morningstar but I have no idea how long they might take to respond… and I might just have something stupid going on, unrelated to the controller. Any help is appreciated, hopefully I haven’t left anything out.

You need a lot more than 5 amps to raise the voltage on four low batts anytime soon. Not enough daylight time in a day.Or if they are not that low, perhaps there is a draw on them while you are trying to charge them at the same time?

I think you are asking too much from that single 95 Watt panel. 5 Amps is about right, so in perfect conditions you might get 50Ah per day from it. That's just a drop in the bucket for that 440Ah of storage you have.

Rough rule of thumb, for every AH you have at 12V, you need at least 1 to 1.5 watts of solar panel to charge it. Since you have 440AH in storage capacity in your batteries, you'll need about 440 to 660 watts of solar panel to get the job done.

Not one answer about the voltage.Triple checking the connections would be my first step. Finding a way to test the controller would be the next. Any settings on the controller that were accidentally changed?Good point about battery drain mentioned above. Gas detector, radio memory, satellite or dvd player, etc.Sorry I couldn't be more helpful.

lasttruck wrote:Not one answer about the voltage.In each answer it is implied, a panel matches the battery voltage and as the current raises the battery voltage the panel output voltage rises.It would take days at 1% charge to get to 14v if it ever did.

PV solar system charging voltage low | Good Sam Community

FloridaFlyer86
Explorer
Apr 15, 2014
So the DLS-45 is hooked up (45 amp, somebody was wondering the output) and the Trimetric monitor is currently showing almost 110% charge level compared to the OEM converter/charger. However the voltage is only 13.9/14.0 and at the charger terminals is 14.2 so I’m thinking the wire gage is insufficient. I’m using 8 AWG and it’s 7 feet from the charger to the batteries, but I didn’t notice the wire chart I was looking at assumed 5% loss to resistance which would be a 0.7 volt drop. Looks like I’ll try 4 AWG and see if I can get full voltage to the batteries… this trial and error thing can be time consuming :-P
mena661
Explorer
Apr 15, 2014
Do you have the IQ4 module with your Iota? You need that for 3 stage charging.
JiminDenver
Explorer II
Apr 15, 2014
The OP hasn't mentioned just how far down his batteries were discharged.

Amps out have to be replaced. I took a 250 ah bank down to 12.1v resting and put a 220w system on it for the 5 hours the sun was out that day. After 5 hours the voltage of the battery had only made it up to 13v while charging even though the system was putting out 12a. I had removed around 120 ah and even without losses the system had only replaced 60 at best. It would need at least 15 hours of direct sunlight if not more to be in float.

On the other hand, I've had my 95 ah grp 27 down to 12.1v and put my 230w system on it pumping out 15a and in 3 hours it was back in float. The system had no problems replacing the 45 ah needed.

So if you have a 440 ah bank down 220 ah and want to get the voltage up fast, you will need to be putting 45-60 a back in and that's a big system. 3 or 4 of my 230w panel for 690-920w would do it.
FloridaFlyer86
Explorer
Apr 15, 2014
JiminDenver wrote:
The OP hasn't mentioned just how far down his batteries were discharged.

I put how far to the best of my knowledge, 75% amp hour wise although I know they were not fully charged, and resting voltage of 12.5. I think the 75% may actually be closer to 65% since the Trimetric only knows how to count up or down from charged.
mena661 wrote:
Do you have the IQ4 module with your Iota? You need that for 3 stage charging.

I do not, for now I think I can do without the 3 stage operation since I want to only do bulk and absorption with the DLS-45 and finish the absorption and float with the PV and SS controller.
MrWizard
Moderator
Apr 15, 2014
I have over 900 AH of battery bank
505 watts of solar panels
And I run my generator almost every morning to replace a hunk of the overnight use
Then the solar can provide the daytime use , while doing the topping off of the bank

Generally I am not an early riser, so I am not disturbing anyone at 6am, with the generator or engine, Not until 8~9am
time2roll
Nomad
Apr 16, 2014
95 watts is a bit light. 5a might be right and will take some time.
Need to disconnect all loads and give it a couple weeks. Sitting at 12.5 might need some reconditioning so it may take longer.
full_mosey
Explorer
Apr 16, 2014
FloridaFlyer86 wrote:

I do not, for now I think I can do without the 3 stage operation since I want to only do bulk and absorption with the DLS-45 and finish the absorption and float with the PV and SS controller.

Good plan.

If you plug the DLS into one of these P3 Kill A Watt Electricity Load Meter and Monitor you will be able to see the Watt draw from the genny. To save fuel, I usually shut down my genny when the charger is using under 200W.

You want to bulk charge early in the AM to allow the solar most of the day to finish charging.

HTH;
John

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