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

MrWizard
Moderator
Apr 14, 2014
Measure the input voltage at the controller with a digital multimeter
If voltage is correct, measure resting voltage of batteries after sundown
Now connect to shore power or generator and charge for six hours
Now measure voltage during day time solar charging
I suspect you are trying to run on solar only, with only one 95w panel
While this is enough to help with a weekend, and maybe recovery while in storage
It is Not enough for extended camping without aux 120v for charging
full_mosey
Explorer
Apr 14, 2014
FloridaFlyer86 wrote:
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.

I have experience with the SS gen 2 controllers.

Yours is working fine. It is a two stage charger(no 3rd float stage). During Stage-1,bulk, it charges at the panel ISC depending on the panel tilt. The Volts then increase to 14.4 where stage-2, PWM, kicks in and current is tapered down. Your solar panel is not supplying enough daily Amps to raise your battery bank to 14.4V and is not reaching stage-2.

The 12.5 resting Volts is too low and proves that the bank is not being recharged daily. This is an undercharge situation that will result in sulphation and ruin the bank.

Consult the mfgrs manual.

HTH;
John
red31
Explorer
Apr 14, 2014
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.
lasttruck
Explorer
Apr 14, 2014
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.
NinerBikes
Explorer
Apr 14, 2014
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.
pugslyyy
Explorer
Apr 14, 2014
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.
BFL13
Explorer II
Apr 14, 2014
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?

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