# Batteries not getting to 14.8 volts Outback 60

Registered Users Posts: 8
Hello,

I Posted in the forum about matching these 2 panels about a month ago, I used them with 2 US batteries 2200 6 volt 232 AH wired in series, and they were charged before 1 PM, I added another 2 (US Batteries 2200) 6 Volt 232 AH 5 days later to make a battery bank of 464 AH, I wired 2 in series and then together in Parallel.

I have tried to charge them in 2 days with the same 2 panels, Pictures attached, they are not finishing the bulk charge (14.8 Volts) Im getting as far as 14.3 volts. i have attached todays and yesterdays Logging stats.

My question is: Is something wrong? or do I need to add more panels?

Thanks for any help

• Banned Posts: 17,615 ✭✭
Re: Batteries not getting to 14.8 volts Outback 60

Let's make sure we've got the info straight:

You doubled the size of the battery bank from 232 Amp hours @ 12 Volts to 464 Amp hours @ 12 Volts?
You did not double the size of the array?
The batteries are not getting to 14.8 before you run out of sun?

If so, I'm not surprised. For that much battery you should have about 700 Watts of PV. (I know, because I have the same 4 batteries in a 24 Volt configuration.)
You have 120 Watts + 130 Watts = 250 Watts which is just above the minimum for 232 Amp hours @ 12 Volts.
In short, the panels cannot produce enough current to bring the batteries up fast enough to where there's enough good sun left to finish the Absorb stage.
Re: Batteries not getting to 14.8 volts Outback 60

A 464 AH @ 12 volt battery bank should be charged at ~5% to 13% of back capacity... Or:
• 464 AH * 14.8 volts * 1/0.77 panel+charger derating * 0.05 rate of charge = 351 Watt array minimum
• 464 AH * 14.8 volts * 1/0.77 panel+charger derating * 0.10 rate of charge = 703 Watt array nominal
• 464 AH * 14.8 volts * 1/0.77 panel+charger derating * 0.13 rate of charge = 914 Watt array "max cost effective"

At this point, your ~250 watt array is really on the small side. Assuming you are getting somewhere around:
• 250 watts * 0.77 * 1/14.3 volts = 13.5 amps nominal peak (clear/cool day)

Then the system is working fine--You just have a very large battery bank that is going to take a few days of charging at less than 5% rate of charge to become full.

You should also check the current to each paralleled battery string (using an inexpensive DC Current Clamp Meter), to ensure that one of your batteries is not "hogging" all of the charging current (possible shorted cell, etc.).

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Banned Posts: 17,615 ✭✭
Re: Batteries not getting to 14.8 volts Outback 60
BB. wrote: »
You just have a very large battery bank that is going to take a few days of charging at less than 5% rate of charge to become full.

This doesn't actually work on a system that is being used every day, especially if there's actually a need for that big of a battery bank. Chronic deficit charging.
• Registered Users Posts: 8
Re: Batteries not getting to 14.8 volts Outback 60

Thanks for the fast replies! should I remove 2 batteries until I get my new Panels? the reason I bought 2 more batteries is because I wanted a little more power at night. But I can wait if it means Ill screw my batteries up.

Sonny
• Banned Posts: 17,615 ✭✭
Re: Batteries not getting to 14.8 volts Outback 60
Sonny wrote: »
Thanks for the fast replies! should I remove 2 batteries until I get my new Panels? the reason I bought 2 more batteries is because I wanted a little more power at night. But I can wait if it means Ill screw my batteries up.

Sonny

Definitely disconnect the extra batteries. But if it's going to be a long wait for those new panels, reconnect them once in a while (or better yet, switch between the two) to make sure they are kept up in the interim.
• Registered Users Posts: 8
Re: Batteries not getting to 14.8 volts Outback 60
Definitely disconnect the extra batteries. But if it's going to be a long wait for those new panels, reconnect them once in a while (or better yet, switch between the two) to make sure they are kept up in the interim.

Will DO! thank you for your help!

Sonny
• Solar Expert Posts: 1,571 ✭✭
Re: Batteries not getting to 14.8 volts Outback 60

Alternatively, you can leave them all connected and reduce your loads, both daytime and nighttime so that there's more available for charging and the batteries are discharged to a shallower depth.
• Solar Expert Posts: 3,123 ✭✭✭✭
Re: Batteries not getting to 14.8 volts Outback 60
Definitely disconnect the extra batteries. But if it's going to be a long wait for those new panels, reconnect them once in a while (or better yet, switch between the two) to make sure they are kept up in the interim.

Removing batteries will insure that the charging current is high enough for good electrolyte circulation, etc. But unless the load is reduced, it will just cause a greater Depth of Discharge on the smaller battery bank and the chronic undercharge will remain. Changing charger parameters to push high current for a longer portion of the solar hours available (more time in bulk, less in absorb or float) may also help. Conservation is the easiest, unless you have already cut your usage to the bone.
SMA SB 3000, old BP panels.
• Banned Posts: 17,615 ✭✭
Re: Batteries not getting to 14.8 volts Outback 60
inetdog wrote: »
Removing batteries will insure that the charging current is high enough for good electrolyte circulation, etc. But unless the load is reduced, it will just cause a greater Depth of Discharge on the smaller battery bank and the chronic undercharge will remain. Changing charger parameters to push high current for a longer portion of the solar hours available (more time in bulk, less in absorb or float) may also help. Conservation is the easiest, unless you have already cut your usage to the bone.

Probably the opposite, since he wants to add battery capacity.

I did say the best was to switch between the two battery strings. That way they should stay fairly evenly matched even if the DOD has increased.

Basically it's a bad idea to increase one part of a system without bringing the rest of it up to match. Especially if the part you increase is the loads!
• Solar Expert Posts: 3,009 ✭✭✭✭
Re: Batteries not getting to 14.8 volts Outback 60
inetdog wrote: »
Removing batteries will insure that the charging current is high enough for good electrolyte circulation, etc. But unless the load is reduced, it will just cause a greater Depth of Discharge on the smaller battery bank and the chronic undercharge will remain. Changing charger parameters to push high current for a longer portion of the solar hours available (more time in bulk, less in absorb or float) may also help. Conservation is the easiest, unless you have already cut your usage to the bone.

Several points:
The PV he has, was plenty to supply his loads + properly charge his battery bank. The problem occurred when he doubled his battery capacity to a point where his existing PV could no longer provide enough amperage to properly charge the larger battery bank. And, since the PV is already supplying all it can, readjusting the controller to demand more from the PV would be useless, the controller cannot get what isn't there. It would be similar to readjusting the pressure switch on a water pump to a higher pressure, when the pump itself couldn't get the pressure up to the original setting. Nothing changes.
As Cariboocoot said, his best plan until he doubles his PV, is to revert to his original battery size which worked fine, and perhaps from time to time interchange the two battery packs (the old with the new). Once he doubles his PV, all will be fine again.
• Solar Expert Posts: 3,123 ✭✭✭✭
Re: Batteries not getting to 14.8 volts Outback 60
Several points:
The PV he has, was plenty to supply his loads + properly charge his battery bank. The problem occurred when he doubled his battery capacity to a point where his existing PV could no longer provide enough amperage to properly charge the larger battery bank. And, since the PV is already supplying all it can, readjusting the controller to demand more from the PV would be useless, the controller cannot get what isn't there. It would be similar to readjusting the pressure switch on a water pump to a higher pressure, when the pump itself couldn't get the pressure up to the original setting. Nothing changes.
As Cariboocoot said, his best plan until he doubles his PV, is to revert to his original battery size which worked fine, and perhaps from time to time interchange the two battery packs (the old with the new). Once he doubles his PV, all will be fine again.

My point, for what it is worth, was that if he was successfully meeting all of his loads with his existing PV and he really was in a chronic undercharging situation once he added batteries, then one or both of two things had to have happened:
1. The extra self-discharge of the added batteries exceeded the extra amount of power that the panels could deliver. (Not particularly credible) or
2. With the added battery capacity, the DOD was only 1/2 what it had been and the corresponding battery voltages caused the CC to regulate to the point where it was no longer supplying the full panel output to the batteries, but was instead spending more time in absorb or float where it was delivering less current to the batteries than the panels could provide.
I agree that the simple short term solution is to go back the original, successful battery configuration, but I do not accept that the full panel output was going to the batteries in both situations!

Not delivering a high enough (>C/12 for FLA) peak current to the batteries will affect the battery health, but it should NOT, by itself, cause a symptom of chronic undercharging.
SMA SB 3000, old BP panels.
• Solar Expert Posts: 3,112 ✭✭✭✭
Re: Batteries not getting to 14.8 volts Outback 60
inetdog wrote: »
Removing batteries will insure that the charging current is high enough for good electrolyte circulation, etc. .

Just to pick the nit, a bit. It is NOT the Charge Current that mixes the electrolyte. It is the later portion of the Absorption stage, and EQ with their higher voltages, BUT lower currents that does the substantial part of the mixing. The high currents of Bulk do allow for the batteires to even get into A.sorb, agreed.
Vic
Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
• Registered Users Posts: 8
Re: Batteries not getting to 14.8 volts Outback 60
inetdog wrote: »
My point, for what it is worth, was that if he was successfully meeting all of his loads with his existing PV and he really was in a chronic undercharging situation once he added batteries, then one or both of two things had to have happened:
1. The extra self-discharge of the added batteries exceeded the extra amount of power that the panels could deliver. (Not particularly credible) or
2. With the added battery capacity, the DOD was only 1/2 what it had been and the corresponding battery voltages caused the CC to regulate to the point where it was no longer supplying the full panel output to the batteries, but was instead spending more time in absorb or float where it was delivering less current to the batteries than the panels could provide.
I agree that the simple short term solution is to go back the original, successful battery configuration, but I do not accept that the full panel output was going to the batteries in both situations!

Not delivering a high enough (>C/12 for FLA) peak current to the batteries will affect the battery health, but it should NOT, by itself, cause a symptom of chronic undercharging.

Im living off-grid. I use very little amperage every night. No refrigeration (Ice in a cooler stored inside an old chest Freezer last 1 week) 1 LED Light powered by rechargeable batteries, 1 laptop, Satellite Internet Modem and Wireless Router, 1 12v fan. I dont have a kill a watt but Im going to guesstimate around 40-50 amps a night.

in my first configuration my batteries were at 12.3 - 12.2 volts in the morning after usage and floating by 1 pm fully charged. I also track the sun, if I get to 12v (50 percent) Im not a happy camper so this is why I added batteries. I wanted to make sure I dont take my batteries below 75 percent. I am an energy "Grinch" "Scrooge" lol! I want my batteries to last and stay healthy!