Just installed a 48v 3000 ah batery bank
Hi
Just installed a 48v 3000 ah batery bank after our 1500 ah battery bank wouldn't hold charge.
The problem is its at 57.2 volts and it's only charging at around 30 amps. This seems off to me .
Shouldn't such a large battery bank be charging at a higher amp rating at such high volts? Not sure how that works.
I think the bank is about 90% full. So is it charging at 30 amps because it's only charging the 10% portion which is 300 amps?
Just installed a 48v 3000 ah batery bank after our 1500 ah battery bank wouldn't hold charge.
The problem is its at 57.2 volts and it's only charging at around 30 amps. This seems off to me .
Shouldn't such a large battery bank be charging at a higher amp rating at such high volts? Not sure how that works.
I think the bank is about 90% full. So is it charging at 30 amps because it's only charging the 10% portion which is 300 amps?
Comments
Thanks
What charge controllers? What are your charge controllers saying?
30 amps each from 6 charge controllers? a lightly overcast day...
...or you are 90% full and you are out of bulk, battery slowly reduces what current it will take, but voltage should be regulated by charge controllers.
If the charge controller say Float stage they are just reducing voltage and will settle in at your set 'float' point.
What does you hydrometer say?
Tools?
-Charge controllers
-Clamp meter
-hydrometer
- Assorted other systems, pieces and to many panels in the closet to not do more projects.
Out of 6 charge controllers only two are working. There is a power draw from the inverters of 10 amps and a charge current going to the batteries of about 30 amps from 6 charge controllers.
I'm confused as to why a 3000 ah battery bank is only charging at 30 ah. Is this normal?
Please answer Photowhit's questions, in particular what controllers are you using?
Do you have an hydrometer? If so, what is the specific gravity of the electrolyte? If not, buy one.
By the way, saying that "battery bank being charged at only 30 ah" makes no sense. I think you mean that the charging current is only 30 amps (not amphours).
--vtMaps
It is best if the controllers are networked or failing that calibrated, so that they all move to absorb and float at around the same time. However multi controller setups will always share unevenly.
If you would like more help please post full system specs.
http://zoneblue.org/cms/page.php?view=off-grid-solar
Yes I mean charging current is around 30 amps.
No I don't have a hydrometer. What's it for?
I have 6 charge controllers. All victron 150/70 connected to 3000 ah 2V batteries arranged in 48v . Running 3 victron Quattro 10 kw inverters arranged in 3 phase.
My problem is I think the charging current of the batteries is low. Also another problem I noticed with batteries is, by the end of the night around 5 am the voltage drops to 47 v . The batteries have a constant draw of 8 amps from sundown around 5 pm to sunrise around 7 am. I think this voltage may be a bit low considering it's a new 3000 ah battery bank! What do you think?
A hydrometer measures the SG (specific gravity) of the battery electrolyte. That tells you the SOC of the battery. You can buy an adequate hydrometer for $10, but I like this one: http://www.solar-electric.com/midnite-solar-battery-hydrometer.html
You need to figure out why your charging current is so low... I would need many more details of your system to make a diagnosis. Time is of the essence, you can ruin those batteries in a few weeks if you don't get them properly charged. We (on the forum) can help you figure this out, but you have a lot to learn and not much time. Who installed your system? Maybe they can help.
--vtMaps
I just question given by poster. Reporting leaves a bit to be desired.
I particularly question the amp draw. 8 amps at what voltage? Battery voltage or 3 phase voltage? Not sure if his inverters can output 480v. Obviously 480v vs 48v is a factor of 10 different.
He does have major issues regardless.
My question for original poster.
Amp draw over night, how is that measured. And at what voltage is that.
What is charging voltage when charging in morning, then mid day. Be more specific about charging as compared to first post,
And hydro meter is a must.
Animatt
What is your charging current in the morning? Charging current when the solar panels (array) is fully exposed to the sun? Do all your charge controllers read the same or is there a single display? If you have a single display does it read for a each charge controller separately?
So you have an 8 amp load and I will guess at 400volts? That would be 8amps X 400volts = 3200watts (amps X volts = watts) 3200 watts ÷ 48 volts = @67 amps call it 70 amps since the inverters will use a bit. . . Over 14 hours 14 x 70 = 980 Amps from your 3000 amp battery bank! If you are measuring the voltage while it still has a 70 amp load I'd say you are in the ball park at 47 volts. If you remove the load and the solar array and wait a half hour to an hour, I would expect the voltage to gradually increase to about 49 volts.
Yes, you have a lot to learn and an expensive system to make mistakes with! You had a previous smaller battery that died, if it had the same load did it fail over night?
I would familiarize your self with a hydrometer, which checks the Specific Gravity(SG) of the Batteries electrolyte (acid). The Specific Gravity of the batteries is the most accurate way to see what state of charge the battery is in. You might check with the manufacturer of the battery or possible on the information plate of the battery to find out what the specific gravity of the electrolyte should be.
Check to see how your charge controllers and display work. You may have a single display that is showing each charge controller individually, There may be a method to set it up to give you a total of the charging current.
30 amps from each of 6 charge controllers would not be out of the question. a 20,000 watt array would be expected to produce 20,000 ÷ 48 = 416 amps. but panels are rated at optimum conditions. Normally they produce about 75% of panel rating or 416 x .75 = 312 amps. 312 amps from 6 charge controllers = about 52 amps each.
The odd thing is rarely do system work at the max, your large array starts producing when the sun comes out, as it charges the voltage rises, so as you approach it's maximum ability the battery voltage rises, and the battery fills. So by 11 you likely reach absorb with the voltage being limited by the charge controllers at about 60 volts. So to do the math at 60 volts 20,000 ÷ 60 = 333 amps. . . 333 amps x .75 = 250 amps . . . 250 amps ÷ 6 (charge controllers)= 41 Amps available, but your battery has reached absorb cycle so it is accepting less amps and will taper off until it reaches the float stage.
Hope this helps, we are working with limited information and all this could be erroneous (badly incorrect)
- Assorted other systems, pieces and to many panels in the closet to not do more projects.
--vtMaps
- Assorted other systems, pieces and to many panels in the closet to not do more projects.
http://zoneblue.org/cms/page.php?view=off-grid-solar
PV brand and model, string configuration, cable lengths & gauges, battery brand and model, charger setpoints, Some photos will help as well.
http://zoneblue.org/cms/page.php?view=off-grid-solar
Thank you for all your replies.
Will try to give as much info as I can.
I will get a hydrometer asap.
I have uploaded a log file of the last 2 days.
Also a chart of the battery bank voltage and amps. Unfortunately because the charge controllers aren't being recognised by the color control gx I cannot include them in the logs.
https://drive.google.com/file/d/0B-SkKoJuefl4ZFVRRHlQcnNrVDg/view?usp=docslist_api
http://imgur.com/t6N2bIG
We just changed all 6 of the charge controllers to victron 150/70 and connected them in parralel. I suspect they need an update though.
Another thing I noticed is that since we installed the charge controllers in parralel they have been charging the batteries nearly all day.
The battery bank is from an unknown Chinese company. We just imported them from China and installed them ourselves. Unfortunately we don't have people who know or supply battery banks here. All I know is they are 2V each and 3000 ah. And weigh a ton! I really hope we don't have to replace them soon!!
PV brand unknown another Chinese OEM.
İ will dig up some more info on them and let you guys know. Total of 20 kw of panels.
Right now in North Cyprus, we have full sun everyday and temps around 20 c.
I'd have to check the settings for bulk float etc. But the log would give a rough idea.
I have a battery meter victron bmv 600 s . İt's supposed to work with Peukert's law. It shows the batteries being 100% full all the time.
this is a GOOD sign, let them run and monitor frequently, ie log the numbers for everything you can see...V, A, hours in a stage of charge, BULK, Absorb,Float etc, of each Charge Controller...
KID #51B 4s 140W to 24V 900Ah C&D AGM
CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM
Cotek ST1500W 24V Inverter,OmniCharge 3024,
2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
West Chilcotin, BC, Canada
Based on the graph you posted it appears that :
1) For the days in the graph there was no PV charging input into the batteries or,
2) You have installed the shunt that the Victron BMS uses in the wrong place ie. not in the common -ve lead that goes to the battery from both the charge controllers and the inverter(s).
I would guess the shunt is on the -ve lead to the inverter - however this should result in the SoC on the Victron continuously decreasing not staying at 100%.
I will have a look at your spreadsheet.
"The batteries are sealed vrla batteries and therefore cannot be measured by a hydrometer"
Do not do any equalization.
I do not know what a vria battery is
but if it is a sealed battery, better not try any equalization until you know what is going on.
Many AGM manufacturers do recommend equilization, but it's not the same type of equalization that a flooded LA battery uses... AGM equalizations may just be an extra long absorb stage, or if the voltage is raised above absorb, it is only by a couple of tenths of a volt.
--vtMaps
Your spreadsheet of data seems to indicate that you are only using a total of ~217ah in a day of which only ~80ah is used from sundown to sun up.
If this is correct then the SoC in the morning should be ~98% - this does not correlate with the battery voltage drop - unless your batteries are severely (totally) sulphated?
Hopefully someone else can assist here as I think I am out of my depth.
I've uploaded another graph of the last week.
http://imgur.com/sxUtW65
It's been 3 days since I've updated and synced all charge controllers. As you can see in the graph. Before the update and sync the charge controllers were in absorb almost all day.
Since sync and update, the last 3 days, it only charged the batteries for about an hour 1st thing in the morning. Which makes more sense given the 3000 ah battery bank and only 500 w consumption throughout the night.
Now the only thing that confuses me is the low voltage drop at night! Next i will connect the battery monitor to the system to get an accurate reading of the voltage.