130ah battery bank, only 2-3 hrs at 500w?

[Steve Fractals]

Hi guys,

Recently installed 4x12v 130ah flooded acid in series to get 48v. They are Snappy Leisure (generic) and I've tried emailing asking them for charge parameters but getting no relpy.

Now from full down to 50% (65ah), I calculate I should be getting around 6hrs at 500w load but only getting less than 3 hours.

I have the following settings.
55.6v bulk
54v float
49v back to utility
54v back to battery
48v battery cut off.

I mostly use less than the 500w and mostly sit just under 400w.

My MMP AIO inverter shows that I'm at 50% charge remaining at somewhere between 49&50v but can't set in between. Tried it at 50v back to grid but get a lot less time. Trying at 49v and still get way less than the expected 6+ hours.

Should I trust my inverter remaining charge scale?

Should I be using different settings?

I know calculating SOC is educated guesswork esp on lead acid but is there a general rule of battery bank voltage to state of charge e.g. 49v=50% or some way for me to work it out approximately?

I did fully charge individually and tested that the batteries all hold a steady charge almost equal to each other. Also full charge and monitored bank holding charge etc.

If these were LifePo then I'd probs do a full to empty test and then calculate from that but reading that I shouldn't do full to empty even for testing in Lead, I know that going down to 0 regularly will knacker them bit is that true even for testing?

 

[MisterSandals]

My MMP AIO inverter show

What is the idle power use of your AIO?
Is this included in your 500w load?

130Ah x 51.2V nominal = 6656Wh (3328Wh usable)
3328Wh / 500W = 6.6h
500W x 24h = 12000Wh per day

How are you determining your 500W running load?
Are you sure your batteries are fully charged when experiencing this?

Happen to have a pic of your battery wiring? We’ve been spotting a lot of issues lately, probably because of the comet.

 

[Steve Fractals]

Thanks for your reply

What is the idle power use of your AIO?
Is this included in your 500w load?

130Ah x 51.2V nominal = 6656Wh (3328Wh usable)
3328Wh / 500W = 6.6h
500W x 24h = 12000Wh per day

How are you determining your 500W running load?
Are you sure your batteries are fully charged when experiencing this?

Happen to have a pic of your battery wiring? We’ve been spotting a lot of issues lately, probably because of the comet.

Thanks for your reply MisterSandles

Idle power is stated as <55w I don't think it includes it in the crappy Watcptower app which is what I'm using to determine loads etc. but I've accounted for it by using 500w as my load calc. Also can confirm that my inverter display is in line with the the app for load usage.

I don't have a pic of my battery wiring but should be able to sort tomoz. They are wired in series -to+ using 6mm cable (changing to 12mm soon but the 6mm not getting warm). + of first battery to inverter and - of last to Inverter.

 

[MisterSandals]

Do you have access to a DC clamp meter?

They are wired in series -to+ using 6mm cable (changing to 12mm soon but the 6mm not getting warm).

If they are not warm when running max load, then you do not have much loss from your wiring.

If you have volts, amps and length we can calculate actual loss and estimate correct wire size. How many watts is AIO inverter?

 

[Cidpineda]

Hi guys,

Recently installed 4x12v 130ah flooded acid in series to get 48v. They are Snappy Leisure (generic) and I've tried emailing asking them for charge parameters but getting no relpy.

Now from full down to 50% (65ah), I calculate I should be getting around 6hrs at 500w load but only getting less than 3 hours.

I have the following settings.
55.6v bulk
54v float
49v back to utility
54v back to battery
48v battery cut off.

I mostly use less than the 500w and mostly sit just under 400w.

My MMP AIO inverter shows that I'm at 50% charge remaining at somewhere between 49&50v but can't set in between. Tried it at 50v back to grid but get a lot less time. Trying at 49v and still get way less than the expected 6+ hours.

Should I trust my inverter remaining charge scale?

Should I be using different settings?

I know calculating SOC is educated guesswork esp on lead acid but is there a general rule of battery bank voltage to state of charge e.g. 49v=50% or some way for me to work it out approximately?

I did fully charge individually and tested that the batteries all hold a steady charge almost equal to each other. Also full charge and monitored bank holding charge etc.

If these were LifePo then I'd probs do a full to empty test and then calculate from that but reading that I shouldn't do full to empty even for testing in Lead, I know that going down to 0 regularly will knacker them bit is that true even for testing?

ok i am using 48volt lead acid at 400AH but 200AH useable i am not getting to that 200AH capacity due to my setting is 48.8volt then it goes to grid so if you want to get atleast 50% of the capacity you will have to change your setting to disconnect to 44volt peukert sucks...and if you check your data 2 to 3 hours after sunset your inverter goes to GRID or disconnects from low voltage.....same thing with my system

 

[Steve Fractals]

ok i am using 48volt lead acid at 400AH but 200AH useable i am not getting to that 200AH capacity due to my setting is 48.8volt then it goes to grid so if you want to get atleast 50% of the capacity you will have to change your setting to disconnect to 44volt peukert sucks...and if you check your data 2 to 3 hours after sunset your inverter goes to GRID or disconnects from low voltage.....same thing with my system

So with your back to grid set at 48.8v, what sort of useable Ah's are you getting? My 49 is as close to that as I could get.

Are you saying I should set my back to grid to 44v in order to use approx 50% of the bank as generic reading suggest 48.8v as you have yours set? Or just that I should set my battery disconect to 44v in order for the battery scale to report more correctly etc?

 

[Steve Fractals]

Hi all,

Some replies are saying I need to set my cutoff to 44v but it doesn't seem clear if that means I should run my batteries down to 44v e.g set back to utility setting to 44v or just the emergency cut off setting. Can this be clarified please?

Also I'm planning on individually load testing each battery using a 400w 12 heater and was wondering, is it safe for my batteries to run them to completely flat just once so I can work out what 0% is voltage wise in order to try to work out what 50% SOC really is?

So far just using the generic advice on sites that say 12v lead acid leisure batteries are normally completely flat at 11v and 50% at 12.2v but not getting any responses from manufacturer/rebadger as to a SOC voltage charts for these batteries etc.

 

[Texas-Mark]

Have you checked the specific gravity of the batteries? Can't just go by voltage with FLAs to determine SOC.

 

[Steve Fractals]

Have you checked the specific gravity of the batteries? Can't just go by voltage with FLAs to determine SOC.

These are brand new sealed flooded lead acid so haven't check the gravity yet, just googling how to check the gravity of sealed batteries.

 

[Texas-Mark]

These are brand new sealed flooded lead acid so haven't check the gravity yet, just googling how to check the gravity of sealed batteries.

Oh, I did not see you mention they were sealed earlier. Are these AGM batteries?

 

[Zwy]

The specifications are listed on this page under specifications tab. https://snappystartbatteries.co.uk/130ah-leisure-battery

Rating is 130Ah at C20 rate. The definition of C20 rate- the battery is expected to be drained at 1/20th of its capacity per hour

That comes to 6.5A discharge rate. At 500W on 48V, you are discharging at 10.41A. Peukert’s Law comes into effect. https://battlebornbatteries.com/peukert-effect/

You need to discharge at the 6.5A rate to see if the battery has the rated capacity. Or you can use a calculator such as this one. http://www.csgnetwork.com/batteryli...er is based on,Peukert number for the battery.

Inputting the rated Ah, the discharge rate of 10.41A and Peukert's number of 1.3 comes to about 3 hours for 50% capacity. Peukert's number of 1.2 comes to 3.9 hours. Considering this battery has a CCA rating, my thoughts are the plates are thinner and spaced close together and I'll wager the Peukerts's number is 1.3 even if it is a AGM.

Second, use a shunt for capacity testing or a dedicated battery tester. If using a shunt, you need a fixed load that will not vary over the test. Usually the capacity rating of any lead acid is from full charge voltage to 10.5V per battery. The bottom cutoff should be 42V for 4 in series; if you wish to test to 50%, then you would discharge accordingly.

Personally, I would test each battery individually because the problem is the series will only run to the lowest capacity battery. You then will have to recharge, break the series down and test individually each battery to find the lowest capacity cell (if one exists).

 

[Steve Fractals]

Oh, I did not see you mention they were sealed earlier. Are these AGM batteries?

No they flooded.

 

[Steve Fractals]

The specifications are listed on this page under specifications tab. https://snappystartbatteries.co.uk/130ah-leisure-battery

Rating is 130Ah at C20 rate. The definition of C20 rate- the battery is expected to be drained at 1/20th of its capacity per hour

That comes to 6.5A discharge rate. At 500W on 48V, you are discharging at 10.41A. Peukert’s Law comes into effect. https://battlebornbatteries.com/peukert-effect/

You need to discharge at the 6.5A rate to see if the battery has the rated capacity. Or you can use a calculator such as this one. http://www.csgnetwork.com/batterylifecalc.html#:~:text=That number is based on,Peukert number for the battery.

Inputting the rated Ah, the discharge rate of 10.41A and Peukert's number of 1.3 comes to about 3 hours for 50% capacity. Peukert's number of 1.2 comes to 3.9 hours. Considering this battery has a CCA rating, my thoughts are the plates are thinner and spaced close together and I'll wager the Peukerts's number is 1.3 even if it is a AGM.

Second, use a shunt for capacity testing or a dedicated battery tester. If using a shunt, you need a fixed load that will not vary over the test. Usually the capacity rating of any lead acid is from full charge voltage to 10.5V per battery. The bottom cutoff should be 42V for 4 in series; if you wish to test to 50%, then you would discharge accordingly.

Personally, I would test each battery individually because the problem is the series will only run to the lowest capacity battery. You then will have to recharge, break the series down and test individually each battery to find the lowest capacity cell (if one exists).

Thanks for all that great info. So I plan to test individually, don't have a shunt or dedicated load tester but do have an amp meter and was thinking of using a little 12v 400w heater and monitor if that load varies on use etc.

So just to clarify, should I be setting my switch back to utility(grid) at more like the 42v as you state for cut off in order to use 50% ish or is 42v completely empty 0% ? I ask because my inverter has two settings relating to this. One is "Back to utility voltage" and the other is "Battery cut off voltage" Now my understanding is that the "Battery cut off voltage" setting is for some kind of backup/emergency cut off for when no utility/grid present as the "Back to utility" is currently switching back to grid at 49v which could easily be the issue if they should be set to 42/44v etc?

 

[Zwy]

10.5V would be what the manufacturer uses for a full capacity test. As this is lead acid, you do not cycle the battery below 50%. Full charge depending on whether flooded (12.6V) or AGM (12.8V). 50% would be 1/2 the difference around AGM (12.23V) flooded (12.07V) times 4. The 49V you see would be close. and would be correct for either flooded or AGM (just a few Ah difference or less and not below 50% SOC, perfect for cycling).

If you want to check full capacity rating when specifically testing, I prefer to go 10.5V (or manufacturer test criteria) and recharge it immediately to prevent capacity loss. Otherwise it is no lower than 50% capacity discharge. Do not let a battery sit at low SOC for any length of time.

A shunt is quite reasonable in price. Once you have one, you will wonder how you did without it. As for any of the inverters out there and the SOC readings from them, I would take it with a grain of salt. The units just aren't accurate unless they contain an internal shunt.

 

[Steve Fractals]

10.5V would be what the manufacturer uses for a full capacity test. As this is lead acid, you do not cycle the battery below 50%. Full charge depending on whether flooded (12.6V) or AGM (12.8V). 50% would be 1/2 the difference around AGM (12.23V) flooded (12.07V) times 4. The 49V you see would be close. and would be correct for either flooded or AGM (just a few Ah difference or less and not below 50% SOC, perfect for cycling).

If you want to check full capacity rating when specifically testing, I prefer to go 10.5V (or manufacturer test criteria) and recharge it immediately to prevent capacity loss. Otherwise it is no lower than 50% capacity discharge. Do not let a battery sit at low SOC for any length of time.

A shunt is quite reasonable in price. Once you have one, you will wonder how you did without it. As for any of the inverters out there and the SOC readings from them, I would take it with a grain of salt. The units just aren't accurate unless they contain an internal shunt.

Thanks for giving me your time in giving me this full and very useful reply ?

 

[Steve Fractals]

Ok, I gave up trying to suss this and bought a shunt battery monitor (I went with the Wonvon) as advised. As suggested, this has given me an idea as to what the issue is but no idea how to solve it.

It seems my MPP AIO inverter is switching into float mode way to early, my inverter doesn't seem to indicate with icon etc. but I can see the charge amps drop to below 2A.

After installing the shunt battery monitor, I discharged by battery down to 44v as that seems the lowest I can go and then set my shunt to 0% battery and set the battery capacity Ah's to the 130Ah. Then set the inverter back to charge with solar and utility at 10 amps (have also tried 20amps but the recommendation for a user on here was around 15amp with my batteries and my inverter only had 10, 20, 30 etc). I don't see a time to set for bulk charging to set but as soon as the inverter detects that the battery has reached float voltage it seems to ignore my bulk charge and switches directly to float and the battery indicator on the inverter shows as full and so it then just floats it around that voltage at anywhere between .60A to 2A and so my battery never gets full. According to my shunt the inverter ramps down the charging to under 2A (mostly .60.-2.30A) at around 21% charged but of course then carries on very slowly charging at this trickle charge rate of around 1A, Trouble is at around 1A that will take 130 hours (or 100hrs to get from the 30ish AHs its reached to fully charge or at least get as high as it can.

Thinking of buying a separate charger but the 48v variety are expensive and surely it should be that my AIO should be charging at bulk for a number of hours before switching to the float rate or am I misunderstanding something?

I'm going mad but at least it seems I now know the issue after getting the shunt monitor as according to the shunt the battery only gets to about 30ah's before the AIO ramps down to the <2amp charge mark, any ideas?

 

[Zwy]

Ok, I gave up trying to suss this and bought a shunt battery monitor (I went with the Wonvon) as advised. As suggested, this has given me an idea as to what the issue is but no idea how to solve it.

It seems my MPP AIO inverter is switching into float mode way to early, my inverter doesn't seem to indicate with icon etc. but I can see the charge amps drop to below 2A.

Model of inverter and list all of the settings.

After installing the shunt battery monitor, I discharged by battery down to 44v as that seems the lowest I can go and then set my shunt to 0% battery and set the battery capacity Ah's to the 130Ah. Then set the inverter back to charge with solar and utility at 10 amps (have also tried 20amps but the recommendation for a user on here was around 15amp with my batteries and my inverter only had 10, 20, 30 etc). I don't see a time to set for bulk charging to set but as soon as the inverter detects that the battery has reached float voltage it seems to ignore my bulk charge and switches directly to float and the battery indicator on the inverter shows as full and so it then just floats it around that voltage at anywhere between .60A to 2A and so my battery never gets full. According to my shunt the inverter ramps down the charging to under 2A (mostly .60.-2.30A) at around 21% charged but of course then carries on very slowly charging at this trickle charge rate of around 1A, Trouble is at around 1A that will take 130 hours (or 100hrs to get from the 30ish AHs its reached to fully charge or at least get as high as it can.

Most likely it is a parameter setting issue.

Thinking of buying a separate charger but the 48v variety are expensive and surely it should be that my AIO should be charging at bulk for a number of hours before switching to the float rate or am I misunderstanding something?

Should not be needed.

I'm going mad but at least it seems I now know the issue after getting the shunt monitor as according to the shunt the battery only gets to about 30ah's before the AIO ramps down to the <2amp charge mark, any ideas?

I didn't see anything for absorption settings in first post so that points to a parameter not being set correctly. List your settings and model and that might shed some light on the problem.

 

[Steve Fractals]

Model of inverter and list all of the settings.



Most likely it is a parameter setting issue.



Should not be needed.


I didn't see anything for absorption settings in first post so that points to a parameter not being set correctly. List your settings and model and that might shed some light on the problem.

Hi Zwy,

My AIO inverter is an MPP PIP6048MT, its a pretty new model and so cannot find a lot of info about it or another user who has it on the forums.

I checked through the manual and also gone through all inverter settings and cannot see any mention of absorption or any settings for it. It has settings for equalization but not absorption which seems strange. Equalization is disabled as this was recommended from my reading on forums etc.

To be honest I've tried various settings on the battery bulk and float as well as back to battery, back to utility and DC low cut off etc.

My current trial settings are

5) Battery type = USE (custom user, tried the standard Lead Acid but was worse lol)
12) Back to utility = 49v
13) Back to battery = 57.6v
26) Bulk charge = 57.6v
27) Float charge = 54v (tried many)
29) Low DC cut off = 48v
30) Battery equalization = EdS (disabled)

With the settings above, my battery is currently sat at 54v and just sat there with an alternating charge between 0-0.10A and so of course isn't even putting any charge in the battery, if I increase the float then it will put a charge in but very slowly and the behaviour of the inverter/charger seems to then be flip flopping between charge at 0-2A but then gets the odd spike of 5-7-A but then immediately starts to use the battery on discharge again only briefly and then repeats.

All very strange behaviour and not sure if it needs some sort of firmware update or just that I've not set a parameter correctly, having said that cannot find any setting for absorption so wondering if that's somehow been missed in the firmware etc.

 

[Zwy]

Hi Zwy,

My AIO inverter is an MPP PIP6048MT, its a pretty new model and so cannot find a lot of info about it or another user who has it on the forums.

I checked through the manual and also gone through all inverter settings and cannot see any mention of absorption or any settings for it. It has settings for equalization but not absorption which seems strange. Equalization is disabled as this was recommended from my reading on forums etc.

I looked thru the manual and didn't see a setting for absorption either. Kinda handicaps the process.

To be honest I've tried various settings on the battery bulk and float as well as back to battery, back to utility and DC low cut off etc.

My current trial settings are

5) Battery type = USE (custom user, tried the standard Lead Acid but was worse lol)
12) Back to utility = 49v
13) Back to battery = 57.6v

I would lower this setting. With it set at the bulk charge setting, the inverter will not go back to battery until the bulk setting is hit.

26) Bulk charge = 57.6v

This appears to be C.V. charging which means it will hold that voltage, the amps decrease as battery internal resistance rises.

For that reason, I would set the battery type in setting 5 to FLD. See if it charges to the bulk voltage, then amperage slowly drops.

27) Float charge = 54v (tried many)

Is that the manufacturer float voltage? I assume it is. 54V would be fine for float, most deep cycle run around 13.5V for a 12V system and times 4= 54V

29) Low DC cut off = 48v
30) Battery equalization = EdS (disabled)

With the settings above, my battery is currently sat at 54v and just sat there with an alternating charge between 0-0.10A and so of course isn't even putting any charge in the battery, if I increase the float then it will put a charge in but very slowly and the behaviour of the inverter/charger seems to then be flip flopping between charge at 0-2A but then gets the odd spike of 5-7-A but then immediately starts to use the battery on discharge again only briefly and then repeats.

All very strange behaviour and not sure if it needs some sort of firmware update or just that I've not set a parameter correctly, having said that cannot find any setting for absorption so wondering if that's somehow been missed in the firmware etc.

 

[Steve Fractals]

I looked thru the manual and didn't see a setting for absorption either. Kinda handicaps the process.



I would lower this setting. With it set at the bulk charge setting, the inverter will not go back to battery until the bulk setting is hit.



This appears to be C.V. charging which means it will hold that voltage, the amps decrease as battery internal resistance rises.

For that reason, I would set the battery type in setting 5 to FLD. See if it charges to the bulk voltage, then amperage slowly drops.



Is that the manufacturer float voltage? I assume it is. 54V would be fine for float, most deep cycle run around 13.5V for a 12V system and times 4= 54V

Thanks again, I have tried 5 set to Flooded before and again and it does the same but is worse as it locks most the settings, tried it both with its default settings and then again with settings that could be altered etc. but with same or worse result.

I purposely set my my 13 - Back to battery to same as bulk just in an attempt to keep the battery charging and to see if it would up the charging amps back out of float but it didn't lol.

I have emailed MPP regarding the seemingly missing absorption settings etc. so will see what they have to say.