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battery capacity

Are my SLA batteries ruined?

I've had them for almost two years. They are generic alibaba type SLAs. It seems like the capacity is getting really bad, such than the SOC is more than 25% off compared to the rated capacity. I never let them go lower than 60% according to the original SOC calculation. I'm not in an area with a lot of daylight hours currently. They're supposed to be 12v 250AH SLAs, and I have 4 of them in a 24v configuration to be 24v at 500AH. Here are my graphs and charge/BMV settings, as you can see it goes to 24v at like 80% SOC. 100% SOC sync happens when the batteries are getting like 300watts. Midpoint looks okay so shouldn't be a bad cell. Is there anything I can do aside from halving the BMV amp hours?




vulture asked
vulture commented ·

2 Answers

Minimum specification for Phoenix 24/5000 inverter.

Is the minimum 400Ah 24v pack recommended in the manual for the Phoenix 24/5000 inverter based on lead acid battery chemistry?

Would I be correct in assuming that as LiFePo4 chemistry has more than double the usable energy of lead, that a 200Ah 24v LiFePo4 would suffice (with a BMS of 1C continuous / 3C for 1s burst) ?

dion-patelis asked
dion-patelis commented ·

2 Answers

Multiplus Compact Alarm on cold mornings?

Hi all, I have been using a secondhand Multiplus Compact 1600VA 12V for 5 years, with errors every now and then. I take this to be a good run for a secondhand product, but it would be a pity to replace a good piece of gear unecessarily.

On cold mornings (<5degC) the unit wont start, and the Alarm LED light up with no pre warning code. When the day warms up, the unit will start, but makes a loud vibration noise!

Also, sometimes after running for 5 hours or so continuously with a moderate load, the unit will go into alarm mode. In these cases, the battery voltage is still good (e.g. yesterday at 13.4V). I can only think this is due to overheating? The load is never near max (1600VA).

My setup is a Victron Multiplus Compact 1600VA 12V. I only have two LiFePO4 90Ah 12V batteries wired in parallel. These are about 6 years old. I also have a Digital Multicontrol Panel but only use it as a remote control for the inverter. I have a Smart Solar 100/50 hooked up and running throughout the day.

My theories are:

1) the unit is no longer tolerant to extemes of temperatures.

2) I need to hook up the temperature sensor that I never installed?

3) My battery bank is of too small capacity for this size inverter?

4) There is some internal component that is failing

Any ideas? The charger circuit still works fine.

Any way to dignose the error? I think I have a USB connector somewhere...

staf-ivory-smith asked
staf-ivory-smith commented ·

0 Answers

Upgraded battery. How to see the capacity changed?

We recently upgraded doubled our battery pack from 10.5KW to 21KW.
But at this point we are not 100% sure if we installed it correctly. Feels like we didn't gain much.

Is there a way to see the battery capacity in VRM or Victron Connect?
Just to double check. Or are there other ways to validate?

We have now 6x polytech us3000c modules connected with Cerbo GX.
Below a picture of our System
Here you can see our Public Dashboard:

Thanks for the help


dave-hakkens asked
dave-hakkens edited ·

5 Answers

Understanding what "BATTERY 100%" really means - 100% yet still shut down low voltage

Hi All.

i have an all Victron off-grid system

48-5000-120-100-120V Inverter

MPPT-150 charger

Cerbo GX + Display

Victron DC shunt

(3) SimpliPhi 3.8 batteries @ 48V

I posess a basic knowledge set regarding electricity and such. i "designed" and installed this system myself - and it has performed flawlessly and to the specs which i targeted ...

QUESTION: What does "100%" mean ?

Can anyone explain (or point me to an article or treatise) that explains what the Cerbo Display unit is telling me as it relates to the "ACTUAL" status of my battery supply -

this morning i awoke early - just in time to hear a click and my entire system switched off/went dark...

(i subsequently figured out that my well pump had malfunctioned and run all night - fixed that problem promptly)

hmmmm. unplugged from my Victron system and dusted off my gen set so i could muddle through breakfast

as sun crested the horizon my Victron system started to "wake up"

one it had awoken - the display Showed 43.7 V (low) yet it also said "100%" in big happy numbers...

As i sit here and type this it is happily recharging, Voltage back up to 52.1V and its packin in 20A from the MPPT.

I can be awfully stupid - but i always remind people that i'm not as dumb as i look -

In the past i recall the %percentage%" battery level goin up and down with loads and charging -


how am i to understand batteries that are basically depleted low voltage (down to 43%) yet my fancy Cerbo Display is showing me an unwavering "100%".

What am i missing ? is there a way to understand this or is the display or shunt borked?

i would really like to be able to "trust the display" when it proclaims 78% that i actually have 78% of my usable Ah avail for all my fancy off grid amenities...

any thoughts or redirects to a knowledge base would be greatly appreciated


/Steve (Panda_North Photon Collective)

panda-north asked
panda-north commented ·

3 Answers

80% battery at 10.99V

I have three 100ah AGM batteries in my campervan. I've used them for 2 years.

(also a 390w solar panel, victron mppt and battery monitor)

Recently, staying in Portugal with high temps, although I've reached 100% battery each day, by morning I'm at 75 or 80%. My fridge tries to start up, runs for a few seconds then stops. When this happens, it takes my batteries from 12.17V to 10.99.

When there's enough light on my solar panel the fridge runs fine.

Being agm batteries, I can use 50% of their capacity. Its frustrating to be at 80% but still not have a working fridge!

Would new batteries help? I don't recall having this problem before, so I'm guessing they just aren't holding their charge as well as before.


missy asked
missy commented ·

1 Answer

How does this not ruin a Start Battery?

In this design example, a Sterling DC to DC converter is used to charge a lithium house bank with the Start battery as the "Source". So for example, if we are charging the Lithium Bank at 60Amps over 3hrs, how is this justified when a Start battery is not designed to provide high current over a long period of time?


ve-user asked
pau1phi11ips edited ·

3 Answers

How can I be sure Conditioning has been successful?

I have a motorhome with two 12v 110ah leisure batteries. I have no idea how old the leisure batteries are, the motorhome is 20 years old and still operating on the original charger! I suspect the charger wasn't designed to maintain two leisure batteries and this is why I purchased a Victron Energy Blue Smart IP22 Charger 1230(3) 230V charger.
It became clear the existing leisure batteries weren't lasting as long as they should powering mainly LED devices. I did what many do and replaced the batteries with new.

I've used the Victron Energy Blue Smart IP22 Charger to condition (Normal Condition) the old batteries and everything seems to have proceeded without issues BUT, how can I be sure the old batteries have been restored to a good/original capacity? I that the purpose of 'conditioning'?

Any comments/tips would be most welcome :)


stitch-up asked
stitch-up edited ·

3 Answers

Victron BMV 700 Important question (for me, anyway!)

Apparently, as part of the setup, you can enter your battery capacity (in my case, 210Ah).

Every time the charging current drops to a low value, the battery is deemed as being fully charged and the charging status is set to 100%.

It sounds as if, even if your battery capacity has dropped to,say, 50Ah, the monitor will still say 100%.

How can you see that your battery has lost capacity?

dave-martin asked
solgato edited ·

2 Answers


Hello from the southern french Alps!

In my house, my 12 OPZS batteries have been in use for 10 years. I think they should be equalized somehow. I tried:

  • the manual procedure (switch to charge only, back to on, back to charge only). No result.
  • Using veconfigure: the automatic periodic equalizing only catches with tube traction opzs. Mine are plates.

Shoul I dare set veconfigure to tube traction batteries or is there any other solution?



Lionel SEYDOUX asked
klim8skeptic commented ·

2 Answers

What size battery storage is recommended for a 3kwp pv system?

Hi, I'm currently in the process of building a 3kwp pv system. Im not sure how many batteries I will need. The batteries need to be either 12v or 24v if possible. Thankyou.

ggi2020 asked
nobodyspecial edited ·

1 Answer

Multiplus inverter low battery Alarm as the power demand increases

Hello [Victron Staff] and @Alexandra ,

I recently installed a backup system consisting of a Multiplus 48-5000/70-100 with 12 Gel batteries of 200Ah each, for a total capacity of 600Ah-48V, the multiplus automatically starts a 13KVA generator when the load exceeds 3500W, and the customer wants to reduce its fuel consumption by increasing the power of the inverter.

The problem is that I noticed that the customer's load very often goes from 2600 to 7000W when he turns on the microwave, as well as all his air conditioners, even if it lasts only a few minutes, and this produces a strong drop voltage in the batteries (High DC ripple)leading to the starting of the genset.

The section of the cables between the inverter and the batteries had been well respected during the installation, this means that the voltage drop cannot be caused by an insufficient cable cross-section and leads me to believe that the batteries are small compared to the load.

What formula can I use to calculate the current drawn from the batteries when the load is high(7500W), and thus determine the optimal capacity of the batteries?

I thank you in advance for your quick reply.

Deutch asked
Alexandra commented ·

3 Answers

LifePo4 200Ah x 2 30% reduced capacity with super long bulk charging times

My 2019 (from former boat owner) purchased 2 x 200 Ah LifePo4 Victron batteries have a significant reduced capacity. Bulk-Charging from landline via Philippi charger and solar bulk charging take forever. The maximum capacity is terminated at 280 Ah in sum of both batteries. The B2B system to an AGM is working fine. The alternator charger (Sterling) from the vessel's diesel to the starter is fine as well.

How can I locate the problem within the batteries? If there is a problem, who can be contacted at Victron, since the batteries worked perfectly the last 2 seasons...

ambutiva asked

0 Answers

Parallel 65AH and 100AH battery in 48v ESS system

I have 4 strings of 4x65AH battery's can i ad a string of 4x100AH battery's to increase the total capacity for my ESS system MultiPlus II 48v 3000VA

The battery's a SUN Battery SB12-65 (12V65AH) and SB12-100 (12V100AH)

jens-due asked
marekp commented ·

2 Answers

BMV712 battery capacity percentage

Just installed a BMV 712 on a ”house bank” of 2 deep cycle AGM Firefly’s in parallel. Just learning how to use the system but it appears that the “battery percentage” indication doesn’t go down as power is used. The Bluetooth app shows the number of amps being also shows a negative value when I turn on the battery charger. But after disconnecting from shore power and leaving my fridge and water heater running the battery percentage is still at 100%. Could anyone help out with an idea as to why this might be. Much appreciated. Thanx.....

seahawk asked
seahawk commented ·

3 Answers

MPPT 100/20 Battery Bank Size/Capacity?!

Am I correct in thinking:

I can keep adding to my battery bank capacity (Ah) as long as its 12 or 48 V and I don`t need it recharged fast with the current MPPT 100/20 Victron charge controller and the limit is how many panels I can add (up to 300W for MPPT100/20)?

I`m planning to increased my Battery Bank Capacity (add a second bank) from 160 to 580 Ah as I was given 2 X 210 Ah Lead Acid Batteries for free, but at the same time don`t want to damage my Victron 100/20...



zandi asked
wkirby commented ·

2 Answers

Probleme mit Victron GEL Batterien 220 Ah

Hallo allerseits,

ich habe Probleme mit 2 Victron GEL Batterien 220 Ah. Die wurden im Juli 2018 in einen Wohnwagen eingebaut. Seit März 2020 haben beide Batterien nur noch eine Kapazität von ca. 10 %. Getestet wurde mit einem professionellen Batterietestgerät, das über mehrere Tage definiert die Batterien auflädt und entlädt und dann die Kapazität berechnet.

Beide Batterien haben jeweils einen Victron Solar-Laderegler 100/50 und ein jeweils eigenes Victron Ladegerät 12-25. Sie sind auch nicht hart parallel geschaltet, sondern über einen Victron Combiner zusammengeführt, so dass ich Querströme ausschließen kann.

Die Solaranlage liefert 850 Wp, so dass immer genug Nachladung zur Verfügung stand. Der Wohnwagen wird ganzjährig bewohnt. Solange der fest steht (98% des Jahres), hängt der am Landstrom, so dass auch die Victron Ladegeräte die Batterien stets voll gehalten haben. Es hat bei einigen wenigen Fahrten im Winter mal eine Entladetiefe auf ca 70% gegeben, also weit entfernt von den 50% entnehmbarer Kapazität. Gemessen wurde dies über zwei Victron BMV.

Jetzt hat mir der Händler mitgeteilt, dass jeder Kalendertag einen Zyklus darstellt, und die Victron GEL Batterien nur eine Zyklen-Lebensdauer von 600 - 700 Zyklen haben. Das würde ja bedeuten, dass Victron GEL Batterien ganz generell nicht in Solaranlagen tauglich sind, wo sie jeden Tag mit Sonnenaufgang einen neuen Zyklus beginnen.

Wer kann mir was dazu sagen? Alle 2 Jahre zwei neue GEL-Batterien von Victron zu kaufen ist mir zu teuer. Wenn die auch nicht länger halten, als billige Batterien vom Discounter, warum dann Victron?

Nette Grüße


gode-re asked
Matthias Lange - DE commented ·

1 Answer

Need a battery backup for the night alone; thought of a single PYLONTECH 48V 2.4KWh

Hello friends

I currently have 37 panels feeding two 5.0 kW inverters with 4 MPPT total. Different position and size panels force me to have all strings covered. During the day I have between 60 to 80% of my power needs covered (on grid installation).

My problem comes once the sun goes, where I have nevertheless some consumption that I want to sort it out. The usage ranges from 250 to 500W on a constant basis, so I thought of getting a simple inverter/charger and one Pylontech 48V 2.4kWh, with no panel attachment; the battery would be charged during the day and if the Pylontech runs out of juice I would then allow the grid to take over.

What do you suggest I use as an inverter and how well do you think a single Pylontech will cope with that small consumption?

Best Regards,


spanishflyer asked
gherlt answered ·

2 Answers

Remaining Battery Capacity display

I have a 200Ah lead acid battery so 200 is entered into my BVM-712. Is the battery percentage display showing 100% (fully charged state) to 0% completely dead and probably ruined? or is it smart enough to show 0% as 100 amps have been used (50% of total amps and probably down to 12.2v)? If the display shows 0% as completely dead and ruined, should I set the battery capacity to 100 instead if I want 0% to be displayed when 50% of the total amps have been used?

wog42 asked
wog42 answered ·

1 Answer

Add more battery or more panels?

My system is ~3 months old and has been working well through our NZ summer, but, on cloudy days the battery voltage drops into the <50% SoC range. With winter coming up, I am trying to prioritise between adding battery capacity or adding panels. My sense is that it's 'now or never' for battery because I hear that new batteries adopt the 'age' of existing batteries.

My question is, what information produced by the system should lead me to decide on more batteries or more panels? Hoping someone can help...

My off grid system comprises:

  • 6x 320 W Trina brand panels (roof mounted so point more east than optimal)
  • 3 kW Victron EasySolar II GX (seems to consist of:
    • SmartSolar MPPT 250/70 -Tr charge controller
    • Multiplus-ll] 48/3000/35-32 inverter/charger
    • connected to VRM about 1 month after install )
  • BMV 700 battery monitor (no VE.Direct connection- should there be?)
  • 4x 12V 260 Ah AGM batteries in series

Our power draw averages around 250 W 24x7 plus 30 W for the EasySolar II GX itself. VRM says over last 30 days, consumption has been 171 kWh and production 192 kWh. I haven't found anywhere that VRM (or the remote console) tells me "but production would be higher by X if you had more storage".

Hope someone with more experience can help.

Thanks, Graham

spicedreams asked
Eduard answered ·

5 Answers

Skylla-TG 24/50 capacity of batteries

GD, sir/madam,

What can cause using batteries with this charger with smaller capacity than minimum adviced by manual (minimum 150Ah, we use one set - 24v 560A 70Ah and second set with second charger - 24v 815A 50Ah)? Last time the working time of this kind of batteries is about 1year, after charge starts fall down, should I adjust any of float/equalize/boost charging time? Thank You

neutral asked

0 Answers

Calculate DYI Lithium battery pack Ah capacity

Hi All,

I build 3 DYI jehugarcia (youtube) 18650 battery packs, each pack consist of 9 times 7x18650 cells with a 24v output. So, in total 63 cells. Each 18650 has an average 2400mAh.

So, in a grand total I have 3 packs of 63c = 189 cells.

Each pack has it’s own BMS and they are charged by a Victron 100/30 MPPT Solar charge controller. A BMV 702 keeps an eye on things and a Raspberry PI with VictronOS on it to log statistics to a VRM dashboard.

All well so far and after weeks of charging and discharging the cells are still very much balanced. A Victron Battery Protect as a measure to prevent to low a discharge and opens at float voltage to keep the MPPT as maximum power. Basically, this pack functions as an equalizer as the total capacity isn’t enough for off-grid purposes. (In The Netherlands we have clouds now and then with the sun disappearing).

The issue I have is to calculate the correct total Ah settings in the BMV shunt. I think each pack of 9 has a 21Ah capacity, so a total 63Ah. But the key question is, did I calculate it correctly?

Hope one of you can assist.

Kind regards,


robert-welling asked
robert-welling commented ·

3 Answers

Evaluate battery capacity

Hi everyone,

My lead battery (12 OPzS) is getting old (9 years). I am figuring out how to evaluate its actual capacity. The steps would be:

  1. Diminish the reporting frequence to VRM to limit error on times
  2. Equalize, measure the electrolite density
  3. In the evening, take note of time (h1) and SOC (S1) of the end of solar charging or at the very beginning of decreasing SOC;
  4. Cut off the feed from panels
  5. Next day follow SOC until 50% (s2)
  6. Note time (t2) and put back on the feed from panels
  7. From VRM note total load L between t1 and t2
  8. Cx=100*L/(s2-s1)
  9. x=(t2-t1)/(s2-s1)

I will not try to evaluate the voltage: not accurate. The electrolyte density should be enough

Any other method?


Lionel SEYDOUX asked
mvader (Victron Energy) answered ·

1 Answer

Can my van electrical setup power an induction stove?

Hi there,

I have a van that I am building out and trying to straighten some things out in my system as I design for kitchen.

The basics:

  • I have 400W of solar on roof.
  • I have 200ah Lithium Ion in battery bank. (I ran some calcs early on and was looking at ~180ah of use per day, so 200ah seemed doable. I left a space open to drop in another if needed.)
  • I have the 3000W 12 V MultiPlus Inverter Charger. (Some of my calculated items pulled a good bit of wattage (hot water kettle=1k W, induction stove ~1-1.8k W) so I figured Ok lets do the 3k W.)

I am hitting a lot of points where the inverter just won't budge though. Sometimes I'll be at a good charge say 75 - 80% of capacity and the inverter light will switch to "low battery" when I turn on the 1k watt hot water kettle. Really, at 1kW? No go. If I start the car, the kettle works. I haven't even bought the induction stove yet since I'm running into these issues.

I saw somewhere that potentially I would need at least 3 x 100ah batteries just to give enough current to the 3K W Inverter to do its thing. Is that right??

I'm hesitant to drop another $1k on a battery, although I would do it if it let me run my whole setup with the induction stove smoothly. It starts to worry me though that maybe I couldn't fill the 300ah battery bank fully with only 400W of solar. I've heard good rule of thumb is 200W solar per 100ah battery charge. I have enough room on the roof for another 50V panel..maaaybe 100W. So I'd be at 450W-500W, not the ideal 2:1 ratio. I do have an Orion that charges while I drive... so there is that. I would hardly ever be parked anywhere for days on end without moving. This is mostly a family extended trip mobile. Going for several days up to 2 months at a time remote work/travel trips. I also have a shore power hookup but don't plan on relying on that for steady refill, more of an emergency backup thing if in a pinch.

The other option would be to just swap out the 3k W inverter charger for the smaller 2k W inverter charger - if that is in fact a more appropriate current draw on 200ah batteries- not buy another battery, and just go propane setup for the kitchen stove instead of the induction stove. Thoughts? What say ye?


  1. Could my 3kW inverter charger (and solar setup) function smoothly with an additional 100ah battery and be able to supply for induction stove? Or
  2. Cutting it too close and best to go to 2k W inverter charger + propane setup?

vannie asked
vannie commented ·

2 Answers

Can I connect two Isolated Orion converters powered from different battery banks?

I want to have a common DC bus for powering a system. We already have a battery bank that has been working for a couple years and we are adding a new battery bank for expansion. Can I include an Isolated Orion DC-DC at each battery bank prior to the Bus to couple all the loads in one bus?

macevedo asked

0 Answers

Battery choice - guidance requested

So I have a small travel trailer with limited space for a battery. Have a Victron Solar controller and SmartShunt but looking for a better capacity battery than the cheap one that it came with. Draw is a handful of LED lights, USB ports etc - no need for large current draw but capacity and lifespan are king

The current battery box is 280x175x244mm so want to look for something that sits inside the same footprint

I am looking at the BAT412110081 AGM Super Cycle or the BAT412600104 Deep Cycle Gel as the two that will fit.

Which would people recommend as the better choice and which has the larger capacity?

Thanks in advance for the help!

ttttfrosen asked
Rob Fijn commented ·

1 Answer

Dumb question? Series and Parallel batteries.

Hi, this may be obvious, but I've got to ask...

I have a 12v battery bank consisting of 4x 6V, 200AH, AGM batteries.

I have 2x2 connected in series to form 12v, then these blocks of two are connected in parallel - giving a 12v system.

My question is: What is the total AH size of my battery bank. Is it simply the combined total of all batteries? ie 4x200AH=800AH

Or is it the size of only those in parallel? ie 2x200AH-400AH?


mlsp asked
mlsp commented ·

2 Answers

what settings do I use for these results on my IP65 24|8 ?

what settings do i need to use to get these results? I am lucky if i get 10Ah charged in a day


hibrn8 asked
seb71 commented ·

2 Answers

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