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charging battery

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Screenshot_20210924-135225.pngI have been watching the charger for a few days trying to get my batteries 100% charged so as I can synchronise my BMV-700.

Also trying to get the charger into Absorption phase.

Maybe this will start happening once fully charged.

The screenshot attached shows a change where the charging pattern suddenly changes & then every 10 minutes there is a downward spike.

There was no change in the weather, clear sky, full sun all day.

Can anyone explain the change in charging & the regular spikes.

nelsonpk asked

0 Answers

Inverter/Charger keeps toggling

Can someone help me out. When I switch the charger to on, the green light "mains on" turns on and blinks. After a few seconds I hear a relais toggling, "low battery" flashes once and it toggles back to "mains on". Can anyone point me in a direction what to do next.

Some more info:

I have a Victron energy combined inverter / charged (Phoenix Multi 12/2000 100). It is in a boat (just in posession) and no experience with the charger. One of the two battery was dead and I replaced both (from 2x12V/130Ah to 2x 12V 110Ah). I am not sure if the charger was working correctly before I replaced the battery.

When I measure the voltage on the battery with a voltage meter it shows 12.4V, same as the Victron BMV-501 indicator shows. I never measure a loading voltage when I switch the thing on. Battery came straight from the shop.

Edit: typos

markwilde asked
jeffles answered ·

5 Answers

Low voltage on a LiFePO4. Is it dead?

I just bought 3 x 12.8v 160AH victron batterys, sold as 'good'.
Two are indeed fine, and I've connected them (separately) to a BMS 12/200 as they haven't been used for a while, to re-charge & re-balance.
The 3rd however is reading 9.8v, and the BMS won't allow it to charge, presumably a low voltage protect.Is it dead? or could I try applying a normal charger, to try & boost the voltage above the low voltage limit?I'm guessing its dead, but I told the seller I'd see if anything could be done.



Also, I can't seem to find any info specific to this battery on the Victron website, just the smart batteries, which look a little different, so could someone tell me more about this battery? ie, is it a 'Smart Battery'? I guess its an older, non-smart one, but I'm not sure.
Also, does it have a BMS built in? so I can just charge it with any charger? or do I always have to use the BMS 12/200?
One more thing :) does that mean it doesn't have the bluetooth monitoring?
If thats the case, is a BMV700 the best kind of monitoring system?
Basically, I have one working system in a camper, with bms12/200, which is great, but doesn't have any monitoring yet, and I'm looking to build a second, larger one, with solar, and monitoring for both.

Thanks in advance.

opus asked
seb71 commented ·

3 Answers

Brand New Victron LiFePO4 battery - cell imbalance


We purchased 2 x Victron LiFePO4 battery 25,6V/200Ah Smart BAT52412041 for a customer install

Upon the first charge 1 battery had 2 cells go over-voltage (BMS cutout) well before full charge state. the other battery is in perfect balance.

Question: what is the factory balancing tolerance?

There seems to be 2 scenarios here;

1. If the cells WERE balanced in the factory and they went out of spec on the first charge then this indicates a capacity defect (ie 20% below) - they should be replaced

2. If the cells WEREN’T balanced in the factory then we also have a defect that cannot be rectified on our end (sealed cells). And this would have reputations implications for Victron. Although we could attempt it, we wouldn’t be prepared to undertake surgery to parallel and balance the cells as this would void any future warranty. Also doesn’t guarantee solving the problem.

I can see that Victron publish a method to bring them back into balance (without opening) however this is supposed to only be needed for batteries that have gone flat or have done thousands of cycles. Note these batteries were sitting at healthy voltages when delivered.

Good battery cell voltages 3.41, 3.40 , 3.40 , 3.40, 3.40 , 3.41 , 3.41, 3.41

"Bad" battery cell voltages 3.71, 3.37, 3.37, 3.37, 3.37, 3.37, 3.37, 3.53

The wholesaler is enquiring with victron but i'd like a second opinion.

Thank you


brette asked
renrgize answered ·

2 Answers

5% mid-point voltage deviation in final 10% of charge


I'am using two serial 12V 122Ah AGM batteries to get 24V. I'am measuring the Mid-Point Voltage via a SmartShunt and a Multimeter.

Between the Batteries there is a thirdparty balancer which measures the voltage of each battery and charges the one with less voltage with up to 2A to equalize.

Also the Battery are AGM of the type "China" :)

+ ---[BAT1]---[BAT2]---- -

I'am charging the batteries with a victron IUoU Charger which delivers maximum 15A

Absorption Voltage is set to 29,4V, compensated by 60mV/degrees measured at the surface of BAT1

so far so easy.

Usually Absorbtion starts at a tail current of around 10A and from around 6-8A tail current (approx. 95% SOC) the Mid-Point deviation reaches 4% or more.

Today: at 94%, 4A Tail Current BAT2 got 15,3V out of the 29,6V feed. For testing reason, the balancer has been removed.

The Age of the batteries is 1,5 Years, i never discharge it more than 70%SOC.

What could be the issue here, higher inner resistance of one Battery? is there a way to mitigate that?

Marco Meile asked
Alexandra edited ·

1 Answer

Charge Lead Carbon batteries

I have a Victron MPPT 100/30 and need advise how to configure it for 3 Lead Carbon batteries (parallell).

Any changes needed?

The spec for the battery:

What temperature compensation should I use?


paros asked
pwfarnell answered ·

2 Answers

Should I change wiring to "in series"


I just moved my 75/15 controller from the portable solar panels (2) closer to the battery as I was getting incorrect info through the app due to losses through the cable.

Now I am getting accurate info through the app but the voltage is not getting to the controller to go from bulk to Absorption phase, again due to losses through the cable.

If I rewire the panels in series this should fix the voltage issue but I'm concerned the lower amps will reduce the charging.

nelsonpk asked
nelsonpk answered ·

3 Answers

Correct Settings with SmartSolar MPPT for Ective AGM DC170S Batteries

Hi :)

Today I installed my first SmartSolar MPPT (100 / 30) and connected it to my AGM batteries (2x Ective DC 170S). Then I opened the mobile app and started with the configuration of the controller. Now I'd like to ask you whether I did well or if I'm just a stupid newb ;-)

First here you can see the battery specification:


In the app I customized the battery settings as follows (simple mode, not expert mode):

- Absorption voltage: 14.90V

- Floating voltage: 13.80V

- Compensation voltage: 16.20V (default value)

The other settings at the battery settings tab are still the default values.

Is this cone well so far? Shall I change something?

What about the setting for the load output? Shall I stay with the mode "BatteryLife"? I use the batteries inside a camper van and got also a alternative power suppliers that are loading the batteries, but I want to maximize the usage of solar power.

Thanks so far! Looking forward to your expert knowledge :-)


julsky asked
Paul B edited ·

1 Answer

Turn on Battery Box Fan with Multiplus-II 48, MPPT-258, Cerbo GX

Looking for a way to turn on the Zephyr vent fan during charging of AGM batteries in an insulated battery box that is in a cold weather location. Charging can come from solar or generator.



jeremyindenver asked
Kevin Windrem answered ·

3 Answers

Why is VE.BUS voltage used instead of Battery Voltage for change of Bulk to Absorption ?


I could not understand why my system was switching to absorption before reaching the indicated value (55,2v) and then I stumbled upon the VE.BUS DC Voltage difference with Battery Voltage ...

There is a difference and there might be reasons for it ... but shouldn't the charging state be triggered by the battery voltage of the system instead of VE.BUS DC voltage ?

Does anyone know if there is a way to configure this and/or make sure VE.BUS Voltage is the same as the Battery Voltage ?


gregoryfierens asked
JohnC answered ·

1 Answer

MultiPlus 800VA – Two DC outputs for charging two batteries

Hello everybody.

Guys I am testing a Multiplus 800 ( NOT a Multiplus II ) ,and I have a question regarding the possibility to charge the ENGINE battery ( i.e second battery ) using a dedicated output on the Multiplus 800. On the Multiplus 800 Manual is written :

Two DC outputs for charging two batteries

The main DC terminal can supply the full output current.

The second output, intended for charging a starter battery, is limited to 1 A and has a slightly lower output voltage.

I noticed that even if the Multiplus is diconnectted from the line power ( i.e 220 Vac ) and is not working as a charger , on the second output ( used to charged the ENGINE BATTERY ) around 13 Vdc are always present. I suppose this voltage / current is provided by the Lithium battery ( in this scenario ).

Question :

Is this behavior correct ? In other words when the Multiplus is not charging any battery is it correct that the Lithium battery is it charging permanently the ENGINE battery ? Can this ( small but ) continuous drain cause a problem to the Lithium battery on long term ? OR is it working "as expected " ? I have a 100 A Lithium battery with EXTERNAL BMS.

Thanks in advance for your help.


Oscar asked
Oscar commented ·

1 Answer

12v-12v 30A Orion smart settings for Probat 130ah deep cycle lead acid battery

I am having difficulty finding a data sheet for the Probat, 12v 130ah, deep cycle, lead acid, maintenance free/sealed, leisure battery.

Does anyone have the data sheet or is anyone using this battery with the Orion smart 12v-12v 30A DC-DC Isolated charger and could provide the relevant settings/setup for this battery.

bigcrazyk asked
Alexandra commented ·

0 Answers

Multiplus II charge - feed-in priority

Hi everyone,

a question in regards to the Multiplus II and ESS:
As per my understanding, when we have AC solar on the Multi's output (with the 1.0 rule obeyed), the solar delivers power to the load first, excess will be used to charge the battery and once they are full it will export to the grid.

So the question is can this be changed to: power the load first, export to the grid afterwards without ever charging the batteries? The charger can be turned on and off in the software I have seen. So, if it is off, would all excess energy be fed into the grid automatically?


The reason is a very high fed in tariff I have for this solar and of course I want to export as much as possible. The batteries will be charged form MPPTs solely.

Thank you.

Andy from the Off-Grid-Garage asked
Nico Bayer commented ·

4 Answers

Why MPPT is overcharging

MPPT 75/15 overcharging

It was working all fine for 3+ months but then I saw that it charges the battery in 16v+ range. Few days before that I used the same controller to charge another battery and then switched back to the main battery. I don’t know if that triggered some problems because it was cloudy on those days.

But now, if it’s sunny, it goes to 16v range and always stays in a BULK mode (flashing fast), never going into Absorbtion or Float. I tried disconnecting everything and connecting to another Victron battery and the same thing, as if the charger thinks that the batteries are 24v, but they are 12v. Could that be a problem? I don’t have a dongle to check it out, can’t buy one because shops are closed. Is there anything else I can do to find the cause of the problem or temporarly fix it?

My set up:

2x 120w solar panels connected in series.

MPPt 75/15

130ah battery.

As I said before, it was working perfectly for few months and then suddenly the problem occured. Currently my solution is to disconnect the panels if its a sunny day, but my campervan fridge drains it quite fast. I tried partially covering the panels but strong wind blows anything off the roof…

Thanks for help.

andzei asked
eltgeorg commented ·

5 Answers

Easysolar/ multiplus 48v, connecting 54v and 48v bateries?


I'm running 24x 2v bats that's goes up to 54V.

I would like to connect Few more 12v batteries (probably 10 or 20)

What would I need to connect in safe way? Is it even possible or I have to just bridge 12v bateries to 48v and scrap my old 54v battery pack?

Thank you


magicmike asked
magicmike edited ·

1 Answer

Charging TS 800 is not working in my van


I installed a TS800 in my Sprinter (2011) but it's not working.

I followed the installation schedule and everything and when I connect my laptop to the TS800 it says that I have an output voltage of 14.5V and 2.5A but my BMV712 monitor says that I'm not charging...

What can be the problem?


coordinotes asked
Matthias Lange - DE commented ·

0 Answers

Adaptive absorption after deep discharge several days ago

Hi, I do have two AGM batteries with a total of 190Ah, 200W Solar Panels and a SmartSolar 75/15. It happens that my batteries go down to 50% and due to not enough sun the charging back to 100% takes a few days. But then only 50 minutes of adaptive absorption is applied. As far as I understand 4 hours would be preferable after a discharge to 50%. But as there are other days where the batteries only move down to around 80% and are fully charged again the same day, 4 hours absorption may not be the best option for every day? Do I understand correctly? And what is the best setting to use? Should I change the setting once a while to get a full 4 hours absorption?


The image shows a 50 minute absorption time today, after 6 days of bulk loading. The batteries where down to around 50% on the 17th. Thats when I turned off the fridge to get them charged again.

momonu asked
momonu commented ·

1 Answer

Batteries won’t charge

After having Victron solar/inverter/ monitor with 6 bb batteries working for a while, the batteries won’t charge past 13.05. The only thing electrically that has occurred is the rv dealersheap had to disconnect batteries/no power to rv while doing some other maintenance. The Victron 712 battery settings are the battleborn recommended settings. Soc is at 88 percent now after I set it to manual, when this started it was 100 percent and on auto.

benbpilot asked
Matthias Lange - DE commented ·

0 Answers

Boondocking with BMV-712: SOC error? Best practices?

I have the following setup: smaller 2015 Lance travel trailer with 2ea 12V lead acid flooded batteries in parallel, BMV-712 and the standard Honda 2kW generator. The trailer's battery charger seems modern (3-stage charging, lots of amps, etc.).

I plan to boon dock (no shore power) regularly and would like to tune the BMV-712 to help keep the batteries charged, healthy, and to know when and how long I should run the generator.

From research, I know I should always keep the batteries above 50% capacity to avoid premature replacement costs. Also, without many hours of charging (e.g., plugged in or on solar), I cannot expect battery capacity to rise above 90% while boon docking.

When charging from, for example, ~60%, the charger will be in the "bulk" mode with high current, and rising voltage. This charge mode is the quickest, but only gets to 80% capacity.

Then the charge mode changes to "absorption" where the charger voltage is held high (14.6v in my case) and then the amps fall off toward ~2amps (in my case) when the charge mode changes to "float" at which the battery capacity is at 90%. To charge from 90% to 100% capacity would take many hours and isn't reasonable while boon docking.

Therefore, while boon docking, I should expect to cycle the battery between 50% and 90% depending on loads and generator run-times.

However, AFAIK, the BMV-712 is designed to treat the 90% charge state as "100% SOC" (?) The BMV-712 decides that when the voltage is the high "absorption" mode, and then the current drops below a "tail current", it proclaims SOC = 100%. But in reality, the battery is at 90% capacity at that moment (i.e., at the end of the "absorption" mode).

If starting from a full-charge (i.e., batteries have been plugged in for a day), the SOC value will be fairly accurate. However, if not starting from a true full-charge (allowing the BMV-712 to auto-sync the 100% SOC value at the end of the absorption mode), the reported SOC value will be 10% lower than reality. So the accuracy of the reported SOC value depends on whether the previous charge completed the float mode? Is this true?

If that's true, then I must tweak other settings to make the SOC value match reality or add-in some fudge-factor or work-around.

I could:

  • tell the BMV-712 that the "battery capacity" is 10% lower than the battery specification.
  • set my "SOC relay (charge floor)" to 60% instead of 50%, and mentally never let the reported SOC value fall below 60%

Is this a known problem with the BMV-712 SOC value? What do others do to work-around this inaccuracy?

Do other boon dockers have tips on using the BMV-712 to stay confident that the generator is running for the right amount of time?


goodguy5000hd asked
captn-mike answered ·

2 Answers

Why is my battery combiner not charging the second battery?
I have installed a Victron Cyrix-ct 12/24V-120A intelligent battery combiner but its not charging the second battery.

Any suggestions as to why its not charging the second battery?

Main battery is 13.9v but the second battery is 10.4v

The 100A fuse is OK and I will check the wiring tomorrow but I'm confident its correct

Peter asked
Peter answered ·

1 Answer

How to setup Smart Blue IP65 Charger on Campingsite

Hi @all, i just arrieved on a shady camping pitch and after approx. 3 days my 120ah agm battery reached 50%.time to plug in the ip65 charger.

The battery was fully charged quickly.

Now the question, do i leave the charger in charging mode as, or is it recommended to switch to power supply mode?

I figured out that everytime my fridge turns on, a new charging cycle start until battery is back to 100%. I wonder now, how this effects battery lifetime.

As i switched to power supply, the battery is discharging to a certain point i do not know yet.

What should be the proper setup regarding voltage?


fitcamp asked

0 Answers

Charging 24v (series) house batteries with 12v starter battery


Is there a way to charge my 24v house battery system with a 12v alternator?


aaron-waller asked
JohnC answered ·

1 Answer

IP67 not charging fully following firmware update

I have an IP67 connected to 2 12v batteries. Today we swapped the batteries and also updated the firmware via the app. Initially the update failed so we wound up using a different phone and the update went through. We are now finding however that the batteries are only charging to 16v not the 24v it used to.

simonwait asked
swait answered ·

1 Answer

State of charge problem

We have a Victron 12/2000/80 multiplus compact inverter on our boat, linked to 2 220ah leisure batteries and a bmv 700 battery monitor which has been working fine for 12-18 months. We are connected to shore power when not in use, we took the boat out last weekend had an issue after 1 day where overnight the inverter stopped working and a low battery light was showing on the multi control panel. Once I started the engine the inverter sprang into life and all was fine until the early hours of that night when the same thing repeated and so on through the week. All the time the battery monitor said we had 92-97% soc. laptop connected to the inverter confirmed this was correct. Returning to shore power the panel shows only a float charge needed ?? Any ideas anyone, fridge and WiFi only 240 power on most of the week

ade7276 asked
Matthias Lange - DE answered ·

2 Answers

BlueSmart 12/15 settings for self-built LiFePO4 (4s) battery

Hi guys,

I just finished building my battery bank (4S 202Ah Lishen A-grade) and I now want to initialise the battery using my new IP65 12/15 charger. The manufacturer sent along a detailed data sheet where a charging end voltage per cell of 3.65V (x4 = 14.6V) is specified. I programmed the BMS to cutoff at that voltage accordingly.


My question now is: Which settings do I use with the 12/15 charger to fully charge/initialise the battery? I want to top balance the pack and then use the Orion-Tr in my vehicle to recharge it. The initialisation/top balance step will have to occur now. And then just once in a blue moon...

Normal (which I understand is for lead acid batteries, is rated at 14.4V) and Li-Ion (14.2) both seem too low, and High (14.7V) seems too high. Inside the app I can select a preset "LiFePO4" profile, but this also has a setting which to me seems too low: 14.2V absorption and 13.5V float and storage, as 14.2V/4cells = 3.55V

Maybe I am getting something wrong? I'd greatly appreciate your help with this.

Cheers, Jacob

jaycobius asked
jaycobius answered ·

2 Answers

Oasis Firefly Profile 2021

Does anyone have a clear profile for the oasis firefly battery? Preferable someone with experience and knows it works over time.

Many thanks

ram-z asked
charlie98117 answered ·

3 Answers

Battery is not charging anymore?!


I am not sure if it's connected to an update I did, but my Battery is not charging anymore. The Smartsolar is showing me Volt from the solarpanel but no Watt is coming in. In the history the battery minimum is always 0... After reconnecting everything and checking the cables it stays on bulk for 2 Seconds and changing to floating. I will ad some Screenshots, maybe someone can help me???

jonny asked
jonny commented ·

1 Answer

Mixing AGM and lithium

On our boat, we currently have AGM batteries for the house bank (3 ea), start battery (1), and the bow thruster (2). We want to upgrade the house bank to lithium. We are replacing our alternator with a 170 Ah high capacity in preparation. We have a Centaur 12/100 charger currently charging all the batteries.
Is there a way to design the system to charge the AGM's for the start and thruster banks, and lithium for the house bank?

cassiopeia asked
cpt-pat answered ·

3 Answers

Battery Monitor on Cerbo GX not accurate when charging via alternator

I have a new Widebeam canal boat which has a complete Victron system.

Cerbo GX with screen, 2 solar chargers, inverter, smartshunt, galvanic isolator and 3 200ah Lithium batteries.

My problem is when charging from the alternator on the engine the battery indicator on the Cerbo only goes up by say 10 to 20 % after 6 or 7 hours of cruising. The voltage get to 14.2 volts and the alternator stops charging but the meter on the screen only shows 30 to 40% charged. If however I charge from a portable generator the boat fully charges in about an hour and a half and the indictator shows 100% charge

Is there a setting that needs to be changed, I have contacted my supplier several times, but having no joy.


sagascoigne asked
pwfarnell commented ·

2 Answers


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