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12v charging batteries in parallel

Hi Everyone.

I’ve got 2 x 12v 90ah batteries wired in parallel (so in theory 180ah) which I will be connecting to a 12/375 victron inverter.

I want to get a charger to charge the batteries would it be best to get a single output charger and charge them in parallel or one with 3 outputs and charge them individually?

Also what would be best to charge them 15/20 or 30amp, not worried how long it takes.

Pfk asked
wild_thing answered ·

3 Answers

Inverter shuts down with "low battery" at 12.6 VDC

So I just installed my inverter a month or so ago. I have the 12v 3000 Multi with 2 Renogy 200 AH's each (400ah). They are a bit old and are not at full capacity for sure. They rest at 12.8 VDC so the capacity is not perfect.

I decided to run a test to see how long they would last. I got them fully charged up and unplugged everything so the inverter was on "invert". I turned all loads off except for my fridge and set a stop watch to see how long it would run. The fridge was pulling 31 amps continuously and after about 30 min the inverter flashed a "Low Battery" warning and shut it's self down. So I checked the BMV and it said the voltage on the batteries was sitting about 12.6 V. So I repeated the steps and did it again and the same results happened. This time it shut down around 12.5 V.

I'm really new to this inverter and I'm just starting to learn how it works. I just purchased the USB bus so that I can get in and change settings but I'm not sure what I'm doing.

What low voltage should my inverter shut off? I know I need to get new batteries and my goal is at least 2 Battle Born 100AH batteries, but It's not in the budget right now.

can I lower the batter shut off to more out of my batteries until I can afford to replace them?

What settings should I change if so?



Dbow32 asked
Rob Fijn answered ·

1 Answer

Multiplus 3000 stop charging

We have a Multiplus 24| 3000 | 70 and we use it early this morning and then we turn it off. When we start it again after a couple of hours it will not charge the battery.

We have 2 different input source, a generator and solar cells and same problem so it must be a problem with the multiplus.

Anyone who has any idea how to find the problem?

Camillanorberg asked
Luis del Campo answered ·

1 Answer

System questions

I am getting to the installation of my system. I have 6- 200W panels in parallel of 3. My MPPT is a victron 100/50. I calculate my voltage will be around 60V and 20a. I was going to put a fuse between the controller and panels. I was going 25A setup. Also, I was going to run a 50 amp between the mppt and batteries? Sound about right? Any recommendations on a source for the fuse or breakers?

I also have two 12V 220Ah batteries I am going to run in series to run 24V. They are the gel batteries. Do I need to vent these? Also, will I need a battery balancer you think?


Pktrusty asked
Pktrusty answered ·

2 Answers

Charging batteries,service,start,thruster


Hi everybody , above is sketch of charging circuit on my boat (without breakers , fuses etc..)

I would kindly ask for some advice.Service battery is AGM and start and thruster normal lead acid high current batteries.

1) is it OK to use alternator(via argofet) and solar charger together(especially on AGM battery) ?

I am planning to add one more 220Ah battery in parallel for service and install more solar panels(about 500 - 600W in total)

2) is it OK to use same 3 years old battery with new one , or should i install both new batteries?

3)Would it be better to use GEL batt instead of AGM for service use?

4)I have to install higher power solar charger, should i charge only service batteries , is it mistake to charge start and service from solar?

5)Is it OK to charge GEL batt with alternator(via argofet) , or with alternator and solar together?

Thanks a lot for any help

mikula asked
dimpi sinha answered ·

1 Answer

VictronMultiPlus-II 48/5000/70-50 Generator to Charge the Battery

I have a Victron MultiPlus-II 48/5000/70-50 5kva system , I want to put a silent inverter generator as backup. What type of Generator do I need to get to charge the battery Lithium Ion 3.5KWh Pylon US3000 in extended period of power outage. What is approved to use on this system

Toli Kanaris asked
Albert vd Westhuizen answered ·

2 Answers

Requirement for delayed battery charging from mains after grid return

I have a requirement for the system to not charge the battery from grid for a set period of time, say 30 minutes, after grid has returned following a power outage/loss of mains.

Ignoring AC in for same set period after grid return would also be a solution but secondary to having only battery charging delayed as loads on inverter output would also be affected. Would be ideal if this can be achieved using some combination of Assistants and programmable relays.

Albert vd Westhuizen asked

0 Answers

Since updating the Victron Charging app it's reporting wrong current

I know my generator.
I know my batteries.
I knew my Victron charger.

Since updating the charging app the app reports float amps when the generator is still running on a high revs- high load - and instead of charging the batteries then idling which it always used to do it now runs very high every 5 minutes.

Ever since I updated the app!!!
Can I roll it back to the previous version or is there something else I can do?
Also when I switch tp HIGH it used to rev up and charge but now does nothing...

Any ideas?

Mathew Hamilton Green asked

0 Answers

12v LA starter battery and 12v Lithium House charging

Just purchased Lifepo4 house batteries, a Multiplus 3KW 12V inverter/charger and have a FLA engine start battery.

Looking for the best way to set up the alternator (has an external Balmar voltage regulator), to charge both the House and Engine batteries. Would also like to charge the engine start battery from shore power, but that's a secondary wish.

Was looking at the ARGO FET Battery Isolator, but saw somewhere it is not recommended for differing battery chemistries.

Was told to use a LI-BIM Lithium Battery Isolator, but from the wiring diagram, the operation looks pretty manual in nature. The boat has a Diesel engine, so there is no hot ignition switch and the on -off-on-off charge cycling seems odd to me.

Did some hunting here and other forums. Lot of varying recommendations. Thoughts?

scfoster asked

0 Answers

BMW i3 Charging on an Victron Quattro + ESS LifePo4 system

Hi everyone,

My about to go live system, is comprised of a Victron Quattro 48V/8000VA + Smart Solar MPPT Charger 250/100 MC4 and 24KWh of LifePo4 batteries. My question is;

What's the proper way to configure my system, so that during Winter, the i3 wont use stored energy from the ESS Batteries to charge it self ?

In other words; its ok if during summer it charges from the ESS available power but during winter it should charge exclusively with evergy from my electricity provider.

would love to ear your thoughts. Thankx !!

Cadoxa asked
Cadoxa commented ·

5 Answers

SONNENSCHEIN A602 SOLAR 8 OPZV 1130 battery capacity

I installed SONNENSCHEIN A602 SOLAR 8 OPZV 1130 with QUATTRO 48/15000/200-100/100.

According to its manual, battery capacity C10 = 908Ah and C100 = 1096Ah. Accoring to label on the battery, its C120 capacity is 1131Ah.

What number is supposed to be input to VE configure program? C10, 20, 100 or 120?



Alexander Ushakov asked
RainerB commented ·

3 Answers

Dual 12v lead acid. Orion tr or tr smart


I have a Smart Solar MPPT 75/15 connected to my main battery. I'm planning to connect a second battery for auxiliary stuff outside the wagon. It is second hand batteries, so I'm not too conserned about them. The main battery are getting good charge every day, and will be able to provide charge for the second one. I'm hoping to connect them so that when the main battery are on/close to full, the second one will be charged. I do not want the main battery to be flattened due to charging the secondary.

Will the Orion-Tr 12/12- 9A, 110W do the job, or do I have to pay the double for the Orion-Tr Smart 12/12-18A (220W) Isolated DC-DC charger?

The lower chargecurrent is no issue.



Crank asked
JohnC answered ·

2 Answers

Easy Solar 24/1600 Absorption and Float LED blinking


I have a problem with a EasySolar 24/1600/40-16 MPPT 100/50.

I have installed as follow:

PV Modules: 2 x JA Solar Mono JAM60S01-315/PR

Umpp = 33.16V Uo= 40.53V Icc= 9.98A

The Modules are connected in series so:

U_PV_IN = 81.06V I_PV_IN= 9.98A

Batteries: 2x AGM 12V/220Ah (100h) in series

The temperature sensor is connected on the minus pole of the batteries.

If the Inverter switch is on the inverter work fine but if I switch it to charger position the absorption and the Float leds start blinking.

What's wrong?


Gian Carlo

giancarlo64 asked

0 Answers

Using generator to charge batteries direct

Friend of mine "donated" to my Victron setup very nice diesel generator.

It is a military surplus 7.5kW unit in very good condition.

My Victron setup (under development) consists of two MultiPlus-II 48/3000/35-32 and one EasySolar-II GX 48/3000/35-32 connected in 3-phaze configuration.

48V/200Ah LFP battery.

Now there are two problems to overcome with this generator.

1. It is 115V unit and my grid is 230V.

2. It is 400Hz model. :(

I cannot use it as strait source of AC but I can make it into 65A DC generator.

Two questions.

1. Is there a of the shelf Victron LFP battery charger that I can use with this generator?

2. Can I connect it to the MPPT 250/70 that I have in EasySolar unit? Of course after converting it do a DC source.

MarekP asked
MarekP commented ·

1 Answer

AGM Charging System

Hi all, probably been don to death here goes anyway. Running a 230AH victron super cycle (agm) as main house in a 7m trailer boat, fridge and all the regular toys on it. Currently charging via 40 amp dc/dc of the ignition side and dc/dc also looking after 220W of solar. Doing a re power, moving away from the single 225 outboard to a set of twins, 2 new cranks and retain the current victon house. Perfect world i'd run a dc/dc of each cranks both charging the house i think but room is an issue. currently considering moving to a system using VRS's between cranks and the victron and topping up the victon with my solar through a solar controller.

You hear/read lots of conflicting things around agm's and VSR style charging. My 230ah victron is 2 years old and a quality bit of kit. My question is that by how much am i compromising the performance and life of this particular battery (230ah victron super cycle) by moving away from dc/dc to a vsr controlled system with 220w solar through mpt controller. Outboards will produce about 80amps combined at max output.

Outstation asked
Matthias Lange - DE answered ·

1 Answer

Victron 3000, 30 amps vs. 50 amps, Shore vs. Solar, Batteries not charging when off, of course

New to the group. To lay the groundwork for the question:

  • We have a 50 amp fifth wheel.
  • We bought the unit used from a private seller, very happy overall.
  • The solar / Victron was installed by the seller or he had it done.
  • We have 4x Battle Born 100ah LifePo4, 4x 190W solar panels, 2x MPPT, SmartBMV and the Victron 12/3000/120-50
  • We (the wife, the dog and I) are fulltimers, three months now!

We have been, in the past three months, mostly on shore power, and always on (confirmed) 50 amps. We found that one of the monitor panels (not listed above) showed us at 30 amps continually. Reached out to seller, he indicated that if I had the inverter on, I'd be limited to 30 amps. Turned it to Off, and I'm back to 50 amps and I can run the air conditioners. Excellent for the Texas heat we'd been dealing with.

Two days ago, we relocated to a park, and were fortunate enough to park in the shade. Sure, solar will be very much reduced, but that's okay: we have 50 amps.

Tonight...the generator kicked on. Turns out we ran down the batteries to 50%. Direct DC usage in the rig, like lights, whatever else is straight DC, ran them down. With the Victron set to off, the shore power doesn't recharge the batteries. If I turn the Victron to just "Charger" (not Inverter), it will recharge the batteries, but I will still be limited to a 30 amp system.

This feels wrong to me. I'm a programmer, have been for 30 years. I'm decent at debugging, but I haven't examined all the the wiring and gotten a deeper understanding of the layout. It just feels wrong that it's this way.

When we have good sun, the batteries always get charged up the next day, even on cloudy days. We've been here, in the shade, for... two full days, I think.

I'm trying to determine if one or more of the following are true:

  • Is this a standard solar implementation scenario? That there is only ONE possible charger/converter to replenish the batteries installed at one time?
  • Is there a possible wiring / schematic / system design oversight or bug. (I don't have a schematic yet, I have reached out to get one, if available.)
  • There would have been an original charger/converter installed on the rig, before the Victron, etc. was installed. Does anyone ever have that still wired into the system?
  • Really, my only choices are "have sun" or "be limited to 30 amps even when 50 amp shore power is available"? This cannot be right.

I'm trying to determine that, if the Victron being on limits me to 30 amps, is there a different way to charge the batteries when on shore power? I know my question might be difficult to many without y'all knowing more about how it's wired up. But I'm hoping I kept my questions as free of the implementation as possible and focused on generalizations, and typical scenarios.

For the moment, there's a chill coming into the area tonight and I don't need two A/C's. I'm okay with the 30 amps for now, and I'll get my batteries replenished. Not a long term solution.

I truly appreciate any help anyone can put forth, or any education I can glean out of your answers. I did do extensive research into solar, DC, AC, converters/chargers, inverters, MPPT, etc. before we bought the rig. I feel sort of comfortable in my general knowledge. I was a little sad I didn't get to do the install myself so I'd REALLY know it, inside and out, but the deal was just too good to pass up and our seller was a pleasure to work with. But I lack the intimate knowledge that installing it myself would have gained.

Thanks in advance for any assistance.

- Will B.
Somewhere in Kansas at the moment.

CaptainPalapa asked
CaptainPalapa answered ·

2 Answers

Buck Boost low temperature charging

Hello, I am using

Victron Buck-Boost in combination with Victron LifePo4 200Ah battery and VE Mini BMS and I want to ask:

1) Does Buck-Boost cut-off charging when it detects low battery temperature from VE Mini BMS?

2) Or do I need additional Battery Protect between Buck-Boost and Battery?

I am asking, because I'll be using my vehicle frequently in sub-zero temperatures and I want to prevent battery damage that can be caused by charging in sub-zero temperatures.

Thanks for reply,


robertb asked
Southwick answered ·

2 Answers

BMV and internal Multi battery monitor

Hello everyone. I have a system composed of the following elements:

1 Venus GX (Firmware 2.33)

1 Multiplus II 48/3000/35-32 (Firmware 456)

1 BMV-712 Smart (Firmware 4.03)

1 Smart Solar Charger MPPT 100/20 48V (Firmware 1.46)

4 Battery 105Ah in series, 48V

The battery is being monitored by the BMV:

Settings → System setup → Battery monitor → BMV-712.

I have two operation problems:

1) During discharge without grid (off-grid), with a C4 rate, it did not respect the configuration of the cut-off value of the state of charge that was SOC = 50% in the BMV. In repeated tests the cut-off voltage value was around 47.40V.


2) During recharge, the process does not respect the values set in the VEconfig3,



As shown in the image below:


The bulk stage was started with SOC = 95% instead of 80% and the load current was 5A instead of 10A.

In the following link: say

“Note that the Battery Monitor setting in VEConfigure3 is irrelevant. For systems like this, changing this setting will have no effect on the charge - or any other parameters - in this type of system.”

In this case, when using the BMV, how can I configure the parameters for the loading stages?

valentin silvera asked
Miya edited ·

1 Answer

BatteryProtect and Charger placing issue

Hello All,

I'm a total newbe and I tried to find a solution for my problem.

For my sailboat I've bought a Victron Battery Protect to prevent the battery for draining.

When I am in a harbour I connect my battery to a 10A Charger. When I am sailing the battery is connected to a solar panel.

Because I red a lot about the wrong installation of the battery protect due to positive current from out to in I'm a littlebit confused where to place the batteryProtect into the system.

Can it be installed at the location of the Master Switch? I'm not really interessed in overload the battery. Underload is my main concern.

I hope some of you can help me in the right direction.

Kind Regards,

Koen de Kruijf


koendekruijf asked
koendekruijf answered ·

2 Answers

BMV 712 hook up with charger on other end of trailer

My trailer has the batteries in front and the plugin in the back. I installed the shunt in the battery box in the front and hooked one end to the NEG of the battery and the solar panel/trailer load box to the other end of the shunt as well. I also hooked power from the POS to the shunt B1 and the midpoint of the two 6v batteries to B2.

My question is. there is a power supply in the rear of the trailer that has AC input from outside plug to a PC type power supply that has 12V cables that go directly into the power box also in the rear of the trailer. I think that ALSO charges and tops off the batteries in the front.

will this work correctly? will it show charging via this PC style AC power supply?

p0lar asked
Harold answered ·

1 Answer

Multiplus goes direct to float

I have a new 12/3000/120 230v being charged by a 5kva generator off grid. I have new 750 amps of open lead acid in 2c cells. After the first charge my multi plus goes direct to float, I have taken 275 amps from them so they should go to bulk?

Barney9304 asked
Alexandra commented ·

0 Answers

Blue Smart IP65 and IP22 can be connected in parallel with another charger?

Let's say a 12 V AGM battery bank is charged by a big, powerful but terribly inefficient "BULK" charger that runs for a limited time up to 14.4 V Absorption, but this charger wastes 50W when IDLE / Float, even when the battery current is less than 100 mA. The Bulk charger can be set to turn off at end of Absorption.

Could I use a Blue Smart IP65 (or IP22) set to Power Supply Mode at 13.5 V in parallel with the Bulk Charger, just to provide a more efficient Float stage?

Would the 14.4 V Absorption of the Bulk charger cause damage to the IP65 or IP22 set to 13.5V?


MondeoMan asked
WKirby answered ·

1 Answer

Generator won't charge batteries anymore

I have a multiplus charging byd batteries connected to an auto start generator, everything has worked fine for two years and then one day it just decided to only supply power to the load and not charge batteries the auto start also stopped working not long after that. Could it be a color control issue?

Many thanks

leongallienne asked
leongallienne answered ·

2 Answers

Can Victron Blue Smart (3 outlets) charge lead-acid battery and Lifepo4 battery at the same time?

Hi! I'm converting my motorhome to Lifepo4 board batteries. However, my starter battery is still lead-acid. Can the Victron Blue Smart with 3 outlets charge batteries with different charging characteristics simultaneously? If not, is it OK to charge my starter battery with Lifepo4 CC/CV characteristics?

Dave Newman asked
Dave Newman answered ·

2 Answers

Multiplus 12| 1600 | 70 Not Charging

Received new 1600 unit today. Will not charge.

I plugged it in directly where are 3000/120 was, which worked.

VEconfig for working 3000


And VEconfig for non-working 1600



Seems to indicate that it does not like the Freq in.

I had updated the firmware out of the box.. but that is all... (note is a unique lithium battery and dc voltage which i have configured many times on other V product).

Is there something I else I can check , or does this need to go back to dealer?

mblowes asked
mblowes answered ·

1 Answer

Alternator Charge Current Estimate at 13.8 Volts


I am planning the upgrades to lithium for my motor home. And I'm trying to estimame and budget for whether I NEED a battery to battery charger or if I can get away with just alternator charing through the BMS.

Looking to start with:

1 x Victron Lithium 12V - 100Ah Smart and CL BMS 12/100

I know i can limit the current using fuses on this BMS to protect my alternator.

Reading the litrature for the battery it recomends charge voltage of 14V to 15V. 14.2 being needed for cell ballance.

I'm only getting 13.8 volts from my alternator and I'm worried I wont be able to charge (or top up ) by lithium batterys without adding a B2B which can boost the voltage.

My question to anyone who can help me is:
My alternator only puts out 13.8 volts.

Will I still be able to charge the lithium pack at a sensible rate with a marginal voltage difference and below the recomended charge 14.0 charge suggetion?

I'd like to be able to top off the batteries at 50Amps from the alternator - is this feasable without boosting the voltage using a b2b?

Not knowing the internal resistance of the lithium pack I can't calculate the sort of charge current I could expect.

Does anyone have some first hand guidance of charging from alternators of lower voltage ?

thanks for the help



TonyJobson asked
KevP answered ·

1 Answer

Blue Smart IP22 Charger Configuration

Hi there,

I just wanted to check that the 'Blue Smart IP22 Charger' can charge Two 'Relion 100ah LifePo4' Batteries at the same time? If I run them in Parallel, do I just feed the cables to one battery?

Also I have a Victron 'SmartSolar MPPT 100/30' Can this charge simultaneously with the IP22? I am also using the Victron 'Battery Monitor BMV-712' trust this is all compatible?

Thanks a-lot for your help.

Bill asked

0 Answers

Charging Lithium batteries from alternator

some examples show lithium batteries being charged directly from alternator. others show lithium battery being charged via DC-DC converter. Which is the correct/ preferred method? I was under the impression Lithium batteries required specific charging profiles?

craigp asked
craigp answered ·

3 Answers

Can MultiPlus Compact 12/1600/70 firmware be updated through VE.Connect?

Hello everyone. I have a MultiPlus Compact 12/1600/70-16 on firmware version 154. Is this firmware out-of-date? Can this Multi's firmware be updated using VE.Connect, or do I need to use the (deprecated, dangerous(??)) VEFlash method?

Reason for wanting to update:

In addition to the Multi, the system has a BMV-702, CCGX, and 2x MPPT 100/50. The MPPTs charge a 12 volt ReLion lithium-ion battery bank from two separate solar PV arrays.

I would like to tell the MPPTs that the battery voltage is what the BMV-702 measures, and not what each MPPT senses at its "battery" output terminals.

This is because in bulk charging there is a discrepancy of as much as 0.7 V between MPPT and battery voltages, depending on charging current. Under float conditions, the discrepancy tends slowly towards 0.1 V. The voltage drop from the MPPT output terminals to the battery's terminals is presumably due to the cabling, fuses, and isolator switches, none of which can be changed.

I want the MPPT to receive battery voltage data from the BMV-702 (or maybe the Multi) to solve this problem.

I read here that I can do this with the CCGX using DVCC and SVS. However, when I tried this I got an error message saying that there is a firmware incompatibility issue. Since all firmware in the CCGX, the BMV, and MPPTs is up-to-date I conclude it must be an issue with the Multiplus' firmware.

Any help greatly appreciated!

glasses asked
glasses edited ·

1 Answer


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