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Battery Balancer

Cable or busbar for correct midpoint voltage?

In this section of the Wiring Unlimited book, the midpoint connections are illustrated as cables. Should the midpoints be connected to a busbar like the positive and negative cables in order to get the same midpoint voltage across each series?


damien-walker asked
JohnC commented ·

2 Answers

Battery balancer configuration

I have just installed 4 new 12/220 gel batteries in a 24 volt/2 string set up in my barge. The wiring is configured as per victron recommendations with buss bars and midpoint cabling between the two strings. I have a single battery balancer in place also per victron recommended configuration.

With charging in float I am seeing .11 to .14 volt variation between the mid point to positive buss and mid point to negative buss. When I measure the voltages within strings I am also seeing the about the same variation between the 1st and 2nd battery in the string for each string. The balancer is showing "on" but does not appear to be re-balancing given the tolerances in the demo app.

I have read several of the other posts on this topic but I wanted to clarify my understanding about the voltage variation within strings. Should I be concerned about the individual battery variances within the 2 strings and consider a 2 balancer set up or will my current single unit configuration suffice?



tcason asked
Ingo commented ·

0 Answers

How many Battery Balancers do I need?

I have 2 series, 4 parallel 12 volt Battle Born batteries in my bank. My question is do I need more than one Battery Balancer for my setup? The little I have looked around it appears that 3 parallel might be the limit.

bill-kathy asked
Kevin Windrem answered ·

1 Answer

How to charge traction battery set with quattro


A bit of background to understand some of our choices.

We have a ship of 24 meters with is used for scouts and their camps.

The ship will lay in remote locations for a longer period of time, this means no shore connection.

Also it wont sail every day most of the time only to the camp location, so charging with alternator doesn’t happen verry often.

We have a generator on board but the less the better of course (cost perspective).

In normal use the ship wont use allot of power only a couple of lights in the evening and phone chargers and the refrigerators.

The ship has a Quattro 24|3000|70 and fits the job for us.

So a big battery pack is just fine for us.

The current batteries are at the end of life that they aren’t useable at all anymore.

We have found an traction battery pack for a fair price consisting of 12x 6Pzs 480 battery’s

With a Volt/capacity of 24 Volts and 533Ah/10h.

We are volunteers organization so funding’s are always an issue, that is why this pack is so interesting for us, It’s fairly good price for allot op capacity.

The big question is how to charge this pack. It consist of 12x 2 Volt batteries, do we need one battery balancer?

Do we need an extra protection/check for uneven 2v battery charging?

Is a standard BMV 702 capable of checking the charging state of this pack?

What are the configurations on the quattro for charging, can these be standard lead acid?

Anny tips for the charging this pack are useful.

niek-van-dijk asked

0 Answers

Victron Battery Balancer with 72v bank

Hi all!

I want to balance 72v battery bank (6*65 Ah AGM). Can i do this with 5 Victron Battery Balancer (similar to 48v scheme) and 5-10A ATO fuses for protection?


sirthomas asked
sirthomas edited ·

0 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

Busbar Copper Directly on Battery Terminal


Hello - Looking for some clarification on batteries in parallel wiring using 110 stock copper of 1"w x 1/4" thick by proper length for clean terminal installation. I understand the cables need to be on opposite ends of the bank (Postive/Negative) as described in a diagonal use case. I will use heat shrink on each bar and have a piece of plexiglass over it for a nice visual and additional safety.

My question is what length of cables are needed to be matched? Is it the length of each copper bar on the positive + the length of the positive cable to the Lynx Power In has to be equal to each copper bar on the negative + the length of the negative cable to the Lynx Power in? Or is it just the Cables coming off the back and not the bars? Or something else?

Thank you.

cory cantrell asked
seb71 edited ·

1 Answer

Battery Balancer with two 24v batteries in parallel

I'm not readily finding the answer to my question. I've got two 24v 200AH LiFePO4 in parallel. The diagrams I'm seeing are looking for a center tap point between two 12v batteries in series which is not an option for me. Any suggestions would be appreciated. Thank you.

nobodyspecial asked
nobodyspecial published ·

1 Answer

4 season RV solar system batteries in series or paralel? -12V or 48V

I want to plan a solar system for Mercedes Sprinter or other converted RV.

On the roof can be mounted 3x solar panels in my oppinion (+vents) for Medium Wheel Base (MWB) and 4x solar panelson a Long Wheel Base (LWB) or even Extended Long Wheel Base.

Similar is the simutation for Fiat Ducato, Citroen Jumper, Peugeot Boxer, Iveco Daily, VW Crafter.

Those solar panels, will have enough power to fill up 2x or 3x battery, probably gel or agm, with 100Ah or 200Ah ( depends on the budget) .

I suse at AT DIFFERENT car a vacum cleaner 1400W and with a 2500W not sinus inverter (not from Victron) It is very handy to clean up my car! Also used a 750W angle grinder, a 700 or 900W rotary hammer and so on. Now it seems I can't handle those devices that inverter which are using 1700W from pure sine wave and all this powered from my running engine : 14.4V and 55AH battery and a small alternator: around 90A. But it is just great to have tools to repair your car or do some mobile workshop jobs ocasionally.

I would like to use a coffe machie: around 1400W-2000W usually, maybe a washing machine 700-1200W, maybe ironing, instant cooking around 1500W , so 2000W sine wave it would be enough, but 3000W for sure and not need huge capacity, just around 3000Wh, that could hadle propably a pizza cooker too. At 12V battery it means: 3000 / 12 = 250A battery. ( but no less). So 4 x 200Ah for sure it is enough and 2 x 200 A h for sure not if I use a high end laptop min 8h /day ( around 640Wh/day)

The Mercedes Spinter has an option to buy it with 190A alternator, but about other vans I am not sure. 190A x 14.4V => 2736W charging power at max. To fill up the 3000Wh with losses propably it would take 1.5h, max 2h running on idle or drive mode, which is fine for me.

As we know in the winter we have fewer sunny days, and a lot less, fewer daily hours and even less usable hours for charging. Maybe 2 or 3h in a good day? And solar panels can have 10-15% of they max power, so I must use the alternator charging mode at the base. (3x solar, at 15% of 270W x 3h = 364Wh)

There are 2 possibilities on which I am hesitating: connect batteries in paralell: 12V or in series 36/48V?

If I do in paralell 3 or 4x batteires I have to do the same with solar panels, I think, but for sure I need to have battery balancer ( how many do I need and how much they will costs?). I am not sure how good are those batteries connection for 4-5 year for sure one of they will be weaker than others and we be an internal consumer. Havinig it in paralel I neep the 12V, but that means it is required to have wider cables, much more heat production and much more risk to fire. I know there are fuses and you know those can fail, like any electrical equipment. The advantage of paralel connection it would be easier to charge from the alternator.

If I do the connection of batteries in series I will have 36 or 48V and lot less Amper, lot less diameter of cooper wire needed to use, lot less heat, of course solar panels would come also in series. The backside of this now the alternator can't chage it, need a DC/DC converter from 12V to 36V or 48V. - which I don't know how much does it costs again. Other thing it is if I want to use a device projected for camping, hence 12V and in rare case 24V I can't, because I have 36 or 48V. For example a 12V water pump probaly is needed for sink or maybe others to fill up the water tanks.

I think that pure sine inverter of 3000W willl be an expensiever item, and for that should be easier to work from 36 or 48 compared to 12, hence should be cheaper again (with something.)

So how is better technically to connect those batteries in my case and which is cheaper with how much?

As I how I see the prices:

Victron Energy MultiPlus 3000VA 12-Volt Pure Sine Wave Inverter 120 amp Battery Charger: 1284 usd

Victron Energy MultiPlus 3000VA 24-Volt Pure Sine Wave Inverter 70 amp Battery Charger, UL-Certified: 1427 usd, so surprise: this is the expensiever one with a few percent.

(it seems this inverter has the charger part too!)

Victron Battery Balancer: 65 usd

Or should I use a 24V system instead of 48V? according to this:

Or simply use a different 230V generator and no solar panel at all? -

Somebody put an inverter to alternators and made from 12V the 230V and on that way charged the 48V:

So many requests for 48V, I don't undertant why Vicron doesn't offer a solution! Should I make it? :)

I just found out it is a 6V battery with 240AH from Victron, connecting in series it will be 24V bus!

Even more:

hakogef asked
offroadflow answered ·

1 Answer

Will the Battery Balancers work across 2 x 24v Strings?


Would the Battery Balancer work across the two parallel 24v strings, or does it only work across 12v strings?

I will soon replace my current 24v bank with a 48v bank (2v cells) and plan to turn it into 2 x 24v parallel strings.

The datasheet doesn't show my scenario, but unless it needs a 12v supply on one of the leads I think it may work?

With the Battery Balancer leads:

24+ on one strings +

0v on other strings +

Common on combined -

Would that work?

Al asked
Al answered ·

2 Answers

Battery combiner limiting current

I am searching a current limiter between the batteries. I have a battery set including slipring between sets. So I need to protect the slipring. May be I can add a cyrix ct-120a before slipring. I expect that if charging current is over 120A, cyrix ct-120A will limit the charge current to 120A by making voltage low. Is it possible?

ihanci asked

0 Answers

Battery Balancer 6v -12v

I have a battery bank consisting of 8 Trojan T105's. They are wired in 4 pairs, series-parallel giving a 12v output. Is there a Victron Battery Balancer that would work with this configuration?

jokani asked
DeVo Tyler commented ·

2 Answers

Interconnecting two banks

I'm in the planning stages of converting my 46' sailboat to a Victron Lithium system. Most of it (in the stern) is pretty straightforward: 3x12v Lithium Smart 160 Ah with BMS connected to a Victron Multi 200w (or 300w, but that's not the issue) charger/inverter and two solar arrays connected through Smart Solar 100/20 MPPT controllers.

The "interesting" part is in the bow, where there is a 12v windlass drawing 100A (fed with a 2/0 from the house batteries) and bow thruster running on 24v. Currently there is a 12v AGM and a relay which puts the battery in parallel with a (separate) 4/0 feed from the house bank for charging and in series with the house bank for running the thruster (I didn't design it; it was installed by the previous owner!).

What I'm planning is to put two Smart 160 Ah in place of the single AGM and tie the two big cables together for a low-resistance charging feed (overkill, I think) and allow these two to function as part of the house bank in normal operation.

This would be an obvious "no problem" with AGMs, but would I be endangering my batteries in such an install, or should I add battery protectors or something else to keep the two banks balanced? Raising the anchor or running the thruster to dock would draw down a max of abourt 20 Ah, but that would be 15% of the two forward batteries' capacity. Almost always the 100A alternator (with a LiFePO4 program) would be running when this is happening.

Thanks in advance!

Walt Knowles
Braesail -- Moody 46

wrknowles asked

0 Answers

Balancer working?

I have installed a Balancer on my 4 batteries, 2 x 2 12V batteries to 24V. The balancer is connetced as it should as I see it. However there is no light on the balancer, and the difference is increasing.

The difference is increasing. The datasheet says;

The Solution: battery balancing The Battery Balancer equalizes the state of charge of two series connected 12V batteries, or of several parallel strings of series connected batteries. When the charge voltage of a 24V battery system increases to more than 27,3V, the Battery Balancer will turn on and compare the voltage over the two series connected batteries. The Battery Balancer will draw a current of up to 0,7A from the battery (or parallel connected batteries) with the highest voltage. The resulting charge current differential will ensure that all batteries will converge to the same state of charge.

Does the sentecne in bold means "start working", or is it so that the balancer will not have any light, even standby light, before it starts balancing?


sveines asked
sveines answered ·

3 Answers

Battery balancer 24v install


Hello I have looked around but cannot quite find the answer. I have a battery balancer to install on my bank its 8 12v 220ah agm in 24v config

My question is how to connect it up to the system. I have looked at the documents and am still some what lost

I assume it connects to plus on one side and negative on the other and then there is a mid point

From what I can see the mid point is a daisy chain along the plus on the 4 batterys

The plus and negative are as that connected to plus and negative no chain down the bank? If some one could help out I may still be sane by new year

ystwyth1 asked
Matthias Lange - DE commented ·

2 Answers

Victron Battery balancers - do not balance to equal voltages

I purchased 3 Balancers and am using it on a 48V string of 4 x 12 V 170AH batteries. What I find after the balancers have
have stabilsed is that there is almost exactly 100mV difference between each pair of 12 V batteries - so the the voltages are as follows from the negative side 13.65 , 13.55, 13.45 , 13.35 V . The charge current is less than 100mA and all LED are green. The bank is stable and voltages will remain like that for days. The balancers do not appear to balance the voltages to all be equal but rather to achieve a 50mv midpoint error (50mv midpoint error equates to a 100mV difference between two adjacent batteries ) Is this correct behaviour? I have tried each balancer seperately on a pair of batteries and behaviour is the same , the lower batter is always 100mv higher in voltage than the upper battery

merlepeter asked
kuban-invertor commented ·

6 Answers

Victron Battery Balancer Wiring for 48v Battery Bank ?

Hello there. I'm in need of some assistance with wiring the battery balancer with eight 12v 138ah lithium batteries. Currently the batteries are parallel series connected in my RV. I've paired them off as four 24v 276ah batteries first and then series connected the four sets of batteries. Hope that makes sense.

As I basically have created four 24v batteries from the eight 12v batteries, can't I just use the simple series wiring diagram that Victron provides vs the more complicated 48v series parallel wiring ?


trocefus asked
Matthias Lange - DE answered ·

1 Answer

Balancing a 48V battery bank built on multiple series-strings of batteries

I have 12 identical AGM batteries, however they have been used in different locations so the age and wear may vary slightly (but not much) between each battery. They have also been sitting around for around 3-4 months without any topping charge. So they were at different states of charge to begin with.

They are now connected in 3 strings of 4 in series, then those 3 strings are paralleled at the far ends of each string (0V and 48V are paralleled, but NO parallel connects at 12, 24, 36V). I have connected my Multiplus II to the battery bank, and as I expected, some of the batteries charge to 14.40V sooner than others that linger at 14.00V.

Do I need a battery balancer for each string? Some guides say to make parallel connections across the series strings. However there are mixed opinions about whether making parallel connections like that is a good idea because it can imbalance the load put on each string. There is also a safety risk about it because if something happens, like an internal battery/cell short, current can rush from one battery to another without any fuse (with my setup, each string is fused individually and a faulty string should in theory blow a fuse). And adding parallell connections with fuses is both messy and expensive. Also, paralleling batteries and connecting at the opposing diagonal terminals, doesn't balance correctly with more than 2 batteries.

So how do people normally deal with balancing battery banks where there are more than 2 sets of batteries in parallel? Is one balancer for each string the only way to go? I might add more batteries later if I get hold of more of them.

freesurfer asked
Matthias Lange - DE answered ·

1 Answer

Using two battery balancers for 4 parallel strings

I need some help with proper configuration of my victron battery balancers for 4 parallel strings of 24 volts. My set up has a Quattro 5000/24v and eight(8) Trojan SAGM 205 batteries configured in 4 strings of 24 volts (820AH)

I am using two battery balancers, as I read one unit can only balance up to 3 parallel strings. So I have separately connected the midpoints of the first two parallel strings and the next two parallel strings. schematic is below.



chisom-onuegbu asked
Herve RV Nizard answered ·

3 Answers

Battery Balancers behaviour. Should there be an alarm?


I have a question concerning the behavior of three battery balancers I have connected to my batteries like in the enclosed picture.

I have seen that the green light turns on on all the balancers , then with a deviation of more than 50 mV the orange led of the balancer in the middle turns on while the others are off.

I also noticed that with a deviation of more than 500 mV there is no alarm on the balancers. Is this behavior normal or maybe there is something wrong with the balancers or connections?



giampaolo asked
giampaolo answered ·

1 Answer

Balancing 8x6v (48v) system with two balancers

first time poster looking for help with battery balancing

I am working on an electric boat conversion using 8 golf cart batteries (flooded lead acid 6v) wired in series. I purchased two of the HA02 balancers ( which each can balance 4 batteries of up to 12v each. i have wired the first to batteries 1-4 and the second to batteries 5-8. This is working well but it does still allow imbalances to occur between the first 4 and last 4 batteries in series.

I have seen people mention that it might be possible to balance all 8 batteries but it would require a 3rd HA02. I am not sure exactly how the wiring would look on this. Can anyone help me out?

second - I was thinking through how it might be possible to balance across the entire bank without adding a third balancer. I was curious if it might be possible to sort of parallel the Two balancers to monitor all batteries. My thought was to wire each input to overlapping pairs of batteries (therefore giving each 12v). This would be wired as:

balancer 1: 1/2, 3/4, 5/6, 7/8

balancer 2: 2/3, 4/5, 6/7, blank

in your opinion, would this work and be safe? Or are there other issues I am not seeing?

robert-martin asked

0 Answers

Options for battery balancing 48V bank of 8x 6V batteries

The Victron battery balancer works with 12V batteries. Handling a 48V bank would take 3x balancers.

But, what about a bank consisting of 8x 6V batteries ? Our bank is 8x Crown CR-430 430AH batteries ...

halfwalker asked
robert-martin answered ·

3 Answers

Battery Balancer Failure?

System: Eight 116 A-h Firefly AGM batteries combined to a 464 A-hr, 24V bank in daily cycle service aboard a sailboat. I installed the balancers for two reasons. Since the Firefly batteries, like most AGMs, can not be "equalized" in the normal sense, they need a balancer when connected in series. I also wanted an alarm system to alert me to an out of balance situation so it could be corrected before batteries were damaged by long term under/over charging.

I used two Balancers, each wired to half the battery bank as shown here: (Half bank shown, the other half had no connections o this side except at the + and - bus bars.)


All cables are all length matched, and connected to proper bus bars.

When I started having unexplained problems with battery capacity, I dove down deeper. The balancers switched on with every charge cycle as designed, and never showed more than a transitory illumination of the balance lights. The alarm never went off.

When charging in absorbtion at 28.8V, I measured the voltage from 24V(+) to the midpoint as wired. 14.4V, and also from 24V(-) to midpoint, 14.4V. So far so good. But them I disconnected the wires between 1H/L and 2H/L, isolating the two series pairs. Now the source of the issue became clearer.

From 24V(+) to the midpoint of 1H/L: 15.2V

From 24V(-) to the midpoint of 1H/L: 13.6V

From 24V(+) to the midpoint of 2H/L: 13.6V

From 24V(-) to the midpoint of 2H/L: 15.2V

Note that this state of affairs was essentially the same on the other half of the battery bank. The batteries were "perfectly" balanced as a GROUP of 4, but the individual series pairs were seriously out of whack. In thinking about this with this data, it becomes clear that when wired as recommended there is NO WAY for the balancers to fix this problem, or alarm when it happens.

Am I missing something? Should I have skipped the midpoint cross-connections and just wired a balancer for each series pair and been done with it? Is there a downside to that (other than the cost of the balancers)?

billknny asked
billknny commented ·

2 Answers

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

Victron Battery Balancer

How many balancer(s) do i need if i have 24 volt inverter system with 4 batteries (2 series and 2 parallel)

aghbari asked
jwfrary answered ·

3 Answers

Wrong SOC % in CCGX (Easysolar 24V -3kVA )

Hallo !

On the display on my CCGX it shows that the SOC is at 46% although the battery voltage is at 28,2 volts -which should be approximately 90-95%.
(I have checked the battery itself with an external voltmeter and get the same voltage: 28,2 volts )

How can I get the CCGX to show the right SOC %?

I have tried to open out the VE Configure after downloading it to my MAC but I cant find the program to open it (the .rvsc -file) . I would greatly appreciate help on how to get into the VE Configure on my MAC.
Do I need to use the VE Configure to solve my problem of SOC % ....or can I do something directly on the CCGX or maybe the VRM?

Could the problem of having 46% SOC be a result of the battery no beeing balanced?

Balancing / Equalization:

The battery is a Lithium Ion battery (approx. 10 kwh) from recycled electric car batteries (Mitsubishi Miev) - and have been working very well since I got the system a year ago.

The maximum voltage should be 28,7 volts for balancing....but now it goes to float at 28,2 volts. The highest battery voltage (in overall history in the CCGX) according to the MPPT (150/70) is 28,67-so maybe the issue here is that the cells have not been balanced?

I have chosen "Equalization" on the CCGX under Advanced...and it shows: "Starting..." . The battery in at 28,2 volts as mentioned -when will the equalization (balancing) start? And it seem that if I go to another menu on the CCGX the equalization stops....-is that right? Do I need to leave the display of "Starting..." to remain in order for it to equalize ?

I would be very happy for help on this :-)


eric-heiberg asked
raymond-nicolas edited ·

5 Answers

LiFePO4 Smart Midpoint Monitoring and Battery Balancer


is there anything to be gained monitoring the mid point voltage, or using a battery balancer, with 2x 12.8v Lithium batteries in series and a ve.bus BMS with Venus?



jasontav asked
mvader (Victron Energy) commented ·

2 Answers

Motorhome advice? 1600-2400W 24V system, BMS, multi-MPPT for shade

My bus has a 24V alternator / starter setup. Seeking advice on a 24V leisure/office setup, as well.

I'm new to this. Does this setup make sense?

Panels: 4-6x 410W 24V / 49.5V Voc, 9.76A Imp each, used in PAIRS


  • 2s2p LiFePO4 180Ah (total 600Ah effective to 80% DoD)


  • 2s4p AGM 200Ah (total 600Ah effective to 50% DoD)


  • 3x Victron SmartSolar 100/20s (3x = top, left, right of vehicle) MPPT-synced with new 1.49 / May update(?) to adapt to partial shade
  • 1x BMV-712
  • 1x BMS-12/200? Needed if each 12V 200Ah battery already has a cheap BMS built-in
  • Something that can charge the 24V starter batteries as well? Recommend?

nick-wiggill asked
nick-wiggill commented ·

1 Answer

Balancing 4 x 48V



I have a 48V system and 4 parallel banks of batteries. I've just connected my 3 balancers (they were just sitting on the wall for almost 3 years since the system installation, just because the certified Victron installer failed to make them work!!!). So, I've extended the diagram available in the manual as attached. 3 out of 4 sets are having now the same voltage, only one set is having 50mV lower voltage. And "high voltage on the upper battery" led is lit, but just on the first balancer, not on all 3. Anything wrong on the installation?


cristimv asked
herb answered ·

2 Answers

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