float

I am going to add a solar panel to my boat just for providing float charge to my starter battery (12v 240ah) and bow thruster battery (24v 240ah). I will use a Smartsolar 75/15 controller and an Orion 12/24 to step up to the 24v battery.

My question is this: what current do I need the panel to provide to enable float charging of these batteries? I'm think a 115w panel will provide typically 8 amps in the sun but rather less most of the day and, of course, nothing at night.

Not worried about bulk charging - the alternator will do that and these batteries will only discharge at start or when the alternator is running

thanks

Rob

Dear All,

Can someone have an idea why the Multiplus II stay in float mode even if the required power for the load is higher then the solar power. Normally, battery power must be combined with solar power to absorb the load power.

Best regards

Mostly, I'm just confused why it says "float" when it's charging at the bulk charge rate.

Specs:

• Victron Multiplus
• Absorption Voltage: 56.8v
• Float Voltage: 54.0v
• Battery: LiFePO4
  • 300AH
  • 48v

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EDIT:
The voltage was previously down to 52.15v, and still said "float". That doesnt seem right.

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I use the following setup: ESS System with a Multiplus II 48V, CerboGX and a Lithium NMC battery that is protected by a built in BMS. The Multiplus does not communicate with the battery. Charging and discharging is controled by voltage.

I am currently testing the following settings:

TAB: General

System frequency 50Hz

Shore current 13.0 A

Overruled by remote unchecked

Dynamic current limiter unchecked

External current sensor connected (see manual) unchecked

State of charge when Bulk finished 100.0 %

Battery capacity 50 Ah

Charge efficiency 0.95

TAB: Grid

Country / grid code standard Germany: VDE-AR-N 4105:2018-11, internal NS protection

LOM detection AC input 1 Type B (grid code compliant)

rise-in-voltage protection U> 253.0 V

start network service HF treshold 50.20 Hz

P(f>) droop 5.00 %

Use Aux1 as disable FeedIn signal checked

Maximum AC current for charge or feed in 100.0 %

Reactive power regulation Use a fixed Cos Phi

Filter time for reactive power 3.3 s

Cos phi at point 1 1.00

TAB: Inverter

PowerAssist unchecked

Inverter output voltage 230 V

Inverter DC shut-down voltage 39.20 V

Inverter DC restart voltage 45.60 V

Low DC alarm level 45.60 V

Do not restart after short-circuit (VDE 2510-2 safety) unchecked

enable AES unchecked

TAB: Charger

Enable charger checked

Weak AC input unchecked

Stop after excessive bulk unchecked

Lithium batteries checked

Configured for VE.Bus BMS unchecked

Charge curve Fixed

Absorption voltage 53.00 V

Float voltage 52.98 V

Charge current 35 A

Repeated absorption time 0.25 Hr

Repeated absorption interval 45.00 Days

Absorption time 1 Hr

TAB: Virtual switch

TAB: Usage

Virtual switch usage Do not use VS

TAB: Assistants

TAB: Assistant Configuration

ESS (Energy Storage System) (size:962)

*) System uses LiFePo4 with other type BMS

(This can be either a BMS connected via CAN bus or a BMS system in which the

batteries are protected from high/low cell voltages by external equipment.)

*) The battery capacity of the system is 50 Ah.

*) Sustain voltage 44.80 V.

*) Cut off voltage for a discharge current of:

0.005 C= 47.80 V

0.25 C= 47.20 V

0.7 C= 46.60 V

2 C= 46.10 V

*) Inverting is allowed again when voltage rises 1.20 V above cut-off(0).

*) Relevant VEConfigure settings:

- Battery capacity 50 Ah.

- PowerAssist unchecked

- Lithium batteries checked

- Dynamic current limiter unchecked

- Storage mode unchecked

Total size of all assistants including the required

(hidden) system assistants is: 1021

It works pretty well...

Now my question:

When there is enough solar to power home consumption the rest is used to recharge the battery. In bulk charge it all works fine, as soon as the absorption phase ends, the inverter discharges a little bit to reach the float voltage of 52.98 V. But then the inverter stays on (green light is on) all the time.... even though there is enough solar power to power the house and therefore the inverter not needed.

How do I have to change the settings in order to prevent this behaviour?

Or is there a way to completely disable float charge, as it is not useful for my type of Lithium-Ion battery?

Thanks in advance for your feedback and help!

Bonjour,

J'ai multiplus 3000kva/48, avec 4 pylontech us2000C en ESS.

Pourquoi j'arrive pas à utiliser l'énergie des batteries ?

En paramétrage, j'ai utilisé :

https://www.sines.fr/compatibilite_vicron_pylontech.html

Qui est identique en paramétrage victron mais synthétisé.

Et le multiplus ne passe jamais en float. J'ai un retour de batterie en : "ralentir la charge".

J'espère avoir donné toutes les informations.

Merci de votre aide.

Float set to 13.6v

Smart shunt set to 14.1V

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Multiplus is going from ABSORPTION to FLOAT charging state when the SoC is at 40% o 60%, which should actually been triggered when the battery is fully charge, if I'm not wrong.

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Multiplus settings are the recommended ones for Lithium batteries. So floating is at 13.5v and absorption is at 14.2v.

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- Could it be the Absorption time?

Any help would be really appreciate!!! thanks in advance to this great community.

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Installed my new Victron 150/70 and programmed the battery manufacturers settings. Turned on the panels to charge the batteries and the MPPT started to charge in bulk for 5hrs as it should than went to absorption for 1hrs than float. After less than 10 mins in float the MPPT went back into bulk, but was not producing any current. There was no load on the batteries and it was early afternoon. Have I missed a setting or is there something wrong with the MPPT?

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I try not to be too hard on my Lifepo4 batteries so I charge to 56v and float at 53.6v. This worked fine with the MPPT charge controllers, but once I added ESS the problems began. The issue is the bulk reset voltage. On the charge controllers this is float -0.4v so bulk restarted at 53.2v, or around 80% battery capacity which was fine.

With the ESS system, Victron in their wisdom have chosen to set the bulk reset at float -0.8v

Why different ?

This means bulk does not restart until 52.8v. With the flat profile of Lifepo4 this is around 63% battery capacity, which is way too low. Until this point it just sits in float. If you heavily load the system to drop the voltage then it changes over to bulk without any problems, but sitting with a low load you lose a lot of charge time.

Does anyone know a way to adjust this bulk reset voltage ? I know I could float at a higher voltage but this seems a poor solution to the problem.

I have a Victron Orion tr 12/12-30 connected to the starter battery in my Ford Transit camper. It seems to be working, but keeps going into absorption and float way too early.

When I start the engine and drive away, the unit goes into absorption for approx 10 mins and then floats. It does keep my battery % at whatever it was when we left but wont increase the %.

I have 1 x 260ah agm battery. I use a victron MPPT, a BMV and a battery protect.

I have attached screen shots, and would love to know why it doesn't seem to be working properly!

I am in Scotland and could do with the power. There is f'all sun!

Paul

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Seen some with similar problem but not seeing many answers. Please help. Trying to improve SOC during daylight hours. Have Smartshunt onto 600Ah Lithium. Po4. Come the afternoon, solar producing close to 50Amps. The voltage moves increasingly higher and then goes into Float. Float set at 14.2v. Trying to keep voltage low and Amps high to increase SOC. Is the charger regulating the max. Output by increasing the charge voltage? When I turn the charger off for a few minutes, voltage regulates to below 13.8 and charger goes into Bulk mode with higher charging current obviously. Running VE Bluetooth dongle and Smartshunt networked

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?

Thanks!

Hello:),

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???