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battery charging

2009 Skylla-TG 24-100 G Universal - Upgrade??

Hi - I have a 2009 Skylla-TG 24-100 G Universal. As far as I can tell this unit does not have the ability to set the Boost voltage, Float voltage, or Absorption time. Is there any way to upgrade/update it, or do I have to buy the new version??

capdave asked
Rob Fijn answered ·

2 Answers

BlueSolar MPPT - Batterylife algorithm thresholds


We're using BlueSolar MPPT 75/15 for solar street light application. The LED source is connected directly to the load output of the charger.

I know, that the Batterylife algorithm is changing the load disconnect/connect voltage thresholds, according to how the battery was charged. But what are the actual thresholds for the 12V system, what is the absolute low/high disconnect/connect voltage and what is the daily increment, if the battery was not charged again?

Knowing this would help a lot configuring the light, taking into account the voltage drop in the cables, and also solving some issues with cases where light doesn't switch ON at all.

Many thanks and kind regards,


peromb asked
vonny232 commented ·

4 Answers

SmartSolar MPPT Load Output vs Absorbtion/Float voltages


I have a SmartSolar MPPT 100/20 with 400w of panels and a 24v flooded lead battery bank.

I have the Bulk -> Absorption threshold set to 28.8v and Absorption -> Float threshold set to 27.6v as per general recommendation.

Separately to this, I have the Load Output "ON" threshold set to 28v and the "OFF" Threshold set to 24.7v.

However, the load output triggers prematurely when Bulk voltage > 28v, even though the battery has not completed its charge cycle at that stage.

Conversely, I have seen recently a few occurrences of the opposite. Namely, the battery is already fully charged, so the charge controller enters float state. Whilst in float state, the battery level does not rise to 28v and therefore the load output is not triggered.

This essentially means I am losing energy as the MPPT controller is only harvesting a minimal amount of energy to trickle charge the battery, but the load output is incapable of triggering due to the trickle voltage.

Surely other people have experienced this problem? Does anyone have any advice here please?

vonny232 asked
vonny232 edited ·

1 Answer

Blue Smart Charger 12/30 Storage voltage.

The charger is set to High which should give 14.7v Absorption, 13.8v Float & 13.2v Storage. The first 2 are spot on but when in Storage the voltage is 13.35-13.4. This is confirmed by my SmartShunt and a standalone multimeter at the battery. (160AH AGM). Is this a fault or should I just change the voltage in the advanced settings?

dave-w asked
wkirby answered ·

1 Answer

What is causing irregular wattage fluctuation in Float charge – MPPT 100/20?

Firstly, here is my solar setup on my Toyota 4Runner:

1 - Victron MPPT 100/20 charge controller (firmware 1.59) with 2, 12V cigarette lighter connections to the “Load Output”. The MPPT is networked to a Victron SmartShunt

1 - Victron SmartShunt 500 amp (firmware 4.08), networked to MPPT to provide battery voltage and temperature

1 – Renogy Eclipse 100W solar panel permanently mounted onto my roof, specs: Open-Circuit Voltage (Voc): 21.2V, Short-Circuit Current (Isc): 6.10A, Optimum Operating Voltage (Vmp): 17.7V, Optimum Operating Current (Imp): 5.70A

1 – 20 amp inline fuse at the solar panel

1 – FullRiver Battery, 105 amp hour, AGM battery

1 – Dual dash camera that is powered/wired directly to the AGM battery (it does not connect to the Load Output of the MPPT), which draws 360 mA or 0.36 amps. It’s constantly on, in “parking mode”.

I have used the “user defined” and “advanced settings” for the battery charging parameters in the MPPT, following FullRiver’s charging parameters perfectly.

Now here is the issue which is sporadic and very puzzling. When in direct sunlight, without any draw from the Load Output (i.e. my fridge is unplugged/off), but a small 0.36 amp draw from the dash camera directly connected to the battery, the MPPT will go through its proper cycle of “bulk”, “absorption” and then “float” charging. I’ve noticed that randomly during the float charge, it will go from 15/16/17/18 watts, down to 1/2/0, then back up within 1-2 seconds. Also the amps will fluctuate 0.5 – 1.2 down to 0. Of course the battery voltage will jump (slightly) up and down during this time. The SmartShunt is reading at a 97% state of charge. Then after some time, the MPPT will settle in, with a steady (maybe fluctuate 1 or 2 watts) watt and amp input. But then goes back into the fluctuations.

When I connect a draw to the Load Output, i.e. turn on my fridge (draws between 35 – 45 watts), the MPPT will automatically compensate for the draw and aim to maintain the float voltage on the battery. At no time does the wattage or amperage have the dramatic fluctuation down to 0 like I mentioned above.

I’ve checked all the connections with a multimeter. Tightened down all the connections to the battery, MPPT, etc. My wiring from the solar panel to the MPPT is 10 gauge (only 16 feet in length total). The wiring from the MPPT to the battery is 8 gauge.

As per Renogy’s solar panel troubleshooting steps, I performed an open circuit voltage test, with it passing – needs to be within 10% of Voc; I measured 20.4V at the panel connections vs. the panel’s Open-Circuit Voltage (Voc): 21.2V. I then performed a short circuit current test, with it passing too – needs to read 50% of the spec sheet number or greater; I measured 4.6 amps with the panel’s Short-Circuit Current (Isc) being 6.10 amps. Therefore the panel is okay. I also cleaned the panel with water and paper towel to ensure it was clean.

I’ve also “disabled the charger” for several minutes, then turned it back on, letting it go through the charge cycle. After a few minutes in float charge, it goes back to the fluctuations.

I have no idea what’s causing this. Can someone please provide some guidance as I’ve done all the appropriate troubleshooting that I’m aware of?

I’ve attached screenshots from the MPPT charging parameters and history, as well as the SmartShunt.


MPPT battery settings 1.png

MPPT battery settings 2.png

MPPT history with fluctuations.png

SmartShunt battery settings.png

SmartShunt SOC.png

cdn4runnersolar asked
cdn4runnersolar answered ·

3 Answers

Smart BMS 12/100 low charge rate

I have a victron lifepo4 90ah battery connected to my smart bms 12/100 and a smart victron shunt. I am using the bms to charge the house battery from the vehicle alternator. The vehicle has a temperature controlled alternator (new hilux) I have fitted 2 x 30amp fuses and set the bms to charge 40amps. This is a new set up and the most charge I can see from the shunt is 12amps when the engine is cold, and drops down to 5amps when hot. The house battery is at 40%. Why can I not get any more charge ? My friend has same car and enerdrive dcdc and he can get 40amps. I have triple checked wiring and all is good.

thanks Luke

luke4140 asked
ell249 published ·

0 Answers

Charger and SmartShunt and Inverter current going the wrong way and miss representing SOC

I have a need to keep 120V maximum 50W of load powered in the case of a power outage and to be able to remotely monitor the SOC of the batteries. The configuration runs off of 2 x AGM 12V 100Ah batteries connected in series with a SmartShunt 500A, a Phoenix Inverter 24V 250VA 120V, a Blue Smart IP65 24V 8A charger all connected to a Raspberry Pi acting as a CerboGX.


Both the SmartShunt and the Inverter are connected to the Pi via the to USB cable and are visible via the VictronConnect Application and VRM.

Since the Charger only has Bluetooth capability, we can not manage it remotely, but only locally which is fine. But non of the devices talk to each other over a virtual Victron wireless network like a SmartShunt can with an MPPT for example.


The problems that I am seeing are the following:

  1. When looking at the inverter, it only show 0% load. That value never changes.
  2. When looking at the SOC on the SmartShunt for the batteries, they are continuously reporting as discharging even though the Charger is permanently connected and charging the batteries.
  3. In the VRM portal, the current flow is going from the batteries to the Inverter and not from the Inverter to the batteries as I would have expected it since the inverter is supposed to keep the batteries topped off when AC power is usually available.

Is this configuration simply not possible because each element do not have a way of communicating to each other?

Or is the Charger not to be connected to the negative terminal of the battery bank but needs to go through the system Negative of the SmartShunt? (I have tried that but to no difference).


The setup is available at

Thank you for any help anyone can provide.

Thierry Douet asked
klim8skeptic commented ·

8 Answers

Lifep04 idle charge


Newbie question .

I have a 100ah 12v lithium battery to run a fridge in the back of my car. It is used infrequently and taken out of the car when not in use. It can charge in the car with a DC-DC charger and I have a 15A Victron Blue smart charger at home.

I’ve read that lithium batteries, including LFP, last longer if stored and about 50% charge.

Does the charger/app have a profile to keep the battery at, say, 60-70% while not being used, then change the profile to full charge a day or two before being used?

Is that something that is practical or desirable?



sedge asked

0 Answers

Mismatched Battery Voltages; MPPT 75/15 vs Storage

BattVoltage_AtBatts.jpgBattVoltage_ExCtrller.PNGPhantomLoadOutput_ExCtrller.PNGMPPT 75/15, VE.Direct Smart, 1 x 250W 24v Panel, 3 x 12v Gel Batteries

Although I've been running this set up for many years, I've only recently reverted to cross-checking outputs with a volt meter, as I've trusted the VE output figures. I have two questions for anyone interested in humouring me:

1. Why don't the voltages at VE Batt and Battery terminals match? Surely they're the same thing. Lately (possibly always!) I see a ~2.0v difference, with the VE 'output', and Bluetooth readout, being higher than the 'battery' voltage. Is this due to drop-off created by the attached inverter? I ask because I seem to be reaching 'Float' level rather quickly, and when the system goes nigh-nighs my VE voltage readout is dropping to sub-12v. Is this due to a 'tired' battery (sorry, a third question)?

2. Like many others, I have never attached a 'Load' to my system. Nevertheless, the VE readout often shows a 'phantom load'. Why is this? I haven't been able to find out why in any of the Victron literature.

Thanking You in Advance, SS

stonysolar asked
klim8skeptic answered ·

1 Answer

Charging vehicle battery from DC to DC charger with MMPT Smart Solar

Hi all - I have a Citroen Relay that I've started the conversion process on. One thing I'm noticing is how quickly these van batteries drain when not in use due to the immiboliser and other gadgetry. I was hoping to come up with a way to have the vehicle battery at least trickly charged so this problem was mitigated. I so far have 2 leisure agm's and have started to piece together the components for a system, with 2 solar panels, an MMPT charger and a multiplus (all victron). I was considering a DC-DC charger too, but have started reading that it can be hard to get that working with an MMPT charger but have little other info on that side of things. Is that true and are there solid workarounds? I'm less worried about needing more power for the leisure batteries as if anything have probably overshot, but I really do want some sort of way to keep the starter battery topped up while sitting on the drive.

Thanks so much

Dylan Tucker asked
Sarah answered ·

1 Answer

Confusion on SmartShunt values

Hey all, I’ve recently installed my first Victron system on an RV. Components in question here are the MultiPlus II 2x120 24V, SmartShunt, and Cerbo GX. The way I’ve set everything up, I thought should be correct, but I’m getting some odd behavior. Because it’s an RV, there is a 12V DC system in addition to the MultiPlus outputs. I have 2 batteries wired to the battery side of the shunt, and system side of the shunt goes to the MultiPlus, DC system, and all the Victron components; that is to say, absolutely no load bypasses the shunt, it should see everything. Because of the DC loads, I have the Cerbo set to “has DC system”.

When the MultiPlus is off, it appears that the shunt registers DC loads as charging the battery, not drawing from it. The little dots on the overview graphic appear moving towards the battery, and the amperage readout on the battery shows positive while on the “DC system” amps show negative.

When the generator is running and the MultiPlus is charging the battery, it seems to mostly behave normally, but the DC system amp readout will bounce between positive and negative.

I’m not sure if this is the root cause or not, but the State of Charge readout is entirely inaccurate, too. I’ve just done my first trip with this system. I had the batteries fully charged before leaving, sync’d the shunt to 100%, and left for the trip. My first night, batteries completely died, to the point nothing would power on even briefly, the 24V battery bank was registering under 10V, yet the shunt still read 82% SoC. Throughout the rest of the trip, I had low batteries at various times, setting off the alarm on the MultiPlus, etc. And the shunt would read <20V while still showing 100% SoC. It also appears this is impacting charging, as the batteries were under 20V and yet the MultiPlus was showing the charging state as “float” within 10 minutes of starting the generator.

Needless to say, I’m rather confused. Any tips would be greatly appreciated!

EDIT: Pictures of installation for wiring purposed added below, thanks @Matthias Lange - DE



knissone asked
knissone edited ·

0 Answers

Connecting Victron blue smart charger to 1 or 2 batteries

Iam using Victron Blue smart charger 12v and Cyrix-ct. The charger can charge 3 batteries. I have connected as on the picture (just without 85 start assist). Shall I also connect the charger (+) direct to the starter battery? Will I then get fully information of both batteries via bluetooth?


larsdenmark asked

0 Answers

Renogy GEL 200ah not lasting more than 2.5 Hours

I have a Victron Multiplus 12/3000/120-50 connected to a 200ah Renogy Gel with two + and - 0g wires while running about 16amps the battery only lasts about 2.5 hours before the system says low battery and shuts off. Let the system completly charge to float and still same issue.

I bought a bluetooth dongle to connect to the system to see whats going on and confirmed amps being used I just ordered the MK3 programing unit but not sure if that is the problem.


These are the default settings from the unit so it looks like there are some changes to make but is it that extreme of a differnce I was hoping for at least 8 hours of use.


Any help would be appreciated.

This is what I see after system goes into float.



And this is after a minute or two disconnected from shore power.



Any help would be appreciated still waiting on the MK3 to come in today

surgess asked
kevgermany commented ·

3 Answers

Quattro not charging freedomwon battery

Hi guys

The system I set up has a quattro and freedomwon battery with no solar as it is just a back up for a server room. Problem is that the battery is not getting charged.

Has ess and is set to keep battries charged

Any ideas?

electric-luke asked
Matthew Walsh commented ·

1 Answer

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