I have the Schaudt booster with LiFePo4. I'm starting to think about fitting a switch in the D+ wire so I could turn it off if the battery is almost 100% and I'm going to drive for a few hours. Would that be a good idea? 
Lippert/Shaudt WA 121545 'booster' DC-DC Charger. Technical support - easy questions
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Me too, just awaiting confirmation from the expertsI have the Schaudt booster with LiFePo4. I'm starting to think about fitting a switch in the D+ wire so I could turn it off if the battery is almost 100% and I'm going to drive for a few hours. Would that be a good idea?
Out of interest, has your battery BMS ever turned charging off? Because of my OCD I probably would have a switch, and it certainly wont harm anything.I have the Schaudt booster with LiFePo4. I'm starting to think about fitting a switch in the D+ wire so I could turn it off if the battery is almost 100% and I'm going to drive for a few hours. Would that be a good idea?
I am not sure if mine has Adrian, but to be honest I don’t log into the Fogstar app much just us the Victron VPM mostly. This is ours is currently wired up, as per original Carthago, which is a bit tight but accessible.
Next time you have a longish drive, check the app - if the BMS has turned charging off then it doesn't like it, or just extend the grey D+ and pop a switch in - if you have a Cerbo close by (or BMV) you could use one of those relays, and VRM to switch....
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- Sep 22, 2023
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There are basically two battery charging modes:-
When set for lithium, the Schaudt WA121545 works in constant voltage mode.
However, the charger also has a charging current limit of 45 amps. It is this limit which gives the appearance of a constant current. But that does not alter the basics, which is that the charger is working in constant voltage mode.
Within the CV mode, the charging voltage is maintained at the maximum battery voltage limit. Consequently, the charging current undergoes a gradual reduction as the SOC increases in the battery, ultimately leading to a longer duration to achieve 100% SOC.
This mode ensures that charging voltage is not exceeding the battery maximum voltage limit, a measure put in place to safeguard against potential over charge and chemical damages of the battery.
In essence, the orchestrated combination of CV mode and current limiting not only facilitates efficient charging but also safeguards the longevity and health of the leisure batteries.
- Constant Current Mode (CC Mode): As the name implies, in this mode, the charging current for the battery is maintained at a constant value by adjusting the output voltage of the DC power source.
- Constant Voltage Mode (CV Mode): In this mode, the charging voltage applied at the battery terminals is maintained constant regardless of the battery charging current.
When set for lithium, the Schaudt WA121545 works in constant voltage mode.
However, the charger also has a charging current limit of 45 amps. It is this limit which gives the appearance of a constant current. But that does not alter the basics, which is that the charger is working in constant voltage mode.
Within the CV mode, the charging voltage is maintained at the maximum battery voltage limit. Consequently, the charging current undergoes a gradual reduction as the SOC increases in the battery, ultimately leading to a longer duration to achieve 100% SOC.
This mode ensures that charging voltage is not exceeding the battery maximum voltage limit, a measure put in place to safeguard against potential over charge and chemical damages of the battery.
In essence, the orchestrated combination of CV mode and current limiting not only facilitates efficient charging but also safeguards the longevity and health of the leisure batteries.
I have the schaudt 25A booster and have a switch in the d+. Most of the year it is switched off because my fogstar is kept topped up enough by the solar panels.I have the Schaudt booster with LiFePo4. I'm starting to think about fitting a switch in the D+ wire so I could turn it off if the battery is almost 100% and I'm going to drive for a few hours. Would that be a good idea?
I don't think so, but sometimes I have cell over voltage alarms in the app after driving with battery almost full. I don't like it, but it seems to be coherent with what folks explained here about the Schaudt b2b not being ideal for LiFePo4.
That's what I'm thinking about to do...
In that case I'd fit a switch.....
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I effectively have a switch but it's controlled by a Raspberry Pi with a relay HAT. This is running Venus OS and node-RED. A relay switches the D+ line off after 30 mins at 100% SOC and switches back on at 90% SOC.I have the Schaudt booster with LiFePo4. I'm starting to think about fitting a switch in the D+ wire so I could turn it off if the battery is almost 100% and I'm going to drive for a few hours. Would that be a good idea?
More details here if anyone is interested: Thread 'Overcoming the shortcomings of Schaudt B2B charger using a RPi' https://www.motorhomefun.co.uk/foru...gs-of-schaudt-b2b-charger-using-a-rpi.315940/
It gives the appearance of constant current mode because that's exactly what it is. If the current is fixed, and the voltage varies to make sure that fixed current flows, then that is the definition of Constant Current mode.
While it is in the first charging stage, in Constant Current mode, there is a voltage limit. If the voltage rises so far that the limit is reached, the voltage becomes fixed at that limit, and the current varies to keep the voltage at that level. That is the definition of Constant Voltage mode.
That is why they describe the characteristic as CCCV. However if you want to think of constant current mode as constant voltage mode where the voltage varies when the current limit is reached, that's another way of looking at it. We're describing the same thing, with different words.
I do have the cerbo go near, but setting that up is above my skill level, I will just go down the manual switch mode( I think?)
- Sep 22, 2023
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The WA121545 does not have stages. It is constant voltage (14.4v) for all of the time it is active (engine running).
What goes on inside the charger to limit the current is not of relevance to us..
We see a constant voltage of 14.4 volts and the current is limited to 45 amps, not controlled at 45 amps.
You will not see a constant 14.4V when the battery is taking a bulk charge where it would happily sink more that 45A given the chance. As already explained, the voltage output would be reduced to limit the current to 45A.
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