Do I need to disconnect my Victron 100/20 from the battery to connect a plug in charger?

[DouglasPaul]

Will using a grid plug in charger while it is hooked up to the battery damage it?

 

[Q-Dog]

No.

 

[Steve_S]

There should be no problem For example if you have an Inverter/Charger and separate SCC, the SCC can be charging away from solar & you can simultaneously use the Inverter/Charger to charge simultaneously without issues. Many of us do so. The only catch is that the amount of Charging Amps cannot exceed the Max amount that the battery pack(s) can take.

 

[DouglasPaul]

Thanks, I thought that was the case but figured I would ask rather than just plugging it in. Appreciate the info.

 

[mikefitz]

Don't forget that fuses/ breakers are needed an all cables connected to the battery, fitted asnear as practical to the battery positive.

 

[CaliSunHarvester]

The only catch is that the amount of Charging Amps cannot exceed the Max amount that the battery pack(s) can take.

Wouldn't the batteries' BMSs determine how much current they pull?

 

[Steve_S]

Wouldn't the batteries' BMSs determine how much current they pull?

A-Typically, a BMS will cutoff charge above a set amperage or voltage. BMS' vary and we have seen some "non-smart" BMS allow far too much with bad results. Even some smart-bms' come programmed with lousy settings but anyone with sense fixes those settings. With LFP the general average is that cells can discharge at 1C and take charge at 0.5C. For example a 100AH Battery can output 100A for 1 Hour but only take 50A for 2 hours to charge. This of course assumes these are 100AH cells rated as such.

 

[CaliSunHarvester]

A-Typically, a BMS will cutoff charge above a set amperage or voltage. BMS' vary and we have seen some "non-smart" BMS allow far too much with bad results. Even some smart-bms' come programmed with lousy settings but anyone with sense fixes those settings. With LFP the general average is that cells can discharge at 1C and take charge at 0.5C. For example a 100AH Battery can output 100A for 1 Hour but only take 50A for 2 hours to charge. This of course assumes these are 100AH cells rated as such.

your answer confuses me more. It seems like it would be possible that a battery gets too much current from a charger?

I always thought:

* voltage is determined by the energy source e.g. a charger could supply 56V DC, or a grid-powered wall outlet supplies 120V AC.

* current is drawn by the load, e.g. a BMS may want 20A from the charger, but my toaster may want 10A from the wall outlet and my desktop computer wants 1.5A from the same wall outlet.

If I had an appliance that wants 50A from the wall outlet e.g. because there's a "short circuit", then the breaker that protects the wire to said wall outlet should trip.

Which part did I get wrong? The only way that I can imagine a battery getting too high current from a charger would be some defect in the battery similar to the short circuit in the appliance.

The reason I am asking is, when people OVERPANEL, isn't that exactly what they bank on?

E.g. my AIO can handle 10kW pv input, but I have 15kW pv panels on there, to catch more pv in the morning hours. So far, the AIO has not drawn more than the max rated 10kW pv input.

Another system of mine is limited to 80A (a 24V system), so that's 2000W. The curve flattens out around 2100W. (80V * 27A = 2.2kW)
However, there are 4p3s panels on there.. 12 * 260W = 3120W. No problem.

 

[Steve_S]

If the BMS is programmed to accept only 50A Charge it simply turns off charge if it sees more coming at it.
The cells themselves will take what comes at them, even if over the 0.5C. Their internal resistance will reduce what they take but that is the wrong way about it. The BMS is a Fail Safe to prevent damage. This is why we program a BMS for Max Amps out as well.

Example:
I run 24V/280AH Packs with 200A JKBMS'. Technically, I can set output max to 280A and Charge Max at 140A based on Cell Specs. Of course my BMS won't do that, so I set Max Output to 200A and Charge at 100A. Now I have 6 packs in parallel which skews this too because Charge/Discharge are split between bank. It can deliver 1200A Discharge & take 600A collectively. My solar can provide 160A, and I can add another 200A with supplemental external charging. If say, 5 packs were off and my solar came in with over 100A the BMS would cut off IF the single pack took more than what I permit with the BMS settings. IF the BMS was set to accept 200A Charge it would allow it if the cells would take it but the Cell Resistance would likely prevent that with the exception of possibly a burst charge (not good for cells).

What exactly would happen if a cell rated for 0.5C charging took 1C or more charge ? Heat up, Bloat & Vent itself ! How fast it would take ? not too long.

 

[Suijkerbuijk]

Thanks, I thought that was the case but figured I would ask rather than just plugging it in. Appreciate the info.

You can do even fun thing lol.

I have set my charger on 13.2 volt and that is 60% charge to the battery.
The solar charger go to 13.8 volt .
So what happens now ?
Well this is how it works .

On the night the charger can charge the battery if i go under that 60% and charge to that point .
Wel of the sun go up means the solar charge is going to charge high volt so the normal charger shutdown it thinks that the battery is full to volt readings.

Wy have i done this ???
I use solar power to life on.
And i pay power from the mainland only if i need it.
So on the port with my boat i do not use the battery 100% i do not have the solar power to full it back up in a day.
But if the port mainland power go off my battery wil still Run the fridge and i can use the 100%>
If the boat move the engine can charge the battery bank.
I use about 10-20% battery power on the night .
So normal the charge will not go on.
Only if i have rain days than it will.

If you like to know .
I pay 0.60 euro cent for 1Kwh power.
So this is the reason i use this setup.

So no nothing gone happens if you use both systeem.
And what people all ready have told .
If you amp not go over the max of the battery bms
Nothing will happen to the battery.

If you use lead Battery than you still need to know what max charge it can take.
You can cook the battery by to fast charging.
I see a lot of battery go dead by over charge or cook thanks to a charger here in the port.

 

[Brucey]

What exactly would happen if a cell rated for 0.5C charging took 1C or more charge ? Heat up, Bloat & Vent itself ! How fast it would take ? not too long.

I don't think this is accurate. It may reduce the total lifecycle count from some theoretical ideal, but if you aren't giving it too much voltage I don't see how it would bloat and vent