Question: Charging a battery from multiple sources - possible limitations

[Haraikomono]

Hi, a little thought experiment here that I had for a while now.

Can you charge a battery from different sources simultaniously ?

If no: What are the restrictions, that prevent it ?

 

Im just curious to know, why it isnt being used.

[Moonzy]

1 minute ago, Haraikomono said:

Im just curious to know, why it isnt being used.

 

[Haraikomono]

2 minutes ago, Moonzy said:

 

I already saw that video, my question was more like having 2 or more inputs to the battery

[Moonzy]

1 minute ago, Haraikomono said:

I already saw that video, my question was more like having 2 or more inputsto the battery

so two battery management system charging the battery simultaneously?

[Haraikomono]

Just now, Moonzy said:

so two battery management system charging the battery simultaneously?

yes

[Moonzy]

Just now, Haraikomono said:

yes

never even thought of trying it, but the possibility of the cells overheating is probably the outcome

probably wont overcharge as all charger should simultaneously stop at the desired voltage, but the input currents may be too much for the cells to handle

[Levent]

I am certain that there are charge controllers that allow you to do that but main limitation would be for battery to handle charging current. I can have a 10A 5V charger but if battery can only charge at 5WH, best case scenario it would charge at 5v 1a and if battery lacks a bms it will blow up.

[Kilrah]

As long as they're all proper chargers for the battery chemistry and that the total charge current from all of them is lower than the cells' max charge current, no problem. But why?

[jaslion]

1 minute ago, Moonzy said:

never even thought of trying it, but the possibility of the cells overheating is probably the outcome

probably wont overcharge as all charger should simultaneously stop at the desired voltage, but the input currents may be too much for the cells to handle

Done it before in a multi way charge setup (solar and mains). The battery is the limit so you still have to have a controller that keeps in within limitations otherwise the battery will cook and burn.

[Haraikomono]

lets expand on the idea of multiple inputs by saying:

 

We assume that we have a battery, where the cells are modular, and are controlled by a micro relay to seperate them from an existing cell group.

And lets say we have a controller that monitors the inputs, in case there are 2 or more inputs, the controller sepereates the cells into groups and let them charge independently by their respective input.

 

Would we gain any performance in charging time ?

[Kilrah]

Only if the inputs were not powerful enough to charge the battery at full speed... But then you'd make a controller that can combine multiple inputs into 1 and use that, not something that splits cells and charges them separately...

[Haraikomono]

6 minutes ago, Kilrah said:

But why?

multi threaded operations do offer certain advantages in computing up to a specific point, until which we can expect marginally performance boosts.

In Battery designs I somehow havent seen anything resembling modularity (Of course, there are modular battery systems, where you can possibly hotswap batteries), but I havent got to see a Battery where the internals also have a own management system and are modular.

[Haraikomono]

1 minute ago, Kilrah said:

But then you'd make a controller that can combine multiple inputs into 1

Is there any reson to why doing that is more efficient ?

[jaslion]

1 minute ago, Haraikomono said:

Is there any reson to why doing that is more efficient ?

You can already charge multiple battery cells in parallel if you want to. The reason for using a single controller is simple. Safety. If multiple controllers desync then disaster is quick to strike.

[Kilrah]

1 minute ago, Haraikomono said:

multi threaded operations do offer certain advantages in computing up to a specific point, until which we can expect marginally performance boosts.

You can't compare a CPU with a battery charger.

 

The only reason a multi core/thread processor/application can benefit from that is that it's not possible to make a single core/thread as fast as multiple, but that limit doesn't exist for a charger.

 

You can't make a 50GHz CPU, so you use 10 5GHz ones. But if you need a 10kW charger there's no problem making that, no reason to use multiple smaller ones.

 

2 minutes ago, Haraikomono said:

Is there any reson to why doing that is more efficient ?

not an efficiency question, just simplicity/practicality. If you had a relay that separated the battery into parts for charging separately you couldn't use the battery while it was charging for example.  

[Haraikomono]

Just now, Kilrah said:

not an efficiency question, just simplicity/practicality. If you had a relay that separated the battery into parts for charging separately you couldn't use the battery while it was charging for example.  

Thank you, that opened my eyes