question about discharge while charging

[fivewin]

Im new with solar. I understand that for 10wp panels you in fact dont need a chargecontroller. Diode is enough and the panel is directly connected to the battery. If i discharge from the 7ah 12v vrla battery 24 hours (eg a 3watt bulb) the battery will also be charge during peakhours.

Are there negative consequences ? Will it effect the lifetime of the battery if i discharge while charging??

[jflorey2]

Are there negative consequences ? Will it effect the lifetime of the battery if i discharge while charging??

You can't "charge while discharging."

If there is current flowing into the battery, you are charging. If there is current flowing out of the battery, you are discharging. If you are not sure how to figure this out, google "Kirchoff's Current Law." It will tell you how to calculate what's happening when you have an input to a node (solar) plus an output from a node (load.)

[SunEagle]

@ jflorey2

What you said is absolutely true.

But in simple terms some people would have a hard time understanding that a 3 watt load is drawing less from the battery then what the 10 watt panel is supplying the battery so the battery must be getting some additional charging.

The problem is that there needs to be a component like a "charge controller" between the panel and battery that would send all the panel power to the battery while the battery is sending the power needed to the load.

@ fivewin
By the way charge controllers at that size are very cheap and will help prevent the battery from getting hurt.

[fivewin]

How about using a handphone while charging?? I do it reguarely. Is a chargecontroller built in in every hp??

[SunEagle]

Ya got me there. What is a handphone and how does it work?

[fivewin]

How does it work? I really dont know. What i know is that i reguarely use my powerbank to charge my smartphone while browsing.

[SunEagle]

That sounds like a portable battery that can be used to charge a smart phone or iPad.

I am not sure how that would work with that 3 watt bulb unless you have the correct cabling.

[fivewin]

I also reguarely charge with my charger ongrid 220v. Ofcourse the charger is a usb charger and gives 4.5-5v i think.

What do you mean by correct cabling??

[ButchDeal]

How does it work? I really dont know. What i know is that i reguarely use my powerbank to charge my smartphone while browsing.

you are not charging AND discharging. You are using some of the charging current to run the phone which means less is used to charge the battery.
There is either current flowing into the battery or out of the battery, not BOTH.

[fivewin]

Also, nearly every laptop user use their laptops while charging ongrid. Im thus wondering if every laptop have a chargecontroller with similar functions as a solar chargecontroller????

[fivewin]

you are not charging AND discharging. You are using some of the charging current to run the phone which means less is used to charge the battery.
There is either current flowing into the battery or out of the battery, not BOTH.

Re my initial question. What happend then during peakhours?? The bulb will burn. Will the battery be charged by the panel??

[Sunking]

Also, nearly every laptop user use their laptops while charging ongrid. Im thus wondering if every laptop have a chargecontroller with similar functions as a solar chargecontroller????

Just about all GGizmos with a battery has a voltage regulator (charger). There is nothing magical about batteries and battery chargers. A battery charger is just a very simple voltage and current regulated DC Power Supply. They are fundamentally a battery with regulated voltage output and a limited amount of current they can supply. When you see a Charger it has a Amp Rating. That is the maximum current possible. Current on any battery charger is from 0 amps up to max rating.

What you are thinking about is what is known as Floating a Battery. All that means is you charge up the battery the some State of Charge (specific regulated voltage) and hold the battery. In other words you set the Voltage of the Power Supply (charger) to say 13.6 volts on a 12 volt system The battery will charge up to 13.6 volts and saturate which means quits charging or Absorbing Current. Meanwhile the Power Supply holds at 13.6 volts. Any loads turned on, the power comes from the Power Supply (charger) while the battery sits there and FLOATs. If the current demand exceeds what the Power Supply (charger) can supply, or if the charger is turned off, the batteries are already on-line, take over and supply power.

[fivewin]

Thank you very much for your explanation. In my case i perhaps can use a stepdown module between the solar panel and the vrla battery with constant output of that module to the battery. The battery will stop charge at my defined output of that module minus 1.2v. Battery charging needs a higher voltage otherwise it will not charge.

Or am i talking nonsense here?

[inetdog]

Thank you very much for your explanation. In my case i perhaps can use a stepdown module between the solar panel and the vrla battery with constant output of that module to the battery. The battery will stop charge at my defined output of that module minus 1.2v. Battery charging needs a higher voltage otherwise it will not charge.

Or am i talking nonsense here?

I would not call it nonsense exactly, but it does not seem to reflect a limited knowledge of basic electricity, at least where batteries are concerned.

The idea that you do not need a charge controller (CC) for low panel wattage at best only correct as a starting point. It depends on the load you will be putting on the battery and how much current it takes to successfully "float" your battery bank.

A more general rule of thumb is that if your panel is small enough that you do not need to use a CC it is also too small to deliver enough power to recharge your batteries if you put any meaningful load on them. Panels without a CC only really make sense to maintain a battery that is not being used at all or that will be recharged when needed from another source (like the example of a starting battery of a seldom used car or tractor.)

[fivewin]

Thanks again for your reply.
This guy on youtube claims that he can charge and discharge simultaniously after combining 2 usb powerbanks together (to1)

https://m.youtube.com/watch?v=iqD2u1vjDcA

Is it true??

[fivewin]

Attached pict i screenprint from a youtube vid. The guy claims that combining 2 powerbanks in paralel he can charge and discharge at the same time cause there are then to charge modules (+output). One can be used for charging, te other one for a load.

Is it true??

[Sunking]

Attached pict i screenprint from a youtube vid. The guy claims that combining 2 powerbanks in paralel he can charge and discharge at the same time cause there are then to charge modules (+output). One can be used for charging, te other one for a load.

Is it true??

He is a Moron. Read my reply #9. A battery can only do one of two tings. Charge or Discharge. It cannot do both at the same time.

[fivewin]

you are not charging AND discharging. You are using some of the charging current to run the phone which means less is used to charge the battery.
There is either current flowing into the battery or out of the battery, not BOTH.

This is in fact what i mean. Using a led with a 10wp solar panel will during peak hours still charge the battery when the current exceeds the load. Right or not?