question about discharge while charging

[ButchDeal]

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?

possibly, most likely not. a 10W pv module will not produce 10w most of the time (rarely in fact).
There is more involved than just watts as well. if you have a good charge controller it will compensate and adjust the voltage but if not then the voltage matters as it takes a certain over voltage to even start to charge. You can not just trickle charge a lead acid battery either, so a 10w pv module even without an LED is not going to do much charging.

[fivewin]

possibly, most likely not. a 10W pv module will not produce 10w most of the time (rarely in fact).
There is more involved than just watts as well. if you have a good charge controller it will compensate and adjust the voltage but if not then the voltage matters as it takes a certain over voltage to even start to charge. You can not just trickle charge a lead acid battery either, so a 10w pv module even without an LED is not going to do much charging.

Perhaps thats your experience. Im in an area where i get more than 4 hours charging per day. Voltage during peak hours is usually much more than the battery voltage.

Here r the specs:
Product Specifications :
- Maximum Power ( Pmax ) : 10Wp ( Watt Peak ) - Maximum Voltage ( Vmp ) : 17:00 Volt - Maximum Flow ( Imp ) : 0:59 Amp - Trails Open Voltage ( Voc ) : 21.60 Volt - Flow Running Short ( Isc ) : 0.63 Amp - Voltage : 12 Volt - Dimensions ( size ) Module : 350 x 310 x 35 ( mm ) - Cell type: Polycrystalline Silicon

[SunEagle]

Perhaps thats your experience. Im in an area where i get more than 4 hours charging per day. Voltage during peak hours is usually much more than the battery voltage.

Here r the specs:
Product Specifications :
- Maximum Power ( Pmax ) : 10Wp ( Watt Peak ) - Maximum Voltage ( Vmp ) : 17:00 Volt - Maximum Flow ( Imp ) : 0:59 Amp - Trails Open Voltage ( Voc ) : 21.60 Volt - Flow Running Short ( Isc ) : 0.63 Amp - Voltage : 12 Volt - Dimensions ( size ) Module : 350 x 310 x 35 ( mm ) - Cell type: Polycrystalline Silicon

To help you understand it isn't the voltage that is charging the battery (although it has to be a few volts above the battery rating) it is the AMPS that do the charging.

So with that panel having an Imp rating of 0.59Amp will perform very little if any charging of the battery. That is something you can find in any basic electrical physics book.

[Mike90250]

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??

I saw a guy on you tube make the Statue of Liberty disappear. But it really didn't.

[ButchDeal]

are you sure it didn't

[fivewin]

To help you understand it isn't the voltage that is charging the battery (although it has to be a few volts above the battery rating) it is the AMPS that do the charging.

So with that panel having an Imp rating of 0.59Amp will perform very little if any charging of the battery. That is something you can find in any basic electrical physics book.

I do understand that a 10wp panel gives not so much amps. But if its charging the
12v battery for 4-5hours daily its perhaps enough to lightup a 3-5watt usb bulb (5v) for in the evenings (with proper stepdown module). I tested a 5watt usb bulb with a cheap fully charged 18650 powerbank and it burned +/- 4hours. Pls dont tell me that a 7ah vrla 12battery connected to a 10wp panel is of no use to lightup low wattage bulbs.

[ButchDeal]

Well it will work for a short time but you will be drastically cutting the life of the battery by never fully charging it. Even though you do not want to hear it, it is still going to happen.
Like
Y the lead acid battery will lose almost as much charge sitting on a shelf as you will be trickle charging it, not to mention the light load.

[SunEagle]

The battery will light up the low wattage bulb. But the 10wp panel may not be able to charge the battery enough so it is full to run that light every night. Eventually the battery runs down.

A 10wp panel is more of a trickle charger where very little amps go into it each day to help keep the battery from self discharging (that is what batteries do just sitting there even not connected to anything) and being totally drained. That size panel will not be able to charge a battery that is being drained nightly from a load even a small one like a 5 watt usb light.

[fivewin]

How about if i charge 2 or 3 18650 batteries in paralel connecting this module to a 10wp panel? Will it work. Its my intention to lightup a 5watt usb led for about 6 hours every evening.

[ButchDeal]

why do you care if you can charge and discharge at the same time?
it has nothing to do with your project.
you can run the light and charge OR run the light and discharge
you just can't run the light, charge, AND discharge at the same time...

[SunEagle]

How about if i charge 2 or 3 18650 batteries in paralel connecting this module to a 10wp panel? Will it work. Its my intention to lightup a 5watt usb led for about 6 hours every evening.

Well that device will accept up to 40VDC and provide 5VDC output through a USB connector which will certainly power your 5 watt light.

And I guess you can wire the output of as many batteries as you want (as long as you don't exceed 40VDC) to the input of that device.

Sounds like you are going to need a box to keep all them devices in. Like that AC voltage sensor and relay you are looking at to turn on the light via the battery when you loose AC power.

[fivewin]

Thanks for all replies. Let me change my initial question. If i charge my handphone ongrid while browsing will this have consequences for the lifetime of the battery or any other negative consequences.

[PNjunction]

Pls dont tell me that a 7ah vrla 12battery connected to a 10wp panel is of no use to lightup low wattage bulbs.

That will work - I'm doing it myself and you already have half the components - assuming you haven't already cooked your little agm with no controller.

Yes, that 10w panel will charge your 7ah agm in your timeframe, since only HALF of that is really usable if you desire any cycle life from it. (3.5ah usable per cycle) Even so, you will be able to burn a 5w bulb for 6 hours during those cycles.

Here's how:

Charge controller: Tecmate-Optimate TM520. The difference here is that this is not a boutique-store camping piece of trash, where the manufacturer could care less if your cellphone doesn't charge, or desktop camping lantern doesn't light. Leaving you and your Moto-Guzzi, Goldwing, or Harley stranded on top of a mountaintop is very bad for business. So get real. This is an EXCELLENT controller for 5-15w panels. You can read up yourself on how it works and differs from cellphone-type buck-boost controllers.

YOU NEED a controller - or you'll just find out the hard way when that 10w panel takes your 7ah agm up to 18v and holds it there day in day out. So it is a viable charger. The flip side, is that on even big batteries with small panels, you CAN damage them easily without a controller as well. The trick with very large batteries is that a very small panel is not able to really "charge", but are only maintainers - that is, to *maintain an already fully charged state*. That they can do, but 99% of the people don't truly get a full charge from a dinky panel. But IF you do, say from some other charge source on a large battery, and plop a dinky panel on a large battery with no controller, here is the result (damage not from current, but from uncontrolled high-voltage corrosion):

https://www.youtube.com/watch?v=z5RtZe9AW2E

Now that you have a controller, you can now use a small ac inverter - even the cheap msw units to drive 120v ac led's from the grocery store:

Ex: Stanley Fat-Max 140w inverter
GE 40w replacement LED bulb. Pulls 4.5w on ac. BUT you are using an inverter so divide by 10. (NOT 12v as you would think!). .45A Yeah, you can measure that right at the battery terminal if you like to prove it.

Soo....

7ah agm vrla battery - only 3.5ah usable. (what we call "50% DOD" to get at least 300 or so cycles. Discharge less to get more cycles)

LED bulb w/inverter pulls .45w per hour.

3.5 / .45 = 7.77 hours operation.

The good thing about this is that your grocery store and possibly an nearby auto-parts store has the things you need. Room-filling light (well about as bright as a 40w equivalent bulb can be) for about 7 hours.

Uh, an I'm actually doing this from a neighbor who didn't understand how to run a small Duralast 700 jump-starter pack.

[fivewin]

That will work - I'm doing it myself and you already have half the components - assuming you haven't already cooked your little agm with no controller.

Yes, that 10w panel will charge your 7ah agm in your timeframe, since only HALF of that is really usable if you desire any cycle life from it. (3.5ah usable per cycle) Even so, you will be able to burn a 5w bulb for 6 hours during those cycles.

Here's how:

Charge controller: Tecmate-Optimate TM520. The difference here is that this is not a boutique-store camping piece of trash, where the manufacturer could care less if your cellphone doesn't charge, or desktop camping lantern doesn't light. Leaving you and your Moto-Guzzi, Goldwing, or Harley stranded on top of a mountaintop is very bad for business. So get real. This is an EXCELLENT controller for 5-15w panels. You can read up yourself on how it works and differs from cellphone-type buck-boost controllers.

YOU NEED a controller - or you'll just find out the hard way when that 10w panel takes your 7ah agm up to 18v and holds it there day in day out. So it is a viable charger. The flip side, is that on even big batteries with small panels, you CAN damage them easily without a controller as well. The trick with very large batteries is that a very small panel is not able to really "charge", but are only maintainers - that is, to *maintain an already fully charged state*. That they can do, but 99% of the people don't truly get a full charge from a dinky panel. But IF you do, say from some other charge source on a large battery, and plop a dinky panel on a large battery with no controller, here is the result (damage not from current, but from uncontrolled high-voltage corrosion):

https://www.youtube.com/watch?v=z5RtZe9AW2E

Now that you have a controller, you can now use a small ac inverter - even the cheap msw units to drive 120v ac led's from the grocery store:

Ex: Stanley Fat-Max 140w inverter
GE 40w replacement LED bulb. Pulls 4.5w on ac. BUT you are using an inverter so divide by 10. (NOT 12v as you would think!). .45A Yeah, you can measure that right at the battery terminal if you like to prove it.

Soo....

7ah agm vrla battery - only 3.5ah usable. (what we call "50% DOD" to get at least 300 or so cycles. Discharge less to get more cycles)

LED bulb w/inverter pulls .45w per hour.

3.5 / .45 = 7.77 hours operation.

The good thing about this is that your grocery store and possibly an nearby auto-parts store has the things you need. Room-filling light (well about as bright as a 40w equivalent bulb can be) for about 7 hours.

Uh, an I'm actually doing this from a neighbor who didn't understand how to run a small Duralast 700 jump-starter pack.

Thanks for your reply. Im now trying to connect a stepdown module directly connected to my 10wp 12v panel. After step down i use a usb charger module to charge some 18650 batteries including discharge protection at 2.5v.

Lamp to lightup is a 5 watt usb bulb.

I hope with this setup that i dont need the 12v 7ah battery anymore.

[fivewin]

My cat is curieus also. What happend here? I charge while im burning a usb bulb???

Is it because more amps r coming in that i can burn and charge???

[SunEagle]

My cat is curieus also. What happend here? I charge while im burning a usb bulb???

Is it because more amps r coming in that i can burn and charge???

More than likely you are providing more power then what is needed to light your usb bulb. The excess is probably going somewhere else if that box is a charger with a battery.

This topic has gotten turned around. I believe you originally wanted to use a solar panel to light a light and charge a battery without using a charge controller in between. That would require the battery to charge and discharge at the same time which it really can't.

But with a charge controller between the battery and solar panel, it can send power to a load as well as any excess power to charge the battery. So technically the battery is charging and the load is powered by the solar panel but the battery is not charging and discharging at the same time.

[fivewin]

That box is a normal powerbank, usually for charging handphones,with 2 usb output and with a small switch to activate the load. I charge that powerbank with a solar panel while im burning that 5watt bulb.

[SunEagle]

That box is a normal powerbank, usually for charging handphones,with 2 usb output and with a small switch to activate the load. I charge that powerbank with a solar panel while im burning that 5watt bulb.

That powerbank has the control features that will allow it to send power to multiple places depending on how much is available. It works similar to a solar charge controller.

All I can say is that you can try using the solar panel to charge it as well as run the usb light to see what happens. Just remember the powerbank is not just a battery but also contains some type of charging circuitry.

[fivewin]

Thanks again for your explanation. Tomorrow i try to measure wether its really charging while burning the bulb.