I bought a foldable solar panel from BCF, the Solution X 25W solar blanket.

https://www.bcf.com.au/p/solution-x-foldable-solar-blanket-25w/387954.html

I put it out in the sun and tested the voltage with my multimeter; it said I was getting 21.4V. It is supposed to be for charging a 12V battery, and supposedly has a max voltage of 17v (open circuit voltage of 20.4V).

It looks as though this is either broken or unregulated; does that sound right?

Obviousman said:

I bought a foldable solar panel from BCF, the Solution X 25W solar blanket.

https://www.bcf.com.au/p/solution-x-foldable-solar-blanket-25w/387954.html

I put it out in the sun and tested the voltage with my multimeter; it said I was getting 21.4V. It is supposed to be for charging a 12V battery, and supposedly has a max voltage of 17v (open circuit voltage of 20.4V).

It looks as though this is either broken or unregulated; does that sound right?

ERB, put a battery on it, the voltage will fall.

sibeen said:

Obviousman said:

I bought a foldable solar panel from BCF, the Solution X 25W solar blanket.

https://www.bcf.com.au/p/solution-x-foldable-solar-blanket-25w/387954.html

I put it out in the sun and tested the voltage with my multimeter; it said I was getting 21.4V. It is supposed to be for charging a 12V battery, and supposedly has a max voltage of 17v (open circuit voltage of 20.4V).

It looks as though this is either broken or unregulated; does that sound right?

ERB, put a battery on it, the voltage will fall.

Should I connect it to a battery, get the panels in the sun and then test the voltage?

Obviousman said:

sibeen said:

Obviousman said:

I bought a foldable solar panel from BCF, the Solution X 25W solar blanket.

https://www.bcf.com.au/p/solution-x-foldable-solar-blanket-25w/387954.html

I put it out in the sun and tested the voltage with my multimeter; it said I was getting 21.4V. It is supposed to be for charging a 12V battery, and supposedly has a max voltage of 17v (open circuit voltage of 20.4V).

It looks as though this is either broken or unregulated; does that sound right?

ERB, put a battery on it, the voltage will fall.

Should I connect it to a battery, get the panels in the sun and then test the voltage?

Panel in sun first, then hook up to battery and measure.

The resultant voltage is going to depend upon the size of the battery, the state of charge the incident light etc etc. When measuring as long as the voltage is above about 12.5 volts and less than 14.5 then you should be good to go.

sibeen said:

Obviousman said:

sibeen said:

ERB, put a battery on it, the voltage will fall.

Should I connect it to a battery, get the panels in the sun and then test the voltage?

Panel in sun first, then hook up to battery and measure.

The resultant voltage is going to depend upon the size of the battery, the state of charge the incident light etc etc. When measuring as long as the voltage is above about 12.5 volts and less than 14.5 then you should be good to go.

Many thanks for that!

Obviousman said:

sibeen said:

Obviousman said:

Should I connect it to a battery, get the panels in the sun and then test the voltage?

Panel in sun first, then hook up to battery and measure.

The resultant voltage is going to depend upon the size of the battery, the state of charge the incident light etc etc. When measuring as long as the voltage is above about 12.5 volts and less than 14.5 then you should be good to go.

Many thanks for that!

No worries :)

That unit doesn’t have a regulator, could you cook a battery without one?

Peak Warming Man said:

That unit doesn’t have a regulator, could you cook a battery without one?

That was a worry of mine.

Peak Warming Man said:

That unit doesn’t have a regulator, could you cook a battery without one?

Yes/maybe. It depends upon the type and size of the battery. You really should disconnect when you get to around 14 volts. If it is a wet lead acid battery then it’s not that big a deal, you boil off some of the water in the electrolyte and just replace it wit distilled water. For a sealed cell you have to be a little more careful as if you lose moisture out of the battery there is no way to replace it.*

Saying all that, the panel is only 25 watts, so if you battery is a 50 amp hour battery then you’re going to be putting in less than 4% of the C10 current so the battery probably heat up all that much.

• Many years ago one company decided that they would top up the electrolyte in some sealed lead acid batteries as a way to save a client some dollars. These were bloody large batteries at around 2000 amp hours each from memory. They used a syringe and injected distilled water in through the vent plugs. About a fortnight later they had to turn the UPS off and wait a few days before entering the battery room again. Batteries exploding everywhere. Lots of excitement. A very embarrassed battery manufacturer.

sibeen said:

Peak Warming Man said:

That unit doesn’t have a regulator, could you cook a battery without one?

Yes/maybe. It depends upon the type and size of the battery. You really should disconnect when you get to around 14 volts. If it is a wet lead acid battery then it’s not that big a deal, you boil off some of the water in the electrolyte and just replace it wit distilled water. For a sealed cell you have to be a little more careful as if you lose moisture out of the battery there is no way to replace it.*

Saying all that, the panel is only 25 watts, so if you battery is a 50 amp hour battery then you’re going to be putting in less than 4% of the C10 current so the battery probably heat up all that much.

• Many years ago one company decided that they would top up the electrolyte in some sealed lead acid batteries as a way to save a client some dollars. These were bloody large batteries at around 2000 amp hours each from memory. They used a syringe and injected distilled water in through the vent plugs. About a fortnight later they had to turn the UPS off and wait a few days before entering the battery room again. Batteries exploding everywhere. Lots of excitement. A very embarrassed battery manufacturer.
  

Well, that battery I am using it for (a deep-cycle lead acid battery from Aldi) is only 80Ah, so that should be okay to leave on charge all day when I am camping?

Obviousman said:

sibeen said:

Peak Warming Man said:

That unit doesn’t have a regulator, could you cook a battery without one?

Yes/maybe. It depends upon the type and size of the battery. You really should disconnect when you get to around 14 volts. If it is a wet lead acid battery then it’s not that big a deal, you boil off some of the water in the electrolyte and just replace it wit distilled water. For a sealed cell you have to be a little more careful as if you lose moisture out of the battery there is no way to replace it.*

Saying all that, the panel is only 25 watts, so if you battery is a 50 amp hour battery then you’re going to be putting in less than 4% of the C10 current so the battery probably heat up all that much.

• Many years ago one company decided that they would top up the electrolyte in some sealed lead acid batteries as a way to save a client some dollars. These were bloody large batteries at around 2000 amp hours each from memory. They used a syringe and injected distilled water in through the vent plugs. About a fortnight later they had to turn the UPS off and wait a few days before entering the battery room again. Batteries exploding everywhere. Lots of excitement. A very embarrassed battery manufacturer.
  

Well, that battery I am using it for (a deep-cycle lead acid battery from Aldi) is only 80Ah, so that should be okay to leave on charge all day when I am camping?

I suspect you’‘ be OK, ERB. It’ll only be putting in a max of about 1.8 amps when the battery has reached 14 volts, so a charging rate of just over 2%. You wouldn’t want to keep that up full time but you’ll be cycling the battery by discharging it overnight and the 1.8 amps is only when the solar cell is working at maximum. Just check the battery every now and then to see that it’s not getting too warm.

perhaps to measure the battery terminal voltage properly the panel has to be disconnected for a short period, then what the charger does depends on if or when it descends to some threshold.

another important thing, of low/fading light, is the regulator needs to not stay connected (or switch to micropower) when the panel output does not cover what’s required to operate the regulator (bias etc), and further as it declines it has to prevent bleed back into the panels.

so you could say the regulator requires some transparency through it, and an on off cycle for sensing.

so a minimum parts regulator design, with lowest losses, may give you maximum unloaded panel voltage.

transition said:

perhaps to measure the battery terminal voltage properly the panel has to be disconnected for a short period, then what the charger does depends on if or when it descends to some threshold.

another important thing, of low/fading light, is the regulator needs to not stay connected (or switch to micropower) when the panel output does not cover what’s required to operate the regulator (bias etc), and further as it declines it has to prevent bleed back into the panels.

so you could say the regulator requires some transparency through it, and an on off cycle for sensing.

so a minimum parts regulator design, with lowest losses, may give you maximum unloaded panel voltage.

….may give you maximum unloaded panel voltage

when there’s no load/no battery connected

dumb drew a picture, not all the dots are joined..

assuming it’s not simply that the load is insufficient to hold the solar reg to its set voltage..

if you used a micropower relay for switching (for example purposes, simplification) rather than MOS or whatever

i’ve possibly worse than NFI, be warned