Blocker Diode

Heybob

New Member
Joined
Jan 7, 2021
Messages
16
Dear Members,
I have a new "Voltage" 4.8w solar panel with no blocker diode attacted. Max: working current 274mA and Voltage 17.5V. I want to attach a blocher diode to my solar panel. The panel is to trickle feed my battery in my little camper when not in use, battery size is a 130ah AGM. Can any member advise what size diode I may need.
Best regards.
Heybob.
 

Substrate

Photon Sorcerer
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Apr 28, 2021
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CAREFUL!

While using a "blocker" diode to prevent back-current from flowing then the sun is down, sounds like a good idea, your panel voltage is still UNregulated!

The use of an inexpensive SCC would solve both problems.

I don't know how many times I show it, but your little 4.8w panel can *cook* a large battery - provided it is already or nearly fully charged in the first place. Don't be that 1% that get's burned. Use an SCC!

 

Northernchateau

Solar Addict
Joined
Apr 14, 2021
Messages
405
Location
Worth, NY
Dear Members,
I have a new "Voltage" 4.8w solar panel with no blocker diode attacted. Max: working current 274mA and Voltage 17.5V. I want to attach a blocher diode to my solar panel. The panel is to trickle feed my battery in my little camper when not in use, battery size is a 130ah AGM. Can any member advise what size diode I may need.
Best regards.
Heybob.
Forget the diode, get one of these. It will charge your batter then keep it on float. You can even charge your phone.
 

Heybob

New Member
Joined
Jan 7, 2021
Messages
16
Thank you, Bud Martin, Substrate Northernchatea, Curiouscarbon and Willowflowage for your input. I have taken what you have said and I am glad I have this website and forum to turn to. I am a beginner and I appreciate the help you all give me. I found a contoller in my toolshed and wondered if this would be ok to use. regards. Heybob.20221104_104246_001.jpg
 

curiouscarbon

Science Penguin
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Jun 29, 2020
Messages
2,860
assuming the voltages it charges to are compatible with your battery, that device may work. it says self consumption 5mA so a panel with 274mA should result in a net positive charge over time.
 

Heybob

New Member
Joined
Jan 7, 2021
Messages
16
Hi Curiouscarbon, I am not sure what I am doing. All that I am aiming for is to trickle charge a 130ah AGM battery so that I don`t have to go out to my camper every 4 or 5 days and put a car charger on my battery to charge it back up again, just to keep it topped up. Maybe that is the best thing to do, because I understand that when the battery charger indicates full, I just disconnect the charger and wait another 4-5 days and do it all again. Best regards. Heybob.
 

Northernchateau

Solar Addict
Joined
Apr 14, 2021
Messages
405
Location
Worth, NY
Hi Curiouscarbon, I am not sure what I am doing. All that I am aiming for is to trickle charge a 130ah AGM battery so that I don`t have to go out to my camper every 4 or 5 days and put a car charger on my battery to charge it back up again, just to keep it topped up. Maybe that is the best thing to do, because I understand that when the battery charger indicates full, I just disconnect the charger and wait another 4-5 days and do it all again. Best regards. Heybob.
That solar charge controller will would fine for lead acid or an AGM battery.
It will charge the battery then go on float so no need to connect and disconnect. Just add a 20 amp fuse or breaker between the battery and controller.
 

Substrate

Photon Sorcerer
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Location
SoCal
The only thing I'm concerned with is the equalization voltage, and what the time interval is for that, since it is not specified.

Everyone goes totally bananas when they see equalization, but this is not a true flooded-eq type of equalization, merely a 0.2v increase above normal - and usually limited for 2 hours or so every 28 days. Helps to keep agm's in particular in good shape under poor solar conditions.

It's my long way of saying that unless I knew for sure, I'd suggest just getting a new inexpensive controller, that if it does have this type of *mild* eq, just look for the above type of specifications before buying.

What they are *really* trying to say here is that instead of using the word "equalization", it merely means obtaining a true full charge for an agm, equalizes the cells internally. I wish manufacturers would have chosen another name instead of equalization - like "refresh". Instead, the word itself scares away owners that could actually benefit from it, because this mild overcharge is usually defeated.

At any rate, It's cheap insurance compared to cooking an expensive 130ah agm! It reads like a lot of unnecessary info, so I can understand why some just want to use a diode and call it a day. :)
 

Northernchateau

Solar Addict
Joined
Apr 14, 2021
Messages
405
Location
Worth, NY
The only thing I'm concerned with is the equalization voltage, and what the time interval is for that, since it is not specified.

Everyone goes totally bananas when they see equalization, but this is not a true flooded-eq type of equalization, merely a 0.2v increase above normal - and usually limited for 2 hours or so every 28 days. Helps to keep agm's in particular in good shape under poor solar conditions.

It's my long way of saying that unless I knew for sure, I'd suggest just getting a new inexpensive controller, that if it does have this type of *mild* eq, just look for the above type of specifications before buying.

What they are *really* trying to say here is that instead of using the word "equalization", it merely means obtaining a true full charge for an agm, equalizes the cells internally. I wish manufacturers would have chosen another name instead of equalization - like "refresh". Instead, the word itself scares away owners that could actually benefit from it, because this mild overcharge is usually defeated.

At any rate, It's cheap insurance compared to cooking an expensive 130ah agm! It reads like a lot of unnecessary info, so I can understand why some just want to use a diode and call it a day. :)
The link below is for a common automotive AGM that I have used many times. It's a drop in replacement for lead acid.
The instructions talk about charge voltage and float voltage. Both fit into the output of that controller and it looks like it has a temp probe for comp which many cheap PWM controllers do not have.
Not saying it is right but I would bet 75%+ of members here running lead acid, gel or AGM never look at the setting you are talking about.

 
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