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Solar charging AGM.

1589 Views 7 Replies 4 Participants Last post by  classicevs
Hi, Trying to charge my 80AH AGM 'S with my solar panel. An 80 AH lead acid will charge quickly to the 14.4v panel regulator cutoff setting, but my AGM's will rise to 13v within 10 minutes and stay there for at least 3 hours. I also am getting the same result from my AGM charger Charger specs:Battery 7-Stage Desulfator Ultipower 6V 12V 1A 2A 3A 4A Smart Charger 4 AGM GEL Battery 7-Stage Desulfator ( 352050613881 )
Battery specs:12V 80AH AGM Sealed Lead Acid DEEP CYCLE rechargeable Battery Caravan Camper ups 12V 80AH AGM Sealed Lead Acid DEEP CYCLE rechargeable Battery Caravan Camper ups
( 351184231134 )
I have looked at sites such as " Battery University "but still need more education. My concern is that I may cause damage by leaving them for such a long time. Are the batteries, the charger or the operator at fault?:confused:
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1,080 Posts
Sorry, I'm confused, what is causing you to think anything is wrong?

Any lead batt once depleted, say to 50%, will take several hours to get back to 100% Full, no matter how powerful (amps available) the charge source.

AGM's faster acceptance rate only applies to the early Bulk stage, doesn't speed up the overall process by more than 15-20 minutes.

Put an ammeter on the batt while the charge is finishing (3-5 hours). Did you get an endAmps spec from the batt mfg? If not use .4A (.005C)

You should set your charge source so it holds Absorb voltage until trailing amps has declined to that rate, that is the 100% Full point, and only then should it drop to Float voltage.

· Registered
600 Posts
Discussion Starter · #6 ·
Thanks for the replies with the blend of old & newer members. My Suzuki carry has 7 80 AH AGM. Each is charged individually using the AGM charger or the Solar Panel:-RICH RS-M60 60WP.At present usable sun is from 7AM to 6.30 PM (EDST.AU).It seems I am expecting too much from this panel,but it certainly is helpful with the amount of sun available at 31 latitude. The suggested site was helpful with a good explanation of why the mppt controller gives more charge than direct output into a battery. Thankyou.

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13 Posts

Hi it sounds like you have experience with my question - hopefully you can answer when you get a chance? (Thanks In Advance! :) I have a few year old Prius plug in and I want to add power to the battery bank via solar panels on top of my car port when it's parked all day (I take the bus to work and I live in a very sunny part of the country it's parked all day so hoping to utilize 'free' energy :) I don't currently have a solar home system and don't have the $ for that right now.

I plan to use as small as possible, yet still adequate, charge inverter (thinking a 1500w pure sine like this one on Amazon coupled with a J1772 120v adapter similar to this one, and approx. 1000w of panels that will output approx. 18v (they come with their own solar charge controller).

According to this site:

"Level 1 Charging

This is the slow charging route that uses a standard 120 volt power outlet. Electric cars sometimes have the option of designating either a flow rate of 8 or 12 amps…The difference between 8 and 12 amps is the higher amperage rating will charge your car faster. 8 amps is like a trickle charger you can plan on three miles per hour." ( [Note: my Prius has option select either 8 or 12 amps]

The 200w panel (5 of them) I'm looking at specs are: Output power / Amp / hour = “16.12 amp”

and the WindyNation VertaMax Pure Sine Wave 1500w Inverter says will "convert battery power to 115 - 120 VAC household power"

and I found on this site re: the Prius plug-in specifically:

Bob answered about a year ago

The 120 volt chargers draw about 12 amps. maximum. A standard 15 amp circuit should be fine. 20 amp even better. The circuit should be for the charger ONLY as the current draw is pretty near the maximum of a 15 amp circuit.

Joe answered 5 months ago

Don't know about previous years, but I just got a 2017 and under vehicle settings/ charge settings you can choose 8 amp or max amp charging. I had my circuit breaker trip twice, switched to 8 amps and the problem is fixed (

I'd prefer to just 'trickle' (again I'll be at work all day so not in a hurry) directly from the panels through the 1500w inverter thru the J1772 120v adapter plugged into the car J1772 port to the onboard batts (as detailed in image in this thread above)

Naturally I definitely don't want to damage my onboard bank, so my question is: if the amount of power produced from the panels while plugged in during the day ever falls below 8 amps (for example, the weather turns very cloudy) will it just not 'transfer' that charge/do anything?

Again any help is much appreciated! Thanks :)

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13 Posts
EDIT: based on member 'yewsuck' tip above I searched and found this thread re: doing something similar for an e-bike:

"BB. Super Moderators, January 5
It can be done... But charging Li Ion batteries incorrectly can cause the batteries to fail or catch fire.

...many AC devices do not like the variable nature of solar panel supplied DC power input).

Another alternative is to power a 12 volt AC inverter directly with a solar panel--But you may have to make a "reset" circuit for when the sun power drops (or shadow falls on panel). Many DC to AC inverter will "shut down" and need a manual reset (cut DC power and reconnect) to start up after a shade event (or during sun rise, etc.)."

Q: Does anyone have more info on such a 'reset' circuit? I searched Google but didn't find anything
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