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Discussion Starter · #1 ·
I have a 2015 Outback that will drain its battery if the time between driving extends beyond 3 weeks or so. Having replaced the battery twice now after extended time away, I'm looking into trickle chargers. Another Subaru owner introduced me to a SOLAR POWERED trickle charger that sits in the car behind the windshield, and connects to the system via its OBD under-the-dash connector. This sounds great when the car is parked outside, as it avoids having an extension cord dangling out of the car into the garage.

Does anyone have experience using a Solar Powered "Battery Tender"? Pros? Cons?
example: Battery Tender® 12V, 5 Watt Mountable Solar Battery Charger

Thank you for any guidance you can provide!
 

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I haven't tried it but Deltran is a very reputable company. Lower quality solar systems could cause problems but I'd trust Deltran to do it right.
 
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Discussion Starter · #3 ·
I haven't tried it but Deltran is a very reputable company. Lower quality solar systems could cause problems but I'd trust Deltran to do it right.
Thanks! Good to hear.
Am curious, still, if the capacity of their unit with the small solar panel is sufficient. I guess I’ll send Deltran an inquiry...
 

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That's something that I also wondered about - 5 watts at 12 volts is 0.4 amps and that's probably only with 100% full sunlight outside of the car's glass. Behind tinted windows in less than absolute direct full on sunlight could be so feeble as to be ineffective. Still, even if ineffective I'm pretty sure the Deltran will do no harm. Won't overcharge the battery and won't cause parasitic drain at night.
 
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Discussion Starter · #5 ·
UPDATE from DELTRAN: I just spoke to DELTRAN sales support, and they said the smaller 5w model I mentioned is NOT RECOMMENDED for a car. He recommended their 17w unit as a minimum, and their 35w unit as being ideal - especially if there are some cloudy days involved during the period when you're storing the car. The 35w unit puts out almost 2a/hr, but if it's cloudy the output great reduces down to "barely enough"; if there are a lot of cloudy days, a smaller solar panel will not prevent the battery from draining...

I also learned that DELTRAN has three ways of connecting the solar panel to the battery: 1) directly, with cables to the battery (somehow snaked into the engine compartment), 2) with the optional OBDII connector that plugs in under the steering wheel, or 3) using a cig lighter adapter - IF the cig lighter outlet stays on when the car is off (not sure if my 2015 Outback cuts it off or not. I'll have to test it).

I hope this helps anyone else looking into battery tending using DELTRAN solar solutions!
 

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I put a solar charger on the rear shelf of a sedan, but in an Outback I'm not sure where it would go? Are you planning on going forward with a solar charger?
 

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Discussion Starter · #7 ·
I put a solar charger on the rear shelf of a sedan, but in an Outback I'm not sure where it would go? Are you planning on going forward with a solar charger?
If I go solar, I'd put it inside the car, up against my front windshield (backed by my sun-shade). But I'm balking now at the price, as their recommended 35w unit and OBD adapter will set me back almost $200, compared $60 for a 4amp unit that plugs into an extension cord coming out of the garage. But the solar is SOOOOO elegant...
 

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Yes I like the idea of a self-contained solar battery trickle charger compared to plug and unplug. If someone developed one that aerodynamically attached to the rear overhang of the liftgate it might be more effective. Less directional sensitivity, no need to prop it up and take it down. Maybe someone with a 3d printer could create a solar panel holder that would be snug and contoured for that. In that case I think a 5 watt one could provide support to keep a battery charged (float mode), but not to charge a depleted battery.
 

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