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forum thread Posted by WhatYaGot • Nov 29, 2023
forum thread Posted by WhatYaGot • Nov 29, 2023

Schumacher SA1589 12V 5W Portable Solar Automotive Battery Charger and Maintainer – 1A USB Port – for Motorcycle, Power Sport, Car, Van, and Boat Batteries $24.99 Woot

$25

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https://electronics.woot.com/offe...maintainer

MONOCRYSTALLINE TECHNOLOGY: Utilizing monocrystalline solar panels, the SA1589 converts sunlight into power to maintain the charge of your vehicle's 12V lead-acid battery
TRICKLE CHARGE: The unit delivers a trickle charge to 12V batteries to ensure your battery stays healthy and fully charged
PORTABLE: Foldable, compact, and lightweight, the SA1589 gives you power wherever you are and features grommets for easy mounting
WEATHER RESISTANT: Water-resistant mesh fabric ensures that you can safely use the SA1589 in most weather conditions
CONNECT IN SECONDS: Hook up the included heavy-duty battery clamps in seconds with the quick-connect socket
CHARGE MOBILE DEVICES: Simply place the unit panel-side up in an area exposed to daylight to charge USB devices and 12V batteries
IDEAL FOR STORED VEHICLES: The SA1589 is ideal to maintain battery charge in stored vehicles or those that are out of use for an extended period
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https://electronics.woot.com/offe...maintainer

MONOCRYSTALLINE TECHNOLOGY: Utilizing monocrystalline solar panels, the SA1589 converts sunlight into power to maintain the charge of your vehicle's 12V lead-acid battery
TRICKLE CHARGE: The unit delivers a trickle charge to 12V batteries to ensure your battery stays healthy and fully charged
PORTABLE: Foldable, compact, and lightweight, the SA1589 gives you power wherever you are and features grommets for easy mounting
WEATHER RESISTANT: Water-resistant mesh fabric ensures that you can safely use the SA1589 in most weather conditions
CONNECT IN SECONDS: Hook up the included heavy-duty battery clamps in seconds with the quick-connect socket
CHARGE MOBILE DEVICES: Simply place the unit panel-side up in an area exposed to daylight to charge USB devices and 12V batteries
IDEAL FOR STORED VEHICLES: The SA1589 is ideal to maintain battery charge in stored vehicles or those that are out of use for an extended period

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24 Comments

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Nov 29, 2023
11,018 Posts
Joined Sep 2007
Nov 29, 2023
papitosabe
Nov 29, 2023
11,018 Posts
Seems like this would be a great product? Any cons besides having to have a car that's outside? what happens at night time, is the battery no longer Maintained? if there's an internal battery, what's the lifespan of the battery? maybe it's almost dead, that's why woot is selling these off?

just wondering cuz I've always wanted one but hadn't seen one offered here b4 by a reputable brand, and was about to pull the trigger but had concerns.

some of the bad reviews issues say the cable is short. (Amazon...@$40, current $35 with coupon) And some say it's a very slow charger,...well no crap, it's a TRICKLE/MAINTAINER charger. TRICKLE! u nitwits. It's not supposed to charge anything fast.
Last edited by papitosabe November 29, 2023 at 04:38 AM.
Nov 29, 2023
902 Posts
Joined Nov 2016
Nov 29, 2023
geo2209
Nov 29, 2023
902 Posts
Quote from papitosabe :
Seems like this would be a great product? Any cons besides having to have a car that's outside? what happens at night time, is the battery no longer Maintained? if there's an internal battery, what's the lifespan of the battery? maybe it's almost dead, that's why woot is selling these off?

just wondering cuz I've always wanted one but hadn't seen one offered here b4 by a reputable brand, and was about to pull the trigger but had concerns.

some of the bad reviews issues say the cable is short. (Amazon...@$40, current $35 with coupon) And some say it's a very slow charger,...well no crap, it's a TRICKLE/MAINTAINER charger. TRICKLE! u nitwits. It's not supposed to charge anything fast.
Unless there's an option to plug it in an outlet, no a solar panel would not work at night.
Nov 29, 2023
11,018 Posts
Joined Sep 2007
Nov 29, 2023
papitosabe
Nov 29, 2023
11,018 Posts
Quote from geo2209 :
Unless there's an option to plug it in an outlet, no a solar panel would not work at night.
Well, if there is some kind of battery inside that keeps power it would. Yea, obviously it wouldn't absorb energy, but it might have a battery bank that keeps a night charge,key word "might." And I'm clueless about solar and batteries so im assuming it wouldn't have to be a huge battery to trickle for 12 hrs, then again, I'm clueless to how big a battery would need to be to do a 1amp trickle for that long.

Otherwise, just trickling during the day only is a huge con.
3
Nov 29, 2023
902 Posts
Joined Nov 2016
Nov 29, 2023
geo2209
Nov 29, 2023
902 Posts
Quote from papitosabe :
Well, if there is some kind of battery inside that keeps power it would. Yea, obviously it wouldn't absorb energy, but it might have a battery bank that keeps a night charge,key word "might." And I'm clueless about solar and batteries so im assuming it wouldn't have to be a huge battery to trickle for 12 hrs, then again, I'm clueless to how big a battery would need to be to do a 1amp trickle for that long.

Otherwise, just trickling during the day only is a huge con.
Yeah if you're up north in subzero temps then you're going to want a real battery maintainer to plug into the grid. For mid and southern latitudes this could work. As far as charging devices on the go, my go to would be a small power bank instead of this. I don't see a situation where this solar charger would be helpful since power banks can keep a phone charged for days. Maybe for backpacking in the wilderness for a longer time than the power bank could support, say a week off the grid? Additionally, if your home power goes out for a week and you have no place to stay and/or a generator? So not really a lot of use cases for this in my opinion.
Last edited by geo2209 November 29, 2023 at 06:26 AM.
Nov 29, 2023
11,018 Posts
Joined Sep 2007
Nov 29, 2023
papitosabe
Nov 29, 2023
11,018 Posts
Quote from geo2209 :
Yeah if you're up north in subzero temps then you're going to want a real battery maintainer to plug into the grid. For mid and southern latitudes this could work. As far as charging devices on the go, my go to would be a small power bank instead of this. I don't see a situation where this solar charger would be helpful since power banks can keep a phone charged for days. Maybe for backpacking in the wilderness for a longer time than the power bank could support, say a week off the grid? Additionally, if your home power goes out for a week and you have no place to stay and/or a generator? So not really a lot of use cases for this in my opinion.
In my case it'd be for maintaining an outside car here in texas. I thought this would be perfect, thinking the solar grid powered a battery bank that did the trickling. Kind of like those $1 cheapo solar lawn lights.
Nov 29, 2023
902 Posts
Joined Nov 2016
Nov 29, 2023
geo2209
Nov 29, 2023
902 Posts
Quote from papitosabe :
In my case it'd be for maintaining an outside car here in texas. I thought this would be perfect, thinking the solar grid powered a battery bank that did the trickling. Kind of like those $1 cheapo solar lawn lights.
Yeah I think what you're talking about would require a lithium rechargeable battery, similar to the ones wireless outdoor floodlights use. I don't think this product has that.
Nov 29, 2023
11,018 Posts
Joined Sep 2007
Nov 29, 2023
papitosabe
Nov 29, 2023
11,018 Posts
Quote from geo2209 :
Yeah I think what you're talking about would require a lithium rechargeable battery, similar to the ones wireless outdoor floodlights use. I don't think this product has that.
Gotcha. So a solar trickle charger with lithium battery is what I need to look for. Thank u!

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Nov 29, 2023
1,907 Posts
Joined Sep 2014
Nov 29, 2023
1-6
Nov 29, 2023
1,907 Posts
The concept is ok but it wouldn't work well in practice. Your windsheild blocks a lot of solar energy and that would limit the effectiveness of these panels. Unless you stick the panels outside, I wouldn't bother with this. It's a good hobby kit though!
Nov 29, 2023
440 Posts
Joined Dec 2007
Nov 29, 2023
Daan
Nov 29, 2023
440 Posts
related question - what kind of voltage does such a maintainer (isn't called a tender?) give out? asking as I have a cheapo that I always wondered if it truly works
Nov 29, 2023
3,236 Posts
Joined Jan 2007
Nov 29, 2023
windnsalsa
Nov 29, 2023
3,236 Posts
Quote from papitosabe :
In my case it'd be for maintaining an outside car here in texas. I thought this would be perfect, thinking the solar grid powered a battery bank that did the trickling. Kind of like those $1 cheapo solar lawn lights.
I use a different brand, perhaps a 10 Watt one?, and it definitely keeps my battery maintained as I don't use the car during this part of the year. It is parked far from my housing unit. Else, my battery would not be able to start the car after a couple weeks of the car not being driven. But this price is meh, especially from woot
Nov 30, 2023
7,066 Posts
Joined Sep 2009
Nov 30, 2023
zzyzzx
Nov 30, 2023
7,066 Posts
Quote from 1-6 :
The concept is ok but it wouldn't work well in practice. Your windsheild blocks a lot of solar energy and that would limit the effectiveness of these panels. Unless you stick the panels outside, I wouldn't bother with this. It's a good hobby kit though!

Depends on what type of solar cells are used in the panel. I've been using one like this (different brand) for years and it works great even inside the vehicle. Doesn't need a regulator because the solar panel output is so small. Vehicle sometimes sits for months before being run.
Nov 30, 2023
7,066 Posts
Joined Sep 2009
Nov 30, 2023
zzyzzx
Nov 30, 2023
7,066 Posts
Quote from Daan :
related question - what kind of voltage does such a maintainer (isn't called a tender?) give out? asking as I have a cheapo that I always wondered if it truly works
If it's anything like mine the open circuit voltage in full sunshine is around 18V. Once put into a vehicle and connected that drops just above whatever the car battery was before. Consult YouTube for better answers as lots of videos where people are testing these things (not necessarily this brand).
Nov 30, 2023
440 Posts
Joined Dec 2007
Nov 30, 2023
Daan
Nov 30, 2023
440 Posts
Quote from zzyzzx :
If it's anything like mine the open circuit voltage in full sunshine is around 18V. Once put into a vehicle and connected that drops just above whatever the car battery was before. Consult YouTube for better answers as lots of videos where people are testing these things (not necessarily this brand).
mine's a plug-in not solar, so I'm thinking that should make the voltage predictable
Nov 30, 2023
122 Posts
Joined Apr 2013
Nov 30, 2023
icanseeyourepidermis
Nov 30, 2023
122 Posts

Our community has rated this post as helpful. If you agree, why not thank icanseeyourepidermis

Quote from papitosabe :
In my case it'd be for maintaining an outside car here in texas. I thought this would be perfect, thinking the solar grid powered a battery bank that did the trickling. Kind of like those $1 cheapo solar lawn lights.
This kind of simple 5w panel is perfect for your need. An additional battery between the panel and the car battery would be useless, or worse*. This "maintains" your car's battery by giving it a tiny amount of charge during the daytime**, which should compensate for normal self-discharge of the car battery and normal, minor parasitic draw of the vehicle (meaning small amounts of power consumed by systems that don't ever switch off, such as the security system).

That said, I would avoid this product! None of the listings say whether it has a blocking diode built in, which would be required to prevent the panel from actually draining power from your car if it's left connected when there's no sunlight on it. Slickdealers laughed last time I mentioned this but it's true - solar panels connected directly to a battery will discharge that battery at night. I would bet that this Schumacher SA1589 doesn't include such a diode because 1) the manual includes the warning below and 2) the similar Schumacher SP-600 Foldable Camo Solar Charger - 6-Watt, has no such diode and similarly warns to use only with the SPC-7A controller (which is in its own right both overkill for this panel, and a steaming pile of garbage).
Quote :
WARNING: The manufacturer strongly recommends using a solar charge controller (p/n 940261073, sold separately) in tandem with this solar charger for optimal results and to avoid overcharge or discharge of the battery.
Instead I recommend this Renogy 5W panel for $16 [amazon.com], or if you're intent on spending more, get their 10w version. I just bought four of these to gift to neighbors who keep needing my help jump starting their cars. These at least include a blocking diode, and instead of the (IMO useless) USB port you get a lighter plug adapter (which is useless in most modern vehicles where the lighter port is switched off with the engine). If you plan to keep these attached, the best way to connect them is with a piggyback style add-a-fuse thingy in the interior fuse panel - just make sure you pick a fuse slot that's always-on, e.g. the power seats in many Toyotas.

*I say an additional, intermediate battery would be worse because it would not only be an added failure point (lithium batteries don't handle extreme temps well and have shorter lifespans than photovoltaic components) but the circuitry required on either side of the added battery would waste more of the power produced by the panel, so the total amount of power pushed into your car's battery would be cut by 30% or more. The car battery doesn't care when you trickle charge it, just how much in total.

**It wouldn't charge all day. You could expect measurable charging for up to 6 hours at your latitude, but almost no one has the patience to consistently orient their car and the panel in the optimal direction so real world outputs are far less than that. Keep in mind that the 5W is a theoretical maximum when the panel's pointed directly at the sun on a clear day, and without a windshield in front of it.
Last edited by icanseeyourepidermis November 30, 2023 at 09:02 AM.
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Nov 30, 2023
122 Posts
Joined Apr 2013
Nov 30, 2023
icanseeyourepidermis
Nov 30, 2023
122 Posts
Quote from zzyzzx :
If it's anything like mine the open circuit voltage in full sunshine is around 18V. Once put into a vehicle and connected that drops just above whatever the car battery was before. Consult YouTube for better answers as lots of videos where people are testing these things (not necessarily this brand).
You're right, 18V is the standard for panels intended for 12V batteries. Themanual for this unit rates power output as "5W max @ 5-16V" [manualslib.com]but doesn't give open circuit voltage. Regardless, these have so little output that you don't have to worry about overcharging a car battery, which has somewhere north of 500 watt hour capacity.

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