trickle chargers - what is everyone using?

I'd like one trickle charger that I just shuffle between vehicles and I can't find something to my spec. 

-must have standardized 12V connector as well as alligator clamps. It's -20 today and my battery died from sitting for 2 weeks. There's 3 inches of snow on the car and opening the hood to fumble around with the battery cover is an absolute pain.

-must take a battery up from low volts. The one I have will throw an error code if the battery is below 7V, which does not help me at all.

-must have at least 4 amps, preferably more. A group 24 is 80 Ah or so I'm guessing, so even to bring it back from 20% charge that would have to be plugged in 15 hours give or take. Not my cup of tea.

I'd like to plug in the vehicle for 4-5 hours once a week via a pigtail and get it fully charged. Am I asking too much? 

I've been happy with my Battery Tender brand and have been happy.  It comes with some semi/permanent pigtails that let you easily plug it in or also has aligator clamps.  I had previously used the couple buck hammer store trickles but they only work for lead acid. 

Pretty sure it's this one as I needed the battery type.

https://www.amazon.com/Battery-Tender-021-0128-Maintain-Damaging/dp/B00068XCQU/ref=sr_1_6?keywords=car+battery+tender&qid=1669927382&sr=8-6&ufe=app_do%3Aamzn1.fos.006c50ae-5d4c-4777-9bc0-4513d670b6bc

Get yourself a CTEK and enjoy. I use the MULTI US 7002 because it plays well with AGM batteries like Optimas and Odysseys. They come with a pigtail that can be permanently attached to the battery, which is useful for things like an RV battery that might not be easily accessible or the battery buried under the trunk of an E39 BMW (not random examples).

https://www.amazon.com/CTEK-56-353-12-Volt-Battery-Charger/dp/B000FRLO9Y/

They're not cheap, but they're cheaper than having to replace a battery.

I use some old Sears charger from 1987.  I used it the other day on my riding lawnmower.  Society tells me to upgrade to one of those rechargeable packs I can toss into my trunk.

I use the small Battery Minder 1510 models on a few things.  Only 1.5 amps, but I've never tried to use one to charge a battery, just to keep one charged (the one on the Jeep goes months without being unplugged, for example).  They do make larger output versions.  And unlike some of the other ones out there, these are temperature compensated, so they work better outside or in a cold garage. 

Getting a battery back from under 7 volts shouldn't be a regular occurrence.  Lead-acid batteries (including AGMs) sulfate badly and lose lots of capacity when sitting discharged.  So if one has been drained that far, there's a good chance it'll never be very good again.  Which means the goal is to make sure the battery never gets drained. 

4 - 5 hours won't fully top off a lead-acid battery unless it's already very close to full.  Just by the nature of how they charge, even the biggest charger in the world can get it to 90% or so pretty quickly, but truly topped off takes a good 4 - 8 hours beyond "mostly charged".  If possible, cars that sit should be plugged in whenever they'll sit for more than a couple of days, not just occasionally topped off. 

I'm using a Battery Tender for both race cars.

Sears die hard i found in the street after I beat someone to a smoking deal on an international travelall and they tore off angrily, slid off their trailer.

I have a $40 or so Battery Tender brand unit on one garage queen.  The other one has a cheap Hazard-Fraught style tender that I got with  a tool subscription box DD#1 bought me a few years ago.  Both seem to work fine.

If it sits outside, one of those cheap solar chargers works great.  Just put it on the outside of the window shade or car cover.

This from Amazon. $18. 

MOTOPOWER MP00205C 12V 800mA Automatic Battery Charger, Battery Maintainer, Trickle Charger, and Battery Desulfator

https://a.co/d/hhaaDiO

Strange timing, I just bought a Battery Tender about 30 minutes ago at Costco. My Harbor Freight one made a large "zap" and emitted a small bit of smoke the last time I attached it to a battery.

I have a Battery Tender that works fine, along with a NOCO Genius. The NOCO works great and has a mode that'll let it jump start completely dead batteries.

Battery tender for me as well. I've had one on the MG for a couple of years now and seems to work well. I just picked up a 4 amp one at Costco that I'll use on the F150 as it sees only occasional use. 

My Harbour Freight one worked great the first year, died the next. 

spedracer said:

I have a Battery Tender that works fine, along with a NOCO Genius. The NOCO works great and has a mode that'll let it jump start completely dead batteries.

I have one as well, and it deals with different battery types, including AGM.

Sounds like you are in an area with more severe cold weather than we have here (Missouri).

What I like does not meet all your criteria (and I don't know what does).  It's the basic Battery tender unit that comes with SAE (I think that's what they call them) style connectors with a set of ring terminals and a set of alligator clips.

It's what I'd call a trickle charger / maintainer.  

4 amps is not a trickle charge on an automotive battery, in my mind.  I'm guessing there's a product out there that will trickle/maintain AND bulk charge at higher rates...but I don't have experience with it.  I expect/assume it won't be as small/portable as the battery tender.

If I let a battery get too dead and the battery tender unit won't start charging (they require a pretty healthy battery state of charge to work) then I have to hit it with a standard charger for a while first.  But if you've got batteries regularly hitting 7 V, that's not realistically a sustainable thing, in my mind.  (but again...I think you're dealing with colder temps than I am).  7V is too far to be letting batteries get to.  They won't take much of that.

But I love my battery tenders and rotate them around regularly to the boats and projects (near outlets) to keep the batteries healthy.  

I feel that what kills a battery around my place is when it is allowed to sit at a damaging state of deep discharge.  If they're always well charged...they last a good, long time.

I have a CTEK that was originally intended for lawn mowers.  Local hardware store was clearancing them out for $5, I bought all they had.  Been working fine on my Viper, gave a way a few, and I think I sold my F250 with one under the hood.

https://www.etrailer.com/Battery-Charger/CTEK-Power-Inc/CTEK56865.html

This one.  Even came with a cute little bag.  

I have a battery tender that I move around a few things for a few days on each item at a time in the winter. I also disconnect batteries on things that will sit for more than a few weeks.

The genius boost things are fabulous and worth it.

Anyone see a teardown of a real Battery Tender and a Harbor freight copy ?

Just wondering on the component quality.

I have a Battery Tender brand maintainer for my motorcycle that I'm happy with but that just a maintainer.  It won't really charge a dead battery.  I have a couple Schumacher charger/maintainers for the race cars that I really like.  I have the 6 amp SP1298 and the 3 amp SP1297.  I actually like the SP1297 better because it autodetects the battery type and the display stays on unlike the SP1298 which requires you to tell it what battery technology you're connecting to and has a display timeout.  They both work great however.

I have a (Deltran) Battery Tender for every battery I own. I much prefer buying them once for each vehicle over constantly buying batteries, with the side benefit of having a battery that will readily crank the motor over on demand as nature intended.

I've used Battery Tender Jr for my motorcycles for years and they worked great.  When it came time to get more maintainers for off-season on other stuff - lawnmowers, generator, etc - I decided to give the "better" Centech/Harbor Freight maintainer a try, specifically this one.  I picked a few up when they were on sale for $15 and have worked perfectly.  I've since bought more and now use them on the race car, dual batteries on the diesel dually, extra cars, diesel tractor, etc. and haven't replaced a battery (or burned down my shop) yet.  Allegedly these do a better job of throttling back on charging when the battery is full, versus the Centech $8 special that just keeps shoving a few amps in regardless.

I don't think I've tried bringing back a battery from completely dead flat, but did bring a very low one back that had sat for months.  It took 2-3 days, but it did do it.  This is a much lower output than 4A, though...you might be looking more at a full-on "charger" versus maintainer.

Battery tender here as well.  Costco typically has them on sale this time of the year

This is what I use, but I also work for the company, so I'm a bit biased. They're permanently mounted in each of my vehicles, with a plug mounted to the bumper (except the race car, the plug is mounted where the glovebox used to be.

https://www.defa.com/ca/warmup-heating-charging-system/onboard-battery-chargers/

Keith Tanner said:

Get yourself a CTEK and enjoy. I use the MULTI US 7002 because it plays well with AGM batteries like Optimas and Odysseys. They come with a pigtail that can be permanently attached to the battery, which is useful for things like an RV battery that might not be easily accessible or the battery buried under the trunk of an E39 BMW (not random examples).

https://www.amazon.com/CTEK-56-353-12-Volt-Battery-Charger/dp/B000FRLO9Y/

They're not cheap, but they're cheaper than having to replace a battery.

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