School me on battery tenders

Klaus

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Hey guys, I just hooked my shelby up to a battery tender. I went with screw to terminals instead of alligator clips. The light indicates charging so it looks like all is well.

That said I have it attached to an extension cord and having it plugged in all the time makes me nervous. I am paranoid of fire risk.

Should I unplug when fully charged? Is extension cord a risk? Anything else i should know?

Thanks
 

MG0h3

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Battery tenders are designed to be left on indefinitely.

Do you see anything on it mentioning auto off/on?

Don’t worry about the extension cord. Unless it’s incredibly cheap, it has a higher load rating than the cord from the tender.

All outlets are (should be) breaker protected and garage ones usually even have a GFI at the outlet (identified by a couple little buttons built into the outlet)


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04MysticCobra

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No worries. I have used Battery Tenders since the 90's and most recently on the 2014 GT500. I leave them plugged in from November To April. Its a trickle charger. If you unplug the battery it will go dead if you are storing for months and not starting. I always used the alligator clips and never had any issues. I have two of them. Make sure your electric outlet is in good shape and if not put a new GFI in.

DSC_0432_zps43944393.JPG
 

tones_RS3

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@Klaus
What year is your Shelby?? '13 or '14? Either way, I'm pretty sure you can just plug into the 12V inlet on the dash. I did that with my '13 Roush Stage 3 and it worked like a dream. No disconnecting connections on the battery or anything like that.
I have a CTEK 3300 with the extender and 12V plug-in adapter. I put the car window all the way up and when I wanted to start the car, just unplug it and you're good to go. When you want to put it back on the tender, just plug it back into the 12V inlet on the dash. Super, super easy and CTEK is a great battery tender. Ferrari, Lambo, Corvette, Porsche all use the CTEK brand.
You can leave it plugged in and it regulates how much juice is going to the battery without overcharging. Great product.
 

DSG2003Mach1

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I leave mine on a tender all the time, most of them turn on/off as needed and the one I have will do a slightly higher rate charge as well. I got one with a harness that hooks to the battery so its just a quick plug/unplug and don't have to leave a window down.
 

tones_RS3

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I leave mine on a tender all the time, most of them turn on/off as needed and the one I have will do a slightly higher rate charge as well. I got one with a harness that hooks to the battery so its just a quick plug/unplug and don't have to leave a window down.
Yup, I got those connections as well.
Just a "quick" disconnect/connect plug and play.
 

Klaus

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Battery tenders are designed to be left on indefinitely.

Do you see anything on it mentioning auto off/on?

Don’t worry about the extension cord. Unless it’s incredibly cheap, it has a higher load rating than the cord from the tender.

All outlets are (should be) breaker protected and garage ones usually even have a GFI at the outlet (identified by a couple little buttons built into the outlet)


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Thanks, that is helpful. I should have asked before I bought one, @tones_RS3 sounds like a better option. Here is the setup

thumbnail (1).jpg
 

04MysticCobra

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Why a GFI? I know that bathroom has one not my garage though.


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Back in the day the GFI's were used in the Bathroom and Kitchen area because of water being nearby and not getting shocked from a non GFI outlet. They started using them a while ago in new construction for garages and my first home in Delaware back in 2011 had them in the garage. I believe its a national code for all new construction.

Are GFCIs Required in the Garage? | George Brazil® Plumbing & Electrical | Phoenix, AZ
 

big dad

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Don't worry Klaus, I have 6 vehicles with battery tenders year round and the only problems I've had are with the Sears ones going tits up for some reason. I would recommend the Shumacher ones for best longevity.
 

tones_RS3

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Thanks, that is helpful. I should have asked before I bought one, @tones_RS3 sounds like a better option. Here is the setup
View attachment 1618568
No problem bro. They're pretty inexpensive. Buy one and use your current one as a "back-up", even though you won't need it with the CTEK. lol

Also, not sure if it matters or not, but I think the battery tenders are supposed to be a bit higher than car level when in use?? Can anyone confirm this??
 

wizbangdoodle

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Battery chargers, tenders and batteries have changed a lot over the past 5-10 years. Lead acid or wet cell batteries have improved in their efficiencies. AGM are an easier battery to maintain and the new lithiums can really take a beating. Battery charging has changed as well and the best chargers/tenders are programmable to take into account the type of battery.

I installed solar panels and batteries on my 5th wheel and learned a LOT during that process. Lithiums can save you a lot of weight. Charge rates make a big difference.

With all that being said, one of those units you can pick up at Costco will do a fine job for a car battery. No reason to spend lots of money for a single battery. You just end up replacing it in 5-7 years anyway.
 

DSG2003Mach1

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No problem bro. They're pretty inexpensive. Buy one and use your current one as a "back-up", even though you won't need it with the CTEK. lol

Also, not sure if it matters or not, but I think the battery tenders are supposed to be a bit higher than car level when in use?? Can anyone confirm this??

My Ctek one has been sitting on the floor the whole time I've had it, I dont see why would it matter.
 

sonicx

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Exclusively use CTek 3300 or its updates version 5.0 MXS is g2g. Plug n play for both. They shouldn’t be higher than the level of your car if you can help it .
 

specracer

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Ctek for the Li-on batteries, Older Deltrans for the "normal" batteries. Taken on a new strategy with any car that no longer has to be plugged in for emissions (in MA 15 years), I disconnect the battery, then once a month or so, put a tender on for a day or 2.

But as to your primary q, I have at least 4 that are plugged in at all times (when not being driven), sometimes with an extension cord. Note, Deltran makes an extender for the 12v side of the charger. I find these handier than tying up an extension cord.
 

CobraBob

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Interesting thread. I had planned using a battery tender from November to late March for my Genesis G70, but found out the battery is in the trunk. First car I've ever owned with a battery in the trunk. So running the extension cord became an issue as I didn't have any holes to run the cord through. I really wanted to use the battery tender, which I ended up returning. So now every 3 weeks I remove a portion of the car cover, climb in, start the car, and let it idle for 20 minutes. I vary the revs during that 20 minutes. I changed the oil before storage and added Stabil to the fuel. So far so good.
 

Klaus

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but I think the battery tenders are supposed to be a bit higher than car level when in use?? Can anyone confirm this??

The instructions specifically say that you should not have it over the battery while on charge. I looked up why, I guess charging process can release hydrogen. I did rejig mine to get off the floor and now have it on a carabiner on a cable overhead.

I think if I just get another set of terminals I can add one to my HC and use the same box for both.
 

olympic

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@CobraBob Couldn't you just close the trunk lid on the cord? The wire between the tender and the battery is pretty small and should't get pinched.

I use a C-Tek maitainer as well for our 6 months of winter. Only problem I ran into was the "cold weather" setting, which they also reccomend for Optima type batteries, made my battery get uncomfortably hot. So now I use the normal setting for lead acid batteries.
 

*Jay*

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Not sure about Ctek but I run my Battery tender through the OBD2 port on my Subaru's and AMG. The Cobra cigarette lighter is a constant on circuit where the others are not. I also have 20' extensions to route over the cars from the 4 bank tender and one outside with no issues. Just dont coil any of the cords and you should be fine. Would def recommend a OBD2 plug for charging, its always at your feet so no chance of forgetting it and driving off with it attached.
 

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