I've had a few Battery Tender brand ~1A versions for years. Boats, bikes, lawn stuff, trucks... no issues. Usually ~$30 on sale. I usually chain the boat batteries together most of the winter and they lasted longer than ever before. Not sure of their anti sulfation thing is marketing smoke or not, I dont care. I'm sold.

I think like Paul said most/many are the the same. I dont like leaving 'cheap' electrical stuff connected when I'm not around though.

Three stage charging generally best for most lead-acid batteries. Below is a good curve.

1. Bulk - max current available until the voltage becomes 14.4V
2. Absorb - hold 14.4V while the current falls off
3. Float - when current drops to zero, reduce voltage to 13.6V

The issue is holding the voltage under the gassing voltage.

http://forums.pelicanparts.com/uploa...1535053601.jpg

Here is a state of charge chart

http://forums.pelicanparts.com/uploa...1535053633.jpg

Good luck with the surgery.

I use a Ctek charger. I don't know which one as it's in the garage hooked up to the 911 right now. It keeps your battery in good condition too, as well as being charged up.

Just finished a small project at the barn and most of the charger are Schumacher.

I'm not as cheap as I thought!

I have had the same one for years - I'm thinking at least 10.

I have two BatteryTender units in use right now. Have used them for over 5 years with no issues. Both cars have them hardwired to the battery, just plug in when in the garage. Have to remember to unplug before backing out...I've forgotten a couple times but it just pops the plug off as you back out LOL.

I thought about this. Thats why I think the cig lighter type is better for me. Hard to miss it when the cord is draped across the drivers seat and the center console lid is up.

Just checked the garage and that is the brand I have. permanent install that terminates at the base of the windshield. The Cayman has a little removable cap there. I think it only puts out 1.5 amps but it works well.

Good luck on the surgery; I hope you heal fast without undue pain.

I've used a Battery Tender (purchased at Costco - saw them the other day for $40) for my 911 for about 6 years. No issues.

Battery Tender connected to a 12 year old Optima. Works great.

Just bought a Ctek 4.3. Used it on my 911, Boat, Tractor, Optima Battery. Even has a "recondition" function.

I recommend the CTEK 7002. The CTEK chargers are very smart and have programs that optimize charging (as opposed to some of the more simple ones here). You can also use it to keep power on the car when the battery is disconnected so settings are not lost. I keep each of my 911s on one and my car at my vacation house. I have installed the connectors on all my cars so that in the winter or if I have not driven one of my cars lately I hook them up and bring them to full charge. They are great for both regular and AGM (Optima Batteries). Regular use seems to extend battery life significantly. You can use one and routinely rotate it between cars...or have several as i do.

Shop around as some folks sell these and accessories for significantly less than others.

I have one of the 4 station battery tenders, I use it on the 911 during the winter and the new Harley year round. I’ve had one the single ones for probably ten years and it works perfect still.

these are known to be the best currently. I have a bunch of battery tender brand units for my Italian and german cars. they are seldom used but if I use them, they start right up.

I will replace w/ CTEK eventually.

Have used a CTEK for about 6 years or so now. Over here they come with a nice short lead to bolt onto the battery and that plugs into the longer lead from the unit.

Its easier for me in my garage as the charger sits in front of the car... bonnet (hood) ajar and all plugged in. Did have to remove the hood light tho'... not a problem for me and how I use the car.

Batteries do last longer than before and it has kept them (72 car with twin batteries) topped up and ready to use despite a very long period of inactivity (8 months due to shoulder issues).

Car gets plugged in after every trip just in case. Other infrequently used cars in the garage use similar units.

I have the Optima 400 charger.

Yes, I have the short ones on all my cars because making it easier todo makes it more likely that i will go to the trouble to do so. If folks are buying these, note that there are two different sizes of eyelet terminals. The larger ones are necessary for most battery terminal connections.

http://forums.pelicanparts.com/uploa...1535117444.jpg

You can get an 8ft extension cable (CTEK 56-304) for about $8-10 that is really handy. I like it for when I want to leave the charger on a car outside as I can leave the charger inside away from rain or dew and runt the thing cable under the garage door. It is also hand in the garage as if I amusing an out let that is far away, I don't need an extension cord and i can keep the unit over near the wall instead of out in the middle of the floor to trip on.

http://forums.pelicanparts.com/uploa...1535117498.jpg

I realize that accessories add to the price, but you can still get a CTEK 7002 for under $100 that comes with several already including clamps for clamping onto the battery of a car that you have not added the connector. You can also get an adapter for a car cigarette lighter. Although I have one, I have never used it as adding the connector is the elegant solution.

http://forums.pelicanparts.com/uploa...1535118552.jpg

Every winter, battery tender, no issues

I've got a CTEK 7002 and I keep my 997TT on that when parked for more than a couple days. I find that the 997 will put a heavy drain on a battery -- I wouldn't leave it undriven or off a charger for more than a couple weeks or you'll shorten your battery life. Ask me how I know... Where the CTEK 7002 shines is in the rejuvenation mode. It can desulphate older batteries and give them some extra life. But it's not magic and you don't want to run that on new batteries as that's not good either.

While I like the CTEK, I'm not sure it's really worth the premium. I also have a Schumacher XM1-5 Maintainer, 1.5-Amp that works great, and maybe better than the CTEK in some cases. First, you can buy them at Wally World for $15 -- can't beat that. Second, they're less sensitive to really low voltage /discharged batteries (which the CTEK won't charge). Third, the lower amperage than the CTEK means I can use it to top off the 12v7amp batteries that are in everything these days (UPS, gate opener, alarm box, etc.). The CTEK is too many amps for those and will cook them.

Hope that helps

So there's actually science behind what I was told? (By a retired engineer, FWIW. He claimed he bought many chargers, tried them out holding a multimeter while they were charging to sort out which ones did the above, and which ones just went straight to 13 volts and sat there. That's how he settled upon the inexpensive Schumacher model. Looks like it's now about $36, though.)https://www.walmart.com/ip/6-12-Volt-1-5-Amp-Maintainer/13005742?dest=9999999997&sourceid=3657613017364785 8317&sourceid=39205868143757610837&wmlspartner=Es5 Ekr9eEBk&wmlspartner=je6NUbpObpQ