In the analysis of buying a Tender Jr. vs. a Tender Plus, the main issues are time to full charge, battery size, & parasitic draw. The Tender Plus (1.25) will get the job done twice as fast as the Tender Jr. (0.75). Both now are similar architecturally, save it be the charging power & lack of temperature compensation on the Jr. They both are 4 stage, both have the same sophisticated computer chip technology running the charging process, etc... I spoke to The Deltran(The Manufacturer) customer service department on 3 different occasions, making sure I had the facts right. The first 2 times I was misinformed about the temperature compensation issue. I am editing this review to be accurate as of today's date of 12/01/10. Because The Plus will bring a battery to full charge twice as quickly as The Jr. will, The Plus has a much better chance at overcoming a parasitic draw on your batteries power. Modern cars have sophisticated electronics that require constant power 24/7. Check all your battery connections & your alternator belt!!! If the connections are not clean & tight, clean it with original coca-cola and a rag / brush, make sure they fit snugly. If your alternator belt is too loose it will not charge your battery properly. If you only want to buy one Tender, don't cheap out, buy The Plus if you have the money to do so. If you want to buy 2 or 3 Tenders to make sure all your batteries are fully charged, the Jr. will probably do just fine. I personally alternate The Jr. between 3 different cars, if I had it to do over again, I would buy The Plus instead as I am not a patient person. Both models will turn off in 72 hours automatically if a full charge is not reached, & neither will start charging without at least 3 volts stored in the battery before initiating a charge. If you left your lights on for 4 days like I did, get a jump, & drive your car around for 30 minutes before hooking up any Tender to charge your dead battery. Either of these 2 Battery Tenders are the best in the world, don't bother doing anymore research, I have done it all for you. Buy one or buy both!!! I bought The Plus model a few months ago also... These babies save you $$$, time & frustration!!! Get the 25 foot extension if you want to charge a car that sits in the driveway, it's only $12. You might also want to buy the Cigarette Lighter Apapter to charge cars that have the battery in the trunk, like the BMW E39 models. [...] Battery Tender 021-0123 Battery Tender Junior 12V Battery Charger
January 2011 update: I've had one hooked up to my 2003 Chevy S-10 since July 2008 and another to my 2004 Kawasaki Z1000 since February 2008. The S-10 has an Optima battery installed August 2006 and the Kawasaki a Deka installed August 2008. Both of these batteries are premium quality and represent the finest in their class available to the average consumer. Nonetheless, I am certain the BT Jr. is the primary reason the Optima retains 81% of cranking health and the Deka 71%. (Search my other reviews for the Argus BB-SBM12 and BB-SBM12-PS Battery Bug monitors as to the source of those percentages.)
As for the 3-step model... It's doubtful you'll ever run into one of these now. Unless it's dust and grime encrusted, hanging on a hook in that truck stop 2 miles off I40 in Two Guns, AZ.
Temperature compensation doesn't seem to have been as critical as I might have expected.
ORIGINAL REVIEW July 2008:
There are two things you need to consider when purchasing this item.
First, unlike its big brother, the Plus, the Junior is not temperature compensated. To find out more about that, go to batterytender.com, click on the FAQs link on the left and read item #18: "What is Temperature Compensation and how important is it?"
I was concerned about this, as living in the desert as I do, the temperature in my garage is 90 to 130 degrees most of the year and can drop to the 50s in the winter. I inquired about this to Battery Tender support and received this answer: "The Junior is not a temperature compensating unit, however, when the temperature is hotter, the unit will actually charge the battery a bit faster and it will not harm the battery." I don't know what to make of this, especially since compensation is so important according to their FAQ.
The other is to make sure you get the 4-step Junior which replaced the 3-step over a year and a half ago. On the back side of the packaging on the left side look for the reference to "Complete 4-step."
That being said, I've been using a Junior for almost 6 months on my motorcycle so I can't post up my experience as well as others here. I'm hoping it will provide my batteries with more service than the 14-16 months I'm used to.
By popular acclaim and editorial content, the Junior and the Plus have garnered untarnished reputations and withstood the test of time. For maintaining your battery, there really isn't anything else out there.
The battery Tender Jr. comes with 1 set of permanent mount ring terminals & 1 set of mini jumper cable clamps so you can hardwire 1 car & use the clamps whereever they are needed.The 1-way quick disconnect on the cord makes things very easy to hook up & unhook. And it is maintaining my battery fine, no more dead car.
Great Product. I needed a way to keep my minivan battery topped off during extended idle time because my electronic rust protection device was draining the battery. This product does the job beautifully! The only trouble that I ran into initially was that the charger would not start charging because my battery voltage had dropped below 3 volts (this is a safety feature built into the unit). Once I got the voltage up above 3 volts (by briefly attaching jumper cables to another vehicle), it charged just fine. It took a few hours initially, but now I keep the battery connected while the vehicle sits in the garage. - Batterytender Charger Battery - Battery Chargers - Motorcycle - Battery Charger'
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