Which Battery Tender/Charger
 

1) Those of you currently using a battery tender or trickle charger to avoid the dreaded dead battery, which do you personally recommend? I am ignoring the fact that BMW sells one and hoping instead to find an equally safe and reliable one for half the price.

2) Anyone that is choosing to use the BMW tender, is there an advantage I should know about?

3) Ours (4.8 with CA and most the other goodies) is driven shorter distances throughout the week and lower than average miles overall, thinking I would put the tender on it during the weekends to get a full charge unless we take a road trip. How many hours does it typically take on the charger to reach a full charge again with the charger you're recommending?

Thanks!

I have been using a Deltran battery tender for about 6 years with no issues. This is the same brand that BMW rebadges as their own.

I have 3 Deltran Battery Tenders: one is nearly 20 years old, (used on my scoots), and the others are 7 and 3 years old, respectively. All run better than my Rolex...

Ctek brand also gets very poz reviews here, fwiw.

I think Deltran makes BMW's branded maintenance charger.

Shop the net for best price, but even at bust out retail, the BT is not expensive. Make sure you get the alligator clips to connect to underhood lugs.

I run one on the 3rd car that sits all winter at the other house, (the X5 every other season), connected to a mechanical appliance timer for a weekly turn on; I come 'home', and it starts up like I never left...
GL, mD

I have a 2011 50i so I probably have not had the experience of having a battery to fail,,,YET! I have seen the dreded "battery discharge" screen on my message board, BUT I refuse to get a battery tender, or anything else that resembles a battery charger! Not being a snob or anything, I think that BMW should build a vehicle and electrical system that does not discharge like these do, reading some of the complaints. I have not seen these types of complaints on any other car to the degree that I see from BMW,,,and I really don't know why. Our systems are not anymore complicated than Mercedes, Porche, Audi, Lexus or any of the other high end vehicles. Sounds like BMW has exectrical systems that are on par from the early Fiat/MBG days. Hey I love my 50i, but I'll be damned if I am going to put a trickle charge on my vehicle for issues that BMW should resolve!! JMHO!

There are now two battery chargers rebadged by BMW. One is the Deltran Battery Tender and the other is the CTEK 3300. AGM batteries require a higher charging voltage than lead-acid which the CTEK (and others) provide with an AGM mode. Battery Tender does not have this mode. The one I purchased is the 3.5 Amp, 8-step NOCO Genius g3500. It is excellent and I am very satisifed with it's performance. If you are looking to buy a charger, you may as well buy one with the AGM mode. The "why we have to use one" is the topic of numerous other threads, so I won't get into that here.

I recently bought a Deltran battery tender and have no complaints.

I disagree, but we may be caught in semantics...when I ref'd Battery Tender in my orig post, I should have pointed toward the newer version, Battery Tender Plus. I have an old BT, and 2 newer BT Plus units. I know the BT Plus performs well on AGM batteries...and I did pitch CTek, which I know to be qual product also. But, BT Plus will do well on any normal AGM batt, imo.
GL, mD

There are two BT+ models, first is a standard/AGM and second being a Gel/deep cycle. So Deltran does claim their first charger is good for AGM as well. When I was researching, I was looking for something with more flexibility, options, and a better display for monitoring. There is no indication or setting on the BT+ for AGM that I can see. The BT+ is probably a fine unit, but my preference was for a charger with more amperage and more settings. I *really* liked the new CTEK US4300 which is now superseding the 3300, but it is only available through a few U.S. channels and they control an artificially high price for this new product. I saw the NOCO g3500 as a comparable, and very flexible unit, with additional modes (6v/12v)+ (std. vs AGM). IMO the NOCO is a good value that lies somewhere between the Deltran and the CTEK 3300/4300. In the end, do your research, and choose a decent microprocessor controlled charger and you will be fine.


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Thank you all for the feedback.

Do I need to determine if my battery is an AGM by looking at/checking it, or is it the only OEM battery in the '08 4.8l?

I hear your frustration. I have owned quite a few VW's, Audi's, BMW's and look at it like this; these cars are all engineered and built very well and are great fun to own and drive. Most of them are not without their quirks though, be it electrical, mechanical, or some compromise in performance vs. reliability, or handling vs. ride quality, etc. Overall I am willing to take the (very) good with the (few) bad and my enjoyment in ownership and just the feeling you get driving these cars far outweighs the occasional headaches.

While I agree with your point, at the same time coming from an E53 X5, I see why the battery may not be able to keep up if not driven enough to provide a full charge, because it's staggering to me the increased amount of electrical goodies on a well equipped E70 from our previous '02 model.

We're all pretty lucky to have these type of "issues" with our luxury "SAV's" :thumbup: We could be in a forum for 1983 Datsun owners right now trying to figure out how to roll up our broken manual window cranks! Cheers!