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Trickle Charge Battery

52K views 58 replies 21 participants last post by  schultz 
#1 ·
I was advised by my SA to trickle charge my battery since I drive about 23 miles (largely stop and go on the freeway) each day and he felt it was not enough to charge the battery well. I had one blind spot detection sys malfunction and the SA felt this was related to low battery charge. In addition, he noted other warnings of the key fob (which I did not know about) which he thought were electrical due to low charge. My questions are as follows:

a) My battery charger at home has a 2/10/25 amp setting. Rather than trickle charge at the 2 amp setting, should I just charge it fully once a month or so? Are there advantages to trickle charging over the regular charge?
b) What kind of battery does the 2011 535xi have: wet, gel or AGM? I have to choose this setting on the charger.
c) Do you charge the battery via the connections under the hood used to jump start the car? I am not sure where the battery itself is located.

Thanks for your insight.
 
#2 ·
I use a Porsche trickle charger that plugs into the accessory jack (between the 2 front cupholders). That seems to work fine and is really easy.
 
#5 ·
+1 Deltran Battery Tender Plus
My SA told me the same thing. I don't drive much, and he said he's seen some pissed off owners after a year have to replace a $700 battery. I just bot this off amazon for 43 bucks, free shipping no tax.
This battery charger is much better than a trickle charger. It has a brain, and knows when to adjust itself , so you don't need to monitor it. You just hook it up to the posts under the hood and leave it alone. The battery is in the trunk, no need to gain access to it.
 
#4 · (Edited)
Porsche, Ferrari and a number of other manufacturers use Ctek chargers. Here's a link to their site. You can buy them all over the net. You can connect them a few different ways. If you use one of the accessory 12 volt connections just make sure it's live when you turn off the ignition, some only work when the engine is running which would obviously not work for charging. If none are live when the engine is off you'll have to connect it to the battery leads under the hood which is no big deal with the available quick connects. I store cars over the winter and have not had a problem, they're "smart" chargers so they charge, maintain, de-sulphate, etc. all automatically (pretty much connect and forget). http://smartercharger.com/
 
#6 ·
I bought the charger from the parts department at the BMW dealer. About $60.
 
#7 ·
F10 team,
Any recommendations on preserving the battery charge is the car is stationary for weeks or months? On my E46 M3, disconnecting the battery is an easy task. Not so much with the F10. Trickle charger is not a feasible option because I do not have a garage with an electrical outlet.
Thanks.
-jc:bigpimp:
 
#10 ·
The service manager at my dealership gave me a battery disconnect switch for when my F-10 is not being used for long periods (like winter in the northeastern US) . They are shipped with all M's and taken off before delivery to buyer. The switch is a Hella.
I still have to decide where to install it . Trunk I suppose,although there is enough cable to run from the battery to some where near the rear seats.
See attached photo- What do you think??
 

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#12 · (Edited)
I hate to double-post, but here is my reply on the similar thread:

http://www.bimmerfest.com/forums/showthread.php?t=530709
The BMW battery tender attaches to the under-hood terminals. I use one on my M3, which sat in the garage, unstarted, from 12/1/10 to 4/1/11. Tender works like a charm - the M3 started right up after its 6 month "nap" with no drama whatsoever.

The BMW tender is reasonably priced with your BMWCCA discount. You can find a cheaper tender without the Roundel on it, but I am more comfortable using a BMW part - presumably, it gives them less "wiggle room" to deny a claim if my battery dies or the tender fries an electronic module. If I had a Brand X tender connected for 6 months, I am sure that BMWUSA would tell me to take a hike.​
For 50-60 bucks (less when you figure you can sell the tender on eBay when you're done with the car), why would you even bother with a disconnect switch? Having to reprogram the seats, mirrors, climate, pre-sets, EQ, etc. every spring would drive me NUTS!
 
#13 ·
Uh- I don't have a garage. When I use the BMW battery tender I have to run an extension cord from my house to the driveway.
That is why the kill switch may work for me
 
#14 ·
I just ordered the Deltran Battery Tender Plus on amazon as well. I drive my car only on the weekends. Picked it up 4 weeks ago. The status in the Idrive is showing all OK. But, based in the info I am getting here, it sounds like I may need to use this to charge my battery sometimes. May be once a month or so?
 
#16 ·
...on Amazon at $47.99 w/ free shipping. I might as well admit it. My office is 1.4mi from my home and I like to ride my bike to work in the good weather = bad for my battery.
 
#17 ·
I was recently looking into the same issue and spoke with several people and here is what I found.

The F10 uses an AGM battery. Using a trickle charger <= 2 amp like the rebadged BMW model charger or the original Deltran is not good for AGM batteries.

AGM batteries need an AGM capable charger, such as in my case the Schumacher XC103. Using maintenance mode or trickle charging an AGM can decrease its performance. AGM capable chargers, like mine, can do 2amp, 5amp, and 12-30 amp mode. The 5 amp mode is the lowest recommended way to maintain charge on the AGM battery with the rating installed in the F10.

I am not a battery expert, but did spend some time on the issue. The BMW charger is perfect for non-AGM maintenance free type batteries on older model vehicles. A look at the charger will indicate it's not state of the art, though that is hardly a reason to dismiss it. Rather, the AGM capable chargers have settings for sensing the battery charge and you can choose slow mode if you are worried about pumping that much into your battery. The fast mode is fine for occasional needs where the battery has dropped to 50% or so. Which is another thing. My battery read 12.34 volts and was 61% charged according to built-in tester on XC103. I used fast mode to bring it up to capacity in under 2 hours. Point being, if you are a battery newb like me, sticking the multimeter on the battery to check voltage is pretty stupid way to understand battery charge.

The BMW trickle charger will serve many people's needs, I'm sure. But the XC103 is about $75 on amazon and has superior capabilities to deal with standard, agm, gel cell, and deep charge variants. It offers 4 battery types, 3 charging speeds, and engine start mode. It also has a battery depletion test functionality and an alternator performance measurement capability. If you are in the market, you might consider something similar to this charger.
 
#22 ·
I was recently looking into the same issue and spoke with several people and here is what I found.

The F10 uses an AGM battery. Using a trickle charger <= 2 amp like the rebadged BMW model charger or the original Deltran is not good for AGM batteries.

AGM batteries need an AGM capable charger, such as in my case the Schumacher XC103. Using maintenance mode or trickle charging an AGM can decrease its performance. AGM capable chargers, like mine, can do 2amp, 5amp, and 12-30 amp mode. The 5 amp mode is the lowest recommended way to maintain charge on the AGM battery with the rating installed in the F10.

I am not a battery expert, but did spend some time on the issue. The BMW charger is perfect for non-AGM maintenance free type batteries on older model vehicles. A look at the charger will indicate it's not state of the art, though that is hardly a reason to dismiss it. Rather, the AGM capable chargers have settings for sensing the battery charge and you can choose slow mode if you are worried about pumping that much into your battery. The fast mode is fine for occasional needs where the battery has dropped to 50% or so. Which is another thing. My battery read 12.34 volts and was 61% charged according to built-in tester on XC103. I used fast mode to bring it up to capacity in under 2 hours. Point being, if you are a battery newb like me, sticking the multimeter on the battery to check voltage is pretty stupid way to understand battery charge.

The BMW trickle charger will serve many people's needs, I'm sure. But the XC103 is about $75 on amazon and has superior capabilities to deal with standard, agm, gel cell, and deep charge variants. It offers 4 battery types, 3 charging speeds, and engine start mode. It also has a battery depletion test functionality and an alternator performance measurement capability. If you are in the market, you might consider something similar to this charger.
Very interesting post. Can you provide some links to your research?
 
#19 ·
Good point, let me clarify. It certainly will if the battery is in the neighborhood of full charge. If it is say 80% not hard to accomplish, trickle charging can eventually lead to reduced battery capacity. The way I understood it is if you plan to trickle regularly, BMW unit is fine. If you prefer to go a few weeks without charging, better to buy a bigger charger and use the slow setting instead of maintenance to avoid decreasing charge battery holds. It is about knowledge and preference I guess in that if you know what your doing it is fine. I prefer to give it 5 amps as needed. Trickle charging this at 1.25A could be your Saturday if battery low.
 
#23 · (Edited)
I got the BMW Advanced Battery Charging System, the one with the alligator clips, not the one that plugs into the dash socket.

When I leave my car at home on trips, I plug it in, and whether the trip is one, two, three, or four weeks long, it keeps it charged, and is not a trickle system.
 
#24 ·
The Battery Tender is not a trickle charger.
 
#29 ·
This is about right except you want push more current into the battery so charging goes to float/maintain mode because battery is charged and not b/c the charger timed out. As opposed to older wet battery designs you can throw literally as much current rate as you want into an AGM battery.

If there is a surprise here, it is how little depletion the 1.5A can recharge before timing out due to the size (90A 900Ah) of the F10 battery. It is hard to calculate it precisely, but I am going to ballpark it. The last bit of charge is the hardest/longest task for the charger as the vehicle battery voltage rises closer to charger voltage level.

But, you are absolutely correct IMO that if your topping off or maintaining your battery the 1.5 should work. OTOH since last bit of charge is the hardest to restore, this is where a higher output unit has another advantage (in the case of even minor depletion)
 
#31 ·
This is about right except you want push more current into the battery so charging goes to float/maintain mode because battery is charged and not b/c the charger timed out. As opposed to older wet battery designs you can throw literally as much current rate as you want into an AGM battery.

If there is a surprise here, it is how little depletion the 1.5A can recharge before timing out due to the size (90A 900Ah) of the F10 battery. It is hard to calculate it precisely, but I am going to ballpark it. The last bit of charge is the hardest/longest task for the charger as the vehicle battery voltage rises closer to charger voltage level.

But, you are absolutely correct IMO that if your topping off or maintaining your battery the 1.5 should work. OTOH since last bit of charge is the hardest to restore, this is where a higher output unit has another advantage (in the case of even minor depletion)
Important question: Do you know for sure that the rating to be [ I assume you meant ] 90AH on our battery? I was unable to find this data.

Since I have installed an external charging jack that is always hot, it is easy for me to check the resting voltage of the battery. I've been at the office for about an hour and the battery is at 12.8V. That's a nice resting voltage for a fully topped battery.
 
#30 ·
I don't think that the current that the charger can push is a factor in the final stages of charge because this stage (acceptance charging) commonly called "topping" is voltage limited. When the battery reaches this level, the charger will limit the voltage and the battery will take whatever current it requires when held that voltage. It is implicit that the battery required less than 1.5A to get to the topping voltage or it would not have gotten to the limiting voltage using a 1.5A charger.
 
#33 ·
I absolutely agree. For topping off the 1.5A charger is just fine and you are right that current is running well below 1.5A at that time. My situation is one where that does not take place b/c the 1.5A cannot put enough charge into the battery before timer shutdown to low current mode.

Just so I'm clear, I want to reiterate that there is nothing wrong with the 1.5A charger if it suits your needs. Mine are such that I need to do more charging than maintaining and I get the same benefits the 1.5A unit offers for maintenance purposes (if I want to hook my charger up more frequently) with the more robust recharge capability of a higher output charger. The higher output model I have is $75 and has a few nice features. I lay it out there as an option to consider for those with similar needs because it is similar in price to BMW model and about $25 more than Battery Tender Plus but it covers more end user scenarios and has nice features (many battery types, several charging speeds, jump start, alternator performance tester, battery tester)

You can do recharge, not solely maintenance, with the 1.5A charger. It might take 12-20 hours to do it, though. The charger I have took the battery from the mid 60% to full in under 3 hours on the middle speed setting (5A). That is all I am trying to say. I would like to put together the charge time calculations b/c it will give people an idea of which charger might suit them better. Those calculations are not static and depend on many environmental variables as well as the actual battery under test, so the end user may need to consider those adjustments. I am sorting out a fair way to do it or will just discharge my battery and recharge in the different modes to see the results and offer them as simply my experience with recharging.
 
#34 ·
I checked out the battery manufacturers maintenance recommendations and they specify, only which types of chargers that can and can't be used and the maximum amperes.
Warning: Gel and AGM (Absorbed Glass Mat) batteries
require a voltage-limited charger. Charging a Gel or AGM
battery on a typical shop charger - even one time - may
greatly shorten its life.
The maximum charge rate in amperes should be no more
than 1/3 of the battery's reserve capacity minute rating.
If the terminal voltage exceeds 16.0 volts while charging,
reduce the charge rate.
 

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#35 ·
That looks good to me. Those amperages are huge! AGMs don't fall under the usual RC/20 or RC/5 rule of other batteries, but RC/5 is over 15A on the F10 battery. The voltage is a very important point. That will damage the battery. AGMs are charged at 15.4V, Standard wet cells at 16.0V, Gel Cells at 14.7V.
 
#36 ·
More on the Battery Tender Plus: It appears that it is not time limited during bulk 1.5A current limited charging.

I found information on the Tender Plus site that says:

"When the red light is on, the battery charger is in the
process of fully charging the battery. In order to properly charge
large capacity batteries, the charger may remain in this mode for
several hours or even days."

So factoring in a charge efficiency of less than 100%, an 8 hour charge could replace up to 12% of our 90AH battery. Perhaps 24% if you figure a typical overnight charge of ~16hrs. Not too bad in my view.

Regards,
Q
 
#38 ·
In a moment, someone is going to assert that I'm employed by the manufacturer, or worse, that I'm a Battery Tender zealot. :) While neither is true...

The product literature says that it does not spark and I confirm this from when I several times, used the included alligator clips to attach it.

I hope you don't mean to keep it permanently attached, or you would never be able to drive the car.

The nominal output is just over 12V and that is too low to shock you through your skin. (Tip: don't lick the terminals :wow: ).

At the end of charge, the unit goes into "float" mode and this is supposed to be an acceptable mode for long term connection.

One important comment about permanently attaching the included charger ring terminals:

Looking carefully at the car (+) terminal before loosening the nut, you can see that there is a thick Red wire going to the stud. This is almost certainly the battery cable. Under the lug of this cable, there is another contact that is a solid copper bus that is molded into black plastic. This is likely where some circuit in the vehicle gets its power. Not knowing what circuit that is, I was very careful to insure CONTINUOUS contact between the battery cable lug and the rest of the circuit while removing the nut and replacing it after inserting the ring lug from the charger cable. I speculated that If I lost that contact, I might have wiped some memorized settings in a similar fashion as would happen if the battery were removed and replaced. Again, I have no way of knowing if this would happen, I just did my best to avoid the possibility of it happening. I did this by continuously tugging on the battery cable during the operation, to insure that it was in continuous contact with the stud that the nut is removed from. And oh, yes... you will want to counter-hold the assembly while cracking loose the nut or the torque could damage the assembly. And oh yes again... make sure you use a ratchet wrench with a long enough socket extension so the handle does not accidentally contact any other metal part of the vehicle and the nut at the same time or sparks will fly!
 
#39 ·
As someone who's been using the BMW / Deltran tender, here's my input.

I connected the Tender to my M3 at Thanksgiving, and it was continually connected till I drove the car again in March. As I stated really early on this thread, the M3 started right up, no fuss, no drama. I did NOT connect the tender to the battery, but rather to the jump start terminals under the hood. On the E9X and E70, the positive terminal is under a red plastic cover up near the firewall, while the negative terminal is a metal stud up near the headlights. Given the fact that there's a 3-foot distance between them, I figured the chance of sparking was nil. Even so, I connected the clips to the M3's terminals before I plugged the Tender into the wall.

Now, I have no idea whether the M3 uses a Gel or AGM battery. And I will be the first to admit I have never understood current, volts, amps or anything else. (On a good day I do remember the difference between AC and DC, but that's about it). Nor do I care. Since my Tender has a BMW part number and was purchased from a BMW Parts Department, I figure if it doesn't work, BMW will cover it.

Someone here is saying "he's an idiot." And that is precisely the point. At least in my case, the Deltran Tender has been (literally) idiot-proof.
 
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