trickle charging how long?
 

I have a "smart" agm compatible trickle charger. I have used it to maintain the boat battery off season. So I am now running an experiment with the charger on our 2007 x5.

The charger charges at 0.75 amps per hour. The x5 has a 6month old battery installed by bmw. The x5 is driven maybe 50 miles a week unless going somewhere out of town. In last.weeks.we.haven't.used out.of.town.

So the charger has a red led meaning I am charging and a green it.is charged led. So far we have gone 10 hours for a total of 7.5amps in and it is still showing it.is charging. So how long til it show fully charged how many total amps in?

So one.would think it should have topped off the battery by now? But I have read about these cars losing battery charge over time especially with short to the store trips and especially with the twin turbo v8s. True? Note this one is a non turbo 4.8 v8

So opinions? comments?

So the charger should put in 24 x .75amp hours per day = 18 amps per day. The battery should be 90 amp hours battery so a impossible completely empty battery would charge in about 5 full days.

On would figure the battery should have more than half charge and.I would hope 3/4 or more so one.would.figure in a day or.at.most.two it.should.show fully.charged.

So here is a question if my battery is 20 percent low now what stops it from going lower and lower til it is out of juice? Can this happen with design of the charging system in these cars? Should I put the trickle charger on it maybe once a month to avoid the possibility of flaky things from a discharged battery?

Following the huge problems with high current usage when car is not in use (that means that it didnt go to sleep mode fully, not that it has a high sleep mode current) with the 7 series E65 and early 5 series E60, BMW implemented some extra functions. If the car was supposed to be in sleep mode, but it continues to draw high current, most of the consumers will be shut down and only a few will be left "armed", CAS and a few others. This function will prevent the battery to be drained completely, but it may stay at a low level of charge without giving some noticeable clues for the regular owner. With DIS and ISTA an "Energy Diagnosis" menu can be accessed where all random wake-ups and other energy related events are recorded.

Not an exact comparo, but our '01 3.0, with a 2 month old newly installed batt, may take up to a solid 'overnight' to get back to green using my ol'Battery Tender.

This comes after some up and down our mtn/local driving. Same goes for our '02 Vette.

The arithmetic is nice but most good low amp chargers don't 'lie', and it takes what it takes to get back to green. Otoh, once up to green, it floats along nicely and barely comes on again, with charger in place.
GL, mD

BatteryUniversity.com BU-400 Charge methods

All About Battery Chargers – Battery University

Battery tender went to green after charging for between 10 to 18 hours. That might mean the battery was 10 to 15 percent discharged.
I will try charging again in two months if the percentage is the same or less then it is no concern. If the percentage rises it will then be worth trying again in 4 more months.

Question is how discharged will the battery become over what time period.

What do you mean by floats along nicely and barely comes on again with charger in place? In place when and where?

I have a AGM battery in our E53. Not sure whether the E70 comes stock with a standard lead battery or AGM.

Every 2 months or whenever I remember, I will put our chargers on it, mainly because AGM's are supposed to be charged up to 14.7 versus a traditional battery, 14.4. Whether those .3 volts is a big difference on whether these AGM's sulphate or not, I don't know. I just try to be proactive about it...

E70 has a agm. For what I have read I am uncertain if a e70 can become discharged due to charging system design. As I understand it there is no voltage regulator always seeking to have the alternator top off the battery. Instead the alternator is only charging when coasting i.e. slowing to a stop or coasting down hill? So question if just short level trips are always done does battery overtime become fully discharged?

Sorry it was unclear...I attach my Battery Tender to the 3 cars and 3 motorcycles, on a regular, rotating basis.

The time it takes to get 'to green' on any of those vehicles is a matter of how long any have 'sat' since I last drove/rode on an extended ride, and how long they have 'sat' with no BTender.

I may leave the BT on for a day, or days, on any given no low or no recent use vehicle, and it simply 'floats' along green for that period. Have never had a problem with extended use or attachment of the BT on any of our stuff, and all 3 Scoots and the Vette have an AGM batt.

That is what I meant by 'floating'.

I read your post of putting your low amp charger on in a couple weeks. I rarely let the cars go that long; they get much more frequent BT charging than a 'couple weeks'...the bikes sometimes get lost in the rotation, and might miss a couple weeks, but not the cars. We simply don't do enough regular long driving, so they get the BT regularly.

Should batts last longer/hold charge a long time? Sure, but they don't seem to these days. So, a BT or charger brand of choice, gets used regularly.
GL, mD

Motordavid did not say I put charger on for two weeks, just 10 to 18 hours. Our use of x5 will be low miles often on level ground. I would like to know if we may deeply discharge the battery this way or not.

So my plan is to manually charge at 1 then 2 and 3 month intervals. If manual charging time increases in like linear pattern then I will know we can face deeply discharging the battery.

I know once a battery has less than 50 percent charge the voltage it provides drops. If lower voltages cause systems to get flaky then I want to avoid that..

Seems nobody really knows what the algorithm of battery charging is so I am left to discover in part by this experimental manual charging.

It will be interesting if I discover x5 would become more and more discharged. There.is no question the alternator can charge the question when and if the computer software has the alternator charge. I believe.the software.design seems to minimize alternator use.to then improve epa gas mileage. But this is problematic if the x5 is used lightly?
We shall find out!

My 2011 X5 35d sat for 16 days with the doors locked and alarm armed and it started right up first time. Zero hesitation or drama. I have not looked to see how old the battery is but I got my X5 in November. My driving routine consists of several one to two mile trips a several times a week and a 50 mile trip once every six or seven days. These longer trips are key, I think.

Incidentally, if you want the best battery maintainer, get a BatteryMINDer. I have several and keep them connected to my cars while they are not being operated regularly, i.e., greater than six months, over the winter, etc. I also use them on my spare batteries or other "bad" batteries that other people have given me over the years.

Between my recovery procedures and strict maintenance routine, I have recovered many of these "bad" batteries to greater than 95% reserve capacity. My oldest battery is over ten years old and recently tested over 120% of it's reserve capacity.

It's a hobby and a profession.

The system will only disengage the alternator under acceleration if the battery charge level is relatively high in the first place, if its low it will charge all the time. This cut off point is, IMHO, set to low and if the battery is older, or conditions arduous such as low temperatures, short runs or high demand, the battery can become discharged.

I used to find in the winter, running my remote diesel cabin heater could render the car unable to start, even though the heater is supposed to cut out if it detects low battery voltage or low fuel.

If I could I would code this function off as I think it's value to economy is pretty much zero and it's there just so BMW can claim to use wasted breaking energy. I have not been able to discover how to code it off or recalibrate it.

My solution has been to fit a 110ah battery and recode the car to suit. This has solved my problems and I now don't need to use a mains charger at all.

I stress this has worked for me in my particular usage patterns and may not be the answer for others.

What tender charger is recommended for an AGM battery in a 4.4 e53?

Thoughts?
NPower Automatic Battery Charger/Maintainer — 2/8/12 Amp Charge Rate, 12 Volt Batteries | Battery Chargers| Northern Tool + Equipment

What type of AGM battery do you have in your E53 X5?




That charger is good for recovering batteries that are severely discharged but not for continuous use.

This from Autozone:
Duralast Platinum/Battery Price: $174.99
Core $15.00

• Part Number: H8-AGM
• Warranty: 3 YR
• Notes: *** 900 Cold cranking amps (1000 cranking amps)***. 160 / 95 reserve minutes. Warranty consists of 3 years free replacement. STOP!: Use a memory saver (located in the store GOTTChA kit) to prevent the need to reset vehicle systems. Battery is vented to outside of vehicle. Battery located in rear under spare tire.

In the summer months, the X5 doesn't get driven as much as we drive our 650. With that said, it was about two-three weeks since my wife drove it into the office and back home (about 40 miles round trip).

I have the BMW trickle charger and had it on for about 1.5 days before it started to flash the Green LED & the Red LED, it then took about another 1/2 day for it to go Full Green LED and stay there.

This I have found is about average for the X5 as my 2011 was the same as my 2013 is.

As well, in the winter time when the 650 is in storage, I might take it out if we have a nice clean day (no road salt etc...) for a quick drive (maybe once a month at most) and it has always remained in a state where it will always start and no issues.

The only difference in my case anyway is that when the 650 is in storage it is locked, and the X5 is unlocked (I don't know if this makes any difference or not). I sometimes think that they use less power (draw) when they are locked.

Given all that I've also recently heard that BMW has started recommending replacing the battery at certain service intervals as they are just 'hard' on the battery.

The only battery issues I've ever had were with my 2011 335i Convertible. After about two years the battery would not hold a charge and BMW replaced it under warranty.

https://www.northerntool.com/shop/to...6185_200596185

NPowerXRP #60109 is what I have used on all of my batteries for some time - diesel tractor battery, sailboat battery, VW TDI diesel battery (gone to a new home) and now my X5 E70 35d N57.

I am not a battery expert. I was qualified to maintain a 126 cell TLX-39B capable of IIRC (40 years later) 1700 A 250 VDC nominal for 3 hours.

The #60109 specifiesI cannot recommend BatteryUniversity.com too highly, particularly for non-experts.