Battery Maintenance/Float Charger Connected While Battery is Removed

[Qsilver7]

Originally Posted by bcredliner

...I have used the high output position a few times but only when the battery was low and I wanted to have enough juice to start the engine and then immediately remove the cables and use the alternator to charge the battery as I drove. ...

Double ditto bcredliner on the above quote. That's the ONLY time I use my charger's 50 amp setting. Its when the battery is dead, and I need to get the vehicle started NOW...and hit the road.

But if my battery was discharged due to some unfortunate circumstances...or it's getting old and voltage is dropping...I use the low & slow recharging method to see if that revives the battery.

To the OP:
You may want to also start monitoring your battery if it fell into a state of deep discharge. Many times this can cause irreversible damage that it will never recover from. IF you've unlocked your OBC...you can quickly (like in 15 seconds) run OBC TEST 9 with the ignition in position 1 (hopefully BEFORE starting the engine) to get an idea of the battery's voltage. If it is consistently below 11.89 volts...it's a sign that the battery is not in the best of health because at 11.89 volts...the battery is a 0% state of charge.

[jim628]

[QUOTE=Qsilver7;1014137]Double ditto bcredliner on the above quote. That's the ONLY time I use my charger's 50 amp setting. Its when the battery is dead, and I need to get the vehicle started NOW...and hit the road.

Hi,
WHen you did this, did you:

A) Start the engine while the 50AMP charger is still connected and charging
or
B) Connect the 50 AMP charger, wait few mins, disconnect the 50 AMP charger then start the engine


Thanks.

[StephenVA]

[QUOTE=jim628;1014145]

Originally Posted by Qsilver7

Double ditto bcredliner on the above quote. That's the ONLY time I use my charger's 50 amp setting. Its when the battery is dead, and I need to get the vehicle started NOW...and hit the road.

Hi,
When you did this, did you:

A) Start the engine while the 50 AMP charger is still connected and charging
or
B) Connect the 50 AMP charger, wait few mins, disconnect the 50 AMP charger then start the engine


Thanks.

If "A" insert credit card. (This quiz was too easy). Now if anyone says "yes" they did, then read below:

If this option is selected and you will "shock" the electrical system, all bets are off on everything surviving the surge. Alt, regulator, control module, etc. Kind of like jump starting car A while car B is running or is at a high high RPM. This is another automotive skill no longer taught in high schools.
Winter is coming so this will be a daily event in office parking lots all over the Rust Belt. Repair shops love the business.

[Qsilver7]

[QUOTE=StephenVA;1014154]

Originally Posted by jim628

If "A" insert credit card. (This quiz was too easy). Now if anyone says "yes" they did, then read below...

WHEW! Glad I picked B.

[bcredliner]

[QUOTE=StephenVA;1014154]

Originally Posted by jim628

If "A" insert credit card. (This quiz was too easy). Now if anyone says "yes" they did, then read below:

If this option is selected and you will "shock" the electrical system, all bets are off on everything surviving the surge. Alt, regulator, control module, etc. Kind of like jump starting car A while car B is running or is at a high high RPM. This is another automotive skill no longer taught in high schools.
Winter is coming so this will be a daily event in office parking lots all over the Rust Belt. Repair shops love the business.

The reason for the boost setting is provide enough current for the starter motor. It is OK to leave the charger connected until the car starts. It is also OK to increase the RPMs of the car providing current. At peak output the alternator is only putting out 14-17 volts.

[Qsilver7]

Originally Posted by jim628

Hi,
WHen you did this, did you:

A) Start the engine while the 50AMP charger is still connected and charging
or
B) Connect the 50 AMP charger, wait few mins, disconnect the 50 AMP charger then start the engine


Thanks.

I did "B". I have a gauge on the charger...and when using the 50 amp "boost charge" I leave it connected until the gauge registers it's okay. Then I removed the charger from the battery posts before starting the car.

Unless you're really committed to buying only BMW or MB batteries...you can use just about any 49/H8 or 95R/H9 class size battery. Most battery brands in the USA are made by the same 3 battery manufacturers (Johnson Controls, Exide, East Penn). You can see in the chart below what the specs are for the East Penn 49/H8 & 95R/H9 batteries are. The ones mfg'd by JC & Exide have pretty similar specs. The warranties may vary by brand label...but again, are usually 2 or 3 years...many times with an extended pro-rated warranty after the initial full replacement years.




I've always suggested checking your local autoparts stores like Autozone Advanced Auto, O'Reillys, Pep Boys etc...then there's Batteries Plus, Sears, Walmart, Interstate Battery outlets/stores, etc. Again, your looking for the 49/H8 or 95R/H9 battery class size. This will be the equivalent of the usually $200+ BMW branded battery. You can also decide if you want lead acid or AGM...either will still need to be vented (so be careful not to lose or pull the X5's vent tube out...you'll need to reuse it and the little elbow).

Here's some examples of replacements:

Autozone Duralast Battery Brands








Sams' Club Duracell Battery Brands:








Batteries Plus Duracell Battery Brands: