Is my battery weak?

Just found this info in the digital manual for my ctek charger (the AGM part is missing from the paper manual I think):

NORMAL MODE:

Battery size 14–140 Ah / Mode 14.4V/4A

Normal mode for wet batteries, MF and for most GEL batteries.
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SNOWFLING MODE:

Battery size 14–140 Ah / Mode 14.7V/4A

This mode is recommended for charging batteries at temperatures lower than +5°C. It is also recommended for many AGM batteries. This setting is not recommended for maintenance charging when the temperature temporarily exceeds +5°C. Here we recommend the 14.4V/4A or 14.4V/0.8A mode.
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I think they're saying that the 14.7V snowfling mode is recommended for AGM batteries regardless of temperature.

Strange that the new BMW charger doesn't support charging at 14.7V.
 
insomnia said:
I had the previous BMW charger (grey little box) for my R1200RT. It destroyed two brand new gel batteries, even though I followed BMW's instructions to the letter. With the first battery the BMW dealer told me to have the charger connected for the whole winter. By spring, the battery was completely dead (tried to refresh it with a different charger to no avail). Got a new battery under warranty. To my surprise, BMW had revised their instructions, so this time the dealer explicitly told me to not have the charger permantly connected during winter. Instead they said to charge the battery every 2-3 weeks and disconnect. So I did this off season and by spring, the second battery wouldn't start the bike unless directly after a charge up. It couldn't hold its charge for more than a couple of hours. BMW wouldn't replace the second battery, even though I had cared for it exactly as they had advised. They stated they would only replace one battery under warranty. So I scrapped the BMW charger, got a Ctek one and managed to salvage the second battery to some extent, but it never came back to a reasonable strength. So I dumped it after a few months and bought a third one which I succesfully charged with the Ctek for many years. I continued with the "every 3 weeks method", never had it permanently connected. Just to be on the safe side.

Sorry for the rant. Point is that I don't trust BMW for taking battery charging seriously, not then not now. Their new charger is supposedly better, but is it really on par with the leading brands? Time will tell perhaps, when there are more long-term testaments. Anyway BMW has no competence in this area - they buy this technology and presumably not from the leading brands.

For convenience though I might buy the new BMW charger if I don't hear bad words about it, and because I don't charge continuously anyway, even with the Ctek. The battery certainly doesn't need a permanent charge, and even if some chargers can be connected continously, it doesn't add any benefit to the battery charging. I have easy enough access to the garage to connect the charger every 3 weeks or so. Another argument for the the BMW charger would be that BMW warns you in the manual from using anything but their own charger. :oops:



Before I possibly spend any money on the BMW charger just for the sake of convenience, I need to make sure what the correct voltage is for charging an AGM battery. Yesterday I had a brief phone call from a buddy who claims that AGM batteries should not be charged at the usual 14.4V but instead at 14.7V which the Ctek is capable of in its "snow fling" or "AGM" mode (depending on model). I don't know if this is correct or not, but it is likely what I've been hearing myself. Started googling a bit, but opinions were all over the place and I still have a cold/fever so my brain couldn't handle it for now.

I suspect that the new BMW charger isn't capable of 14.7V. Anyone know? I think the voltage is stated on the display whilst charging?
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ANYONE telling you to not have any liquid chemical (e.g. lead-acid) battery permanently connected to a battery tender is either lying or misinformed. The moment sulfuric acid and lead meet each other, the galvanic process process begins immediately. This is why 50+ year old DRY lead acid batteries will work like new when fresh sulfuric acid is poured in, and 5-year old WET lead acid batteries sitting on a shelf will be next to dead. The trick is to keep the WET lead-acid cells continuously connected to a battery tender, so as to reduce the galvanic degradation.

Or...if you're really hardcore, you can pop open the vent caps, drain the sulfuric acid, flush the lead plates, and ta-da! a lead-acid battery that WON'T degrade over time, even when not connected to a tender.

Also, for your 14.7v question, any reason you want to charge that high? Are you trying to equalize your cells or something? A typical motorcycle battery maxes out at a peak 14.4v. Overcharging for extended periods increases the risk of boiling the water/acid out of your cells, causing the acid to leak out, drying out the lead plates but also causing acid corrosion to any metal components on your bike it comes in contact with.

OTOH, 14.7v sounds more in line with lithium technology, not lead-acid. Also, I have the BMW intelligent charger and it does have both lead-acid and lithium charging modes built in, FYI. It's quite convenient actually, as it simply plugs into any power port on the bike. For me, I plug it into the plug on the dashboard, hang it off the right handlebar, and it hums away quietly, "tenderizing" my battery for me 😁

Mike
 
insomnia said:
Just found this info in the digital manual for my ctek charger (the AGM part is missing from the paper manual I think):





I think they're saying that the 14.7V snowfling mode is recommended for AGM batteries regardless of temperature.

Strange that the new BMW charger doesn't support charging at 14.7V.
Click to expand...
After I wrote my response, I saw this post from you...

Really? ctek recommends 14.7v for AGM batteries?!?!

My initial reaction:
wtf-gif.gif

But then, I started Googling, and found out that some AGM chemistry can tolerate up to 14.9V!!!! :oops:

So...I learn something new everyday. I guess my only takeaway is: Check out your specific battery model and find out EXACTLY what its AGM chemistry will tolerate volt-wise, not the charger.

the-more-you-know.gif 🤣

Mike
 
The original question was if a battery voltage of 12.8 was "too low" with the bike "on", but the engine not running. The answer is no. Your battery is a 12V battery, not a 14V battery. What your particular external charger outputs while charging the battery is beside the point. You are making assumptions relative to what the bike's meter is measuring by expecting it to show the voltage that is output from your external charger. I'm not aware of anybody here having an electrical diagram for the R18, but when you turn the bike "on", it's disconnecting the external charger from the circuit. The charging port isn't a direct connection to the battery itself. It goes through a control module. You are watching your battery discharge, as expected, when you leave it on, but the bike's engine driven alternator isn't charging the system. When you do eventually start the bike, it will show 14.2, or whatever the charging system puts out.
 
tommymck said:
The original question was if a battery voltage of 12.8 was "too low" with the bike "on", but the engine not running. The answer is no. Your battery is a 12V battery, not a 14V battery. What your particular external charger outputs while charging the battery is beside the point. You are making assumptions relative to what the bike's meter is measuring by expecting it to show the voltage that is output from your external charger. I'm not aware of anybody here having an electrical diagram for the R18, but when you turn the bike "on", it's disconnecting the external charger from the circuit. The charging port isn't a direct connection to the battery itself. It goes through a control module. You are watching your battery discharge, as expected, when you leave it on, but the bike's engine driven alternator isn't charging the system. When you do eventually start the bike, it will show 14.2, or whatever the charging system puts out.
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I don't know how to respond to that - I don't make the assumption that you suggest. And I don't use the 12V outlet as a charging port. And battery discharging with only ignition on is pretty obvious.
 
Keehn said:
ANYONE telling you to not have any liquid chemical (e.g. lead-acid) battery permanently connected to a battery tender is either lying or misinformed. The moment sulfuric acid and lead meet each other, the galvanic process process begins immediately. This is why 50+ year old DRY lead acid batteries will work like new when fresh sulfuric acid is poured in, and 5-year old WET lead acid batteries sitting on a shelf will be next to dead. The trick is to keep the WET lead-acid cells continuously connected to a battery tender, so as to reduce the galvanic degradation.
Click to expand...
The argument for only charging periodically, e.g. every two or three weeks, would be that overcharging the battery is more harmful than a slight discharge would be, combined with the suspicion that not even modern "intelligent" chargers can be trusted to not overcharge to some extent. True or not, I hear this advice quite often.

But I also hear what you say about the galvanic process. It might be more important to stop that from being irreversible, than to be overprotective about overcharging.
 
R12C-R18TC said:
While riding, my screen reads 14.3V with auxiliary lights on, brights on, heated seat on, heated grips on.
Well, it reads 14.3 with none of the above on too.
(With engine off it was 14.2, but that was immediately after shut off)
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Thank you for updating your post and clarifying the 14.2V with engine off. Your picture in the other thread was what triggered me to start this thread in the first place.

In a few weeks I'll ride my bike for the very first time. Out of curiosity, I'll keep an eye on the voltage immediately after engine shut off.
 
insomnia said:
See the first post in this thread.
Click to expand...
OK, fair enough, but why not use the charging port?

In any case, if your battery is fully charged when you are running your experiment, your charger shouldn't be operating at 14.4v when in the maintenance phase. Some smart chargers go into a sample and pulse mode where they essentially disconnect from the battery except periodically, and others adjust their voltages down to around 13 once the charge current drops below a certain limit.
 
tommymck said:
OK, fair enough, but why not use the charging port?
Click to expand...
Bike is new and I'm considering the alternatives for charging. So the crocodile clamps is a temporary solution.

My next step would be to confirm the correct charging voltage for the battery. It seems that 14.7V is appropriate for many AGM batteries, but I probably should check what applies to my own specific battery, as @Keehn suggested above. I think that all R18 models have a 26 Ah AGM battery, perhaps they all are of the same brand and model?

Ideally, I'd like the new BMW Plus charger for maximum convenience, but I doubt it can charge at 14.7V. And I've been burnt by the experience with the previous BMW charger. Perhaps some other CAN bus compatible charger can do 14.7V.

I already have a Ctek charger which is capable of 14.7V, but has to be pigtailed to the battery for convenience.

Funny thing if it turns out that the BMW charger isn't the best for these AGM batteries, but warranty claims will be discarded if you don't use that charger.

My search for the right charger is somewhat slow though - I'm low on energy because of a cold and the Ctek isn't bad. So the crocodile clamps will do their job for a while.
 
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