Charging the R1200RT w/gel battery

[Richard G]

I know this has come up before, but I need some re-assurance from someone who might know for sure.

 

I bought a Battery Tender Plus for my R1200RT before winter.

Hooked the loop end harness right to the battery terminals and left it plugged in.

 

This weekend I went to the motorcycle show in NYC and stopped by the Battery Tender booth and told him what bike I have and which charger I bought.

 

The person said if I have a factory BMW GEL battery (which it is)the charger may overcharge the battery because it will go to 14 volts, and the BMW battery is only supposed to be charged to 13 volts??

He said if I switch to any aftermarket GEL battery it doesnt matter. The charger will work fine.

 

Sounds odd to me. What voltage does the bike itself charge the battery to?

 

I checked their website before I bought the charger and nothing referring to this is mentioned.

Was this person misinformed or is there some truth to this?

 

Thanks Rich

[eaglemike]

Well, I don't know the official answer.But there's a short test you might consider. With the bike running, put a voltmeter on the bike. See what it reads at say, 2500 rpm. I haven't done this to my bike yet, but I could in a few minutes.....

 

all the best,

 

Mike

[FIRST_BEEMER]

That`s a little odd sounding to me. This system is based on the standard automotive 12 D/C system and charge rates are 14 plus volts. I have the same setup as you and use my tender with no none problems.

[ShovelStrokeEd]

The salesman is full of crap. Most alternator/regulator systems charge the battery at somewhere between 13.6 and 13.8 volts. I have seen 14.2 volts in many cases. Charge away. So long as you don't allow your battery to read the instructions that came with the charger you should be fine. All of this controversy arose from a pissing match between Exide, the manufacturer of the BMW battery and the Battery Tender folks. There is a slim chance, if you allow your battery to become deeply dishcarged that the charging rate/pattern of your Battery Tender Plus will not match the pattern required by the OEM. So long as you are just maintenance charging, you should have no problems.

 

I currently have 3 BMW gel batteries in service on my bikes and have had no problems. Of course, living in S. Fla, I don't have the same environmental conditions as you up in Joisey. I use no form of external chargers on my bikes. At least not for maintenance charging. I just let 'em sit till I plan on riding them then, if they won't start, I'll just toss a little 2 Amp charger on them for an hour or so and I'm good to go.

[David_S]

I'm sure he would have been happy to sell you the "correct" charger? I've been using a tender on my 05 R12RT, 2000 DR650, and 1952 ford 8N and they all have been fine. I just rotate it ever few days. Like Ed said your alternator will put out more than 14 volts.

[Ken H.]

someone who might know for sure.

Well that's a hard commodity to come by!

 

There are differences in the ideal charging rate curve between different battery technologies. Lead/acid vs. gel vs. AGM, etc.

 

How much real difference adhering to the exact ideal curve, and thus having to buy 'special' charges to do so, is where the matter of some debate happens. Purest will say yes, you must spend $110 to extend the life of your $80 battery 5% longer.

 

The more pragmatic amongst us say, "What the...? That makes no sense at all.” Charge the battery with what you have (presuming some sort of 'smart' charger) and buy a new battery with the money you saved when the time comes three years minus two days down the road.

[MaxG]

I have an R1200RT on order (last bike was a 2000 K1200LT) so I've read these conversations for a while.

 

My question now is: Why bother with the BMW gel batteries? When the OEM battery goes bad because I didn't use the BMW-approved charger, is there any reason at all why I shouldn't replace it with another brand of battery? Then my Battery Tender (or other charger) will work fine.

 

Roger

[RFW]

The person said if I have a factory BMW GEL battery (which it is)the charger may overcharge the battery because it will go to 14 volts, and the BMW battery is only supposed to be charged to 13 volts??

He said if I switch to any aftermarket GEL battery it doesnt matter. The charger will work fine.

 

Sounds odd to me. What voltage does the bike itself charge the battery to?

 

Absolute Rubbish! He's full of it! **NO** 12V lead acid battery (not the standard flooded cell, nor an AGM nor a gel cell) can be charged at 13.0 Volts! After all, a FULLY CHARGED 12V lead acid battery of any type in good condition actually has a terminal votage (with the charger disconnected) of about 13.2V. How would it be possible to charge a battery so it "rests" at 13.2 volts if you only let the charger go to 13.0??

 

Gel Cells are little different than ordinary flooded cells. The main difference is that they do not tolerate overcharging as well. But the chemistry is the same. EXACTLY THE SAME as a flooded cell battery. Therefore the charging voltages are fundamentally the same too.

 

The problem with a gel cell is simply that it cannot easily get rid of gassing that is caused by overcharging. After all, the electrolyte is a gel, not a liquid, so the gas bubbles tend to get trapped against the plates, reducing the useful plate area.

 

Monitor your charging voltage and simply cut off the charger when the battery voltage reaches 13.8 volts. You may not quite get a 100% charge (so what!) but this way you will not get significant gassing either, and your battery will not be damaged.

 

Bob.

[FIRST_BEEMER]

Mine will be replaced with something better when it bite`s the big one.

[Richard G]

Thanks everyone.

 

I have worked on cars and my own bikes for years, but having the new BMW with all this new stuff, I wasnt sure.

 

My first impression was this guy was telling me some bull.

It didnt sound right at all. Maybe he was only repeating something someone else told him.

 

I will use the charger I have and hopefully the warm weather will come soon and I can ride the bike to take care of the charging issue.

 

Rich

[RFW]

I will use the charger I have and hopefully the warm weather will come soon and I can ride the bike to take care of the charging issue.

 

Rich

The other point is that there is no need to charge the battery more often than once every 6 weeks or so, if it is in reasomably good shape (i.e. has no significant internal leakage).

 

A lead acid battery DOES exhibit some self discharge, but not a lot. Typically, a battery in decent shape can be left for at least 2 months and still retain most of its charge.

 

The only thing you are trying to guard against is sulphating, and this only occurs when the battery is left so long that it self-discharges itself to a very low charge level. It takes a lot longer than 6 weeks for this to happen, unless it is stored in a hot place. The cooler the battery is kept, the longer it retains it charge (like any chemical reaction, self discharge falls off with lower temperatures).

 

Bob.

[wasselr]

After some discussion about electrochemical reactions and the use of a standard 12v charger, I was told that one could use the 12v charger on the "new batteries" with no harm. The only problem would be the lack of a full charge, and that it would take the battery to approx. 95%. The charger should be connected direct and the bikes system would take it up the rest of the way when run for a period of time.

[FIRST_BEEMER]

I don`t know who your talking to but they are full O Beans.

If you use a standard charger you can over charge the battery. If you fail to check it. At about 115 deg. the battery will be fully charged. Anything past that and damage will occur. Use a battery tender plus and forget about it.

[RFW]

I don`t know who your talking to but they are full O Beans.

If you use a standard charger you can over charge the battery.

 

....which was why I said to terminate the charge when the voltage reaches 13.8V. This is perfectly safe for a gel cell and will result in a near-full charge, with no damaging gassing.

 

There really isn't any magic about lead acid battery charging of any type (flooded cell, AGM or gel cell). All it takes is a bit of understanding of the basic principles involved and a bit of knowledge of the quirks of each indidual type you are charging. This ain't rocket science! Lead acid batteries of all types have been around forever!

 

Bob.

[FIRST_BEEMER]

Yes you did, but he posted this after your post. So I thought I might try to add my 0.00000002% of 0.02 Pennie`s

[camfarm]

I imagine the person at the show was as poorly informed as those posting here. Most of this is misinformation, poor information, popular myth, and what not. Everybody's own experience dictates what they believe is true.

 

Best to do some research on your own - at sites where data, information, and opinion are kept clear and separate - rather than try to determine who on an internet board is credible and knowledgable.

[ShovelStrokeEd]

Enlighten us, Oh wise one.

 

And while your at it, explain why the charging system on the bike is the same regardless of external maintenance charger. Gel battery, AGM, conventional.

[glennda]

First Beemer

You have pennies in USA? Does that mean I can bring mine over when i visit?!!!!

[FIRST_BEEMER]

You bet.

[FIRST_BEEMER]

Poorly informed. ER AH I don`t think you should make statements of facts to witch you know nothing about in regard to what I or someone else knows. You don`t know that I know. So how do you know that I don`t know what I know you know. You know what I know, you know. I know I know. How about You.

Poorly Poster Uninformed.

[RFW]

Yes you did, but he posted this after your post. So I thought I might try to add my 0.00000002% of 0.02 Pennie`s

 

OK. I get it!

 

Bob.

[RFW]

Enlighten us, Oh wise one.

 

And while your at it, explain why the charging system on the bike is the same regardless of external maintenance charger. Gel battery, AGM, conventional.

 

Not sure who the wise one was intended to mean, but the simple answer is that a vehicle charging system is voltage limited. It stops charging when the voltage reaches a specified value (generally around 13.8 to 14.0 volts.

 

Many aftermarket chargers are not voltage limited. They can push the battery voltage to way above 14 volts. With flooded cell batteries, this is not much of a problem, because when the voltage floats too high, and gassing starts, the cells just bubble harmelessly. But that is the kiss of death for a gel cell.

 

Other more sophisticated chargers cycle the battery through several defined charging regimens, including the so-called "Absorption Charge" where the cell is allowed to charge at a higher voltage (sometimes close to 15V) for a short (controlled) time before dropping down to a safe "Float" voltage. This ensures the various cells in the battery are all balanced (or "equalized") and that they are charged to 100% of their capacity.

 

The problem with the Absorption Charge is that it causes cell gassing, which, as with uncontrolled charging (above) can damage gel cells.

 

An automotive system avoids the problem entirely by never charging the battery to 100% of its capacity. By eliminating the Absorption Charge cycle, and simply holding the final charge voltage at a value that minimizes gassing, the battery will never reach a full 100% charge, but that doesn't much matter, since a car or bike battery's main job is just to supply short bursts of very high current to the starter, not to supply current to a load for the longest time possible.

 

Bob.

[wasselr]

My mistake in not being more specfic! Allow me to clarify.

When I stated "I was told", I should have added that this does not mean I believe. Secondly, the post was more to show, as noted earlier, the amount of disinformation, even within the bmw shops.Understanding electrochemical cells, (voltaic and electrolytic), the activity series of the many metals used and their redox reactions is more complicated than the average mechanic or sales person needs to/wants to deal with. On top of that, what the outcome of placing various electrical potentials at various current flows to produce an electrolytic cell for recharge is also complicated and different for each metal. I also should have noted the bat. charger in question has a "tender" built in. Not being an EE that designs bat., I am forced to just use the kiss method....and just RIDE to keep it charged.

[wilsons]

if they won't start, I'll just toss a little 2 Amp charger on them for an hour or so and I'm good to go.

 

Thanks thats answered my question cuz me battery is dead!

[wilsons]

oh um so its ok to charge as is and NOT disconnect battery from the circuit?

[rickmoen]

I bought the BMW branded charger with my '05 R1200RT. Does everything said here apply to that charger, too? Any difference between the BMW charger and the BatteryTender charger? Thanks.

[Ken H.]

Any difference between the BMW charger and the BatteryTender charger?

Whew, what we need is more battery charging threads...

 

But to answer your specific question, yes there is a difference. But it's not so much how the battery is charged, but the circuitry in the official BMW charger specifically for the R1200xx series that when used through the bike's accessory socket, keeps the socket 'live'.

 

Normally the accessory socket(s) shuts down a period of time after the bike is shut down. By communicating with the CAN-BUS system the spiffy BMW charger keeps the socket connected so the battery can be charged.

 

Many of us just say to heck with all that rigmarole and wire a charging jack directly to the battery for a conventional (and cheaper!) battery tender, with no issues.