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Discussion Starter #1
Howdy All Y'all,

While in Florida, I had a BMW dealer check Traveller's old 2002 lead acid type battery. Sure enough, the battery was about to give out. The only battery the good ole dealer had was a new BMW brand maintenance free type. So rather than get stranded, we bought us one real fast.

Well, I've heard that my old Battery Tender charger that I bought 4 years ago for the lead acid type battery can't be used on this new BMW brand maintenance free type battery. However, the good ole dealer said the rumor I heard was not true. I could use my old type Tender on this new type battery. He did not want to take my money and make me buy a new type charger.

I'm confused! I do not want to purchase one of the new type BMW brand Battery Tenders to the tune of 79 bucks, unless I have to.

Was the dealer correct, or is the rumor true?

What say ye, good folks?
 

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Wrencher Extraordinaire
2005 K1200LT
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Allen,

I would say yes you can use the charger, BUT I would not leave it on the bike for weeks on end. But 24 hours of use in a weeks time will not hurt anything. If the bike has to sit for longer - charge it a few days before you ride again. Your old charger most likely does not switch to a "float "mode once the battery is full charged. Extended full charging is what eventually fries a gel cell or AGM type battery. It causes them to gas and they are already under slight pressure (sealed case). Once the seal goes they lose the pressure and dry out.
 

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The new battery tender has a rest period in its charging algorithm requested by the gelcell battery manufacturer. I would say the old one would charge it ok, but don't leave it continuously charging as John says.
 

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Spend eighty bucks for the proper charger and be worry free! Dick
 

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DRothermel said:
Spend eighty bucks for the proper charger and be worry free! Dick
Your mechanic was right; the old tender WILL go to float and is fine. Leave it on it all winter and forget it. This has been discussed ad nauseam by many smarter than me and the consensus is: Although BMW will "recommend" their new tender - guess what - the battery is charged by the same old alternator on the bike!
 

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2005 K1200LT
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Alternator hasn't changed ?!?

TPadden said:
- guess what - the battery is charged by the same old alternator on the bike!

Everyone seems to focus on that fact and it is true. The battery has changed but the old alternator is the same so why do I need a better charger?

But it is apples and oranges.

The most important difference is that when the engine is running the battery is never exposed to a terminal voltage higher than 13.5 to 14.3 volts (alternator regulator defined). Go measure the terminal voltage of the battery after a tender has been on it for a few days and it will read 14.9 - 15.2. That is the big difference and if the current is not limited at that voltage - that is where damage occurs. Older chargers do not limit the current as well as the newer designs.

Like I said earlier they are safe to use just don't set and forget.
 

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Discussion Starter #7
More on BMW Battery Tender

Well I found an article in the Nov 2004 BMWMOAs ON magazine. The letter was written by the president of Deltran Corp. who makes all Battery Tenders.

He says something to the effect that the BMW Gel is made by Exide with changes to the charge curve, one being a timed sequence during the absorption period. The charge algorithum has to comply specifically with the new Exide Gel battery.

So...."The BMW Gel Battery Tender is in fact different than the normal Battery Tender Plus".

Dog Gone! Guess I'll just have to buy one next winter!!
 

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jzeiler said:
The most important difference is that when the engine is running the battery is never exposed to a terminal voltage higher than 13.5 to 14.3 volts (alternator regulator defined). Go measure the terminal voltage of the battery after a tender has been on it for a few days and it will read 14.9 - 15.2. That is the big difference and if the current is not limited at that voltage - that is where damage occurs. Older chargers do not limit the current as well as the newer designs.

Like I said earlier they are safe to use just don't set and forget.

Not true - just measured 2 PC680 batteries that have been plugged with tenders (NOT TRICKLE CHARGERS) for over two weeks and both were under 13V (12.7 and 12.9) not even close to your 14.9-15.2V. This makes sense because the float voltage of the tender is 13.2V but it doesn't go back to the charge mode until voltage drops to 12.0-12.5V.

YMMV but I use tenders plugged in all the time on all my bikes when they are parked - never had a problem.
 

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wardenross said:
Well I found an article in the Nov 2004 BMWMOAs ON magazine. The letter was written by the president of Deltran Corp. who makes all Battery Tenders.
......Dog Gone! Guess I'll just have to buy one next winter!!
Read something newer - as I said it has beed discussed and like oil everyone has an opinion - from Deltran's own webpages both the standard Tender Jr. and Tender PLus are recommended for Gel!

"The Battery Tender is capable of charge maintenance on all lead acid battery types, including both AGM and GEL cells. "


"Fully automatic two-stage lead-acid battery charger. Perfect for all lead-acid, sealed maintenance free and gel cell batteries."

But hey - it's your money
 

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Slow Old Guy
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I have to agree with Tom on this one. Just went out and checked and my old style Tender is floating the GS battery at 13.36. No problem there.

Hook up the Tender you have and monitor the voltage for a few days. If it gets up over about 14.2, spring for a new one. Otherwise, forget about it.
 

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Wrencher Extraordinaire
2005 K1200LT
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I guess I did not word it right. That was the point about a good tender. It will take it up high to complete the charge and then go into current limit for the float. At a C/5 C/10 charge rate the battery reaches full charge at a terminal voltage of 14.7 - 14.9. Then to limit the current the charger reduces the the voltage and floats the battery. That is why you can set and forget.

The older chargers don't do this, they continue to hold the higher voltage. That is a good way to check the capabilities of an older charger. Check the terminal voltage after a few days and if it is in the "float "range you may as well keep it and use it.

Sorry for the confusion.
 

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I have an 05 with Gel. Yesterday I bought from BMW dealer:

Battery Tender Jr. Part #0210123, Price: $29.95
BMW Adapter Lead, Bat Tdr, Part #72601470290, Price: $14.20

Was told by dealer that this setup allows a trickle charge for as long as one cares to leave it plugged into the bike accessory jacks and with NO damage to a gel battery (asked him twice).

Also has a nice little set of pigtails should the battery drain so that I can directly charge it (or a brother in need).

Dealer basically said why shell out 80 bucks for the BMW charger when this will get the job done for a lot less.

Hope he's right. Raffy may carry these items cheaper.
 

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Gel Battery charging ?

I know this is a little long but I just asked Deltran the question about BMW gel batterys and this was the reply:

The following is a message from the company president.

I will try to end the confusion about the new BMW Gel battery Battery
Tender.

The BMW Gel Battery Tender is in fact different than the normal Battery
Tender Plus. Although the Deltran Battery Tender Plus and the BMW Battery
Tender appear the same they are quite different. Approximately one year ago
BMW contacted us concerning their new Gel battery that is manufactured by
Exide battery in Germany. We were instructed to redesign the charge
algorithm to comply specifically with the new Exide Gel battery. Exide
recommended very specific changes to the charge curve, one being a timed
sequence during the absorption period. Please keep in mind that our
engineering staff has been designing charge curves for over fourteen years
and prior to this design request had never seen anything quite like the new
Exide Gel.

As the old saying goes, "the customer always knows best," we can only
do
as requested. If BWM/Exide says charge it to their instructions and the
battery will last through the warranty period who are we to argue. If it is
any consolation, we have found it to be a very good battery and should give
you many years of service.

We do claim per our packaging that we correctly charge gel batteries,
prior to seeing the Exide battery that statement was true, we are now
changing our packaging to indicate otherwise. Due to the new battery design,
and to comply with the BMW warranty, the customer must purchase a "Gel
Specific" battery charger.

After all these years in the charger business we are still amazed how
every manufacture try's to re-invent the battery. We realize that with all
the different batteries in the market place the customer becomes very
confused and is usually forced to spend more money. Approximately three
years ago Harley-Davidson changed their battery design and manufacturer, it
proved to be a very wise decision and we can only hope it works out best for
BMW, and most importantly, you the customer.

Sorry for the Confusion,
Mike Prelec
President,
Deltran Corp.
 

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Battery Tender

This has been beat to death and I already had five Battery Tenders on my "other " scooters in the barn so I called Deltran direct also and was told the Battery Tender Plus part #021-0128 ($40) is not for a gel battery --period. The Battery Tender Plus part #021-0156 ($89 BMW) is made for gel batteries only. They are all over the internet for $45, I just got mine from batterymart.com in four days for $46.95. Deltran said the bottom line is for a "true gel" battery there is a difference. For the money I have in the battery and the security, what the hell......... :cool:
 

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Gel battery Charger

Some interesting info about the BMW charger vs. the Battery tender warranty.I used the Battery tender Jr. for years with good success. When I bought my LT I bought the BMW gel battery charger. It lasted 2 years and fried itself one day. I found out that the warranty on the regular Battery Tender was 10 years while the warranty on the BMW charger was only 1 year! HERE"S THE GOOD NEWS! I called Deltran and they said they would fix the BMW charger for $15.95...in fact they sent me a brand new charger!! Deltran is a GREAT company that stands behind their products. Ron Ray
 

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Battery Tender

First of all let me say I know nothing about electrical systems, batteries, etc. BUT, I do notice the Battery Tender does sell a charger that is says is for Gel type batteries-which is about the same price as the other one, neither of which costs $80.00. If the old ones are ok for gel batteries, then I wonder why they sell two types? Just curious. jrlakin
 

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If the BMW gel cell battery comes with your bike, you'll need to make a decision on which charger to use (as discussed above). However, if you're replacing a battery and you have a choice, get an Odyssey PC680 AGM battery instead of the BMW gel cell and use your old, "smart" battery charger with confidence.

- Bob
 
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