Battery question?

It is starting to get cold here in MN and I am going to put the bike up for the winter. I had a gel battery installed this summer, My question is, do I need a battery tender on the Gel battery? with the other battery I plugged in the tender and forgot about it, I have been told that the Gel battery dosn't need the constant charge, Just forget about it and replace it every 4 or 5 years, Thanks,

Den

Den,
It wouldn't hurt to keep it on the Tender too. If you pull it out of the bike and keep it around 70 degrees or so, you can just hook the Tender up every 3 months or so.
They don't discharge much at all in storage.

Mick

Den,

Items from the R1150RT Maintenance Instructions:

"Use only electronically controlled battery charges with a voltage limit of 14.4 V to charge the battery."

"The battery must be charged prior to storage periods of more than one month."

"If the battery is in storage fo an extended period of time, recharge it approx. every 4 months. If the battery has not been disconnected from the motorcycle's system, recharge it every 2 months at the latest."

"CAUTION: If the battery is not disconnected, the onboard electronics (clock, etc.) will discharge the battery. This can cause the battery to become completely drained. In this case, warranty claims will not be accepted."

I don't want to hassle with the tupperware to remove the battery, so I'm leaving the charger connected over the winter.

If you're not going to ride the bike all winter, you'd be better off taking it out and keeping it someplace warm.

An engineer-friend from Thermo-King was the EE in charge of their truck trailer refrigeration engine electrical systems. He always talked about internal corrosion of lead-acid batteries (which is your gel cel too I understand) and how it doubled every 14 deg F that you raise the temp. This jibes with a chem prof in college that said all chem reactions double about every 14 deg F.

The EE also said the internal corrosion was proportional to the state of discharge in the battery. I. e. don't let it get discharged.

His conclusion from this (and I follow it too) was to keep a battery as cold as possible, charged, but whatever - don't let it freeze. He says the concept of setting it in a warm place on wood rather than concrete was an old wives tale. He added to NEVER let the electrolyte get below the plates, even if you have to put water from a mud puddle in it. I suppose with gel cells, just be careful not to over charge.

My thoughts at least.

...keep a battery as cold as possible, charged, but whatever - don't let it freeze. ...My thoughts at least.

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Spot on. It's actually the self-discharge that speeds up at higher temps, but it's for the same reason. The discharge is essentially corrosion happening (that's how batteries work).

Cold but keep them from freezing. If they're charged, they can get REALLY cold without freezing.

Another weird point the EE friend raised - The open circuit output voltage of a lead acid cell rises as they become colder. Hot battery = lower O. C. voltage. That's why voltage regulators have to be temperature compensated.

He was always quite concerned about batteries that were overheated - like in light aircraft applications where they may be in the engine compartment.

I use a conventional charger giving maybe 2 Amps or so in thru the accessory connector. I then use a clock timer, & measure the current so that I get on the order of 15 amp-hours in each month. It means it only runs about 10-15 minutes per day.

Otherwise the bike & battery is all kept in (very) cold storage here in MN. This also minimizes engine cylinder corrosion.

The concept of discharge being a form of corrosion is very novel and I suspect he would completely agree.

nrpetersen said:

Another weird point the EE friend raised - The open circuit output voltage of a lead acid cell rises as they become colder. Hot battery = lower O. C. voltage.

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I think the OCV goes the other way. On charge, hotter is lower.

I didn't know of this hoopla about the new BMW "gel cell" and left my '04 R1150R on my old BMW charger for several months last winter. No apparent problem.
Still ignorant, two months ago replaced battery in wife's '99 R1100S with new gel cell.
THEN I read the stuff in last month's MOAN and previous article in April issue.
Talked with dealer about issues. His only good news was that correct BMW charger is now only $70.00 (not $150.00).
What I've thus far concluded is that charging voltage can not exceed 14.2 volts. That being the case, I'm amazed that no one has devised a cheap VR for old BMW/Battery Tender chargers.
I have to wonder if there's more to this issue than voltage management.
Figure in central Ohio, we have about another month to ponder this (ride some more) and then if I can't discover a mod to the old chargers- we'll have to spring for at least one new one (and remember to swap it back and forth every few weeks).
Come on inventors- let's hear some ideas.

Chargex

This charger has been used on gel batteries with no problems. Easy to store if it is on the bike all the time.

http://www.cyclegiant.com/index.php...oup_descrip&pid=4707&return=?category_id=2669

What I've thus far concluded is that charging voltage can not exceed 14.2 volts.


Actually they say 14.4 is the max charging voltage for the Gel battery from exide.
Have you taken your old BMW charger apart and adjusted it? I did this to mine years ago so it doesn't turn off until about 14.0 instead of the 12.8 it was set at when it was new. I made this adjustment when I changed all my wet batteries to AGM sealed Panasonics.

Mick

Loraz-
That's a slick concept however, they are silent about output voltage which seems to be the issue. Might be worth FU with manufacturer to learn more specs on this unit. Something about absorbtion rate of gel cell and maximum 14.2(4) volts. I think I'm hearing that exceeding that voltage can damage battery, ie dramatically shorten life.
Note also they say minmum amperage is 2.0. I think old BMW and B-T minimum is in the range of 1.25. Mysterious- wish I knew more about electricity!

Pete43011 said:

Mysterious- wish I knew more about electricity!

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Reading material and easy to understand...
YUASA Technical Manual

also...

Anton's Battery Tech

As an incentive...see how long you can get a battery to last. My BMW Mareg battery lasted 8 full years and went into the 9th. My Toyota Panasonic car battery just passed the 14 year mark and is still going strong, even at -20??F.

When I last measured it, my 2000 R1100 RT drew about 30 milliamps with everything shut off. This means about 0.7 AH per day is taken out of the 18 AH battery. It would seem like the battery would be fully discharged in about a month if it just sits around. I suggest we should worry about the charging current as well as the charging voltage.

NEVERMIND

Mick

Chargers may be RATED for 2 or 3 Amps but are they delivering that much current? I doubt it. If nothing else you can add a series resistor to one of the leads to cut down the continuous charging current - or use a clock timer so that it runs for only a small part of the day. If necessary, get your meters out & measure the charging current & adjust the clock switch timing accordingly. Remember that the first say 30 milli-amps won't do anything except make up for the bike's drain. The trick is not to over charge the battery or cook the water out of it.

If you want to measure the drain of your bike - go ahead and put your current meter in series with the plus lead coming from the battery. But first jumper across the meter leads with another jumper so that the initial current surge when connecting things up (and it is pretty high) doesn't damage your meter. after connecting, pull the jumper off. This is especially important if you have a digital meter as they are fused at typically 300 milliamps or so.

Don't turn on any lights, accessories or touch the starter when the current meter is in the loop, or your meter will be toast.

I'm curious how much steady state draw you see. I'm surprised it is that high on my RT (30 Ma). That can keep a lot of electronics alive.........

In my Colorado (unheated, but relatively warm) garage, I keep a Battery Tender, Jr. on my Odyssey sealed battery all the time. I did the same with the previous WestCo sealed battery, although the WestCo began to fail to the extent that the ABS would not initialize after cold startup. I inquired about the BatteryTender, Jr.s compatibility with the Odyssey and was told it was fine. I went to RadioShack and purchased a simple cigarette lighter plug and wired it into the BatteryTender output line after cutting off the spring clamps. I plug this into my accessory adapter plug on my RT's panel, so I don't have to fiddle with any plug hanging out behind my side cover.