Tender: turn it off when green?

[Voyager]

I did a search and read as much as I could stomach on the battery tender saga, but didn't get to this question.

 

I got the "sensing" tender which supposedly switches to "storage" mode when the battery is charged. Once charged, is it better to leave it on or disconnect & recharge a few weeks later?

 

Oh, yea. I have a gel battery.

[ttorborg]

I leave my charger on for the winter while the bike is off duty. Have not had a problem. I replace the battery every third year.

[Voyager]

I replace the battery every third year.

 

Mmmm. Yea, this is year three. Probably a good idea.

[Jerry Johnston]

I've got a Westco battery that is five years old. This is the first year I had a lot of trouble with the ABS lights. I'll put in a new battery next Spring. I've always left the B.T. on all Winter long.

[topdal46]

why don't you ask the manufacturer,, they know more facts than a bunch of heresay. Deltran

[Voyager]

why don't you ask the manufacturer,, they know more facts than a bunch of heresay. Deltran

 

Yea. The book that came with it says leave it hooked up all season during "storage" and the ice cream I have in the freezer says "lowfat". Point being, things aren't always as advertized and I figured there was a good bit of practical experience (heresey) on this forum. (kind of the point of this forum, actually)

[CLEAN1]

Just plug it in and leave it on until you are ready to ride again. I have three battery tenders. I always keep the bike on the battery tender. When we go away on vacation, I also plug them in to each of the cars. Never had a problem.

 

The battery on the Harley I used to own lasted 5 years, the one in my Corvette lasted almost 5 years and was still good - I replaced it just because I thought it was time. The original battery in the BMW was on the battery tender whenever the bike was parked. I never had a problem with the battery in almost three years - it was working fine, but I switched to an Odessey battery recently because I was tired of taking off the tupperware to check the fluid level in the original battery.

 

The battery tender will always keep watch on your battery. If you disconnect it, you will have to remember to reconnect it from time to time. Why bother?

[johnt650]

I leave it plugged up when it's sitting in the garage. I've checked the battery for water loss and it does not seem to be a problem, except for the time lightning screwed things up and it stayed on the charge mode. Seems that it is best to have it plugged in to a surge protector.

[Voyager]

Thanks for all the replies. Just what I needed!

[DavidEBSmith]

The whole point of having the Tender is that you can plug it in and leave it plugged in. As your bike sits and your clock or your alarm system drains the battery, the Tender will kick in occasionally and top up the charge. When you return from a ride, you plug in the Tender and it tops off the charge if your battery needs it.

 

If you believe this battery tutorial, letting a battery sit undercharged or with no energy input leads to sulfation, which reduces the life of the battery. Which would suggest that leaving it on the Tender to occasionally put in energy that keeps the battery charged would be a good thing.

[Green RT]

For what it is worth...

 

I have a car that I never drive. I left it on a battery tender on green for about 6 months. The only drawback I noted was that about half of the alligator clip on the positive terminal disappeared. There was lots of gunk built up on the positive terminal, but it didn't seem to erode the terminal just the alligator clip.

[smiller]

Low-end battery chargers fold back to a low charge current at the end of the charge cycle to keep the battery topped off and it's not necessarily a good idea to leave these types of chargers connected continuously. More advanced chargers (including the Battery Tender series) will shut of completely at the end of the cycle and then turn on again when battery voltage drops, and these chargers are designed to be left connected indefinitely without harm to the battery. I don't think you need have any worries about leaving your Battery Tender connected all of the time.

[MichiganBob]

I leave it on all winter so that I can have some visual connection to my motorcycle. I love to go out to the garage and see that little green light on. Makes me all ooey gooey. When you live in deep freeze country, you need "cheap thrills." And my wife says that men are not evolved.

[questrider]

I leave it on all winter so that I can have some visual connection to my motorcycle. I love to go out to the garage and see that little green light on. Makes me all ooey gooey. When you live in deep freeze country, you need "cheap thrills." And my wife says that men are not evolved.

 

I couldn't have said that better myself.

[RockLives]

Low-end battery chargers fold back to a low charge current at the end of the charge cycle to keep the battery topped off and it's not necessarily a good idea to leave these types of chargers connected continuously. More advanced chargers (including the Battery Tender series) will shut of completely at the end of the cycle and then turn on again when battery voltage drops, and these chargers are designed to be left connected indefinitely without harm to the battery. I don't think you need have any worries about leaving your Battery Tender connected all of the time.

....The difference between Battery Tenders are as follows...The one made for the Gel is programmed to top off at 80% of cpaacity. It prevents the battery from ahceiving more than 80% because the Gel will over heat and cook . When you use your motoercycle it should reach a charge over the 80%. Now the regular Battery Tender will charge your battery to a higher cpacity because it was designed for wet cell batterys that can maintain 100% charge without negative effects. So to wrap up the controversy..respect manufacturers recomendations, they are responsible for warranty on products.

[smiller]

Low-end battery chargers fold back to a low charge current at the end of the charge cycle to keep the battery topped off and it's not necessarily a good idea to leave these types of chargers connected continuously. More advanced chargers (including the Battery Tender series) will shut of completely at the end of the cycle and then turn on again when battery voltage drops, and these chargers are designed to be left connected indefinitely without harm to the battery. I don't think you need have any worries about leaving your Battery Tender connected all of the time.

I have to eat my words I'm afraid... after checking deeper on the Battery Tender site I found this:

 

6. What makes the Battery Tender Plus battery charger different from other automatic battery chargers?

 

Many automatic battery chargers turn off when the battery voltage rises or the charge current falls to a preset level. Then after a period of time, when the battery self discharge characteristics have reduced its terminal voltage significantly, sometimes to the point where the battery has given up almost 90% of its stored charge, the charger will turn on and recharge the battery. This type of cycling will dramatically reduce battery life. The Battery Tender Plus battery charger does not turn off. It automatically switches to a safe float voltage level that keeps the battery charged and yet does not do any harm to the battery or cause any reduction in its useful life.

 

This statement on their part is rather controversial and I do not agree with it, at least in this application. What they say may be true for well-monitored stationary battery plants where the proper float voltage can be positively established and monitored, but... in general real-world applications the exact continuous float voltage requirements vary from one type of battery chemistry to another and (IMO) the safest maintenance mode is to have a charger turn off and on as necessary vs. a continuous float voltage that may be too high or too low. Both methods have their pluses and minuses but in the real world my experience has been that turning off and on is definitely the lesser of two evils. If the Battery Tender continuously floats the batteries then I would not suggest leaving it connected continuously for extended periods of time unless you know the exact specs for your battery and know how to adjust the float voltage accordingly.

 

BTW while it's true that it is not a good idea to continuoulsy deep-cycle lead-acid batteries only a very poorly designed or defective maintenance charger would let a battery lose 90% of its charge before turning on. Using that as an example of their competition does not exactly boost their credibility.

[DavidEBSmith]

This site (which is not Battery Tender) says that a battery is 100% charged at 12.65 volts, 50% discharged at 12.24 volts, 75% discharged at 12.06 volts, and fully discharged at 11.89 volts. So it's a very small voltage drop for a large drop in capacity. A not-so-sophisticated charger that turns on at just 0.2 volts less than a more-sophisticated charger may be imposing a huge drain-and-recharge cycle on the battery (especially if the not-so-sophisticated charger doesn't compensate for temperature).

 

As far as the float charge, Battery Tender no longer has actual numbers on their battery algorithm charts, but this site does. The Battery Tender float charge is 13.2 volts at 50 to 100 mA. The chart here says that 13.2 volts is an acceptable float charge for all types of batteries (the other voltages in the charging algorithms vary significantly among the various battery types). 50 to 100 mA will be barely enough to overcome the parasitic drain from the clock and the self-discharge of the battery - it won't be doing significant charging at that voltage and current. On the other hand, if you let turn the charging on and off, letting the battery discharge more in between cycles, you'll be needing higher charging currents, which you would expect would more gassing than would happen at the slower float charge rate.

[smiller]

Well, yes, an on-off charger that is poorly designed or using incorrect settings is a bad thing, just as a float charger that is poorly designed or using incorrect settings is a bad thing. In my example I was intending to compare good models of each. Assuming you do that, I know from experience that if I float lead-acid batteries at a 'safe' 13.2 volts indefinitely they will lose electrolyte (eventually enough to damage the battery if one doesn't keep up on it), and for that reason I don't do it if I want to let batteries set for months without maintenance. As I noted there are pluses and minuses to either method, I have just found the on/off method to be safer in the real world, in my own experience.

 

That said, all of the information you referenced is quite correct and if your experience dictates that floating batteries for long periods of time is the best way to go then by all means do so. It's just not what I would personally recommend.

[PETDOC]

My understanding of how the Battery Tender works is it goes thru a sequence of bulk charge charging the battery to 14.4 volts then goes into a float charge maintaining the voltage around 13.8-13.9 volts. If left attached for > than 2 months

the total charge the battery can accept will be reduced by irreversible sulfation. So if you don't go for a ride every 2 months you should disconnect charger for 30 minutes (or less?) and when you reconnect the charger it will again go thru its sequence and charge up to 14.4 volts before going into float mode. I have an '04 GS with gel battery with accessory voltmeter and routinely (all year) keep it hooked up to Battery Tender when not riding. I can attest to the fact that it cycles as I've described by virtue of repeated connects/disconnects and watching my voltmeter. Whether or not you get irreversible sulfation between 13.9 and 14.4 after 2 months of constant float mode will have to be answered by someone who knows a lot more about battery chemistry than I do.