Tender killing battery

mleach72

Member
This is kind of a nonissue because I figured out what I have to do. I was just wondering if anyone else has had this problem or knows why this happens. For the first 3 years I owned my bike, I didn't have a tender, so I would unhook the battery and bring it in the house in the winter. The fourth year I bought a tender and I started keeping it on the battery. Within a few weeks, the battery slowly died. I figured 4 years is about normal lifespan, so I bought a new battery and kept the tender on it. Same thing happened. Each time I would start it, it would turn over a little slower than before until not enough juice to start the bike. I figured I got a bad battery, so I got a new one. Same thing, battery dead within a month, so it has to be something with the tender. The next battery, I started unhooking the battery before putting the tender on. This solved the problem. This battery is 7 years old and still going strong. I heard the '05 have an electrical system that draws some voltage when the bike is off, so would this have something to do with it?
 

Mr. Wright

Guru
Lifetime Supporting Member
Supporting Member
I don't use a tender for that same reason. I believe the batteries last longer with out one. When I'm going to ride the next day and the bike has sat for a week, I'll put the tinder on it the night before.
 

mleach72

Member
I have the harley supersmart. Seems to be a good tender. I hook it up in the fall and forget about it til spring. I just have to disconnect the leads.
 

mleach72

Member
I read on another thread that the'05s draw some juice when the bike is off. Apparently, this was changed in following years. I'm no electrical engineer, but I'm wondering if this constant discharge/charge is what was killing the battery.
 

RBennet

Member
This is kind of a nonissue because I figured out what I have to do. I was just wondering if anyone else has had this problem or knows why this happens. For the first 3 years I owned my bike, I didn't have a tender, so I would unhook the battery and bring it in the house in the winter. The fourth year I bought a tender and I started keeping it on the battery. Within a few weeks, the battery slowly died. I figured 4 years is about normal lifespan, so I bought a new battery and kept the tender on it. Same thing happened. Each time I would start it, it would turn over a little slower than before until not enough juice to start the bike. I figured I got a bad battery, so I got a new one. Same thing, battery dead within a month, so it has to be something with the tender. The next battery, I started unhooking the battery before putting the tender on. This solved the problem. This battery is 7 years old and still going strong. I heard the '05 have an electrical system that draws some voltage when the bike is off, so would this have something to do with it?
Yes
 

awg

Well-Known Member
So now its not good to leave them on a smart charger 24/7? Heck we need a survey.
 

mleach72

Member
Like I said, I think the supersmart is a good tender. Bike cranks over really strong when I unhook the tender and hook the leads back up. Battery is 7 years old, so it must be doing some good.
 

Ernie12

Active Member
Being on a good battery maintainer is a GOOD thing. I use a Plusetech charger maintainer and if they are good enough for the military and Police force its good enough for me. They make everything under the sun when it comes to battery stuff.
 

Iman

Well-Known Member
I only put it on a tender when I know I will be taking the bike out. Other than that, I don't have it on. I had the same issue
 

Ed U. Cator

Higher Ed.
Supporting Member
I currently use a high-end model BatteryMinder, not the Battery Tender. The minder is more advanced than the Tender brand although I've never had problems with my Tender + when I left it connected. As for current draw from the EHC, it's a very tiny amount.... tiny like what an LED draws (a few milliamperes) so that shouldn't be the issue causing a dead battery too soon.
 

Sven

Well-Known Member
The next battery, I started unhooking the battery before putting the tender on. This solved the problem. This battery is 7 years old and still going strong
Are we saying you got prorated and kept on replacing the same battery? But this time you set the charge remotely and it's been 7 years since? And too, you never replaced the charger, but still used the same one. If yes to both questions... Interesting.

I'm going to paraphrase a military penned high school book published in the early 1940's: Magnetism = 'You cannot separate heat from the chemical reaction.' It's my understanding that sulfation weakens the battery. The chemical reaction of not cooking the fluid-is acid to water separation. That has to remain in a mix or the white powder on the plates cannot pass (+) over to (-) kind of ampspeak. WATT did you do to have such a long life of the same made battery? I removed the phantom draw from the battery so the charger is designed for a non-drawing battery loop.

How close am I?
 

Mr. Wright

Guru
Lifetime Supporting Member
Supporting Member
Are we saying you got prorated and kept on replacing the same battery? But this time you set the charge remotely and it's been 7 years since? And too, you never replaced the charger, but still used the same one. If yes to both questions... Interesting.

I'm going to paraphrase a military penned high school book published in the early 1940's: Magnetism = 'You cannot separate heat from the chemical reaction.' It's my understanding that sulfation weakens the battery. The chemical reaction of not cooking the fluid-is acid to water separation. That has to remain in a mix or the white powder on the plates cannot pass (+) over to (-) kind of ampspeak. WATT did you do to have such a long life of the same made battery? I removed the phantom draw from the battery so the charger is designed for a non-drawing battery loop.

How close am I?
I believe your spot on. I removed a battery from a bike, that was 7 years old, then used it as a test battery for several more years. Just charged it up when it was dead.
 

mleach72

Member
Are we saying you got prorated and kept on replacing the same battery? But this time you set the charge remotely and it's been 7 years since? And too, you never replaced the charger, but still used the same one. If yes to both questions... Interesting.

I'm going to paraphrase a military penned high school book published in the early 1940's: Magnetism = 'You cannot separate heat from the chemical reaction.' It's my understanding that sulfation weakens the battery. The chemical reaction of not cooking the fluid-is acid to water separation. That has to remain in a mix or the white powder on the plates cannot pass (+) over to (-) kind of ampspeak. WATT did you do to have such a long life of the same made battery? I removed the phantom draw from the battery so the charger is designed for a non-drawing battery loop.

How close am I?
When I would hook up the tender with the battery hooked up to the bike, it would slowly kill the battery to the point that it wouldn't take a charge enough to start the bike. I replaced the batteries until I figured out it was the tender that was doing it. Yes, same tender. Harley Supersmart. I have one on my deluxe and it works just fine with the battery hooked up to the bike. That's why I figured that it's something to do with the big dog electrical system and the tender that the battery doesn't like. The tender works great on my big dog, I just have to unhook the leads to the bike.
 

TapioK

Well-Known Member
When I would hook up the tender with the battery hooked up to the bike, it would slowly kill the battery to the point that it wouldn't take a charge enough to start the bike. I replaced the batteries until I figured out it was the tender that was doing it. Yes, same tender. Harley Supersmart. I have one on my deluxe and it works just fine with the battery hooked up to the bike. That's why I figured that it's something to do with the big dog electrical system and the tender that the battery doesn't like. The tender works great on my big dog, I just have to unhook the leads to the bike.
So you say the tender and Big Dog are collaborating to suck the juice out of the battery you sure that tender is actually charging? Or does disconnecting the battery just prevent EHC from milking your juice
 
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