battery tender question/damage

J

justgotaboat

Member
Joined
Jun 18, 2009
RO Number
31427
Messages
159
so, this question is actually about my motorcycle battery, but i would assume the results are the same for any battery... and i really don't want it to happen to my boat batteries, as they are a hell of a lot more expensive.

I had my bike hooked up to a battery tender for most of the winter (in fact I typically leave it hooked up year round). Its a single battery charging unit that will recharge a drained battery or tend a fully charged battery automatically. It has a quick connect plug that runs up to a unit that pugs directly into the wall. Leave the unit plugged in, but unplug the wire by the seat and go for a ride. plug it back in when your home again. easy system.

Sometime through the winter, a family member unplugged the tender from the wall, but left the battery hooked up. I have no idea for how long as I was away for business but I would assume a while. Now it seems that the battery won't hold a strong charge. I can jump start the bike with a different jumper/charger unit and it will run fine. I run the bike for a while so the battery should be charged, but as soon as I shut the bike off the battery already doesn't have enough charge restart the bike. If i plug the battery tender up to the bike and let it charge over night, it will read fully charged, however still lack the power to start the bike.

I figure the batter is dead and I need a new one... Question is...

Do you think the battery tender being unplugged from the wall but still hooked up to the bike destroyed the battery? Or is it just a coincidence and the battery is on its way out anyways.

don't wanna kill any extra batteries by making the same mistake again
 
It is a poorly designed unit there is probably no isolation diode so the battery was back feeding through the charging circuit. The description of the problem indicates a weak/dead cell in the motorcyle battery. If there is a funny part of this is a $1.00 diode could and would have avoided this problem.
Bill
 
I think this is a coincidence, leaving a Battery Tender connected like you describe is not going to hurt the battery. I switch mine between my two SeaDoo batteries during the winter and about every 3rd week un-plug it altogether leaving it connected to one of the batteries -- never a problem. I think your battery was on it's way out...
 
I doubt you have a problem with the battery tender. I have used battery tenders on my motorcycles for years and when a battery is going sour it will indicate a full charge but not hold it.
 
I would agree it is on way out. I had a battery hooked up to the tender all winter and light on the tender was green--fully charged. However, it wouldn't turn over the outboard. Had it tested and battery was shot.
 
Are you guys missing the point he left the tender hooked up to the battery with no power to the tender for an unknown period of time? Has anyone ever left a power supply/charger hooked up to a laptop with the laptop off and the end result with a fully charged battery in some computers will discharge the internal battery through the charger depending on the model. I know the battery is bad he is trying to figure out if the battery tender caused the battery to become fully discharged and damaged it. I'm saying it is possible depending on the battery tender.
I wouldn't dismiss it what model battery tender do you have?
Bill
 
I'm going with others; most likely not the battery tender but just the battery. A battery charger may bring it back to life especially if it has the battery reconditioning function. I had a two year old car battery that was drained due to an interior light being left on. I could jump start the car and let it run; shut it off and it would not start. I bought a 15 amp Black & Decker battery charger at theit outlet store for $20; charged it and reconditioned it. Has been working fine for over 4 years.
 
I'm going to blame both the battery and the charger.

Even a good brand of charger will produce a very tiny drain on the battery if left disconnected from the wall ( unless it uses a mechanical relay to disconnect, which is unlikely ).

Add to this small loss over a moderate period of time and the normal self discharge characteristics of a lead/acid battery and you can get a substantial draw down over a "longish" period of time. Batteries tend to fail at a point of "low charge state". At this point you likely developed a shorted cell, also known as sudden death of the battery. Once it gets an internal short, there is little to do but recycle it.

Just mu opinion, and worth every cent you paid for it... ;)
 
...If ... it is not mainenance-free type, have you checked fluid level ?
Is it possible the battery could have frozen in discharged state? ( unheated garage.)

Personally, I prefer to occasionally analyze, fully recharge & load-test stored batteries with a decent automatic multi-stage charger rather than ever use trickle chargers.
 
BillyIII - are you saying the Battery Tender if left connected to the battery but un-plugged from the AC outlet can cause a discharge or damage to the battery? I have done that in the past, I'll leave an extra SeaDoo batter on the charge for a few weeks and then un-plug it. Never had a problem, maybe I have been lucky -- maybe I have learned something tonight.
 
You can test the Battery Tender to see if it has diodes to control one-way flow. With the BT unplugged, put ohmmeter or other continuity tester leads to the 2 battery clips. Then reverse them . If it only shows continuity with one combination and not the other it shouldn't allow discharge through the BT.
 
The Brand BATTERY tender is probably the best selling motorcycle battery charger ever made. Im sure it has an isolation circuit. Its just probably a bad coincidence.

Rob
 
It is a battery tender brand but says nothing about a draw if unplugged.

http://batterytender.com/motorcycle/battery-tender-junior-12v-at-0-75a.html

It could have been unplugged for a pretty long time. The way I had the bike parked in the garage and the battery tender hooked up, I hadn't noticed it even when I was home for some time. of course now I check on it just to make sure. but thanks for the ideas, and the way to check it maybe.
 
quote:
Originally posted by Robski97

The Brand BATTERY tender is probably the best selling motorcycle battery charger ever made. Im sure it has an isolation circuit. Its just probably a bad coincidence.

Rob

Click to expand...

Pet Rocks were bigger sellers to at one time doesn't mean they have an isolation diode to prevent backfeed.
In all likelyhood the battery was probably on it's way out but I am curious about the tender. I used them on some of my collection of car's when I used own them to keep the batteries rom self discharging which is normal for wet batteries in fact all batteries.
Why would a manufacture advertise a negative about a product justgotaboat?
BillyK a week off probably wouldn't be long enough on a good battery but one on it's way out it might be enough. The original poster admits not knowing jow long it was "unplugged"
Bill
 
I agree with BillyIII. Same thing happened to me. Battery was connected to the Battery Tender most of the winter. Springtime comes and I realize that the Battery Tender was not plugged in, but the red LED was still lit (the battery was powering the LED) I was lucky and able to get the battery to recover - only about 50% discharged when I found the problem. But if the battery discharged 100% there's a good chance that it wouldn't have recovered.
 
I'm going with the theory that the battery was unplugged for a while, discharged because whether or not the tender was pulling current while unplugged- there are a few extra connections in there now that could be draining current, and then froze and shorted while it was unplugged.
 
BillyIII ... i agree they won't advertise a negative. I was thinking more if they said on the website that it had a system in it to block a draw like that they would say it as a positive. obviously if they have nothing and know it will draw the battery down if unplugged they won't say anything about it.

I will assume its a combination of a lot of things. older battery, draw from the charger when unplugged, cold weather. and will just make sure that I (or no one else) unplugs it like that again.

thanks for the input and the info. was curious on everyones thoughts.
 
You must log in or register to reply here.
Back
Top