Topic: Battery Tenders

[KevinK]

Over the years, I was constantly running into the dead battery problem when the cars were sitting  for some time.  I finally got smarter and bought  a Battery Tender Junior.  It work well and infact so well that over the last few years I bought one each car. Now it would be great if I remebered to hook them up to each every time and my issues would be gone.

As luck would have it, I forgot to put one on my 89 which had been sitting for much of the past 5-6 months.  A few weeks ago I went to move the car and it was pretty much dead.  I put the Battery Tender on it and left it for a week. Tried starting it again, only to find it barely cranking over.  I figured maybe the charger was having issues so I  put a different one on it and came back a couple of days later.  Still just barely cranking over. Now I'm thinking a bad cable connection as the interior lights were working this time.  I open the hood to find an exploded battery! Not sure how many days prior this occurred.

My first concern was the battery acid everywhere. I did a quick clean up with baking soda, removed all the parts around the battery and battery tray. I removed and tossed the hood pad aside.  I have no idead how long it sat there leaking acid and hoped for the best down the road.  More damage might show up a while later.  Granted this was not a pristine show car but it had won a few awards.

Fast forward to today.  I found the same thing happened to my wife's 88 show car.  The really really bad news is my unrestored 84 SVO show car was stored under the lift below her car. My car got a bath of battery acid over the hood, fender and bumper.  We spent all day cleaning both cars.  It was not a fun day.

I will admit, the battery was in both cars and the caps were not removed.  Having this happen twice in such a short period of time is just unbelieveable. I can only conclude it is absolutely unsafe to use a battery charging device with the battery in the car. Please learn from my misfortune.

[markb0729]

Yikes!  Thanks for the heads up.  I typically don't use battery tenders.  I usually trickle charge (1.5-2A) the battery for a couple of hours (around 12 hours) every 6 to 8 weeks.  Never had a battery explode with this method.

[Bob Gaines]

Over the years, I was constantly running into the dead battery problem when the cars were sitting  for some time.  I finally got smarter and bought  a Battery Tender Junior.  It work well and infact so well that over the last few years I bought one each car. Now it would be great if I remebered to hook them up to each every time and my issues would be gone.

As luck would have it, I forgot to put one on my 89 which had been sitting for much of the past 5-6 months.  A few weeks ago I went to move the car and it was pretty much dead.  I put the Battery Tender on it and left it for a week. Tried starting it again, only to find it barely cranking over.  I figured maybe the charger was having issues so I  put a different one on it and came back a couple of days later.  Still just barely cranking over. Now I'm thinking a bad cable connection as the interior lights were working this time.  I open the hood to find an exploded battery! Not sure how many days prior this occurred.

My first concern was the battery acid everywhere. I did a quick clean up with baking soda, removed all the parts around the battery and battery tray. I removed and tossed the hood pad aside.  I have no idead how long it sat there leaking acid and hoped for the best down the road.  More damage might show up a while later.  Granted this was not a pristine show car but it had won a few awards.

Fast forward to today.  I found the same thing happened to my wife's 88 show car.  The really really bad news is my unrestored 84 SVO show car was stored under the lift below her car. My car got a bath of battery acid over the hood, fender and bumper.  We spent all day cleaning both cars.  It was not a fun day.

I will admit, the battery was in both cars and the caps were not removed.  Having this happen twice in such a short period of time is just unbelieveable. I can only conclude it is absolutely unsafe to use a battery charging device with the battery in the car. Please learn from my misfortune.

I am sorry to read of your experience. I have used many battery tenders and the smaller JR's  for many years on dozens and dozens of batteries without a problem. The explosion is most likely from a hydrogen build up that somehow ignited . With that said and for future reference the battery JR does not have the power to bring back a battery that is dead or almost completely dead. The larger battery tender will bring one back from completely dead but even with its larger capacity it may take up to 3 days to charge fully . If it takes more time then that with a full size tender then that battery is a lost cause . FYI once a battery goes completely dead it basically halves the life of the battery when you try and charge it back up. Sometimes when a battery is a older one I have found that even one time going completely dead will ruin the battery . Calcium build up is what kills the battery.The calcium builds up over time between the plates and once it builds up enough to make contact between two plates in a cell it shorts out the battery and does not allow it to take a charge . The process of going completely dead accelerates the calcium deposit build up between the plates. Sometimes when a battery has one of the cells shorted it has the symptom of being almost dead (not enough power to start but enough for lights in car to go on) .  If you try and charge a shorted out battery this explosion scenario can happen because of a build up of hydrogen which is a side effect of the charging process (think Hindenburg blimp ). Now the Battery tender brand is supposed to sense this dead cell and it will not go in charge mode and show a green light. The short cycling of the Tenders maintaining a full charge does not cause a large build up of hydrogen like charging a significantly discharged battery does. Something went terribly wrong with your case regardless. I am not sure if this explains the situation or not. I thought this was a good place to talk about this . #1 try not to let the battery go dead to begin for the sake of the life of your battery  but if it does go completely dead don't ever try and charge it in the car or risk the explosion scenario. Other then that I don't have a issue with using the tender to maintain a battery but do have a issue if trying to charge a completely dead battery in the car. The thing I don't like about regular trickle chargers compared to the Battery Tender brand is that with the trickle charger you don't know when they have completely charged the battery . If you leave them on too long you risk the hydrogen build up at the worst ( possible explosion) and at the least it will boil off (if left too on long) some of the electrolyte which is needed to completely cover the cells in the battery to charge properly. If you don't leave the regular trickle charger on long enough it will not bring the battery to full charge and you have the accelerated calcium build up scenario . The Tender and Tender Jr sense the appropriate voltage in the battery and automatically turn on or shut off which is why you can leave them connected all of the time . Speaking for myself even after hearing the sad events as long as the battery isn't completely dead I have confidence on leaving the battery in the car while leaving the Tender connected during storage mode. With that said the extra precaution of taking your battery out of your car every time you charge it no matter how little can be seen as extra insurance none the less. I would also like to say that on a late model car with all of the electronics running things even when the car is turned off the battery will go dead if not charged or driven in as little as three weeks depending on year and car.  On a vintage car you may go a few months or more without going dead. It is hard on batteries to let them discharge that much during storage without bringing them to full charge.

[carlite65]

i am completely in agreement with bob on his points. i have 5 tenders & never had a problem. my 2007 mustang original battery lasted a little more than 7 years using one. that car is not driven much at all. however in my 2006 mustang that i bought used the battery had already been replaced within one year. that one died on me before i started using the tender. as bob said the electronic drain killed it within 2-3 weeks. i don't know why i was not smart enough to start using one when i purchased the car.

[mikelj5S230]

Not sure what brand you had, but agree with Bob and carlite65.  I have 7 of them and have not had any problems for many years, but I did when I used one called "Battery Tender", it did short out on me once and not work after a few months hooked up.  Now I use Odyssey Ultimizer and BatteryMINDer Plus for my vintage cars,  and CTEK cigarette lighter plugins for my new cars.

[jwc66k]

I had battery problems for years on my 65 and three (at that time) 66 Mustangs.
First: I bit the bullet and bought reproduction Autolite batteries. They didn't last more than three or four years (I use off the shelf anybody now). It could be a battery problem.
Second: I had a drain on the battery, the Rally Pac clock. There's a screw type battery shutoff on two now with Rally Pacs.
Three: I had a trickle charger that did not put out the required voltage of 14VDC, it was all of 7V. It killed the battery. I saved the alligator clips.
Currently, the two Rally Pac cars are on trickle chargers and I check the voltages before, during charging and a day or two after. I use a Schumarcher 6/2 amp charger and an unknown trickle "thing" that the label came off but it still works. I use the trickle chargers about once a month for two or three days between my periodic drives around the block. My 66 Hardtop daily driver will get it's turn in a day or two. Granted, it don't get cold in parts of California but I have friends on the East Coast that remove the battery in winter and keep it indoors on a charger. A pain in the a**? Maybe, but it's like anything you want to do - just do it well.
Jim

[KevinK]

Bob, Thanks for the kind words and taking the time to review batteries and charging.  I was familar with most of the issues. Anytime you have a dead battery, I guess you take a gamble on a potental disaster (in the car).

 In both cases the battery was not new but had not failed previously with normal use.  The 89 battery was 5-7 years old Interstate and the 88 battery was a 2007 Motorcraft (100 month warranty). I buy into the hydrogen exposion idea except in both of these cases the car was started and ran before the Battery Tender Junior was put on. I would have expected the first week of charging to be greatest amout of hydrogen generated.  In both cases, it was much later. The 88 was probably last moved Christmas-New Years and the Battery Tender Junior was put on at that time.  The battery explosion happened within the last day or hours before I found it.  It would seem to be over charging and burst due to pressure IMO.

I know the battery companies will probably point out a disclaimer. Will have to see what Battery Tender says. Both cars were well insured so we will have to see how the insurance company treats it.

Anyone have experience with the long term affects of exposure and clean up?

The 88 damage seems to be limited to under the hood area and did not go as far as one might imagine.  The battery tray is actually a good design.  The 84 will need a front end repaint. Its a good thing I guess that it already earned the Unrestored Medalion.

[svo2scj]

Sounds like you have a fox collection (like me) !   Personally after getting tired of buying 7 batteries at a time , and dealing with issues of junk modern batteries I too when the Battery Tender route.

I chose to use the "battery station" route (my guess is you will too now) !   This allowed me to keep on 3 or 4 new batteries at a time and install when moving cars for service. garage shuffling or work.   I really wanted a 7 battery unit but got talked into 4 unit at Carlisle by rep.

Kind of glad now as I don't have batteries in any cars (except my neighbors C4 LT1) in my garage (on the tender).      Not sure if that works for you but a STATION with the batteries out of the cars works ESPECIALLY with the hood pad Fox's and any outgasing !

Mark

[rodster]

Long shot, but I've heard of Chinese knock-offs that are just trickle chargers and don't go into a float mode when the battery is charged. Most people swear by the Deltran Battery Tender brand and it's surprising to hear you had trouble with two.

I use Schumacher tenders/chargers and when I check the current being supplied to the battery at full charge, (~13.2vdc) they are about .1amp.  Maybe you could test out your suspect tenders on a known good battery (with safety precautions) and see what they are supplying.

You may want to dissect the units to see what is inside after testing.

I've had bad luck with tenders this year, lost 2 during a thunderstorm and the quality of the replacements I chose, Stanley and Schumacher, have been poor. Waiting the receive a Schumacher replacement as we speak since the one I sent back for warranty work was returned in the exact same condition as I sent it out.    All of the lights work but it doesn't hold a full charge voltage in float mode.

Sorry to hear about your misfortune, keep us posted on what you find out.

[NEFaurora]

I've heard some nightmare stories over the years of some of these Battery Tenders burning up and causing fire damage and house fires.. That's enough for me to stay away from them.  I just use simple Battery Cut-off switches...  Works for me.. Cheaper too.

)

Tony K.

[GT500KR]

I've heard some nightmare stories over the years of some of these Battery Tenders burning up and causing fire damage and house fires.. That's enough for me to stay away from them.  I just use simple Battery Cut-off switches...  Works for me.. Cheaper too.

)

Tony K.

+1 on disconnecting the battery. A healthy battery in a car that is stored indoors should hold out 6 months without a charge IF the neg cable is removed. I try to start my cars at least that often. My battery life is typically 7 years or more under these conditions. The trunk mounted battery in my Boss 429 is going on 14 years now!!
A battery that lasts for 84 months costs you about $1.50 per month. I don't know how much it costs to keep a battery tender plugged in for a month, but....

My 2 cents 

[67gtasanjose]

... I don't know how much it costs to keep a battery tender plugged in for a month, but....

My guess: 

MUCH less than an insurance deductable and replacement of the car 

I might unplug my chinese one today...all this gives me the heebey-jeebey's!

[jwc66k]

The best "battery tender" is you. I use a trickle charger and monitor it. All three of my 65-66 Mustangs were started and run yesterday without problem. A car stored in a cold climate should have the battery removed and placed in a warmer area. Just common sense.
Jim   

[KevinK]

My post here was not intended to slander the brand or model charger I used.  It certainly is not positive comments either.  I know lots of people use these chargers and I wanted to put out a warning about using them in the car. I purchased the charger new and as far as I can tell it's not a knock off but still made in China.  I am pretty sure they came with a 10 year warranty but now I see its down to 5 years. Mine are probably between 3-10 years old. I have probably 4 of them.

It's probably going to be impossible to identify the culprit which caused the problem and we all pretty much know when you deal with charging a battery there is some risk involve. It's all labeled, charger, battery and owners manual.

I would not say that I would never use one again but certainly not in a car.  I am also considering using a timer of some sort to insure it gets turned off.

[KevinK]

Update: I just inspected the 4 Battery Tender Junior units I have. 2 seem to be older and 2 are newer. The newer ones have a color code for the light on the top side.  The unit in use was one of the older ones. If the numbers on the back represent some sort of date code, my guess is 2005. All 4 units are made in China.

On closer inspection, I see the case housing is slightly melted and deformed.  I have a call into the manufacturer