Battery Tender
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Intermediate
Joined: Dec 2004
Posts: 27
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Battery Tender
I am wanting to connect a Battery Tender on my 89'. I am wondering if I should connect the positive and negative cables directly to the battery terminals or if I should connect the postive and ground the negative. If so, where is a good place to ground it?
Team Owner
Joined: Mar 2001
Posts: 54,124
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From: Cincinnati, Oh USA
The safe way to make charger connections to car batteries is to connect the positive clip to the battery post and the negative clip to a ground that is away from the battery. When disconnecting, remove the negative terminal first. This keeps sparks away from the battery which normally emits hydrogen and oxygen gas which is explosive. You should also make connections when the charger is unplugged from an outlet. Bare bolts or nuts usually are connected to ground, but you can use any bare metal parts like brackets that are fixed to the engine. You can also use the negative cable from the battery if it is of the braided wire type.
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Melting Slicks
Joined: Dec 2004
Posts: 2,687
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From: Manteca CA
I have 2 cars that are garaged and seldom driven, battery tenders hooked directly to the terminals on both of them for years. No problems.
Last edited by Mrs. glass car; Jan 3, 2011 at 12:56 AM. Reason: sp.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
A word to the wise should be sufficient.
Team Owner
Joined: Jan 2003
Posts: 20,306
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From: Summerland B.C. Canada
YET! The danger occurs when making or breaking the contact with the battery post. A spark right at the battery can ignite the hydrogen/oxygen gas that all lead acid batteries generate, both during charge and discharge and it is explosive. Making and breaking connection away from the battery ensures no explosions. Never having a problem in the past is no guarantee that your unsafe practice will continue to be problem free. Sulfuric acid can destroy your eyesight.
A word to the wise should be sufficient.
A word to the wise should be sufficient.
Melting Slicks
Joined: Jul 2008
Posts: 2,269
Likes: 142
From: Ottawa Ontario
It should as the only current draw would be to power the polarity indicator on the charger. Now boosting a car with jumper cables is a different story...
Le Mans Master
Joined: May 2004
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From: Hellinois
Finalist 2020 C4 of the Year - Modified
That and the fact that the pigtail connector is over a foot away from the battery. I run mine out between the hood & inner panel then close the hood. Common sense tells you to unplug the charger before disconnecting it too.
Melting Slicks
Joined: Dec 2004
Posts: 2,687
Likes: 1
From: Manteca CA
YET! The danger occurs when making or breaking the contact with the battery post. A spark right at the battery can ignite the hydrogen/oxygen gas that all lead acid batteries generate, both during charge and discharge and it is explosive. Making and breaking connection away from the battery ensures no explosions. Never having a problem in the past is no guarantee that your unsafe practice will continue to be problem free. Sulfuric acid can destroy your eyesight.
A word to the wise should be sufficient.
A word to the wise should be sufficient.
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Burning Brakes
Joined: Nov 2004
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From: Land of Whiskey Rebels, PA
Re: Sparks while connecting clips on a battery
You might be thinking of when you are using jumper cables. In that case, you most certainly should clamp the negative jumper away from the battery, onto a ground such as the alternator bracket.
I've had a Battery Tender Junior on my '90 for about 3 years now without a problem. I elected not to use the ring terminal adapter for concours reasons. I use the color-coded clips and I have never had a spark while connecting it. By the way, I got it on sale at PepBoys for $18+tax. One of my better investments.
You might be thinking of when you are using jumper cables. In that case, you most certainly should clamp the negative jumper away from the battery, onto a ground such as the alternator bracket.
I've had a Battery Tender Junior on my '90 for about 3 years now without a problem. I elected not to use the ring terminal adapter for concours reasons. I use the color-coded clips and I have never had a spark while connecting it. By the way, I got it on sale at PepBoys for $18+tax. One of my better investments.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Not true. Battery tenders usually have an electrolytic capacitor on their output circuit and when you connect the charger clips to the battery with the charger not plugged into the wall socket you still get a spark. My tender does. You are betting your eyesight, do you want to do that?