Battery Tender Use
 

I never used a Battery Tender before so I was wondering if I'm going to be gone 3 months or more, can I use a battery tender for this? I sure hope nothing goes wrong like an explosion or something for that 3 months while I'm away.

Also, is a battery tender a good tool to use for recharging a dead battery? How long would it take to recharge a dead battery if you need to get on the road quickly?

I just bought my battery tender Jr off Amazon. Plan on using it this winter when my car is in storage.

I have used a Battery Tender on my S2000 for the last two winters. There is really not much to worry about. It stops charging when the battery is at full charge and kicks in if it drops below a certain charge. Red and Green leds let you know the status.

Battery Tenders are the way to go if you're going to store the car for an extended period. Used one on my car last winter and the last 3 years on my motorcycle. Never had any problems.

Awesome, good to know. Does the battery tender work for recharging a dead battery when you need it quickly to go somewhere?

No, it is a "trickle charger" and delivers it's charge slowly. I'm unsure if it will charge a dead battery.

No, its usually a 1.5a or less charge. Typically if you drop to where you can't start, the tender will take 4-12 hours to re-charge. BTDT a few times with mine.

Otherwise the tender trickles and auto shuts off once you are at full strength. I use one on a motorcycle and will top off a car when needed :)

- b

If the battery is very dead at all, the battery tender won't charge it at all, because the "no spark" circuity does not let the charger kick in unless it detects +12V (approx - I don't know the cut off, but I do know that I had to use a manual charger to bring a motorcycle batter back once after I left the lights on and discharged it completely).

Sorry for bringing an old thread back up but I was just wondering how safe battery tenders are? I read their manual and it mentioned that it needs to be in a well ventilated area or there could be an explosion. I believe that my garage has some ventilation but I'm not sure how much I would need. There are no windows or anything in the garage to ventilate.

So my dilemma here is if a battery tender is worth the risk or should I just disconnect the negative battery terminal? Also, what was it that you weren't supposed to do with the windows when the battery is disconnected? It was something about the windows not rolling back up and it could damage the door frame.

Thanks.

If the battery is charged when you start, the battery tender will not charge the battery "hard" enough to produce much Hydrogen. You should still make sure that there is some ventilation to minimize the danger of explosion. Propping the hood open a few inches with the battery cover off should be enough.
The main explosion hazard is when you dis/connect the tender clamps and a spark is produced. This can be minimized by unplugging the tender before dis/connecting.
For maximum safety, there is also a "trick" to the sequence you dis/connect the tender. To connect, put the + tender clamp on the + battery terminal. Then put the - tender clamp on a chassis or engine ground a foot or so away from the battery. Turn tender on. To disconnect, turn tender off and reverse process, ie, disconnect ground first.

I just plugged mine up my battery tender jr yesterday evening...the light is still red right now...I guess it takes awhile before it turns green?

3rd year using it on my Z. 1st year had the same concerns as most people do but now into the 3rd year using it and its hook up and forget about it till the spring.

It depends on the state of charge when you started, condition of the battery, and how fast your tender will charge. If the charge was low when you started and the tender doesn't charge very fast (I thinks that's true by definition, but depends on the make/model and who wrote the ad copy), I wouldn't be too surprised if it took a few days.

Edit: I'd trying charging the battery with a "real" charger and then see if the tender is happy.

Edit 2: If the battery is in the car, the parasitic load of the control module may be fooling the tender.

good help! Thanks man

One other thing you can check is battery voltage with the tender disconnected. Should read close to 13.2VDC when fully charged. If it reads much below that, it's still charging. If it reads 13.2, the tender may be defective.
If it's still charging, wait a few hours and see if you're making any progress. If voltage is going up, relax. If the voltage doesn't increase, the battery or tender is probably bad.

Or wait a little bit and maybe someone that knows more about your tender will chime in. :)