Can I attach the battery tender to the car right after driving when the engine is hot or should I wait until it cools down? I recently got a Deltran Plus tender and attach to battery terminals both red and black. It is working great and goes automatically into floating or maintance mode when battery is fully charged.

Also, how many days can I leave the car in garage in moderate temps. (Maryland) before I should use the tender (e.g., if I know I won't be driving her for several days or a week should I put tender on prior)? Battery is 6 months old and just had car serviced and checked at dealer. He suggested if I"m not going to drive her for 2 or more days I should attach tender. Typically in winter I drive a couple of times or more per week but if snow or rain I have gone about 2 weeks without driving. Prior to this I have gone through a couple of batteries over the past several years after not driving and had problems starting and with battery). Now with a tender hopefully I have put an end to battery issues.

 

The unit should of come with a harness that will allow you to permanently attach to your battery . the harness has a blade fuse in it as well as a plug and cap end so you can plug the charger in. I plug my charger in as soon as i leave the car in the garage and i leave it plugged in all the time. It cant hurt the battery . Mine is a 2005 OEM battery and still going strong

 

I use one for my SC430 which I don't drive much if at all during the 4 or 5 months of winter. I would recommend to you the quick plug kit so that you can attach the Tender to the car quickly and without opening the hood. Secondly, any car should stand for at least two weeks without being started. This is a quite normal occurrence (airport parking lots). In my case, I seldom use the charger unless the period of storage is going to be two weeks or more. But, as noted, it can't hurt. In fact, the very slow charge is the best kind for a battery (I have had the Tender take two or three days to reach full charge). If you have a few days and want to charge up the battery, then plug it into the Tender. A last word of advice: if you are going to use this often for short periods of time, try to place the cord over the windshield or near the driver's door - you do not want to drive off with the Tender attached. (Don't ask me how I know this, but I recall that the SC battery is on the passenger side.)

 

I use a battery tender (Harborfreight cheap $5.00) on my car when I leave it for 5 months in Cave Creek AZ, where the garage temps get well over 100 for weeks on end. No issues.

My question, if you have a new ish battery, why are you bothering?

As a rule of thumb, batteries loose about 1% a day, so in theory your battery would be close to dead in 3 months or so.

Unless your car is going to be idle in extreme temps, hot or cold for over a month, I wouldn't bother.

Machog

 

A genuine "Battery Tender" (which is a Brand Name) has some sophisticated electronics to sense when the battery is charged, at which point it lowers or even terminates the charging to prevent damage from overcharging.
I've bought tools from Harbor Freight before, and it is a great store, but unless it is selling actual "Battery Tender" devices, I would avoid a $5.00 charger; especially for long term use (over 14 days) as I would think that the risk of overcharging would be pretty high.