Battery Maintainer through Trunk
#16
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Not according to Battery Tender's "Battery Charging Basics & Charging Algorithm Fundamentals" PDF - page 11.
#18
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I have two of them for both my 911s, in Denver where the winter temperature regularly drops near 0 at night and is often below freezing for days on end. These chargers not only maintain my battery voltage at 12.8 volts (full charge spec), but will charge them to that voltage from a discharged state in those temperatures.
I couldn't believe the answer I got from Battery Tender..."publishing the specific voltages corresponding to any timeframe usually just generates more confusion than any resulting benefit". Let me be the judge of that. The main reason why I never took BT too seriously and do not own one.
#20
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Not according to Battery Tender's "Battery Charging Basics & Charging Algorithm Fundamentals" PDF - page 11.
#21
Burning Brakes
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FWIW (and that may be not very much): On my 993 (and previously on my SC) I placed a heavy gauge wire from the battery thru the firewall and under the carpet to a tender in the foot well behind/under the driver's seat. I have a coiled AC cord that I simply pull thru the driver's window to a nearby outlet. When I get in the car I just pull it out of the outlet and it drop it in the foot well behind the set. This has been servicing my cars for 25 years with zero problems. Easy to see the green light with the seat back forward. I'd hate to screw around with the cord coming into or out of the front. Plus, I'd hate to be opening and closing the hood regularly just to get the charge. Further, this process keeps the garage "clean" of stuff and cords laying around. --- Just one guy's approach.
#22
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Hmm. Interesting. Is it possible the pdf is out of date? Here are excerpts from the manual that came with them. The third paragraph is where I got the information I posted. I interpreted it to mean both chargers are 3-stage units, but I can see how the wording might only cleverly imply that.
Measure the voltage as it is increasing during the constant current aka bulk mode and once it reaches a peak at about 14.2 to 14.4V, see if it switches instantly to a float mode in the mid 13 V range.
If after the bulk mode it stays in a constant voltage mode for a few hours before switching to float mode, then it is a 3-stage charger.
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Any battery charger is better than no battery charger if a battery would normally be neglected. As for battery chargers and how well they charge, there is a world of difference.
BTW, that PDF is right from their present-day web site.
#24
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I just run the cord out the front of the trunk and close the trunk. No harm to the seal. Have been doing this for almost 20 years on 2 911s and the 993 with no issues. (The 997 goes out the back of the front lid.)
I do tie a flag on the drop down extension cord to prevent driving away without unplugging it in my haste to get on the road.
I do tie a flag on the drop down extension cord to prevent driving away without unplugging it in my haste to get on the road.