royal flush

I have 3 of the BT Jr..iput my Fluke multimeter on to check float voltage--all 3 units read low from 13.06 up to about 13.12--all battery manufactures suggest 13.20 as being the lowest up to about 13.60 volts--my meter is fairly accurate--anyone else notice low float voltage?

J.Moore

Doesn't sound like a problem. My Schumacher 1.5v tender shows the same float charge. 13.06 to 13.20ish. Thats after a full charge session bringing battery volts to 14.70ish, then float takes over, drops and maintains the 13.05-13.20 range.

mikeCsix

Your float voltage readings look great with very little water loss. I floated mine at 13.02 (settable, this was a very high end charger/conditioner) for years and the batteries needed water about once per year, though I would check them every six months.

OkieBikerDude

I may not understand "float voltage" but my little Battery Tender, Jr. doesn't starting charging until the battery voltage drops down to 12.65v. I'm not sure at what voltage it goes into standby mode. Whenever I disconnect the charger and go for a drive the voltmeter shows 14.4v - 14.7v which makes me think the tender isn't maintaining the battery correctly. Any thoughts? OBD

ben dover

Sounds about right, mine runs 13.11 to 13.19.

FortMorganAl

A fully charged lead acid battery runs 12.6 to 12.65 volts. How are you measuring the 13.06-13.20? If it is hooked to a battery (which a Battery Tender Jr. must be before it will produce any output voltage) then it is just supplying the current needed to run the car's computers in low power mode. The ~13.5 volt recommendation is for stationary batteries that are never discharged and recharged. That level will cause some liquid loss. The world is a compromise. Deltran compromises on trying to keep the battery as fully charged as possible without risking electrolysis of the water. I trust the Deltran engineers to know more about batteries that most people certainly including myself.

As far as 14+ volts when the car is running, GM doesn't care as much about how well they treat batteries. They are only interested in recharging the battery as fast as possible at the least cost. They can't spend a lot of money on fancy float circuits that the owner will never notice except in the price of the car.