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Battery Tender Plus - Design Changes

I have the latest version of the Battery Tender Plus and it terminates the constant voltage phase (Green LED Flashing) earlier than expected. The orig inal design appears to have been an analog design and the manual showed the constant voltage phase ending when current declined to 0.1 amps. My tests on the new design show the constant voltage phase ending when the charge cu rrent has declined to 0.8 amps. Testing was done with an automotive battery in good condition.

Does the change from 0.1 amps to 0.8 amps sound like a concern? The manual refers to bulk mode, absorption mode, and float mode charging but no longer includes a specification or chart showing the current cutoff threshold.

I'd be interested if others have taken any measurements on either design. M y device charges at 1.25 amps and the constant voltage phase starts when th e voltage reaches 14.5 volts. The float voltage measures 13.1 volts.

Saturation might still be possible in float mode given enough time dependin g on the float voltage.

The latest design uses switching technology. The charger does appear to be more efficient with AC power measuring a maximum of 24 watts. The power lev el declines to 16 watts at the end of the constant voltage phase and then d rops to a very low level in float mode.

Reply to
kt77
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I bought a Deltran Battery Tender Jr., 6 volt, years ago. It was garbage, never got a single successful charge with it. Lifetime "warranty" likewise garbage, shipping to Florida and the required fees for handling, diagnosis, return shipping, etc. were near the retail price of a new one. A sledgehammer that I made in High School metal shop class took care of it.

Reply to
triangles

What is your battery voltage at rest without a surface charge?

Cheers

Reply to
Martin Riddle

The battery typically reads 12.5-12.7 VDC depending on the time since the l ast charge.

I do like the Battery Tender Plus better than my Black & Decker 2 amp charg er/maintainer. The Battery Tender Plus does have three state charging and i t also has temperature compensation. That is actually quite important over a wide temperature range. Temperature compensation typically requires a 0.1

8 volt change for every 10 degrees Centigrade for a 12 volt battery.

The Black & Decker charger appears to start out constant current and then s witches to float after the voltage rises to about 14.2 volts. The float vol tage has reached 13.68 volts in the summer which seems a little high.

The Battery Tender Plus has been charging at 14.5 volts in the constant vol tage phase. That is not as high as an equalizing charge but still could pro vide some benefits.

It's possible that Battery Maintainers today have implemented changes to ha ndle the multiple types of vehicle batteries now in use.

Reply to
kt77

There is an interesting update on this thread. My new Battery Tender Plus i n earlier testing was ending the Constant Voltage Phase when current declin ed to about 0.8 Amps before going into Float mode. The original Linear Desi gn was specified to end the Constant Voltage Phase at 0.1 Amps.

Last week I noticed the current at 0.29 Amps while doing a different type o f test. The voltage measured 14.51 VDC. I don't know the final current befo re going into Float mode.

Any theories on what could have changed? I wonder if the algorithm includes other criteria.

The battery had been charged a number of times with the Battery Tender Plus and also a new CTEK Eight Step Charger. In both cases the battery was expo sed to higher voltages than it sees in the vehicle which is typically 14.2 VDC or less.

The additional testing was measuring the current in Float Mode which was in tended to get a feel for the parasitic drain from the vehicle. I measured c urrent as low as 25-30 milliamperes after a long stabilization which should be a good sign. The parasitic drain from the vehicle should be less than t he measured float current. This test requires a relatively low Float voltag e for the best results to minimize charging current.

Reply to
kt77

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