BatteryTender vs Schumacher vs Black&Decker ?

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TmanP

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I have a 2-year-old Group 34 (a fairly large battery, ~700 CCA) Johnson Controls AC Delco silver battery in my car that I'm looking to make last for a while. So I'm shopping for a battery maintainer, and I had a couple questions.
The .75 amp Battery Tender seems like it'd be a little "underpowered" for a car battery of this size, although they say it can be used to maintain only (not charge) car batteries and not at all on trucks or SUVs. Is that still my best choice or should I get the Schumacher 1.5 amp maintainer, or the Black and Decker 1.5 amp maintainer? Already have a 2/6/10 amp charger, so I'm not concerned with bulk charging, just "topping off" and maintaining.

I'll throw a couple of few batteries on it overnight once in a while and use it in the car when we're out of town and it has to sit for a few weeks.

And is it safe to use the cigarette lighter connection or the quick disconnect pigtail, or should I stick to the alligator clamps?

Thanks.
 
Originally Posted By: TmanP
And is it safe to use the cigarette lighter connection or the quick disconnect pigtail, or should I stick to the alligator clamps?


The cigarette lighter socket may be disconnected when the key is off, so there is a good chance that you will need to use the clips.

Battery Tender brand does have higher amperage offerings. A 0.75 charger is not the one to use when you run the car battery down and want to get the car working. It is really easy on the battery for trickle charger use.
 
I can vouch for the Battery tender Plus, but one of my four Battery Tender Juniors died during the five year warranty period. With a heavy metal case, the Plus is more stout but not much more costly to buy.
 
Originally Posted By: Donald
Battery Minder. It's the best out there in battery maintainers. Temp compensated and desulfation.


+1, they are my preference. Look at the model 2012.
 
My El cheapo Harbor Freight model and also their "premium" Centech brand work fine on a 750 amp F150. After 3-4 hours it's done. No need for power.

I don't doubt the legitimacy of all these temp compensation models, but my original battery is only halfway through its life five years in, and I didn't start using it until after three years.

I don't need immortality. Just excellent longevity.
 
Last edited:
I have a tender jr, but I can't figure out how old it is. It's at least 5 years old. I bought the jr to be able to fit it under my hood since my car is stored outdoors. It's not as fast because of the 1/2A output, but it does the job.
 
Had a Battery Tender Jr. for over 10 years. Use it all the time rotating between our 8 vehicles. Not for quick charges, but great for maintenance and overnight.
 
Originally Posted By: JHZR2
Originally Posted By: Donald
Battery Minder. It's the best out there in battery maintainers. Temp compensated and desulfation.


+1, they are my preference. Look at the model 2012.

+2
 
The schumacker 1.5A model from the 80s was a solid machine - we had one in use 24/7 and it lasted for years and was sold with the car. Sadly, the 2 we've bought since then both quit after 2 years each.
 
Originally Posted By: meep
The schumacker 1.5A model from the 80s was a solid machine - we had one in use 24/7 and it lasted for years and was sold with the car. Sadly, the 2 we've bought since then both quit after 2 years each.


Schumacher makes junk now that over charges batteries. I've had one of their 15 amp automatic chargers that went well over 16 volts
 
The key to ideal battery maintenance is the proper voltage for specific battery for its temperature.

Obviously it would be great if such a maintainer come with a battery temperature sensor and perhaps a toggle from 13.2v for a flooded battery and 13.6v for a AGM.

The Tinkerer who does not mind a little hands on adjustment can utilize one of these adjustable voltage inexpensive power supplies:

https://www.amazon.com/Genssi-Power-Supp...50+power+supply

I used one of these as a regular 30 amp bulk and absorption charger, and it would actually do 38 amps, but made this clicking noise over 36 amps, and I had to adjust voltage to keep it under 36 amps and keep twiddling voltage upward for the first half hour, as the well depleted battery recharged.

When I got sick of twiddling voltage I sacrificed it to science and just set it to 14.8v and let it go on a depleted battery. After 17 minutes at 38 amps, the magic smoke released and I then bought a much higher quality Meanwell powersupply (rsp-500-15) that has constant current limiting on overload. as well as overvoltage and overtemperature protections.

The linked product above has a fairly wide voltage range, from the mid 12 to mid 15v range. I'd have no issue putting it on a battery that cannot accept more than 30 amps. The little voltage adjustment potentiometer is only rated for 25 or 50 adjustment cycles though. It comes with no AC or DC wiring. I recommend splicing a wattmeter on the DC output:

https://www.amazon.com/Tenergy-Precision...power+wattmeter

It will not adjust voltage automatically for actual battery temperature, but it is not difficult to adjust it with a jewewlers screwdriver.

I snipped the legs to the micro potentiometer and soldered wires to reach a 10 turn Bourns potentiometer rated for thousands of cycles.

I realize the impracticality of this approach for the 99.95% of readers. But it is kind of neat to get a 30 amp adjustable and fully manual charger for such a low price. I've a growing contempt for automatic smart chargers as they cannot seem to ever complete the job, dropping to float votlage very prematurely when the battery is still far from fully charged.

I used my schumacher sc2500a on a neighbor's unintentionally depleted to dead, group 27 starting battery. When I checked on the charger after 1:40 is was making 15 amps at 15.79v, which is very abusive. An EQualization charge can go to 16.2v, but only after the battery has spent several houra in the 14.8v range and is otherwise 'fully' charged. A battery should not be pushed past 14.8v with more amperage than 5 amps per 100Ah of capacity. 15 amps at 15.79v was well over this and very hard on the plates of the 100Ah starting battery.

I then stopped charger, dropped voltage using the headlamps as a ~15 amp load, restarted charger, and the darn thing would skyrocket past 14.8v then stop and goto float voltage unless I used the 2 amp setting which could not get past 13.4v at that stats of charge. After wasting 10 minutes trying to get the schumacher to charge and hold 14.8ish volts, I gave up, got my adjustable voltage power supply, set it to 14.8v and walked away.

About 4.5 hours later amps had tapered to 0.95 at 14.8v, and the 100AH( when new) battery had accepted 22 more AH after the 'smart' schumacher refused to do anything more other than float, or overvoltage the battery.
 
I use the 'Optimate' tenders/chargers. I have the '3' and a newer Optimate 4. I think there is a newer model or two now. I use them on many batteries, works for me.
 
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