LT4BUD

Just bought a Schumacher SP2 battery extender/maintainer.......connected to my battery, which was low and in need of charging.......three hours later I read the instruction manual and found this:


Maintaining a Battery
The Schumacher SP2 is a battery maintainer that maintains both 6 and 12 volt batteries, keeping them at full charge. It can charge small batteries and maintain both small and large batteries. If you are maintaining a fully charged large battery, you are properly utilizing the battery charger. However, if you use the battery charger to charge a large battery, such as a marine deep cycle battery, that was not fully charged, you may lose some of the battery’s capacity. This would cause the large battery to be unable to hold a charge and become useless. Therefore, we do not recommend charging a large battery with this unit.

WTF you can ruin a battery by connecting a maintainer to it when it is not fully charged!!!



BTW the manual defines a "Large battery" as a normal size car battery, not just a deep cycle battery

383vett

A car battery is not considered a "large" battery. Have you ever seen a 100lb marine battery? That is a large battery.

LT4BUD

The chart in the Maintainer Manual shows "Small" as Lawn Mower, motorcycle etc rated 6-32 A_Hr...........and "Large" as literally all full size car batteries starting at 200 CCA.....the largest being marine batteries....

Nathan Plemons

Generally speaking, for the health of the battery, you want to charge it as slowly as possible. I wouldn't think that a maintainer would be able to throw enough current to your battery to cook it, but you never know.

I always use the small/slow charge option unless it absolutely won't take a charge that way. If it won't I may kick it up a notch to get it started then back it back down, although if it won't accept the slow charge that is generally a symptom of a battery that is starting to go south.

I know that an alternator is not designed to charge a discharged battery, rather just maintain one. As such if you try to charge a "dead" battery with your alternator you may burn up the alternator. It's a matter of the battery trying to demand more than the alternator can put out. In your case, however, it would seem like even if the battery wanted more than the charger could put out that it would be the charger that would be in danger, not the battery. Maybe a battery expert knows, I certainly don't!

QCVette

I have used a Schumacher maintainer to charge mine quite a few times. It may take it a day to bring it up to full charge, but it has worked fine. No damage to the battery.

Not only didn't they damage the battery, but my maintainer has a desulfation mode that has improved a nearly dead battery that wouldn't hold a charge very well.

Michael Dowd

I agree with Nathan. I have always been told that it is better to slow charge a battery than rapid charge to maintain the life of the battery. I have an Optima Battery in my car and have a Battery Tender on it all winter. I am in the garage every weekend that I can get there and doing something to it that is requiring the hood and/or doors open for hours at a time. Although many people have had less than favorable opinions on the Optima brand I have had it for 4 years now and it has always been juiced up and ready to go when I turn the key.
I would my opinion that someone at sometime had an issue charging a large marine style battery and this was included with the paperwork to release them of any future liability.

Churchkey

Same here.

Best little charger/maintainer I ever purchased. Cost (IIRC) was around 30bux at WallyW orld.

LT4BUD

So I called the Schumacher Tech line......

1) The SP2 Maintainer I bought is rated 1 amp and is NOT reccommended for Corvettes because there is a continous current draw on the battery when the car is just sitting. I should have bought a maintainer with a 2 or 3 amp rating.

2) The lady I spoke with was very critical of the Owner's Manual and stated it should not have said what it said.

3) The Model SP2 is in a package labeled "Battery Extender...Maintainer". In fact all Maintainers are Extenders.....nothing different about this unit regarding being an Extender

4) You do get the longest life out of a battery by keeping it fully charged.

BTW I have been using a Schumacher 6 amp Automatic battery charger that is at least 25 years old...no microprocesser technology...I put it on the battery maybe once a month during the winter. I am only on my second battery, still good, in the almost 16 years I have owned my 96. So not sure what I am going to do except the unit I bought is going back for a refund.

Nathan Plemons

Well I can tell you that much is BS. ANY modern car, not just Corvettes does have a power draw on the battery even when it's not running but I promise you it's in the milliamp range, IE 1/1000th of an amp. If you put a steady 1 amp draw on a car battery it would be dead VERY shortly. If your car has so much draw that a 1 amp charger can't still maintain it, then you have something wrong with your car.

LT4BUD

Honestly I was not very impressed with the gal I talked with.......perhaps a tech rep in training, but not the person I would have wanted representing my company...but that is what she said

....and I sure would not want a manual out there saying things my "tech rep" could not support

Chuck Tribolet

FWIW, my '87 has been on a Schumacher for many years. IIRC, the
prior battery lasted 11 years. And the current battery is getting close
to that.

But these "battery tenders" are designed to keep a battery charged,
not to recharge a dead battery.


Chuck

383vett

Should have asked for a guy.

Nathan Plemons

Well at my company in tech service we've got a chick who is every bit as good as any of the guys in the department, although I admit that is the rarity.

One of the parts stores in town has the best 2 guys of any of the stores but the worst girl of any. I cringe when I go in there and she is behind the counter. When I walk in there and she asks "can I help you?" My first thought is always "I seriously doubt it."

BADDUCK

You would buy a 1 amp maintainer and use it to fully charge a low battery. Seriously?

LT4BUD

No I have a "charger" ......I bought the maintainer to maintain.....

what I was shocked about was the statement in the manual that putting this maintainer on a low battery could ruin it!!

I would not have expected that......I would have expected a very long time to charge a low battery, not ruin it!!