Battery charger????

B

bucket-o-rust

Senior Member
I need to buy a 6 volt battery charger that you leave connected to your battery all the
time to keep it charged. What would you suggest I purchase.
 
I also tried 4 Black and Decker BM3B maintainers last year. 2 on 6V setting and 2 on 12 V setting (had 4 batteries). Worked OK on the 12V.


In my unheated detached garage and on 6v they stopped working once temp got below 25 degrees F. They did not drain the 6 V batteries, and on 6v they started working again above 30- 35 degrees.


So far this year the above NOCO GS750s have worked down to 7 degrees F, waiting for even colder weather to see if they hold up.
 
I've had 2 old model Deltran Battery Tenders for many years. They still work but I do not leave them on my vehicles continuously, I just attach them when I need to. I had a question about the 6 volt unit last year and Deltran told me to send it to them and they would check it out. That just cost me the postage, they said it was OK and returned it. Good people to work with.
 
I use a Craftsman Diehard Battery Charger/Maintainer "https://www.sears.com/diehard-battery-charger-maintainer/p-02871219000P?plpSellerId=Sears&prdNo=2&blockNo=2&blockType=G2#"
Been using two of them for 3 years, no problem. The first one I purchased was a Schumacher and it died with 9 months..
 
I have used Battery Tender, Schumacher, Black and Decker and NOCO for the 14 batterys I have.most are 6v, but many are 12V. The Battery tenders are the oldest and have never failed. The NOCO is new this year and so far so good. Black and Decker were total junk. none made more than one season, most failed within weeks. Shumacher is not great. I have 3 different models. some are 3 years old and some failed after one year. I sent one back that failed in a few weeks and they replaced it after a 3 month delay.
 
First,what is wrong with your car that makes it need a charger on it all the time?My cars sit for months,start them up and go.Second,chargers scare me.The new smart chargers scare me the most.They don't always do what they are supposed to.I did leave one of those little Deltran maintainers on a tractor in the shed,I went out one day and it was melted inside with the paint burned off.It was laying on the head of the Kohler engine,so nothing was hurt.I will use low rate chargers sometimes,but keep an eye on them.I will never leave a charger on in a building unless I am around to watch it.I would rather fix the car than cover up the problem by keeping a battery charger on it all the time.
 
Keith True said:
First,what is wrong with your car that makes it need a charger on it all the time?My cars sit for months,start them up and go.Second,chargers scare me.The new smart chargers scare me the most.They don't always do what they are supposed to.I did leave one of those little Deltran maintainers on a tractor in the shed,I went out one day and it was melted inside with the paint burned off.It was laying on the head of the Kohler engine,so nothing was hurt.I will use low rate chargers sometimes,but keep an eye on them.I will never leave a charger on in a building unless I am around to watch it.I would rather fix the car than cover up the problem by keeping a battery charger on it all the time.
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I think I would get in touch with the manufacture to see what the problem was. They are decent people to deal with.
I have and have had several 'Battery Tenders' and have never had a problem. I keep one hooked to my motorcycle all of the time. Good Products.
 
I will use low rate chargers sometimes,but keep an eye on them.I will never leave a charger on in a building unless I am around to watch it
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I won't leave a charger on overnight. I have never had an issue but have heard from those who have and I think it is better to be safe than sorry. I also seldom have to use a battery charger. JMHO


TerryO
 
In a different application, (battery powered back-up sump pump) I have found that "smart" chargers/battery tenders are not so (smart.) One can tell if the battery is overcharged using the charger by loss of electrolyte. If you find the electrolyte low and have to fill up then your battery charger is "boiling off" the water in the electrolyte.

The owner of this installation (neighbor-not me) is into Boxter cars and keeps his collector car battery topped up with what he considers a high quality Mercedes brand battery tender.

On my attributing his sump pump short battery capacity to "low charge using the built in battery charger" he suggested we try the Mercedes unit on his sump pump. The result seems to have sufficient battery capacity for 8 hours of sump-pumping (well above what one would expect) BUT the high end charger "boils off" his electrolyte over a period of 5 or 6 months requiring a top-off. (automated, the system gives alarm on low electrolyte.)

I suggested adding a timer to turn the charger on perhaps 20 minutes a day.

We're doing this now - I don't have a result on either battery capacity or boiling down yet.


Joe K
 
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Joe K said:
The result seems to have sufficient battery capacity for 8 hours of sump-pumping (well above what one would expect) BUT the high end charger "boils off" his electrolyte over a period of 5 or 6 months requiring a top-off. (automated, the system gives alarm on low electrolyte.)

I suggested adding a timer to turn the charger on perhaps 20 minutes a day.
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What you're describing, and what others have alluded to, is a function called float voltage. Good chargers need to reduce the voltage being sent to the battery when it's fully charged. The proper long-term voltage varies by both battery type and ambient temperature. If the voltage is too high, the battery dries out. This is a common problem with UPS (uninterruptible power supply) batteries. Some vendors' batteries wear out after two years because their float voltage doesn't adjust for how warm those batteries can get.

Many "smart" charging solutions go through a set of programmed steps. For example, the Mercedes charger does this:
  1. Charge at 3.6A until detected battery voltage reaches 14.4V
  2. Gradually reduce amperage to 0.4A
  3. At 0.4A, shut off and monitor battery voltage
  4. When battery voltage drops to 12.7V, repeat cycle

If your sump pump battery isn't playing by the charger's rules (for example, if it never gets to 14.4V or if it drops quickly to 12.7V), then the charger will spend too much time in full-charge mode and it'll boil off the electrolyte.

Bottom line: Smart chargers can be good or bad for long-term charging depending on how the battery being charged reacts to the charger's float voltage or intermittent charging cycle. You should read your charger's manual to understand what it's actually doing and make sure your battery is compatible.
 
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