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Battery Tenders


SydneyTii

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1 hour ago, Simeon said:

There is a factory sticker on my car advising that the battery should be disconnected before charging. This is related to the diodes in the alternator but may only be relevant for high current, old school battery chargers.

 

I have a CTek MXS5 multi-stage, processor controlled charger / tender which says it can be connected to any battery while still connected. Not actually done that (old dog, new trick) but probably would at a push. 

I agree about “Disconnect during charging “ but, battery tenders are

not chargers and are meant to

just maintain.

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No big deal. Hook it up, walk away. Been doing it for years without ever removing any from any of the cars.

 

For my ATV's and boat, I remove them and keep them in a warm area until it's time. Then I hook them up to a tender and let it rip. 

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2 hours ago, SydneyTii said:

Tii John, negative is kinda under the snorkel, I have one of those disconnect switches on the battery that you screw in, but it drives me nuts trying to line up the screw thread and the bolt bit.

 

Mine's also a tii.  I have the CTEK connected with the battery connected.

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1 minute ago, John_in_VA said:

 

Mine's also a tii.  I have the CTEK connected with the battery connected.

 

@SydneyTii

 

As well as the usual croc clips, the CTEK comes with a connection lead that terminates with two ring terminals to go on the battery terminals and a plug coupler.  You could maybe even feed this out of your front grille permanently so you don't even need to open the bonnet - certainly you can run this somewhere handy.

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1 hour ago, Simeon said:

Got one from the first link, great price, thanks Simeon!

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Dont know why some of these tenders cost so much.

My $24 Battery Tender  jr. works just fine.

And I dont disconnect the battery when it is charging.  

No issues. 

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2 hours ago, Simeon said:

You could maybe even feed this out of your front grille permanently so you don't even need to open the bonnet - certainly you can run this somewhere handy.

 

Or run the wires to a plug back by the boot, so you don't even need to unplug it - it simply unplugs as you drive away.

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As to the 'why', yep, it's for the diodes in the alternator.  BUT it only means that you

should not use an old- style constant- current charger, as they can run the system voltage

over 25v, which is probably the reverse breakdown voltage of the diodes.

 

On more modern cars, there are electronics continually connected to B+, so again,

any charger that can develop over 16- 18v AC PEAK should be avoided.  Yup, AC-

pulsed DC counts as AC, you know.  It's the way they 'condition' batteries, and it's hell

on semiconductors from the 80's and even well into the 90's and beyond.

 

But most of the tricklers are OK- one of the dead giveaways is the cigarette lighter adaptor.

If it comes with one of those, it'll almost certainly be safe to use it with the car still attached

to the battery.

 

I use an overpriced Battery Tender rated for AGMs, and it does an OK job-

never gets above about 13.8v, so it won't recharge a dead battery effectively.

But it works to keep the stored modern cars from going flat.

 

t

 

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3 hours ago, TobyB said:

Yup, AC-

pulsed DC counts as AC, you know.  It's the way they 'condition' batteries, and it's hell

on semiconductors from the 80's and even well into the 90's and beyond.

 

I have had  a Battery Minder "pulse conditioner" on my 1989 and 1990 E30s that comes into play above 13.5 v. for over 10 years now without negative effects. The "3 year" batteries have lasted as long.

 

I have used them on all the PV solar standby systems that I design with lead acid batteries, whether they are wet or AGM.

 

In addition, I have modified the voltage regulator to provide 15 volts so there is sufficient voltage when all the accessories are on.

 

My C-Tek only puts out a maximum of 7 amps, which is less than 10% of the capacity of the battery. In "recondition mode" the time that the battery is at above 16v is small in relation to the overall usage or charging from an alternator. Will 16v cause bubbles to outgass? Sure, but not really a lot. Of course if you can add water do so.

 

I will however, agree that Battery Tender products are not a good value.

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3 minutes ago, Einspritz said:

 

I have had  a Battery Minder "pulse conditioner" on my 1989 and 1990 E30s that comes into play above 13.5 v. for over 10 years now without negative effects. The "3 year" batteries have lasted as long.

 

I have used them on all the PV solar standby systems that I design with lead acid batteries, whether they are wet or AGM.

 

In addition, I have modified the voltage regulator to provide 15 volts so there is sufficient voltage when all the accessories are on.

 

My C-Tek only puts out a maximum of 7 amps, which is less than 10% of the capacity of the battery. In "recondition mode" the time that the battery is at above 16v is small in relation to the overall usage or charging from an alternator. Will 16v cause bubbles to outgass? Sure, but not really a lot. Of course if you can add water do so.

 

I will however, agree that Battery Tender products are not a good value.

 

I got a "Costco-only" 3A Battery Tender Plus for use with my AGM battery. They were on sale for $30 and it was convenient to just toss it in the cart, knowing that if it sucked I could just bring it back and not give it a second thought. It's been good for a year so far but it is absolutely a maintainer not a charger. The fault detection will prevent it from even trying to resuscitate a flat battery.

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