No static auto battery minder

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I got tired of having to charge up my cars that stay in the garage most of the time so I bought a small 2 amp “battery minder”.  It plugs into a 120V. AC outlet and while it works okay, it puts static in the AC power line that we hear when trying to listen to our AM radio. It’s really bad and my wife has a favorite station on the AM radio she likes to listen to.

So, I’m wondering if anyone knows of an auto battery minder that will keep my cars charged without all the static being put in power line.  A 2 amp unit is what I’m looking for.  Thanks in advance for any help with this.

Being 20 something in the 70's was so much better than being 70 something in the insane 20's

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As far as I know all automotive chargers produce a significant amount of RFI/EMI interference (i.e. radio static) because of how they operate.

Normally it isn’t a problem because most of them use a “grounded” A/C power cord (i.e. it has a 3 prongs) which reduces the RFI/EMI unless you’re within a few feet of the actual charger itself.

You didn’t specify what make/model your battery minder is but, if it doesn’t use a “grounded” A/C power cord, switching to one that does should help.

The other option would be to buy a “clip-on” ferrite RFI/EMI core like this and place it on the A/C power lead to reduce the RFI/EMI (the core actually soaks up the magnetic field that produces the RFI/EMI interference.)

FYI, you’ll need to measure the A/C power cord diameter to ensure the core you buy will fit tightly but not so tight it bites into the rubber insulation.

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Charlie

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This is what I suspected but wasn’t sure.  My regular 2-10-50 amp battery charger is grounded and only affects the car radio if I turn it on while charging.  It doesn’t affect the AM radio in the house though as you said.  Thanks again for the info.

Being 20 something in the 70's was so much better than being 70 something in the insane 20's

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I have and use many small charger/maintainers of multiple brands and have yet to see one with a 3-prong cord like a charge n’ start such as you describe may have. An RFI choke as described above may do the job and is a cheap initial attempt at a solution but may or may not do the job well enough.

If I may suggest an alternative or backup solution, would using a lamp timer that turns on a circuit as people sometimes use for security while away for a weekend or before coming home in the evening be feasible? If you set it to turn on and off at a time when you’re quite certain the radio won’t be played, say 1am to 5am, that should be plenty of time to top off most batteries.

Amazon lamp timer

 

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Charlie

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There are a number of battery maintainers that treat a car battery like a laptop battery… they charge it until it is full, then stop charging and monitor the voltage (which is tied to a given percentage of charge) until it drops below a certain threshold, and then it charges up again. Most of the time when the car is just sitting there, it is idle, not charging at all, and there would be no interference at that point.

I have a ten amp flavor of one of these, the Noco Genius 10. It’s not two amp as you requested, but since it’s only charging when the battery voltage is below the threshold, it’s not overcharging it. It is selectable between traditional lead acid, AGM, and lithium car batteries.

I have no idea how much RFI it would create when charging, but it’s a lot quieter and a lot cooler than my 40 year old Sears battery charger (2/10/50 amp start). That gets very hot on ten amps, and the 60 cycle hum is notable. The NOCO is much smaller and has a sealed plastic case rather than the heavily ventilated metal case of the Sears, and it gets warm like a laptop brick, but nothing like the Sears. I haven’t noticed any 60 hz hum, though I am sure it is there if I were to listen for it. It’s inescapable with the old one.

 

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Charlie

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Yes, the heat my big charger makes is a problem in the summer heat.  That’s why I’m looking for something smaller, cooler, and little or no static.  Thanks.

Being 20 something in the 70's was so much better than being 70 something in the insane 20's

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Noco sells a variety of battery tenders covering a range of amps. I can’t speak to AC line or RF noise they might create.

https://no.co/products/charging/genius

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Charlie

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One thing I’ve noticed is that they don’t show the type of AC plug (whether it’s grounded or not).  So I’m going to have to either go physically and look at the chargers or contact the places and ask them if the plug is grounded.  My big charger is grounded and I don’t have a problem with static.  Thanks!

Being 20 something in the 70's was so much better than being 70 something in the insane 20's

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Lead acid (car) batteries are happy to be trickle charged forever. Your existing charger should drop back to trickle when the battery voltage is correct.

What is the charger model (the big one)?

cheers, Paul

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My “big” charger is a Delco 2 – 10 – 50 amp switchable unit and the 50 amp is supposedly only for helping to start a car with a semi dead battery.  One of my cars is new enough that it has a computer or two in it, therefore I need to keep charging it or the computer will drain it down.  Tickle mainly works on older cars without computers.

I’m looking around for the right one for me and in fact have my eye on a deWalt unit sold at Home Depot which does what you described and cuts back or off when it reaches full charge.

Thanks

Being 20 something in the 70's was so much better than being 70 something in the insane 20's

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Charlie wrote:

Tickle mainly works on older cars without computers

They work for all cars because they monitor the battery voltage and only put out enough current to maintain the voltage. My 4A charger has no problem maintaining the battery in my 4yo fully computerised car.

Something like this: https://www.ringautomotive.com/en/product/RSC804

cheers, Paul

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Charlie

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Hey @Paul T, that’s a really nice charger and the images on their website show it does use a grounded, 3-prong A/C plug.

But it’s only available with a UK/EU style A/C plug (i.e. electrical outlets using 240 VAC 50Hz) so it wouldn’t work here in the US where our electrical outlets are 120 VAC 60Hz.

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Charlie

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Paul T wrote:

My 4A charger has no problem maintaining the battery in my 4yo fully computerised car.

Yes indeed, a 4 amp charger will overpower the computer drain easily.  If I can find a 4 amp charger, that would be better than 2 amps.  Thanks for the info. Paul.

Being 20 something in the 70's was so much better than being 70 something in the insane 20's

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The charger goes into trickle mode after a while  and doesn’t need to “overpower” anything. Modern cars only need to listen for the key fob or mobile phone comms (they have a SIM built-in) and your phone will run for a week in that mode with a tiny battery.
The last thing car manufacturers want is flat batteries after a couple of weeks of sitting idle.

cheers, Paul

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Getting back to the problem of static, it would seem what I need to find is a charger as described above and that has is grounded.  In the U.S. the grounding may be a problem, I’ll find out.  Seems the only No-Go units that were grounded were the ones for the U.K.

Being 20 something in the 70's was so much better than being 70 something in the insane 20's

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I don’t think grounding is the answer. The interference is because the charger emits very high frequency radiation – something it should not do.
Most modern power supplies, like your laptop charger etc, are switching units that by law must emit very little RFI.

I would look for a better charger (more money). 
Can you return the current one because it is rubbish?

cheers, Paul

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I didn’t pay a lot for it so no great loss.  My “big” charger doesn’t emit any RFI to the AC line.  I will make sure the one I buy is better quality.

Being 20 something in the 70's was so much better than being 70 something in the insane 20's

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