How often to trickle charge my car battery?

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6,614
Location
southeast US
Measure the voltage first. Technically, if it's below 12.6V, sulfation will start and need to charge. I doubt using car once per week is a problem, unless you have some crazy parasitic current.
 
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35,688
Location
NY
I have a van that is driven less than that. The battery lasted over 13 years doing nothing. Unless you have a problem with the alternator, or some kind of parasitic loss I really don't see a need to trickle charge the battery. I'm interested in seeing what others have to say.
 
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25,950
Location
MA, Mittelfranken.de
I don't know, most of my cars don't see 25 miles a week and never saw a trickle charge in their life. Never a problem even after sitting 5 mo over the winter. If the car has a security system lock the doors with the key if its not moving for a few days not the remote, that will drain the battery faster.
 
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9,108
Location
Marshfield , MA
My 528es have a parasitic drain of about 20 mA sitting for 2 weeks will flatten the battery. Same situation with Rat. It is from the radio memory and maybe the ECU.
 
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5,722
Location
Charlotte, NC
Why would you disconnect the battery?? You can charge the battery any time you want without disconnecting it, after all, the alternator is charging the battery all the time the engine is running. What car are you asking about? The 2014 Mitusbishi Mirage ES CVT? If you feel it necessary to provide additional charge, just hook it up once a week for a day when you will not be driving it. Even that is probably not necessary, but it shouldn't hurt. Something to consider, if you want to interact with the normal charge/discharge function of your electrical system, you need a decent volt meter and learn what the battery voltage should be for various conditions. I hope the above is helpful. Wayne
 
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36,465
Location
ME
You're fine. I made it through a whole winter driving my dodge dakota 4 miles round trip to the dump every other week. Sometimes I let it run, sometimes I shut it off after 2 mi then started it again.
 
Messages
25,814
Location
Upstate NY
First there is what is called a trickle charger that is a plain charger normally around 2 amps but it continues to charge (forever). Then there is a float charger or battery maintainer, around the same of 1 amp to 2 amp but it will keep the battery 100% charged and can be left on indefinitely. This is what people (should) use on boat batteries over the winter. In your case, I would fully charge up the battery either by driving normally or with a plug in charger. Wait 24 hours and measure the battery voltage. Then just before you are going to drive it, measure it again. See how much charge is lost in that week. If the temp changes a lot you will need to factor that in also. A float charger can be used every week with no harm. But probably not needed. Decent float chargers are Battery Tender or Battery Minder. I would skip the HF $9.99 special on a float charger.
 
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7,116
Location
MIchigan
Originally Posted By: Oldmoparguy1
after all, the alternator is charging the battery all the time the engine is running.
That's not exactly a true statement....It's more like the alternator charges the battery after startup and the electronics run off the alternator.
 
Messages
884
Location
CA
My cars sometimes see short trips / infrequent use so I've also considered this topic of looking after my car batteries a few times. Then I figured it wasn't worth the time. The average battery is $100. If I go from a 5 year life to a 10 year life, then it's only a $10 a year saving. Not worth the effort imo. And as has been pointed out, the OP's case is not taxing the battery much if at all.
 
Messages
2,222
Location
california
We do not know the health of the Op's battery, and flooded batteries can self discharge 15% a month at 75f. The less healthy the battery the higher the self discharge. We do not know the parasitic drains on the Op's vehicle, and how much of the batteries capacity is remaining, so the question is unanswerable. Fully charged resting voltage varies battery to battery so the 12.8 or 12.6 absolutes one hears time and again do not apply to every battery across the board. AGM's can be have fully charged resting voltages over 13v while some healthy flooded batteries are fully charged and resting at 12.6v. Without knowing the specific brand battery in the OP's vehicle, voltage absolutes as to state of charge are not applicable. Float/ maintenance and trickle chargers vary widely in effectiveness, voltage setpoints maximum amperage and capabilities. Since we have no Idea what charging source the OP has access to, any recommendations are rendered moot. In general the higher state of charge the battery is kept at, the longer it will last. You can trust your charging source and all the marketers claims, but there is only one polygraph as to how any charging source is fairing on a flooded battery, and that is Hydrometer. A glass turkey baster style hydrometer with a glass float and with a means to adjust SG readings for electrolyte temperature. If you have a plastic hydrometer which claims to be temperature compensated, give it to your enemy. If you have a cheapo hydrometer with the floating balls, then give up all hope of knowing what is going on with your battery for ever after and hope the prorated warranty can be applied when necessary.
 
Messages
1,815
Location
South Dakota
We were averaging about two years on a battery, then replacing under pro-rata warranty. We do a lot of short trips. I charge my battery at least twice per year. GM rep stated that batteries are often overtaxed with today electronics and all of our electronic toys. Often, they do not see a full charge, especially if you are short tripping. In your case, I wouldn't buy a charger specifically for yours, but if you have one, use it.
 
Messages
12,925
Location
Northern Kentucky
Originally Posted By: friendly_jacek
Measure the voltage first. Technically, if it's below 12.6V, sulfation will start and need to charge. I doubt using car once per week is a problem, unless you have some crazy parasitic current.
This is not true, sulfation doesn't even begin til you get below 12.40 volts or 1.225v per cell. A battery at 12.6v after resting will be over 90% charged, and is very good. To the OP, it depends on the application, some vehicles will drain the battery while sitting faster than others, while some will last weeks without being driven and still have a good charge. My Buick can sit a long time without draining but my Taurus will drain the battery flat in 2-3 weeks. I suggest you get a cheap digital multimeter and check the voltage 6+ hours after you drive it and let it rest, and then check it again right before you drive it again next and see if it's draining a lot. If it's above 12.6v you're fine.
 
Messages
496
Location
Australia
With your usage pattern, I wouldn't think it's necessary to worry about supplementing the battery charge. Having said that, you mention a charge process(Trickle Charger) that's extreme, and can potentially do more harm than good. A far better solution will always be to utilize a top quality "Maintenance Charger".(There is a big difference.) There's no requirement to check or monitor the battery terminal voltage. Just connect the charger and set it to the correct mode. Then forget about it, as the charger will take over from there. The Ctek brand of chargers come to mind, and are widely available. I have 2 of them in constant use around here with 0 issues. The model you would most likely be looking at using will be the MXS 5.0 It's a very good allround charger.
 
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Messages
1,061
Location
Minnesota
I see no reason to pull or disconnect batteries. I have gathered that later vehicles have more loads for the alternator than earlier-and that parasitic draws during 'shut down'also are higher. When some of my 'stuff' has sat for weeks/months, I will measure voltage and the result often indicates it's a good idea to charge.
 
Messages
3,558
Location
SE Pa
Originally Posted By: cookiemonster
I travel maybe 20-30 miles per week on average, using the car once or twice a week. How often should I disconnect the cables and trickle charge the car battery?
If you're only using it 1-2x / wk, you shouldn't be running down the batt all that far, unless you have a very electronics-laden car with a heavy draw alarm system. Running it 20 miles should charge it back up no problem. But the deeper cycling than usual will probably shorten the battery's life a little. If you want and it's an expensive battery, I'd put a Ctek system on it. This is an automatic tender/maintainer, so does a little more than a raw trickle charger. You can wire in a Ctek plug on the car, so disconnects from the unit take a second. The monitor plug will also indicate battery state (green-yellow-red) when not connected to the unit, so you can keep a quick eye on things. These things are very popular with the seasonal car crowd, where the car might sit all winter long.
 
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