I have a full-size Battery Tender in the metal case that has been used every winter for 14 years, but I have had mixed results with Battery Tender Juniors. The Juniors seem to die prematurely.
Safe to trickle charge batteries all winter?
- Thread starter AngryScientist
- Start date
As long as it's a battery Tender and not a trickle charger.
14 yr old Odyssey in my HD, 12 yr old OEM battery in one of my snowmobiles still going strong. Always on Battery Minders when parked and stored in off seasons with sub zero to 90f temperatures.
I don't hook up a charger permanently not least because I don't have a modern switch mode charger only an old fashioned 4 amp mains frequency transformer charger although it does have a float setting of 13.5 volts. Besides the fact that permanent float charging is unnecessary particularly for an AGM battery, it's also has a cost.
I assume people leave a charger hooked up for economic reasons i.e. they don't want to pay for a replacement battery more often than necessary. But what about the cost of charging. I measured the power consumption of my old charger on float hooked up to my motorcycle battery and it came out at 12 watts. Yes the transformer losses make it grossly inefficient.
That means over the 19 years of one post here the consumption would be 2000KWh which at UK prices is £506. Substitute a modern charger that consumes only 5 watts and the electricity bill over 19 years is still £211 at UK prices which is 6 times the cost of my last new motorcycle battery which lasted 11.5 years without being permanently hooked up.
I see no economic case for permanent float charging a small battery even at US electricity prices which are half the UK price.
I assume people leave a charger hooked up for economic reasons i.e. they don't want to pay for a replacement battery more often than necessary. But what about the cost of charging. I measured the power consumption of my old charger on float hooked up to my motorcycle battery and it came out at 12 watts. Yes the transformer losses make it grossly inefficient.
That means over the 19 years of one post here the consumption would be 2000KWh which at UK prices is £506. Substitute a modern charger that consumes only 5 watts and the electricity bill over 19 years is still £211 at UK prices which is 6 times the cost of my last new motorcycle battery which lasted 11.5 years without being permanently hooked up.
I see no economic case for permanent float charging a small battery even at US electricity prices which are half the UK price.
I leave a CTEK on my Corvette all winter. No problem. Have no experience with other brands.
I use a moose optimate duo on the motorbike and the lawn tractor. High tech, works great, lead acid, agm, lithium. No worries. Completely automatic. Pretty darn cheap. Around $50 IIRC.
My YJ battery was on a tender whenever I was not driving it. The battery lasted 10 years, as far as I know, as I sold it that way.
Last winter I kept my JLU on a trickle charger. The light was always green, as I check it often. Now I find my charger is getting weak and doesn't switch from yellow to green easily anymore, so I will go out and unplug/plug it in and it switches. So, I only use it a day or so at a time to play it safe until I get a new trickle charger. Right now, since I work 7 days a week until the end of the month I plug it in for the weekend and unplug in on Sunday night in case my wife needs to use the Jeep if our unreliable van won't start during the week. I have a company truck I use, so the Jeep sits a lot.
I do not fear a healthy trickle charger.
Last winter I kept my JLU on a trickle charger. The light was always green, as I check it often. Now I find my charger is getting weak and doesn't switch from yellow to green easily anymore, so I will go out and unplug/plug it in and it switches. So, I only use it a day or so at a time to play it safe until I get a new trickle charger. Right now, since I work 7 days a week until the end of the month I plug it in for the weekend and unplug in on Sunday night in case my wife needs to use the Jeep if our unreliable van won't start during the week. I have a company truck I use, so the Jeep sits a lot.
I do not fear a healthy trickle charger.
Our '21 RX45h F Sport lives on the Battery Tender. I think it sucks the juice even when it's just sitting... So far so good.
JTK
$100 Site Donor 2025
I got 14yrs out of the battery in my Craftsman LT2000 riding mower by keeping a harbor freight tools trickle charger on it all winter. It would have probably lasted longer. I bought the mower used with that battery in it.
I keep my cars for weeks at a time and my mower battery all year round on pulsetechs and battery minders. My cheapo walmart mower battery is going to be 4 yrs old and still tests @ 100% state of health. Prior to this regimen I was lucky to get 2 yrs out of a cheap mower battery.
It doesn't take long to top off a lawn tractor battery on a trickle charger, like a few hours. You can easily just occasionally leave it plugged in overnight. However, if you get leaves, I highly recommend using the lawn tractor to much leaves off season which will extend your lawn tractor usage season.
Never use a trickle battery charger hooked up all winter!
It will slowly over-charge the battery & cook (wreak) it; as a trickle battery charger never turns off.
Use a battery charger & MAINTAINER.
For example:
NOCCO GENIUS5
CTEK MUS 4.3 POLAR since you are using it in a cold garage.
I have a couple of CTEK MUS 4.3 POLAR battery charger & maintainer that I use outside on AGM car batteries.
I had it hooked up to my Camaro that had a new AGM car battery during 2020 for 18-months.
& on & off on my daily driver that I didn't drive much.
My Mustang is on a battery maintainer all winter.
Started out with a CTEK and got 11 years out of that and a AAP Gold (Pre DieHard) battery.
Replaced the CTEC with a NOCO Genius 2 and am on year 5 with a Costco Interstate battery presently.
Started out with a CTEK and got 11 years out of that and a AAP Gold (Pre DieHard) battery.
Replaced the CTEC with a NOCO Genius 2 and am on year 5 with a Costco Interstate battery presently.
Get quality battery maintainers. The good one will have high/low temp compensation.
I like Battery Minder. But more $$ than the HF ones. I have 3 that I can find.
I like Battery Minder. But more $$ than the HF ones. I have 3 that I can find.
CleanSump
Site Donor 2026
Plain old Battery Tender brand on my motorcycle and lawn tractor. No overcharging and they're always ready to go.
I ran an extension with matching plug to the Tender on each so I don't have to mess with removing seats and battery clamps.
They sell them on Walmart, Amazon, local HW stores as "Battery Tender Ring Terminal Adapters".
I ran an extension with matching plug to the Tender on each so I don't have to mess with removing seats and battery clamps.
They sell them on Walmart, Amazon, local HW stores as "Battery Tender Ring Terminal Adapters".
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This is the answer.
Smart Battery tender/trickle chargers first charge your battery to full, and then let it drain very very slowly. Once it drains just a bit (I actually don`t know, but for the sake of example, lets say to 99%) it kicks in and starts charging to 100% again.
Can they faill and overcharge it to a catasrophic explostion? I am sure that is not impossible, just like a big comet falling on your garage giving humans a similar ending to dinasours.
So I would not worry about it at all. Also I would buy pretty much the lowest ampere trickle charger needed. 1 amp is more than enough for virtually everything I owe. Only downside is it takes longer to charge a battery fully, but for your purposes, it is way more than enough.
This may be the best deal going. I’ve had several of the Schumacher maintainers quit. I’ve given a couple of these away and they have been great. If I needed something to leave on, these seem to hold up well and stay “in bounds”
MOTOPOWER MP00205B 12V 1000mA Automatic Battery Charger, Battery Maintainer, Trickle Charger, and Battery Desulfator with Timer Protection - Grey https://a.co/d/2q5ORom
MOTOPOWER MP00205B 12V 1000mA Automatic Battery Charger, Battery Maintainer, Trickle Charger, and Battery Desulfator with Timer Protection - Grey https://a.co/d/2q5ORom
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