battery tender (maintainer), completely off NOT FLOAT.

[rphillips]

Naw, I guess I'll just keep doing like I am, put the home charger on 2 amp. connect to 1 bike, a day or few later, when the fully charged & green light is on, move it to another bike till I notice the little green light again, a day or few more to another, till all 6 are good, then start over again. All while the boat is just sitting there, glancing once in a while to see all 3 lights are green. If one of the 3 batt. drops a little, the auto charger will kick on & boost that batt. back up to full charge again, then kick back off. red light indicates topping batt off again, constant red means bad batt. Next spring unplug charger & head to the lake, knowing the batteries are at full charge

[posplayr]

Naw, I guess I'll just keep doing like I am, put the home charger on 2 amp. connect to 1 bike, a day or few later, when the fully charged & green light is on, move it to another bike till I notice the little green light again, a day or few more to another, till all 6 are good, then start over again. All while the boat is just sitting there, glancing once in a while to see all 3 lights are green. If one of the 3 batt. drops a little, the auto charger will kick on & boost that batt. back up to full charge again, then kick back off. red light indicates topping batt off again, constant red means bad batt. Next spring unplug charger & head to the lake, knowing the batteries are at full charge

If self charge is your only problem then this charts suggests that you can get down to 75% SOC in about 2 months at 40 degC (104 degF). That means you don't have to cycle any more often than 2 months which is also a pretty good rule of thumb based on experience. Of course if you have a volt-meter or USB port powered all the time you might have 10-20 mAmp draw that will bleed the battery down much faster.

[salty_monk]

Anecdotally in my experience leaving a battery on a tender full time causes issues (I always use AGM's), I know others that do it with no problems though....

I prefer to bung them on the tender when I think of it.. usually every 2-3 weeks. Often they take less than 2mins to get back to "green"

[jsandidge]

Anecdotally in my experience leaving a battery on a tender full time causes issues (I always use AGM's), I know others that do it with no problems though....

I prefer to bung them on the tender when I think of it.. usually every 2-3 weeks. Often they take less than 2mins to get back to "green"

I do the same. I ruined a brand new AGM by leaving it on a smart charger all winter. It would read fully charged, but wouldn't take a load. It's a quad bank charger, and the lead-acid batteries that were hooked up at the same time survived just fine.

[rphillips]

Never realized all batteries would lose a charge at the same rate. I just figured battery size, weight, type, quality, age, would all affect the rate a battery would lose charge Also never realized tender, maintainers may cause as much problems as they do, heck in this little thread here's 3 folks that have had problems. Who knows, maybe if those tenders just topped the batt. off when needed then turned off, instead of keeping charging constantly, may have helped, maybe not. Back to the gas can, when a little evaporates, fill it back up, when a little evaporates again, fill it again, just don't see the need for keep pouring when the can is full. don't see the need to keep charging if the batt. is full. Heck, maybe I'll just invent one.

[Baatfam]

I've lost some batteries to the older style, cheaper Battery Tenders, when I left them on too long...
The last couple years I've been using a BatteryMINDer Model 2012-AGM
A more advanced charger specifically for AGM batteries.
Temp compensation, multiple batteries...works well.
Had no problems since I got it, but I do still disconnect from the charger regularly.

The link above is to BatteryMINDer's site, but you can get it at Amazon for about $85

[bwringer]

That's exactly how, um, y'know, Battery Tender brand battery tenders work.

I guess I'm not seeing why you have any trouble finding such devices. Old-school float or trickle chargers are pretty rare nowadays.

After having done a deep dive on BatteryTender.com, I find that I was wrong; their maintainers do indeed continue to provide a small "float" voltage and do not shut off completely.

They even admit this strategy prioritizes readiness over longevity:

http://www.batterytender.com/Float-Charging

Their "smart" float charging is better controlled than the old-school simple "dumb" float chargers, but it's still very much suboptimal for keeping small batteries functioning for many years.

MIND = BLOWN. I couldn't figure out what the OP was talking about... sorry about that.

Obviously, any sort of float charging is not OK for small motorcycle batteries and will eventually damage them. Over a long winter's sleep, I don't really care whether the battery is always at 98% vs 100%, but I do care deeply whether I get only two years out of a battery or four.


Anyhoo, I'm really cheap, and so I only have one Battery Tender for three bikes. I only hook it up maybe a couple of times each winter to each bike in turn, and only leave it connected for a few hours while I'm doing something else in the garage until the light indicates it's done charging.

So by being cheap, I was sort of inadvertantly using the BT in the only way that's good for motorcycle batteries.

So with decent AGM batteries, all you need is to hook up a BT or similar device for a few hours every few months. There's no point at all in leaving it hooked up for weeks at a time, and this will indeed damage the battery.

I do not know of a "smarter" charger with some sort of timer that does this automatically, but perhaps this sort of thing exists.

[Grimly]

Easy enough to plug the charger into the mains via timer, but a lot of / most floaty-type so-called 'smart' chargers don't resume duties after a power interruption.
That's actually a safety feature.
Otoh, I had damn good results with a dumb wall-wart (14V DC out) plugged into a timer coming on for half an hour per day, to keep a battery topped up over the winter.
That's also how I keep a few old cellphones in ready-to-go condition.

[Gorminrider]

Never realized all batteries would lose a charge at the same rate. I just figured battery size, weight, type, quality, age, would all affect the rate a battery would lose charge Also never realized tender, maintainers may cause as much problems as they do

Yes roughly self-discharge at the same rate, depending on the type (Wet? AGM? and all the others have diferent characters. Lithium can sit a long time- I've heard they even store longer partly discharged....) but a partly-ruined battery will seem to lose more right away- it never took a full-charge in the first place.

Just a thought but a larger (car) battery needs a "stronger" trickle charge. Using the same charger on a small m/c battery might be a problem. I do similar to Grimly except just once a month for an hour on the "trickle charge" 2 amp setting of a car charger. That's about a 1/5 to a 1/6 capacity of a M/C battery but it soon drops to a trickle.

A M/C battery is a starter battery so it's intended to be slapped at 5 or more amps right after the bike starts but very soon the regulator kicks in and the rate falls to much less.

[rphillips]

Back to the orig. post. It seems most folks, including me, periodically thru the winter, connect & disconnect their chargers. It seems it would be kind'f handy to have one that, like the newer home or on board boat chargers, monitored the charge of the batt., completely off till batt. dropped appx. 5%, then kick back on & bump it back up to full charge, then off again. Just knowing the technology has been around for several yrs. in other applications, Hoping there was one out there for bikes, hook it up & forget about it.

[Baatfam]

Put the charger on a smart plug, and have Alexa run a schedule...

[rphillips]

Timers will work, but who knows how often your batt. needs to be topped off & how long it needs to be on to get your batt. back up to full charge? If the technology in other chargers were used in these maintainers, when yours needed bumping up, it gets it, if once a wk, once a month, or once every 2 mo., it would all be "totally automatic". I could buy a home charger for each of my 6 bikes, & it should work fine, off till need charge topped off, kicks on 2 amp. till topped off, then back off till batt. needs topped off again. Wouldn't mind a little maintainer hanging on each bike, but really don't want a home chargers laying under each of them. I know it ain't a big deal, just seems so simple & handy, if I could just find someone who made them.

[Steve]

Back in the days before Alexa and battery maintainers, I had heard one guy say that he ran a cord to the garage door opener light and used it to power his battery charger. Every time he opened/closed the door, his battery would get a 5-minute charge. Seemed to work well. I don't know Alexa to know if 'she' can do any better.

.

[rphillips]

Alexa won't have a clue if your batt. needs to be topped off or not. A modern charger will.

[Baatfam]

Alexa won't have a clue if your batt. needs to be topped off or not. A modern charger will.

Not if we are going with the theory of occasional charging, using a modern float charger.

She could turn it on for...say...6-10 hours every four weeks, or somethin' like that.