Battery Tenders - Yes/No and What size to get?

[scott_m]

This issue rears its ugly head every so often so I thought I'd write about it.

When you decide to utilize a Battery Tender (or other manufacturer) type charger to maintain your battery, (and I strongly recommend it), please do not waste your time and money on the 750mAmp wall plug in model. It does not have enough beans to do the job on a Moto Guzzi (or other make) motorcycle.

I charge literally hundreds of motorcycles every year in my shop (every motorcycle that comes through the shop door goes onto a charger from day 1) and through extensive trial and error, I have found that the best all around unit size, is a 4A charger. The Battery Tender 4A units in my shop (I have a dozen or more) have always maintained my customers batteries during waiting for repairs and long term winter storage. These particular Battery Tender brand chargers have a 6V switch which I have only used very rarely, but the AGM/Flooded and LiFePO4 settings are fantastic as I have some Lithium battery bikes of my own and customers too.

I also use them exclusively on my personal motorcycles.

The 4A unit can usually (98% of the time) bring back a badly discharged batter, and restore it to full functioning capacity. The 750mA unit will think the battery is fully charged, and shut itself off, when the battery is actually almost discharged.

That 750mA unit just doesn't work at all in my experience or the 2 dozen customers who have brought me dead batteries that were supposedly maintained by that crap unit..

FWIW: Utilizing this exact method of using the 4A charges, my brand new 2012 Stelvio, finally had to have the OEM battery replaced after 10 years! Yes, 10 YEARS! My Ural, has been using the same battery for 5 years now and so have my other 6 motorcycles (batteries in service for many years now). These things work!


JUNK 750mA UNIT:





GREAT 4A UNIT





One bank of four, 4A chargers on the wall of my shop floor. I really love these things!

 

[BrianR]

Thank you, Scott. As always informative and shaming to the less qualified like me who have relied on the "junk" 750 mA charger and of course have had batteries fail, yet thought I was doing the right thing. The ones I have will go on Craigslist and I'm off to buy the 4A units. Thanks so much

 

[Mayakovski]

Very interesting to read these details.
I just talked to a local (well respected) motorcycle mechanic) and he said that the 750mA units are just fine for my battery (the original from Guzzi). He said that as they are just trickle chargers they are fine, but not for recharging a dead battery.
I am going to get my battery load tested this morning and see what the story is.

 

[scott_m]

Very interesting to read these details.
I just talked to a local (well respected) motorcycle mechanic) and he said that the 750mA units are just fine for my battery (the original from Guzzi). He said that as they are just trickle chargers they are fine, but not for recharging a dead battery.
I am going to get my battery load tested this morning and see what the story is.

You have to go with what you feel but I tell you that here in my shop, we have tossed at least 15 of those things (our original ones and customer ones they brought in) into the trash can. They are pure garbage in my estimation.

I have NEVER had an issue with the 4A units and they have charged several hundred customer bikes for durations ranging from 1 day, to 1 year or more. My personal 8 motorcycles all live on 4A units and I already wrote about my experience with that. 10 years on the original Stelvio battery!

In my shop I have several pieces of equipment for battery testing, maintenance, charging and reconditioning. My computer printouts give detailed information about the batteries so I am speaking from real world data, which is as reliable and tested as Todd's Dyno runs on his fueling options!

I only share stuff like this of which I am absolutely positive about and I make it available for free to anybody who wants the info. I'm not into trying to convince anybody who thinks otherwise. You have to make up your own mind.

 

[Mayakovski]

Thanks for more info. I was not discounting what you said. Merely mentioning what I have heard from another bike mechanic. Your many, many posts over the years have already taught me that you know you stuff beyond argument. Same with Todd.

 

[scott_m]

LOL. Thank You Very Much! I didn't mean to imply you were doubting me, (although I am not offended if people do) only that people have to make up their own mind. If they choose to ignore what I offer, then so be it. I will not fight anybody to persuade them.

I will say that lately around here, some curious people seem to want to argue everything including established facts or at least, established precedents. It's become quite frustrating trying to offer assistance and information to people lately. I don’t know...Maybe it's me. I can be abrupt and direct to a fault. I realize it but I'm too old to change at this stage in the game.

In my defense on this specific topic, I really do practice what I preach here. I took this picture 5 seconds ago of a 2012 Harley-Davidson Electra Glide Ultra in for a full pre-season service. Notice what it's hooked up to?





EVERY MOTORCYCLE that comes in my door, is sitting on a 4A charger. Every single one. Why?

It is because I do not chase my tail on running and electrical issues, when a screwed up battery may very well be the cause.

After sitting overnight on the 4A charger, and first thing after the bike gets rolled onto a lift, I use my battery load testing computer, to get a detailed analysis of the condition of the battery, BEFORE I go chasing anything else, running issues or electrical gremlin wise.

When I implemented this practice a few years ago, I never once have been sucker punched by a faulty battery.

It's also the reason that I charge a $10 shop supplies fee for every motorcycle that comes into the door. If the unit does not have a SAE charging port on it, I put one on it as part of that fee. That way, I have instant access to the battery, and so does the customer, and then when it comes back in, I can easily hook it up to the 4A tenders around the room.

 

[Raven]

As the saying goes "You can lead a horse to water but you can't make him drink".

 

[Sasazuka]

Good info . I did have my battery on a 4A charger but I read that constant 4A into a small motorbike battery can damage it, but if it's a smart charger it should know when to ramp down the amperage right?

I keep my 750mA charger on a 2 hr timer each day but like you said it only seems to charge for a minute or two then it says it's fully charged so I assume it has enough juice in it.

Do these modern bikes place a large load on the battery when sitting with ignition on without the engine running? I see the volts dropping quite quickly if I do so. If I were to be out somewhere and left the bike on for 10 minutes without the engine running the voltage maybe too low to start it back up.

 

[Kevin.NZ]

4 Amps is the maximum the charger can deliver, ordinary chargers have a fixed output voltage and varies the charge delivered depending on the terminal voltage, ie as the voltage rises on the battery the current drops. My one is a 7 stage 4A smart charger and as it says has 7 distinct programmes it goes through on its charging cycle. I have just measured my Breva 1100 and it draws 3 amps with the ign "on" and not running. I wouldn't be leaving in on for 10 min especially if you forgot to turn off the heated grips.

 

[Guzzi Surfer]

I just talked to a local (well respected) motorcycle mechanic) and he said that the 750mA units are just fine for my battery

They are just fine. I've used them for years with ZERO issues, batteries last 5+ years. Tons of people, including bike mechanics, use them. This thread is the first time I've heard someone say they won't work, and goes contrary to my experience. I'll be keeping mine

 

[Roblatt]

Interesting read. Scott, can you leave those chargers permanently connected? I often leave the bike long periods without riding (tender connected) and don't wish to cook the battery.

 

[scott_m]

On my bikes: Connected the moment I’m done riding and I park in in my workshop or garage. The Battery Tender unit (and most high quality other makes) is microprocessor controlled. It varies the output based upon need, and then shuts itself off. It monitors the battery and will cycle on and off as needed. It has never overcharged or “cooked” a battery.

Customer bikes: Connected the moment they enter the shop. Connected to one when the motorcycle goes onto a lift for work. Reconnected at storage, waiting for customer pickup. Disconnected when given back to the customer, with a fully freshened battery.

There are mechanics who do all sorts of things or make all sorts of recommendations. Some I agree with, many I do not.

If you want proof that the 750mA charger is woefully pathetic, leave your ignition on for the night. Come back in the morning and hook up your 750mA unit. If it turns on at all, it will shut itself off shortly later, not having been able to restore the battery back to full health. A 4A unit will make the battery whole again, like it never happened.

The 750mA unit is only good for very minor trickle charging at best, and if you use your battery heavily with additional accessories like running lamps, GPS, cell phones, Bluetooth speakers, etc, and your battery is stressed electrically each ride, the 4A will never let you down.

Bottom Line: You must decide for yourself and if you don’t agree, that’s fine. I don’t care either way. This is for those who would like to know.

Be happy!

 

[scott_m]

Good info . I did have my battery on a 4A charger but I read that constant 4A into a small motorbike battery can damage it, but if it's a smart charger it should know when to ramp down the amperage right?

This post is about SMART CHARGERS.

So…Yes. Microprocessor controlled, self-regulating battery tenders. They will not damage your battery.

I have manual cycle, high amperage direct chargers at my shop as well but those are not for maintaining a battery. They are for restoring function to an otherwise dead as a doornail battery if possible, or providing up to a 200 A boost to start anything.

 

[Guzzi Surfer]

If you want proof that the 750mA charger is woefully pathetic, leave your ignition on for the night. Come back in the morning and hook up your 750mA unit. If it turns on at all, it will shut itself off shortly later, not having been able to restore the battery back to full health. A 4A unit will make the battery whole again, like it never happened.

The 750mA unit is only good for very minor trickle charging at best, and if you use your battery heavily with additional accessories like running lamps, GPS, cell phones, Bluetooth speakers, etc, and your battery is stressed electrically each ride, the 4A will never let you down.

This is true, the 750mA is really only useful as a maintainer, not so much as a charger.

 

[Roblatt]

Yeah, Scott, that exact thing happened to me with my ride on mower.

Thanks for the info.

Robert

 

[tris]

I have the 5A CTEK MXS 5.0 smart charger so comparable to the 4A Battery Tender you are advocating.
It has a "reconditioning" mode that CTEK recommend running once a year.
What are your thoughts on running this programme?

 

[Moto-Uno]

I too have a Ctek charger ( but the low output unit) , that feature has been seen working on an older car battery that I use
for things around the garage . It came on after about a week on the charger and the battery continues to work well as a
booster for my marginal car battery . I wasn't aware that it was a separate mode you could operate . May just be with the
lower output unit . Peter

 

[scott_m]

I have the 5A CTEK MXS 5.0 smart charger so comparable to the 4A Battery Tender you are advocating.
It has a "reconditioning" mode that CTEK recommend running once a year.
What are your thoughts on running this programme?

My expensive shop base charger has a reconditioning program in it. I have resurrected many very dead batteries with it.

I learned from my Electrical Engineer friend that this modified wave-form technology has science behind it and it does work, so I’d say yes.

Many of the newer microprocessor controlled battery chargers have both desulfation and reconditioning modes.

The desulfation mode is internally triggered by the unit when it first “reads” the battery condition. What desulfation does is use pulse technology to desulfate the battery by “shocking” the battery with high voltage pulse bursts.

Reconditioning does a similar thing but does not pulse. Instead, it applies a higher voltage for an extended period of time, designed to de-stratify the electrolyte inside the battery by making it bubble, thereby “mixing” the electrolyte into a homogeneous solution again. It also intentionally overcharges the voltage in the battery in the repair process to accomplish this. This is not a bad thing per se, but not something you want to do all the time.

CTEK I’ve been told, has good information about this on their website but I haven’t looked.

To clarify, I advocate for a 4A charger. I just happen to like the Battery Tender brand but any quality charger of 4A size would be fine.

It’s just my preference from my workshop experience.

 

[tris]

CTEK plugged in and running

Thanks

 

[Mayakovski]

Just ordered a NOCO double battery charger for both our batteries. Love how much I learn on this site.