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

scottmastrocinque said:
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:
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GREAT 4A UNIT

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

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Mine works great on my 2 bikes. Small, handy and quick to use. I use a 3 amp for my diesel pick ups that have 2 batteries each. Imo, slow is the way to go for maintaining a battery. I’m thinking they’re just not meant for production line type service. Maybe step up and use a professional charger.
 
scottmastrocinque said:
I can literally tell by your comment, that you didn’t bother to read the thread from beginning to here.
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Probably not, I mean, it Was long winded lol, but I read enough to feel like you were saying that you were trying to frame a house with an 8oz ball peen hammer and were blaming the hammer for its inadequacies. “Proper tool for the job”is all I’m saying. And fyi, It’s not hard to see or necessarily critical to read to the end, to recognize when someone is irresponsibly trashing a product. Be Professional 👍🏼
Cheers! 🍻
 
DINOV9 said:
Probably not, I mean, it Was long winded lol, but I read enough to feel like you were saying that you were trying to frame a house with an 8oz ball peen hammer and were blaming the hammer for its inadequacies. “Proper tool for the job”is all I’m saying. And fyi, It’s not hard to see or necessarily critical to read to the end, to recognize when someone is irresponsibly trashing a product. Be Professional 👍🏼
Cheers! 🍻
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Be Professional? I am a professional.

I’ve been contributing literally tons of user guides and how to’s and other information here on GuzziTech for over 10 years.

Like I said, you didn’t read the thread, not even the entire 1st post, and your negative and unrelated comments reflected that. It was obvious.

This wasn’t about a maintenance charger. It was about the fact that upon a large discharge event on a Moto Guzzi battery, the 750mA charger will not be able to resurrect the battery. In fact it will run for about 2-3 minutes then shut itself off thinking the battery is fully charged when it isn’t. They are junk and not worth the money because of this inadequacy.

This was not based upon an opinion but rather upon professional experience in my commercial shop.

Your “slow is the way to go” comment is non-sequitur and replying to absolutely nothing that I wrote about.

Also, I wasn’t “unnecessarily trashing a product”, I was making a post of interest to those who bother to actually read what was written. I know, too “long winded” for you. I understand.

Lastly, your “ It’s not hard to see or necessarily critical to read to the end” comment makes me want to ask you to please do me a HUGE favor.

Click my username and when it goes to my info, look down an inch to the IGNORE button. Please press it and go about your merry way.

Thanks.
 
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scottmastrocinque said:
This wasn’t about a maintenance charger. It was about the fact that upon a large discharge event on a Moto Guzzi battery, the 750mA charger will not be able to resurrect the battery. In fact it will run for about 2-3 minutes then shut itself off thinking the battery is fully charged when it isn’t. They are junk and not worth the money because of this inadequacy.
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This is exactly what was happening with my 750 mA charger, even though the battery was not dead just low. Have now replaced it with a good quality charger, and have peace of mind. Thanks Scott.
 
scottmastrocinque said:
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?

View attachment 24621



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.

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Hi Scott,
Thanks for this thread, I actually had already bought the 750mA charger before coming across this post but just returned it for a 3 AMP Battery Tender instead (the 4A wasn't in stock but I assume 3 will do the trick). I am an electrical novice and since you seem to be the expert I have a quick question about using this charger for the first time. My bike (2016 V7 II Stone) is equipped with an SAE charging port already, so can I just plug and play this charger directly into the existing port? Do I need to disconnect anything first? My bike has been in storage for the winter and the battery is essentially dead, a slight flicker at the headlamp when the ignition is turned on, so it will need a full charge.
Thanks for the info.
 

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devanburry, you may find your battery is finished and needs replacing. Allowing them to totally discharge is quite often a death sentence.
You may want to remove it from the bike and try charging it up. If it seems to take a charge bring it in and have it load tested. Your local Canadian Tire might be able to do it for you.
Is Old Man Winter finally losing his grip on The Rock?
 
devanburry said:
1. My bike (2016 V7 II Stone) is equipped with an SAE charging port already, so can I just plug and play this charger directly into the existing port?

2. Do I need to disconnect anything first?

3. My bike has been in storage for the winter and the battery is essentially dead, a slight flicker at the headlamp when the ignition is turned on, so it will need a full charge.
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1. Yes

2. No

3. Yes, however it depends upon the programming of the charger, if it will be able to resurrect your battery or not, but the 3A certainly is much more up to the task than the 750mA version.
 
Raven said:
devanburry, you may find your battery is finished and needs replacing. Allowing them to totally discharge is quite often a death sentence.
You may want to remove it from the bike and try charging it up. If it seems to take a charge bring it in and have it load tested. Your local Canadian Tire might be able to do it for you.
Is Old Man Winter finally losing his grip on The Rock?
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Thanks for the info, I had been living for the past few years in a much warmer climate by comparison (Vancouver, BC) where I essentially rode the bike all year. This was my first time actually storing the bike for a long period and it was a cold and long winter in an unheated/no power shed. I should have removed the battery and kept it on a charger elsewhere, but live and learn!
 
scottmastrocinque said:
1. Yes

2. No

3. Yes, however it depends upon the programming of the charger, if it will be able to resurrect your battery or not, but the 3A certainly is much more up to the task than the 750mA version.
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Thanks for the reply. I'll give the 3A charger a try, but looks like the battery will need at least 3 volts in order for the charger to kick in, so like Raven mentioned above I may need a new battery anyways. At least now I have a proper charger 👍
 
I have sometimes been able to get automatic chargers to start charging by temporarily connecting a 9V battery in parallel with the deeply discharged 12V battery and charger. Then I disconnect the 9V battery after charging starts. I also keep an old manual charger (basically just a transformer and full wave bridge rectifier) to start charging batteries that are too low to satisfy an automatic charger.

Unfortunately, lead-acid batteries that have been deeply discharged (especially if they have been left discharged for extended time) usually have short remaining life even if they accept charging.
 
I bought one of these 100 amp battery load testers the other day. Harbor Freight or Amazon sells them for 20-30 bucks. Not sure how much insight into battery condition they really give but better than just testing voltage with no load on it. 100 amps is half of what a 200CCA motorcycle battery is, which what battery load tests are supposed to be. Another kind of battery load testers are carbon pile load testers which are variable up to 500 amps. Maybe a more worthwhile investment if you like to test larger vehicle batteries also. Anyway I'm no mechanic so correct me if I'm wrong.
On ammeter it tested out to 96 amp load. Voltmeter was 0.2v too low but has some adjustment in it.
 

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I have one of those, you operate the switch and hold it for 10seconds, then read of the voltage, there is a scale to let you know how good the battery is. It should only drop 1V and then return back to 12 to 13V. My unit puts 0.1 ohms across the battery so draws about 120A and produces 1440W so be careful where you store it as it stays hot for a while.
 
I would like a chance to chime in on this. I am a recognized expert in lead acid and other batteries, a paid consultant to electric car companies, and have 22 years experience in designing and testing chargers and batteries.

A 750mA battery charger should be adequate to maintain and charge any motorcycle battery. 24 hours at 750mA is 18 amp-hours, more than most motorcycle batteries can hold. I have never tested the battery tender brand 750mA charger, so that charger's design may be the problem. The charger has to supply any drainage the motorcycle is requiring plus have enough left over to charge the battery, but if the ignition is off this shouldn't be an issue (again, if there was 750mA of leakage the battery would be dead in a day while parked in the garage).

I have been maintaining all my vehicles with 800mA PowerStream chargers for many years. This is a precise microprocessor controlled multistage charger, despite its low price. I had to change the battery in my R1150GS after spending 8 years of winters on this charger.

Kaladin
 
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