Testing Battery Charger

[Canadian FJR]

A question for the electrical guru's. I feel that my charger may be shitting the bed.

I have an older 2 amp charger that have been using on all of my bikes during the winter months. Each month give them an hour or so charge.

I always check the battery voltage before and after the charge. On the FJR, it was at 12.4 before the

charge and showed the same after the hour, thought it should be higher but figured no biggie.

I then charged the KLR and the voltage actually dropped after charging for an hour.

When I check the charger, it is putting out 13.6 volts so it seems to be working. Anything else I should

check on the charger?

Canadian FJR

 

[Millrat]

Check battery voltage with charger attached. Should be higher than original battery voltage.

Charger may come up to voltage but not be able to maintain it under load.

 

[RossKean]

Sounds to me like your charger isn't putting out enough current although the (unloaded) voltage isn't necessarily bad. ~13.5 V is the float voltage for a lead-acid battery (depending on temperature). A "dumb" charger (even a low capacity 2 amp one) would normally be a higher voltage than that. If you are charging a battery that has a fairly low state of charge (less than maybe 12.3 V), try running it with an ammeter in series with the battery and charger. That will tell you pretty quickly if the charger is doing its thing. Note: Make sure you use the 10A plug or setting you will find on most meters or you could blow the fuse.

Even if the charger is OK, the current is likely to be significantly lower than 2 amp assuming it isn't a constant current or regulated power supply. If the initial battery voltage is significantly less than 12.6-12.8 V (resting V of fully charged battery) and the charging current is less than 0.25 amp or so, then the charger is in need of replacement. You would only get 2 amps when charging a battery that is essentially flat but should get at least a quarter amp for a partly discharged battery.

For a top-off charge, I often use a dumb low current charger like the one you describe and make sure I don't leave it on too long. If I were to replace the charger, I would likely go out and buy a decent temperature compensated battery tender. Cheap "tenders" may not be temperature compensated and might overcharge or undercharge if the temperature is not "normal". I would use it as a "safe" low-rate charger rather than as an actual tender. The FJR has a VERY low fugitive current draw and it takes several months before the battery is substantially depleted. (Assuming the battery itself is in good condition without "soft shorts" causing a high self-discharge rate.) A twice-per-winter top-off is all I find necessary. Certainly no need for a full-time battery tender for the FJR. I got 10 years and 160,000 miles out of my OEM battery treating it like this - still worked but with reduced capacity when I swapped it out.

 

[mech 1 twa]

Replace it. Most automatic chargers go to about 14 or so volts and then cycle as voltage drops. 12.4 starting voltage is a little low but should come up with a good charger.

Cold batteries charge slower and take more amps. A very dead battery won't charge with many Float type chargers until it sees 9-12 volts. Never charge a frozen battery. A charged battery won't freeze but a dead one will. Frozen battery is toast breaks plates inside.

 

[art miller]

Sounds to me like your charger isn't putting out enough current although the (unloaded) voltage isn't necessarily bad. ~13.5 V is the float voltage for a lead-acid battery (depending on temperature). A "dumb" charger (even a low capacity 2 amp one) would normally be a higher voltage than that. If you are charging a battery that has a fairly low state of charge (less than maybe 12.3 V), try running it with an ammeter in series with the battery and charger. That will tell you pretty quickly if the charger is doing its thing. Note: Make sure you use the 10A plug or setting you will find on most meters or you could blow the fuse.
Even if the charger is OK, the current is likely to be significantly lower than 2 amp assuming it isn't a constant current or regulated power supply. If the initial battery voltage is significantly less than 12.6 V (resting V of fully charged battery) and the charging current is less than 0.25 amp or so, then the charger is in need of replacement. You would only get 2 amps when charging a battery that is essentially flat but should get at least a quarter amp for a partly discharged battery.

For a top-off charge, I often use a dumb low current charger like the one you describe and make sure I don't leave it on too long. If I were to replace the charger, I would likely go out and buy a decent temperature compensated battery tender. Cheap "tenders" may not be temperature compensated and might overcharge or undercharge if the temperature is not "normal". I would use it as a "safe" low-rate charger rather than as an actual tender. The FJR has a VERY low fugitive current draw and it takes several months before the battery is substantially depleted. (Assuming the battery itself is in good condition without "soft shorts" causing a high self-discharge rate.) A twice-per-winter top-off is all I find necessary. Certainly no need for a full-time battery tender for the FJR. I got 10 years and 160,000 miles out of my OEM battery treating it like this - still worked but with reduced capacity when I swapped it out.

Very informative info. Question, I have been using a Battery Minder Plus (charger, maintainer, conditioner w/auto-float control & pulse mode circuitry). My 2011 auto that I drive rarely and the 2014 FJR have been on this model since vehicles were new. Both have original batteries and both crank over like new. Do you not suggest using a full time tender? Thanks.

 

[RossKean]

In my opinion, there is no need for a full time tender on an FJR. As I mentioned, parasitic draw on the bike is very low and a modern AGM battery in good condition has a low self-discharge rate. Should not need anything if you ride it once every couple of weeks or more. I have been able to start the bike after sitting idle for as much as a couple of months. Not using a tender didn't seem to hurt the lifespan of the original battery on my '07. If the battery is not in good condition (due to abuse or substandard manufacture), the self-discharge rate might be high. If that is the case, a tender might be needed to keep it alive between rides.

According to some literature I have seen, at 68°F an AGM battery will discharge to 50% in 15 months! Greater self-discharge rate at higher temperatures. I don't think I would trust it to be that low but the fact is they will last a long time.

Parasitic draw on the FJR is something on the order of a couple of milliamps. it would take months to draw the battery down substantially.

 

[Powerman]

I've had good luck with the Battery Minder Plus, I have three.

When you say temp compensated, what does that mean? Ambient temp, or actual cell temp. Wouldn't battery temp require an embedded sensor, like the Dewalt battery.

 

[RossKean]

Just compensated for ambient temperature. Float voltage changes as a function of temperature. IIRC, that is one of the main differences between Battery Tender Plus and Battery Tender Jr. (Higher current capacity too)

 

[MrZappo]

No intention of raffling featheres but my opinion is that with all things there is a fine line between being careful and going overboard.

My disclaimer is that my bikes live in a heated garage. So things such as temp compensated chargers don't have much value to me. Maybe if it was zero degrees in my garage id have a different experience.

In any event, I do strongly support the use of a maintainer (weather you need it or not) as it generally does no harm and does generally guarantee that you will never drain your battery. Weather there is parasitic load or not. It's correct that FJR has minimal parasitic load.

But since I'm a little nuts, I keep it plugged in. I sleep better. I could be wrong. Who cares. I'm old.

But with most of there things, oil, tires, batteries etc etc etc, I try to find middle ground. For me that is a battery maintainer, mid grade oil changed on time, good tires (changed too often) and I even use lemon pledge on my windshield.

So a few beers, and this forum and you are blessed with my opinion.

Don't tell my wife or I might get in trouble.

 

[RossKean]

My feathers don't ruffle easily. We are each entitled to our opinions. When you demonstrate improved battery lifetime as a function of the use of a battery tender, I will change my opinion (and practice) with respect to battery maintenance.

One cautionary note on battery tenders. There are lots of them out there and they are not all equal in terms of quality. If the "float" voltage is slightly too low, there is no major downside other than the fact that the battery won't be fully charged - it will get topped off when you go for a ride. To check, take the battery off the tender and wait several hours for the "surface charge" to dissipate before measuring the unloaded voltage. If not ~12.8 V, it might be undercharged (or on its way out).

If the tender is not adequately regulated for "float", it could be overcharging the battery. This will eventually "cook" the battery and effectively destroy it within weeks (or less). I have seen this with some products marketed as battery tenders but were, in fact, trickle chargers. (Very different modes of operation.) I have also seen actual battery tenders cook batteries because they were defective (or poorly designed). Slight overcharge or undercharge can occur at different charging temperatures if the tender isn't temperature compensated although this is may not be an issue if charging under "normal" conditions.

If I were to purchase a battery tender, I would buy a name brand, temperature compensated device and I would periodically verify the float voltage. Note: Optimum charge rate for an AGM motorcycle battery is something on the order of C/10 (C is the capacity in ampere hours). So for a 14 ampere hour battery, optimum charge rate is no more than 1.4 amps. Up to 2 amps is unlikely to be a major problem but I would try to keep it below that. Unfortunately, if you flatten a battery by leaving an accessory on, boost-and-go is not the best way to restore it. The bike's charging system dumps in current at far too high a rate for best battery health. However, there usually isn't much choice under the circumstances - you can't always wait 5 or 6 hours to conduct the optimum slow charge!

 

[MrZappo]

Good info. Thanks.

I have used the Yuasa battery maintainers for a few years now. They are 1 amp and have a few modes from charge to float.

I have not read the specs in some time so I can't rattle off the voltages but as it is Yuasa being used to maintain my Yuasa battery, I tend to think that it is specific for the task and therefore correct.

I've had good life and tend to have less issues than buddies who don't follow this course. But as you've pointed out, I don't have enough data to make a case.

The model I use is not temp compensated cuz I didn't want to spend the extra money. I've no doubt that the temp compensated models are better at what they are designed to do.

Either way, I'm on 5 years on my current FJR battery. I'll get back to you in 5 more with results !

 

[Gitbox]

I know some who love the NOCO Genius 750. If I were to use a maintainer, that would be the one. https://no.co/g750

 

[Canadian FJR]

Thanks for the input, I just purchased another 2 amp charger and all is well with the world again. My old one must have been

close to 30 years old.

Canadian FJR

 

[RossKean]

What did you get for a charger? Just a 2 amp dumb charger or a tender-type device?

 

[Canadian FJR]

A three level charger from Crappy Tire

It has a 2,4 & 6 amp charge setting. Pretty much all I need for the various garage toys.

https://www.canadiantire.ca/en/pdp/motomaster-eliminator-intelligent-battery-charger-6-4-2a-0111517p.html

Canadian FJR