Well this is interesting...

"Honda Accord and CR-V battery drain problems have caused a class action lawsuit that alleges the batteries are too small to power the vehicles. In addition, the plaintiff alleges the 2017-2019 model years suffer from a parasitic draw that kills the batteries." ...Dead Battery in Accord and CR-V | Honda Problems.

 

Maybe anecdotal, but I have had battery issues since the first year of owning the 2015 fit ex CVT, in canada here.
went through 3 batteries so far, and last year, i got so frustrated that i replaced the 151 with a 51R.
was great for a while and i noticed it just slowly start getting weaker and weaker.
my 51R is now about 1.5 years old. and depending on the temperature outside, it lasts anywhere between 2 days and 5 days if i don't drive it.
the battery is pooched again, as i even attached a battery tender to it to try to keep it charged, .. so i'll need to change the battery again. probably went through a freeze cycle and killed it.
i've tried to attach an ammeter to find a parasitic drain, but it seems to be fairly low in terms of drain, Though i need to figure out a better test.
I now always have one of those small lithium usb booster packs in my car and use it quite often.
i'm sure that there is either a parasitic drain or the charging system performs like garbage on my car. I just don't know how to diagnose or fix it.
I read somewhere that there is some strange "intelligent" charging mechanism in the charging system that could theoretically be at play here (it may not charge battery if low load or some other specific conditions) but I find that a bit voodoo and impossible to diagnose..

Anyway thats my 2 cents

 

I heard that if you leave the headlights on, the alternator charges full time.

My first experience with Honda's "intelligent" charging system was when I had a 2009 TSX a while back. Before I bought it used with 130k miles, I checked the alternator, and it was only putting out 13.7-13.9 volts, so I knew it was going bad. I plugged in my scangauge one day and decided to look at the voltage at some point on my trip. It was putting out 13.7 volts until suddenly I saw it drop to 12.3 on the scangauge. I thought the alternator had given out, but there was no battery light on the dash. I rushed home with no accessories turned on, everything unplugged, preparing for a huge repair. Until I got back and checked it with a volt meter and it was putting out 13.7-13.9 volts in my driveway. Needless to say I was confused. Until I did some searching on the web and apparently Hondas lately have part time charging for fuel savings. That car would also drop its idle speed from 900 to 650 rpm when stopped in drive, and would drop from 0.34 gallons/hour to 0.24 gallons/hour. In neutral it would do 0.22-0.27.

 

I have a 2018 Sport 6MT and the stock battery has been fine so far. Granted I live down south.

 

I finally fixed it. Now you wont believe it but the 2015 Fit and the 2016 both had the same issue, with the batteries going flat dead after a few months with normal use. So I searched and came across this... Honda's Underpowered Battery is Subject to Parasitic Drains

Now it didnt say anything about the Fits but I suspected it was a similiar or same issue, so took it to the dealer and had him do a complete electrical check to see if he could find any problems when the battery died again. Everything tested out fine, but since they have changed the battery on the cars more than 6 times, they agreed to change the push button starter.... Both cars are fixed, and they have been working fine for the last year, and I even drove the 2015 to Texas with no issues and driving it back in a few weeks.

 

my fit doesn't have a push-start system. only regular key.
Also its cvt and i never use the hand/ebrake and don't have electronic hand brake. (so the VSA issue) doesnt apply.

I ended up unplugging the smart battery charging system, (the little connector attached on top of the battery
haven't had a problem since.
My suspicion is that the smart charging system is shit for colder places like Canada or Northern USA, because from what i've been reading, it seems the thing tries to control the charging to keep the battery around 70% or something of that nature, to minimize alternator and charging system use (reduce fuel consumption),
and if you add on sporadic or relatively short driving patterns, plus the cold, its just not suitable.

so far my theory is panning out, after i replaced my battery 6-7 months ago (again), even through a recent -30 cold snap for a week, i left the car sitting there for 3 days and car started without even a hint of the battery feeling weak.
the year before that i changed the battery, and 1-2 months later, the car would be dead in the cold winter after 1 day, or be too weak to start. then once the battery freezes once, it becomes shit going forward.

 

Does the dealer cover it of have you had to pay for any of the batteries.

 

the dealer covered the first 2 i think, i stopped asking after that, because i changed the battery to 51R instead of that original mini 151R.

 

Hello Everyone. I am new to this site but love my Fit!!! I bought it used. It is a 2013 but i have a question. I live in Canada where it gets really cold in the winter. This past week its been in the -30s. When its this cold no way will my battery start. Last winter i had to replace the battery that was in it when i bought it and then three months later replaced it again. Thank goodness for warranties. That one lasted from last May until this week and now i have to boost it to get it to start. My garage guy puts the meter on it overnight to make sure nothing is drawing the power and nothing ever shows. Is this a common thing for these smaller type batteries?? Is there something i can do so i wont have this issue??

 

Do you have a block heater? If so, do you use it?
Aside from that, you might wanna consider adding a battery blanket. That should get it going!

 

Also getting -30C weather here. I've moved to the larger 51R battery since I do a lot of small jumps and that smaller battery kept dying. Also was out of warranty anyway. I haven't had a no start yet but the cold does seem to limit the starting power. I'm gonna try out that smart battery charging system for winter and see if that helps. Anyway I would totally recommend the larger battery if you are paying out of pocket.

 

My '19 LX CVT keeps dying after sitting for 3ish days. Hasn't even been that cold here. Could you add a picture of this "smart charging system" because I would love to test this.

 

sure,
Assuming your battery hasn't frozen once (once its frozen once it'll basically never retain a good charge anymore.. unfortunately)
but if the battery cells are all still good, and you unplug it, use a charger to charge up the battery or go drive it around for a longer trip i'd say probably 45min at 1 hr, to try to charge it back up.
Circled in red is the thing i disconnected. had 2-3 weeks of -30 in december and didnt go out that much and battery was fine and started right up.
not saying it'll fix your problem, as your problem could be different and have some phantom drain or something but.. ya. good luck.

 

What blows my mind is that batteries are supposed to last so much longer than they seem to on these fits. I really feel like both the batteries they use are undersized (151) and the alternator just doesn't provide enough juice. I'll definitely be trying the smart charging system removal. And, at the end of the day, when I need to buy a new battery, I'm just going to do the ever so popular 51R battery mod. Fuck these 151's lol.

 

ya, i changed the 151 to 51.. i hated the micro battery.
after first winter it died, then got weaker and weaker second year, honda replaced it under warranty, was dead again in a year.. i said f it i dont care if its under warranty, replacing it.. with 51. then the 51 died in 1.5 years and i'm like wtf... then just lived with it for another year or two, bought one of those mini usb battery packs with jumper capability lol.. jumped the car like probably 50 times over that time period.. then got pissed and replaced the battery but disconnected that stupid thing and now its been probably 8-10 months and theres no sign of the battery getting weaker.. headlights dont dim when starting car .. etc.

 

The 151 lasted about 5 years on my GK. Then I stopped driving because of the pandemic and the batter died. I replaced with a 51R and so far so good, though I drive it maybe once a week.

 

How can I actually test if it is my battery failing or my alternator?

 

Hmmm. I'll have to check that myself. I figured that connector was a fusible link or something protective of that sort.

Our last cold snap finally finished off the battery. It was still working but marginal, quite weak on cranking. I replaced it just for my peace of mind, pretty sure it's the original 151R. I've just upgraded to a 51R, as it was the only compatible size in stock locally.

I don't think the battery is undersized for the starter, but I do think it's slightly undersized considering how much time the headlights are on. We've been a little unkind to the old battery. I took the opportunity to upgrade it since I was in there anyhow. I'm usually quite careful with starter batteries, but the auto headlight logic is a little odd in this car. We've been caught by surprise a few times when the headlights flattened the battery.

 

A lot of auto parts stores can run tests on your car in the parking lot. The only way to accurately test a battery or an alternator is to take them out of the car and run diagnostic tests.

That's not the way I usually do it though, that's a lot of work. I kinda miss the old days where cars had voltage meters, so I usually add one in all my cars. You can get a decent idea of what's going on with a cheap cigar lighter voltmeter/charger, . They're cheap online.

It's not a perfect test by any means, but it's far better than guessing or just replacing parts willy-nilly. They should display a little over 12V with the car not running, about 13V running at idle, and perhaps up to 14V when the car is driving at higher RPMs. Anything over 15V is likely to damage the battery, and suggests a problem with the alternator. Anything under 12V suggests a problem with the battery.

I would also recommend a cheap solar charger to keep the battery topped up, but they are admittedly somewhat inconvenient.

 

To properly test the battery you need a battery load tester which will draw at least a hundred amp to simulate what the starter motor would draw. The voltage of the battery drops when this draw test is run and the size of the voltage drop on the tester indicates the condition of the battery. If the battery voltage drops significantly under heavy current draw then the battery is in poor condition. The tester only draws high current for a few seconds so it doesn't significantly affect the battery. Note that the test is run with the car engine off.

Load testers are what automotive places normally use to test the battery. A volt meter is no good for a battery test because the battery voltage can be high even if the battery is shot. It's only when you draw heavy current that the voltage drop shows the true condition that the battery is in. You could use a volt meter and crank over the car to see what the voltage reads while that is happening but a proper battery load tester which clips onto the battery is easier to use and doesn't cost much. Admittedly, a load tester isn't something that you'll use that often unless you have a lot of friends and family members with cars and yes you can usually just go to a local automotive parts store and they'll test your battery for free (since they're hoping to sell you a new battery).