Go back and read my original post. Never said dead battery.
Is it my battery or something else? (2016.5 CX-5)
- Thread starter SBMongoos
- Start date
Well, let's run a few numbers.
Say the starter runs 3 seconds and pulls 200A average for that time,
(3/3600)*-200A = -0.17 A-Hr
If the 100A alternator puts 40A average back into the battery over 7 minutes
(7/60)*+40 = +4.7 A-Hr.
CTEK (56-382) Comfort Connect Indicator Eyelet
A 40 amp charge is very high. Typical stand-alone chargers put 10 amps, maybe 20, into the battery, and that amount only when the battery's voltage is lower. Amps decline as the battery charges up, and it's voltage rises.
It's not high for the 100A alternator. It is high for portable chargers. Then I have one that's a brute that can run over 15.6V and push at least 50A into a healthy battery that's 12.5V, or so.
Or,
I have a 1 amp of this brand that is always connected to my MINI which gets very few miles, and a 2 amp that I connect to my 23 CX-5 every month or so just to bring it up over night. I have added permanent aux volt and amp meters to both so I can see what is going on. This is easy for me since both are garaged with easy access to electrical power. Just a suggestion.
HyFlyer
2019 CX5 sig 2.2 diesel / 2016.5 CX5 touring 2.5na
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- Southwest Ohio
As a data point, our 2.2 diesel after a cold start will run 120-170 amps from the alternator for several minutes before dropping to more normal amp levels needed by the electrical devices running.
Here's the drive home from work tonight with an ambient temp of about 35°F ... 310 seconds (5min 10sec). That's a lot of juice flowing into the battery.
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- 2016.5 CX-5 GT AWD titanium/black 2016 Miata Club ST MT white
Assuming you're starting with a fully charged battery.
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- Pueblo county CO
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- CX-5 Sport 16.5 6M
I have some kind of "amazon version" of the Genius. It's not only important to keep a battery fully charged to ensure a quick start but also too prevent sulfation and ruin of the battery. I kept my original Panasonic battery fully charged and away from heat and it lasted over six years. A chronically run down battery will sulfate. Also anytime a battery is discharged excessively and requires a jump it will shorten the life even though it will seem ok to drive.
I still maintain that most of that current is NOT going into the battery. Heated seats, fans, lights, fuel pump(s), etc. I know that deep cycle batteries (with their thicker plates) can handle the stress of higher currents, and the angler crowd says to limit to 20 amps to prevent plate warpage from overheating. Twenty amps at 14.5 volts is 290 watts. That's a lot of heat.
HyFlyer
2019 CX5 sig 2.2 diesel / 2016.5 CX5 touring 2.5na
- :
- Southwest Ohio
I was curious about how much power goes where so I experimented with different devices on and looked at the change in alternator output. It's (approximately... I'm going by memory ) about like this ...
AMPS DEVICE
7 only the car running
25 rear defrost (which includes mirror and front window heating elements as well)
15 seat heat (1 on high)
10 steering wheel heat
15 HVAC blower motor (70% speed)
7 headlights (with all exterior lamps on as well)
In my screenshot example above when the alternator output dropped from 100ish to 28 amps, the electrical devices on were headlights, HVAC blower (medium speed), 1 seat heat on low. That's it. The only place for those 60-70ish extra amps (in the example) to go is the battery as far as I can tell.
On cold mornings my alternator is pumping out closer to 150 amps for several minutes. I'll have to try monitoring output with a cold start and nothing but the engine idling, no electrical devices on to see what that output is.
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- 2016.5 CX-5 GT AWD titanium/black 2016 Miata Club ST MT white
Are you testing with a clamp on meter probe?
HyFlyer
2019 CX5 sig 2.2 diesel / 2016.5 CX5 touring 2.5na
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- Southwest Ohio
Nah, FORScan data from all the onboard modules of the vehicle.
I pulled my head out of... And remembered I have a clamp meter. Stone-cold engine (5w-30 PUP) in 38f garage took this as peak. FYI for anyone who might wonder. 2016.5 GT 2.5L.
150A charge... Wow! Thanks for the info!
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- 2016.5 CX-5 GT AWD titanium/black 2016 Miata Club ST MT white
A stone-cold engine doing what? Being started I assume?
You zeroed out the meter before taking the reading, right?
Think I could also do a little battery terminal cleaning. If I'm going to pull the +/_ terminals off the car battery what things should I consider with my 2016.5 CX-5 GT? I assume the infotainment system will loose all if its setting, etc. Is it best to connect a 12v source to the car while doing this? Maybe nothing to bother with or a concern?
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Which CTEK charger are you pairing this with? Thanks by the way!
It appears that you have more than one wire inside of the clamp. If so, all of the doc I've read says the reading is not valid if more than one wire is clamped. I've used my clamp meter on those negative wires for 'shutdown' type of testing (where the current values are very low and have a slow rate of change), by testing both wires separately and adding the current values. I don't know if it's even possible to be quick enough to be able test both wires separately with a clamp meter, on a running vehicle, where the draw is high and changing rapidly.
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- 2016.5 CX-5 GT AWD titanium/black 2016 Miata Club ST MT white
I saw those two wires inside the clamp too. I'm not sure how that will affect the reading as they both appear to be ground wires coming from the battery. Those wires look somewhat different than the wires on my CX but on my car one wire connects to a ground point near the shock tower and the other runs underneath somewhere, they both Y off of the negative battery terminal.
