Smart Charging System Differences

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A good site explaining the differences between fixed voltage charging systems and smart charging systems.

https://www.redarc.com.au/alternator-vs-fixed-alternator

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Explaining the difference between smart alternators and fixed voltage alternators

The alternator is the power supply for the vehicle for recovering the start battery from engine start and provide power to vehicle electrical consumers while running. There are two main types of alternators commonly used in todays vehicles, the traditional fixed voltage alternator and the modern smart alternator.

Fixed voltage alternators are becoming less common on new vehicles as reduced fuel consumption targets and more stringent emissions standards are adopted by manufacturers. A fixed voltage alternator has a high enough voltage to successfully charge a secondary battery in the vehicle to a usable level for leisure or auxiliary use.

The smart alternator system allows the vehicle to control the output voltage from the alternator based on vehicle operating conditions to reduce electrical load and in turn mechanical load on the engine by the alternator, this renders it unsuccessful at charging a secondary battery system to a usable level.


Fixed voltage alternators
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A. Engine is not running, relatively full open circuit voltage of the start battery approx. 12.6V

B. Engine is started, alternator produces current to raise system voltage. Current level will depend on alternator capacity, design, battery current acceptance, and engine speed at the time.

C. The alternator regulator will aim to hold the target voltage, generally around 14V. Whilst not a full charging voltage, this selected voltage will be appropriate for maintaining the start battery and is not excessive for long term running at this voltage level.

D. Current will flow into the start battery to recover it from the engine starting consumption and run loads that are on at the time. This current will decrease as the battery comes up in charge, generally this will occur within the first few minutes of run time.

E. The current will be regulated from the alternator to maintain the target voltage, and can increase and decrease as loads are switched on and off.


Smart alternators
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A. Engine is not running, relatively low open circuit voltage of the start battery approx. 12.4V, as the system does not aim to achieve a full state of charge in the start battery. Specific battery types are used in this application in order to achieve good performance and service life when operating at partial charge for starter operation.

B. Engine is started, alternator produces current to raise system voltage. This voltage level can be very high to produce fast inrush of current into the battery to reduce start battery recovery time. Current level will depend on alternator capacity, design, battery current acceptance, and engine speed at the time.

C. The alternator regulator will aim to achieve the target voltage, generally upwards of 14.5V.

D. Current will flow into the start battery to recover it from the engine starting consumption and run loads that are on at the time. This current will decrease as the battery comes up in charge, generally this will occur within the first few minutes of run time. The voltage will be decreased when current flow into the start battery falls below a predetermined level, generally below 30A, meaning that the start battery is only partially charged, well enough for repeated starting.

E. The current will be regulated from the alternator to maintain the target voltage, and can increase and decrease as loads are switched on and off. The target voltage will change on factors such as temperature, electrical consumers, start battery state of charge, and engine load.

F. During acceleration and cruise the target voltage will be low, around the open circuit voltage of the start battery.

G. During deceleration the target voltage may be lifted to replenish any discharge of the start battery that may have occurred during acceleration and cruise.

Note: the output voltage and current levels from different alternator systems and vehicles will have varying characteristics. The descriptions here give a general view of the output types.
 
Some have regulators on the alternator controlled by the ECU, some have it in the ECU like Chrysler. The only way to tell is to watch the voltages and look for something similar to the above. I know on my Journey it would go as high as 14.7 down to 13.1. On the Highlander it would either show battery voltage of 12.3 - 12.6 or charging voltage of 14.4 to 13.8 at various times as monitored by my Scangauge.

There is no hard/fast rules for this as each OE is doing it slightly different and then when alternators have clutches involved it changes this as well.

The best is to keep the RPM the same for a period of time like cruising on the highway with as many accessories off as possible and see if it drops from the 14's to 13's or 12's for a little while and then goes back to the 14's Typically conventional charging systems will keep the voltage north of 14.0 volts at all times above 1000 rpm under low accessory load conditions.

Keep in mind that multi-meters and cigarette lighter voltage gauges can be off by .2 of a volt or so unless you have a highly calibrated meter so don't panic if the numbers above aren't exact.
 
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I wish they were a little smarter (i.e., programmed equally for mileage AND battery life)

There was a TSB and a reflash to correct insufficient charging issues in my '15 Legacy, resulting in poor battery life. I jumped right on that one! I'll gladly give up 0.2MPG to keep my battery a little more topped off day-to-day.
 
I have a charger on all my vehicles and plug them in nightly to keep the battery fully charged. I figure it's taking further stress of my alternator for at least part of my daily commute and considering I re-start my vehicle multiple times per day in between customer visits sort of thing.
 
Originally Posted by StevieC
I have a charger on all my vehicles and plug them in nightly to keep the battery fully charged. I figure it's taking further stress of my alternator for at least part of my daily commute and considering I re-start my vehicle multiple times per day in between customer visits sort of thing.


Which charger do you have and how do you hook it up to your vehicles?

I would charge daily, if:
.
1. It was easier to do.
My smart charger uses only alligator clips, so two-prong pig-tails are out of the question. When this charger need to be replaced, I'll keep that in mind. It was nice not having the pop the hood, using the supplied Battery Minder pig-tails.

2. I could be assured that my wife would remember to disconnect every morning. I know I might forget to disconnect hers from time to time, so I can only imagine that she would forget eventually, too, even if I try to make it obvious that it needs to be disconnected first (e.g., put the cable in the way of her getting to the driver's side - yea, I'm sure that would work out well for me...)
 
I had a Noco Genius but didn't like the way it was charging my AGM battery in the Journey so I bought the Odyssey AGM / Flooded Cell 20 amp charger when it was on sale on Amazon. That works great and it does a really thorough job balancing the cells in the battery but there wasn't an easy way to use this one regularly so I would just hook this up once a week to give the battery a top off and condition it properly.

Now I have a C-Tek I bought with quick connect/disconnect connector with a waterproof connector that comes out in the grill. I put a waterproof connector also on the bottom of a waterproof outdoor plug box that is mounted to my house where the vehicle parks so I can connect/disconnect it with ease. (I don't have a garage)

The charger itself is inside the house sitting on a window sill that is next to the fuse panel so I can see the LED's from outside in the driveway where the car is. (The charging wires run through the hole in the wall to the plug box and connect to the waterproof connector) I have the charger plugged into a smart plug that will turn it on via my smart phone manually or on the schedule I have setup that is set by default to 9pm - 6am.

I also have an outdoor rated smart plug that turns on my Block Heater on a schedule in the really frigid months so I don't have to wait forever for heat to defrost the windshield etc. and it's easier on the engine. I mention this because it's not inconvenient for me to disconnect an extra wire before driving away.
 
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Sounds like a pretty clever set-up!

How does your "Odyssey AGM / Flooded Cell 20 amp charger" balance cells? Does it perform automatic equalizing charges periodically? What's the highest voltage you've seen it jump to? I don't have much experience with chargers, but I haven't seen one that can perform an equalizing charge. I use my DC power supply for that.

I've actually recently found that I prefer to use my DC PS over my smart charger, because I can leave it at 14.4VDC (constant voltage) for much longer than the smart charger will remain at that voltage. I actually left it at 14.4VDC until current dropped down to almost nothing yesterday, which took a many hours. The battery remained at ~ ambient temp.
 
It will not go past 14.7 on the Oddsey charger and will ramp up the voltage to this point once it has determined the SOC.
At 15v the vents open on Odyssey batteries according to the manual so that is why it keeps it at 14.7v or less.

Page 9 of the PDF explains what it does and when, I read somewhere that the conditioning causes the cells to rebalance by holding a stable charging voltage with minimal current over a long period of time. The conditioning on all the batteries I have run the charger on takes 8 hours minimum and sometimes 12 hours to complete so I typically do it over a weekend where the battery can sit on charge for a day.

http://www.odysseybattery.com/documents/ODYSSEY_battery_charger_manual.PDF

It's honestly the best charger I have ever used both for Flooded Cell conventional batteries and AGM. (20 amp version)
 
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I've got a 12v AGM industrial charger. Originally designed for a 12v walk behind hand truck. It's as big as one of the cells and fit in the battery case with the cells.

But it has an equalizer setting. A separate button turns it on and off. It is a timed setting at around 2 hours. It will give a higher amp charge while it's charging compared to the auto setting.

Just had to replace a 14 year old Odyssey PC 625 I have had on my John Deere. So even with it's rudimentary charging system the AGMs will out last the flooded batteries hands down.
 
Analogous to marginally "smart" alternators, the nominal 12-v system in Prius maintains about 14.7 volts after start-up, for a period that varies with the battery-compartment temperature (longer time at that voltage when cold). Then it abruptly drops to about 13.7---not tapering---for the rest of the trip, unless the lights are on, in which case it doesn't.

The temperature sensor is mounted at the top of the battery compartment, above the battery. I'm considering moving it lower, where the temperature is likely to be lower, in order to better keep the 12-v battery charged better in winter.
 
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Originally Posted by CR94
Analogous to marginally "smart" alternators, the nominal 12-v system in Prius maintains about 14.7 volts after start-up, for a period that varies with the battery-compartment temperature (longer time at that voltage when cold). Then it abruptly drops to about 13.7---not tapering---for the rest of the trip, unless the lights are on, in which case it doesn't.

The temperature sensor is mounted at the top of the battery compartment, above the battery. I'm considering moving it lower, where the temperature is likely to be lower, in order to better keep the 12-v battery charged better in winter.


There was a video I watched that showed disconnecting the temperature sensor on another Toyota model to have it default back to a normal charging strategy. You could also just work out the resistance hot versus warm and use a fixed Resistor. I know this secondary way works on Chrysler Vehicles with the battery temperature sensor.
 
Originally Posted by gathermewool
Originally Posted by StevieC
I have a charger on all my vehicles and plug them in nightly to keep the battery fully charged. I figure it's taking further stress of my alternator for at least part of my daily commute and considering I re-start my vehicle multiple times per day in between customer visits sort of thing.


Which charger do you have and how do you hook it up to your vehicles?

I would charge daily, if:
.
1. It was easier to do.
My smart charger uses only alligator clips, so two-prong pig-tails are out of the question. When this charger need to be replaced, I'll keep that in mind. It was nice not having the pop the hood, using the supplied Battery Minder pig-tails.

2. I could be assured that my wife would remember to disconnect every morning. I know I might forget to disconnect hers from time to time, so I can only imagine that she would forget eventually, too, even if I try to make it obvious that it needs to be disconnected first (e.g., put the cable in the way of her getting to the driver's side - yea, I'm sure that would work out well for me...)



Just want to say it's good seeing you on here... And I hope you've been doing well and kicking rear end.
 
Originally Posted by StevieC
Which one of us?
grin2.gif



ME, give ME all of the attentions!

Thanks, bud. I'm doing well enough.
 
Originally Posted by gathermewool
Originally Posted by StevieC
Which one of us?
grin2.gif



ME, give ME all of the attentions!

Thanks, bud. I'm doing well enough.



Good deal buddy. Always good to see ya on here... I understand what it's like to have rough times... And yet you keep on keeping on... It is not easy but it is what we have to do...

StevieC I am glad you are here too...
smile.gif
 
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