AndyH said:
Is this really a suggestion to replace the Lead-Acid battery in the Leaf with a Lithium?
If not, then the comment is irrelevant to the discussion. If it is, how does one modify
the charging algorithm from Lead-Acid to Lithium?
Solutions to 12 Volt Batteries and Chargers Posted Here
- Thread starter 69800
- Start date
Help Support My Nissan Leaf Forum:
Is this really a suggestion to replace the Lead-Acid battery in the Leaf with a Lithium?
If not, then the comment is irrelevant to the discussion. If it is, how does one modify
the charging algorithm from Lead-Acid to Lithium?
69800 said:
1. Has the Leaf's 12V battery charging been evaluated for those Leafs that have the solar panels?
2. If so, has a champ-on amp meter been used to measure the 12V battery charging current
when the vehicle is not being charged thru its charging port?
Note: The 'sleep'/standby current draw (hood closed, doors locked) is 60-70 ma without any
sun (morning overcast). Based on this and assuming half capacity (usable battery) of a 70 Ahr
battery, then that results in about a maximum of 21 days (70 Ahr / (2 X 70 ma X 24) if left
without any external charging.
AndyH
Well-known member
The Nissan owners manual clearly outlines their process for both charging the 12-volt battery and 'jump starting' and they're plain-vanilla standard. The only reason I think there's ever been for connecting the charger or jumper cables to positive first, then connecting the negative to an off-battery ground is so that the spark during connection doesn't ignite any hydrogen that might be leaving the battery.69800 said:
(This is for the 2013, but other manuals for other model years are similar and available from the same site.)
https://owners.nissanusa.com/conten...sanLEAF/2013/2013-NissanLEAF-owner-manual.pdf
In case of emergency - page 6-11
AndyH said:
Actually, page 6-11 does not explicitly state the cable connection process for charging the 12 volt battery,
only for jump-starting. Unless I missed it, the Owners Manual does not describe how to charge the 12 volt
battery by use of an external charger. It does describe how the vehicle should be kept 'on' for 20 minutes
to allow the Lithium battery to charge the 12 volt battery if jumping starting was necessary.
The need to externally charge the 12V battery seems unnecessary based on the constant voltage
level (13.0), if one monitors that voltage using the LeadDD or LeafSpy. That voltage stays basically
constant at 13.0 with various heavy loads, e.g. the A/C and/or the cabin fan at high speed. Charging
to 13.0 is adequate to maintain the battery in good condition based on my experience with many late
model vehicles, e.g. Porsche, M/B, & BMW.
AndyH
Well-known member
Recall that the 'problem' charging and jump-starting procedures are solving is the generation of a spark near the top of the battery. While it is possible to find a battery charger that will not create a spark when it's connected to the battery, that's not a universal situation. It's much safest overall to make the last connection to an off-battery ground point as a "universal/always works" procedure. This has nothing to do with any car, it has to do with 100+ years of experience working with hydrogen-emitting lead-acid batteries without blowing them up.lorenfb said:
Page 6-10
TimLee
Well-known member
I believe you are confusing the voltage those ICE vehicles used to charge the battery while driving with the no load battery voltage measured with the vehicle off.lorenfb said:
A no load 13 volts is typical for a fully charged lead acid battery.
But those vehicle alternators when at higher rpm charge the battery at a much higher voltage than 13 volts.
Unless you do routine say weekly top off charging, the LEAF 12V will often not read 13 volts when the LEAF is off and the battery has no load on it.
Some people have driving pattern that will get four years out of the LEAF 12V battery.
But many do not.
In particular the LEAFs that have the 6.0 kW on board charger spend a lot less time with the 12V being held at 13 volts if people aren' charging to 100%.
AndyH said:
Your post states:
"The Nissan owners manual clearly outlines their process for both charging the 12-volt battery and 'jump starting' and they're plain-vanilla standard."
My post states:
"Actually, page 6-11 does not explicitly state the cable connection process for charging the 12 volt battery,"
No where in the manual does Nissan describe "CHARGING THE 12-VOLT BATTERY" as you have stated.
Re-read the manual as it's written! The manual JUST describes jump starting.
Yes, we all are aware of the proper procedure for jump starting to avoid an explosion which also avoids
an incorrect battery polarity connection by always connecting the negative cable to the chassis on the
vehicle to be jumped.
TimLee said:
Actually 13.0 volts is not typical for a fully charged lead acid battery after the charging has stopped
and the surface charge has dissipated. It's probably around 12.5-12.7 volts. As long as Leaf is driven
a few days every week, its lead acid battery should have a life very similar to an ICE lead acid battery.
Maybe those having shortened battery lives probably should measure the battery's off-state current
draw (Leaf in the sleep mode) and not assume that the shortened battery life is related to an
inadequate charging voltage. As previously indicated, my Leaf draws about 60-70 ma in its
sleep mode with no solar panel charging. On a fairly sunny day, the battery is charged by about
10 ma from the panel, which is not much but it's positive into battery and it has overcome the
60-70 ma sleep current and eliminated the draw current completely. Given my data and previous
years of battery experience, I would not recommend attaching a 12 volt battery charger to a Leaf.
"But those vehicle alternators when at higher rpm charge the battery at a much higher voltage than 13 volts."
An alternator is basically constant voltage source which implies its output current is not limited, and
as such it reaches maximum output voltage within a few hundred RPMs off idle.
AndyH
Well-known member
Nice try but still no. The quotes and reference are spot-on as both instances - jump starting and connecting a charger - involve connecting cables for the purpose of CHARGING THE BATTERY. What exactly do you think happens when one connects a lead-acid battery to another with a lower voltage? That's right - electrons start flowing from the battery with higher potential to the one with a lower charge.lorenfb said:
Nissan does make clear in multiple locations of the manual, however, that if one doesn't understand the process they should pull the car over, shut it off, and wait for a flat-bed ride to the dealer...
AndyH
Well-known member
Well, every day is a chance to learn something new. Today I'm reminded of how challenging it can be to write an owners manual that works for the entire user base. I also learned about Morgan's Maxim of Poe's Law. Life is good.
RegGuheert
Well-known member
Thanks for starting this thread!69800 said:
I'm wondering if you might add some of the information from this post to the OP to clear up some questions that have come up. Here are the pertinent points:
I have measured the tare current for the LEAF 12V battery with the EVSE unplugged. Here is what I found:
- For the first ten minutes or so the car drew 330mA.
- After about 10 minutes, the tare current dropped to a lower value. It normally sat at 15mA, but pulsed up to 24mA every two seconds or so.
- Occasionally it would rise up to 115mA for a few seconds. I do not know how often this occurs.
Simply put, the average draw on a LEAF which is sitting unplugged, but OFF, is about 25 mA.
I don't know the exact capacity of the OEM battery in the LEAF battery, but if we assume it is only 25Ah after some level of sulfation, then the average draw from the car is still less than C/1000. That is sufficiently low to allow for a decent estimate of SOC by simply measuring the voltage after a long rest period (having already opened the hood, since opening a door causes a draw on the battery for about 10 minutes).
That is how the curve shown in the OP was measured. As you can see, with a LEAF that is not driven often, even a fairly new 12V battery drops to about 60% after only 21 days. That's equivalent to a C/1000 load being on the battery almost continuously during that period with no charge being replaced. Clearly the few times the LEAF was charged and/or driven during that period did not replace much more charge to the 12V battery than it took out of it.
But the system does not allow the 12V battery to drop much below 50% if used occasionally. Why is this true? Because the float voltage of 13.1V which the LEAF typically uses WILL charge the battery up to around 60% or so. Unfortunately, the other 40% of the battery's capacity is sitting around as lead sulfate which is steadily hardening and will soon not be available for the charge-discharge reactions of the battery. In this way, the capacity gradually depletes until there is not enough remaining to hold the voltage up overnight and start the car in the morning. It's a real waste resources which could easily be resolved with a slightly-improved charging algorithm. I believe the poor performance of modern vehicle charging systems is the main reason why we have seen lead-acid battery warranties drop from seven or eight years to one or even less.
What makes matters much worse is the fact that many of us now use the LM327 to monitor our LEAF's traction battery. When that is plugged into my LEAF it draws about 175mA continuously, or about 7X what it would normally draw. This results in a much more rapid discharge and a much lower typical SOC with the 12V battery. (The chart shown in the OP was made BEFORE I purchased the LM327. I have not measured it since that time.
FWIW, I went out and measured the voltage of our LEAF's battery today and it was a bit above 12.3V after sitting for a while. The last time it was charged with the BatteryMinder 1500 was only a week or so ago. It's back on the charger/desulfater now...
desiv
Well-known member
Is that while paired to an active device (actual Bluetooth activity) or just the LM connected to the Leaf?RegGuheert said:
Just wondering if that makes a difference. I keep mine plugged in all the time, but my Android device is only powered on while driving.
desiv
baustin
Well-known member
I would say that's without an active bluetooth connection. I left mine plugged into the OBD port without driving the car for a couple days and came out to find a dead battery (low enough I had to use the key to get in and open the hood). I drive the car every day, now, but only plug in to the OBD port when I want to use Leaf Spy.
RegGuheert
Well-known member
Just a follow-up on this comment: After the BatteryMinder 1500 charged and desulfated the battery for about a day, I charged and drove the LEAF on an errand and then removed the ELM327 and popped the hood after arriving home. After the car's electronics went to sleep, the voltage rose up to 12.87V, which is quite a bit higher than it ever was in the 22-day graph shown in the OP. (BTW, I have never added water to any of the cells in the OEM battery that came with the LEAF and all of the cells are still at the "Upper Level" mark. They had originally been just above that mark.)RegGuheert said:
Since that voltage reading, it has now been 24 hours and the voltage has dropped to 12.78V. Note that this 90mV drop is LESS than the drop which occurred over 24 hours in the 22-day graph when the voltage dropped from 12.76V to about 12.66V in the same amount of time. My conclusion is that the battery condition today (at about four years of age) is better than it was when I originally made that chart (at about two years of age). I attribute that solely to the excellent charging and desulfating which has been done periodically by the BatteryMinder 1500 since that time. (OTOH, I attribute the relatively poor condition of the battery at the time that chart was made to the rather miserable charging algorithm used by the LEAF for the 12V battery.)
If I can manage to let the LEAF sit for another 24 hours, I'll see what the voltage is at this time tomorrow. My guess: 12.70V.
Nubo
Well-known member
RegGuheert said:
The long-term persistence of the electrolyte level is another indication that the car's charging algorithm is quite mild. I.e, no gassing of the electrolyte. I've wondered if perhaps one of the design goals was to minimize any off-gassing due to concerns about corrosive effects under the hood. Very much unlike Lithium cells, Lead-acid is happy at 100%; even happier to be slightly overcharged.
RegGuheert
Well-known member
Agreed 100%.Nubo said:
And it also tells me that the desulfating algorithm in the BatteryMinder 1500 is equally gentle on the battery, as it has likely charged the battery (above 13.1V) for as long or longer than the LEAF charger. The point being that these batteries can be charged gently AND still be maintained in very good condition without the risk of excessive acid being released under the hood.
Most of the gassing that occurred with my 12V battery likely was during my attempts at desulfation before I purchased the BatteryMinder. On several occasions I added 1V or so to the output of my other charger, bringing the voltage up to around 16V, similar to what the OP showed the C-Tek unit putting out. The battery was bubbling pretty steadily when I did that. I'm glad I chose the BatteryMinder over the C-Tek, since I feel the BatteryMinder algothim is much more elegant: desulfating without gassing off excessive electrolyte. Brilliant!
Put bluntly, there is no good reason that in the year 2015 (or even 2011) car manufacturers cannot build 12V lead-acid battery chargers that can consistently give nearly a decade of service life. (At least in the climate where I live. Perhaps this is not a reasonable expectation in hot places like Phoenix.) Instead, modern vehicle chargers abuse their lead-acid batteries in the name of fuel efficiency and those batteries only live for a few years. What a waste!
AndyH
Well-known member
Yup - Nubo gets my vote here as well. The auto industry's been pushing for more than 15 years to lengthen service intervals and minimize or eliminate user maintenance. Spark plug changes from ~30,000 to 100,000 miles and oil changes from 3 months/3000 miles to 1 or 2 years/30,000 miles for just two examples. The Benz/smart also undercharges the battery - not only from a maintenance perspective, but because the battery's in the passenger compartment under the passenger's left foot.RegGuheert said:
Maybe. Lead acid is the most recycled battery in the developed world at over 98% last time I found numbers. Heat kills batteries of any type, and my car's starting batteries had regularly short lives in Tucson - but they didn't last nearly a decade even in Michigan's cooler climate. I'm tickled to get five years from a starter battery. (ok, was...don't own anything with a starter battery...).RegGuheert said:
The lithium battery has a BMS that 'can' and 'must' monitor every cell. Lead/acid will give a maximum life when all six cells are managed as well, but we cannot access each individual cell. So we're forced from the start to go to "plan B" which uses lead/acid's tolerance of not being damaged by a controlled overcharge. We normally use a regular controlled overcharge to both fully-charge and balance all the cells, but that overcharge and the hydrogen generation also stirs the electrolyte. That stirring breaks the tendency of the electrolyte to stratify by specific gravity and moves particles around so they're less likely to bridge the plates and short a cell. To give the best service life it can, a flooded lead acid battery MUST receive a regular overcharge. But...in order to use that overcharge, we have to regularly add water to the cells, and that is counter to the whole user maintenance goal. And we've closed the circle - the EV manufacturers have chosen a sub-optimal life span in order to use a less-expensive battery tech and eliminate user maintenance for most users. (Of course, geek/nerd/tech/engineer-owners aren't "most" users.
)
RegGuheert
Well-known member
Waste is waste. Recycling after three years when it could have been ten is a BIG waste.AndyH said:
Granted, as I stated.AndyH said:
But extreme cold also kills lead-acid batteries, particularly if they are not kept at full charge. The lead-acid batteries in my other vehicles typically last seven years. Eight in my Honda Civic Hybrid. If they would use a three-stage charging system as is found in most maintenance chargers, they would last even longer. Advanced pulse-based desulfation like the BatteryMinder has would get you past ten years, IMO.AndyH said:
I think that's reasonable in TX.AndyH said:
That's good advice for stationary batteries like you have in your home PV system. Automotive flooded lead-acid batteries get stirred by driving the car. As such, an equalization charge is not required and simply wastes electrolyte.AndyH said:
The LEAF is the PERFECT vehicle for something like the BatteryMinder approach. No need to do anything different than it does today for READY mode, but since it charges for many hours for each hour of driving, a better approach to ensuring the 12V battery is completely charged when plugged in and charging would go a long way toward extending the life of the 12V batteries. But the engineers didn't take advantage of this golden opportunity to extend battery life without impacting range one bit.AndyH said:And we've closed the circle - the EV manufacturers have chosen a sub-optimal life span in order to use a less-expensive battery tech and eliminate user maintenance for most users. (Of course, geek/nerd/tech/engineer-owners aren't "most" users.
RegGuheert said:
Is it an implication that the issue of Climate Change should be of less concern than the reduced longevity
of the lead-acid battery in modern day vehicles? Where's Andy on this aspect of the lead-acid battery?
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