The 12V battery charging algorithms

[eaf]

Speaking of 12V battery charging, I have a problem...

Driver side blue light flashes all the time. According to the manual it could be either due to Climate Control Timer, HV Battery Heater or 12V Battery Charging. It appears to be the latter one because there are no timers configured, it's not too cold, and I can see that the 12V battery is indeed being charged, as it has 14V on it.

What happens after I turn off the Leaf is that voltage on the battery briefly drops to 12.6V, then jumps to 14V, water pump starts making noise and the light starts flashing. All of this was going on for 24 hours already and HV charge is definitely dropping.

Any idea of what could be wrong here?

What year is your car? Any chance your high voltage battery (not the 12V) was ever swapped? We've had a couple people who posted that a 2011 battery was swapped into a 2012, which caused the light to illuminate and the battery to drain because the car was constantly searching for the battery heater that doesn't exist in the 2011 pack.

Nobody mentioned water pump noises, though, so I think your problem is different.

Yeah, it started happening right after swapping old battery. For a brand new one though. Leaf 2012. It's back at the dealer for troubleshooting.

Funny part was how at some point I decided to disconnect 12V battery to stop wasting charge, and it just continued to run inverter and the pump self-fueling itself. Had to cycle the car on and off. That stopped it. And once I've reconnected 12V in the morning, it didn't run charger until I again powered the car on and off.

 

[Lothsahn]

Speaking of 12V battery charging, I have a problem...

Driver side blue light flashes all the time. According to the manual it could be either due to Climate Control Timer, HV Battery Heater or 12V Battery Charging. It appears to be the latter one because there are no timers configured, it's not too cold, and I can see that the 12V battery is indeed being charged, as it has 14V on it.

What happens after I turn off the Leaf is that voltage on the battery briefly drops to 12.6V, then jumps to 14V, water pump starts making noise and the light starts flashing. All of this was going on for 24 hours already and HV charge is definitely dropping.

Any idea of what could be wrong here?

What year is your car? Any chance your high voltage battery (not the 12V) was ever swapped? We've had a couple people who posted that a 2011 battery was swapped into a 2012, which caused the light to illuminate and the battery to drain because the car was constantly searching for the battery heater that doesn't exist in the 2011 pack.

Nobody mentioned water pump noises, though, so I think your problem is different.

Yeah, it started happening right after swapping old battery. For a brand new one though. Leaf 2012. It's back at the dealer for troubleshooting.

Funny part was how at some point I decided to disconnect 12V battery to stop wasting charge, and it just continued to run inverter and the pump self-fueling itself. Had to cycle the car on and off. That stopped it. And once I've reconnected 12V in the morning, it didn't run charger until I again powered the car on and off.

So this started happening after the dealer swapped the high voltage battery (~$5500)? If so, that indicates they put the wrong battery in your car--if they installed a 2011 battery into your 2012 (without the battery heater), you would get this behavior.

 

[gncndad]

This might be interesting to someone...

2015 LeafS. Replaced OEM 12v with Bosch AGM12v in January, 2019, at around 26k miles (car wouldn't shut off, various buzzes/clicks...signs of 12V depletion, wouldn't hold a charge)

Now at 37k miles, 11bars. Car is driven daily, over 90% short trips...3 to 10 miles. Rarely go below 25m on the GOM.

Plugged in the 12V Battery Tender Plus for the first time in 6 months. It took 2 hours to go to 80% charge, 6 hours total to go to 100% charge.

So, my 2015 LeafS is keeping my AGM battery very close to 80% charge at all times, and I've never had a random failure.

 

[DaveinOlyWA]

This might be interesting to someone...

2015 LeafS. Replaced OEM 12v with Bosch AGM12v in January, 2019, at around 26k miles (car wouldn't shut off, various buzzes/clicks...signs of 12V depletion, wouldn't hold a charge)

Now at 37k miles, 11bars. Car is driven daily, over 90% short trips...3 to 10 miles. Rarely go below 25m on the GOM.

Plugged in the 12V Battery Tender Plus for the first time in 6 months. It took 2 hours to go to 80% charge, 6 hours total to go to 100% charge.

So, my 2015 LeafS is keeping my AGM battery very close to 80% charge at all times, and I've never had a random failure.

YA but... 80% is good for Li, but not so good for Pb.

 

[gncndad]

YA but... 80% is good for Li, but not so good for Pb.

80% is problematic for a Pb battery? How? Isn't it ideal that it's cycling between (approx) 60 and 80% all the time?

 

[DaveinOlyWA]

YA but... 80% is good for Li, but not so good for Pb.

80% is problematic for a Pb battery? How? Isn't it ideal that it's cycling between (approx) 60 and 80% all the time?

I guess it depends on the situation but I have to say "no, its not ideal" Pb is supposed to be stored at relatively high SOC mostly because it doesn't hold a charge all that well. I did the inventory thing for a while so ran into battery people a few times (nearly all stores that sell them, do so on consignment and one the biggest reasons is very poor shelf life) and they would come in at regular intervals and charge the batteries on the floor or in some cases swap them out. But any battery that was detected at anywhere from 50 to 75% SOC was considered bad. The actual level varied from one guy to another and some didn't actually know. They plugged it into the charger and the charger itself would say either Charge it or discard it.

Now unlike LEAF batteries, ICEer batteries are literally charged ALL the time the car is on. So other than the brief few seconds required to start the car, they live nearly all their life fully charged. Now is that a good thing or could Pb have a longer life if it wasn't constantly topped up?

Well, so far the LEAF track record on 12 volt batteries is not helping to prove that theory.

 

[LeftieBiker]

I guess it depends on the situation but I have to say "no, its not ideal" Pb is supposed to be stored at relatively high SOC mostly because it doesn't hold a charge all that well.

No, that isn't the reason. A good lead-acid battery will actually hold a full charge very well - sometimes for years - if not connected to a power drain. The reason they should be kept at or near 100% is that lead-acid batteries get sulphation on their plates at lower states of charge. If it is allowed to remain it becomes permanent, reducing the capacity substantially. A lot of people who work with batteries but aren't engineers don't understand them. Quite a few lithium powered devices come with instructions to cycle the battery to virtually dead and then back to full. This will calibrate the capacity monitor for something like a cell phone, but it's BAD for the battery. That instruction is a holdover from NiCad batteries, which did benefit from that procedure - or at least weren't harmed by it. Lead-acid batteries should be kept as close to fully charged as possible, to maximize their life.

 

[frontrangeleaf]

What Leftie said.

Lead acid starter batteries are optimized for high amperage output, and want to never see <95% charge. Discharging below 80% can cause permanent damage. Deep discharge to "dead" can be fatal.

"Deep cycle" lead acid batteries come in 2 types: marine/rv, which are combination starter/deep cycle batteries (start your boat or motorhome, and tolerate some discharge overnight) and "true" deep cycle batteries, which are not optimized for high amperage output but tolerate deeper discharge cycles. In the latter case, up to 50%. The difference is in the thickness and number of plates, and the details around the exact chemistry (additives and alloys, essentially). High amperage output implies more numerous, thinner plates (more surface area), which are more susceptible to damage due to sulphation. True deep cycle batteries have fewer thicker plates as I understand matters, and can manage 600 deep discharge cycles to 50% (Trojan brand for example). We use a group 30XHS Trojan Signature deep cycle battery in our camper, for example. Cost a few dollars more, but a much better battery for that application. No CCA rating at all, meaning it is not a starter battery.

"Deep cycle" is not protected commercial language to my knowledge, and so can be pretty much meaningless. You can tell the difference if the literature mentions a CCA rating, it's a marine/rv type, not a true deep cycle.

Lithium ion are a completely different animal.

-b

 

[LeftieBiker]

True deep cycle batteries are often subjected to much deeper discharges than 50%. No lower than 20% is the rule of thumb for small EVs that use them, but they do deteriorate more rapidly when taken below 80%. If they are recharged immediately after a deep discharge, before sulfates can take hold on the surface of the plates, the damage is lessened because most of the sulphation is removed again with immediate recharging. As with many things in life, it's a compromise.

 

[frontrangeleaf]

True deep cycle batteries are often subjected to much deeper discharges than 50%. No lower than 20% is the rule of thumb for small EVs that use them, but they do deteriorate more rapidly when taken below 80%. If they are recharged immediately after a deep discharge, before sulfates can take hold on the surface of the plates, the damage is lessened because most of the sulphation is removed again with immediate recharging. As with many things in life, it's a compromise.

Agree. As I understand matters, a recharge does need to be immediate, before the lead sulfate converts to crystal form. But you cut the life by as much as in half by cycling that deep on a regular basis. Not advisable in a lead acid.

Lithium ion is much more comfortable discharging to 80% DoD, as I'm sure you know.

Edit: I guess I should clarify that for fleet, RV and PV applications, sizing the battery for 50% of expected draw is the best compromise for most. Don't plan on 80%, unless you want to replace your battery more often.

But again, this is all lead acid stuff. To be clear for newbies here, lithium ion is a different animal entirely. There, the recommendations to be found elsewhere on this site around a general rule of 20-80% depth of discharge for lithium is best. Store around 50%.

And to bring this around to the Leaf, I am surprised that the 12v charging algorithm is/was so poor - not like this hasn't been worked out for decades now. Should we encounter shorter starter battery life in our car, we'll be purchasing a yellow top deep cycle (actually marine/rv) AGM to replace, unless we decide to sell the car first. In a brief search, I haven't found any other deep cycle in our size. YMMV.

 

[DaveinOlyWA]

Ok, maybe Pb has improved (about time!) but the previous general consensus says they lose about 3% per month at room temperature. That rate is cut if battery is stored at its ideal temperature at 45-50º. But Battery U shows several charts and recommends SLA be charged up every 6 months. My portable power pack which is SLA, they recommend boosting it every other month.

 

[LeftieBiker]

Lithium ion is much more comfortable discharging to 80% DoD, as I'm sure you know.

Yup. Back in the day, though, lithium packs were for rich people. We made do with crappy 24 or even 12 volt SLA batteries. A 36 volt SLA pack was a big deal then.

 

[frontrangeleaf]

Lithium ion is much more comfortable discharging to 80% DoD, as I'm sure you know.

Yup. Back in the day, though, lithium packs were for rich people. We made do with crappy 24 or even 12 volt SLA batteries. A 36 volt SLA pack was a big deal then.

They kind of still are. I'd swap our Trojan 30XHS for lithium on our camper, but can't justify 4-5x the cost. That's just goofy, 2x maybe. Would take about 30# off the tongue too. I would also need a new solar charge controller and a shore power charger as well. So not a trivial swap.

 

[LeftieBiker]

I can sell you a good used 24V 20AH Ping lithium pack, but I suspect you need a bit more capacity. ;-)

 

[gncndad]

I've read all of the above, beginning to get a grasp on all this.

Will the AGM, living 50-80%, live any longer than a traditional lead-acid battery?

 

[LeftieBiker]

Will the AGM, living 50-80%, live any longer than a traditional lead-acid battery?

I'd like to just say "yes" but the answer is more complicated. All other things being equal, an AGM battery will outlast a starting battery when they are both kept in the range you specified. However, a LOT of batteries that are just sealed lead-acid batteries with a little fiberglass added are being called "AGM" these days. One of these batteries might not last significantly longer than a high quality starting battery. So if you do get an AGM for your Leaf, either get one that's a only a little more expensive and has a higher capacity (as this seems to work better with the Leaf's charging algorithms) or that is substantially more expensive and really is a full-fledged Absorbed Glass Mat battery, with higher tolerances for deep discharge and for shock and vibration.

 

[gncndad]

Will the AGM, living 50-80%, live any longer than a traditional lead-acid battery?

I'd like to just say "yes" but the answer is more complicated. All other things being equal, an AGM battery will outlast a starting battery when they are both kept in the range you specified. However, a LOT of batteries that are just sealed lead-acid batteries with a little fiberglass added are being called "AGM" these days. One of these batteries might not last significantly longer than a high quality starting battery. So if you do get an AGM for your Leaf, either get one that's a only a little more expensive and has a higher capacity (as this seems to work better with the Leaf's charging algorithms) or that is substantially more expensive and really is a full-fledged Absorbed Glass Mat battery, with higher tolerances for deep discharge and for shock and vibration.

Since I already have replaced my OEM 12V with the Bosch AGM, I'll watch and learn (that's why I continue to post my experience). I have a feeling the Bosch AGM is probably a lesser quality AGM, with minimal fiberglas added, as the dimensions are identical to the OEM.

 

[LeftieBiker]

Your experiences will be valuable, as replacing the OEM battery with a 51R AGM is what most of us recommend.

 

[frontrangeleaf]

I’ve had great experience with Bosch batteries in the past, but have never had an AGM.

 

[frontrangeleaf]

Anyone know the C20 Ahr rating of the factory 51r battery?

Just curious. The yellow top is 38. Seems really low.