Alternator tested at 13.8 v…seeking guidance . (1 Viewer)

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H

HSR

Joined
Dec 31, 2017
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Location
Doylestown, PA
Hey everyone, first-time poster here on the 200 Series forum. Last year, I picked up a 2016 Land Cruiser — previously had a 2005 100 Series and loved it. The 200 has been great so far. It has 168,000 miles, is completely rust-free (originally from California), and was used primarily for highway driving. Never been off-road… yet!

I’m planning a 1,200-mile one-way trip to Nova Scotia, Canada soon. Just had the vehicle fully inspected — oil change, fluids, brakes, etc. I also asked the shop to check the alternator, and they said it’s charging at 13.8V, which they considered within spec. They indicated have a “ few years “ left on it .

That said, with the mileage, I’m thinking about buying a new OEM alternator just to keep in the vehicle as a backup — especially since I can get it for around $340 ish…

I’ve attached a few pics …love this thing.


IMG_3747.jpeg
IMG_2705.jpeg
IMG_2556.jpeg
 
That voltage is completely normal. Not sure it is worth carrying around a spare, but that just my $0.02.

Nice 200.

How are those Michelins?
 
94SRUNNER said:
That voltage is completely normal. Not sure it is worth carrying around a spare, but that just my $0.02.

Nice 200.

How are those Michelins?
Click to expand...
Thanks for the reply . Michelins have been great ..they had a lot of tread when i purchased them so im going to keep running them . I wish the were better in the snow …my 100 series i ran the wild peaks at3. They were excellent in the snow but super loud. I quite enjoy the smooth ride tbh. I may get a second set of steelies and run blizzaks in the future .
 
No alternator needed, totally normal operation. Ours generally don't fail unless you submerge them in mud or pull a lot of electrical loads, such as charging a travel trailer or similar.

For what it's worth, I replaced the brushes in my alternator as I approached 200k miles.. and they still had life left in them. The bearings were absolutely perfect at that point too.
 
bloc said:
No alternator needed, totally normal operation. Ours generally don't fail unless you submerge them in mud or pull a lot of electrical loads, such as charging a travel trailer or similar.

For what it's worth, I replaced the brushes in my alternator as I approached 200k miles.. and they still had life left in them. The bearings were absolutely perfect at that point too.
Click to expand...
Thank you , I forgot to mention the reason I tested it . In April we drove back from Savannah, Ga and about 20 mins from home ( after driving 11 hours) the navigation screen turned off and reset . Also I think the instrument cluster dimmed also. It was a split second, but enough for me to catch it. Since then nothing as it was a one time occurrence . The battery was replaced last August so no issues there . Knock on wood it’s running fantastic .
 
I replaced my alternator as part of a 150K overkill baseline of the entire rig. It was easy enough to do as I was replacing the radiator and all of the other things that spin on the front of the engine. I took the old one to a rewind shop to have it rebuilt and keep as a spare. The shop looked at it and told me that while they could rebuild it, it didn't need to be. The guy said that they could just replace brushes and some other parts but he couldn't guarantee genuine Denso or OEM parts. Too many counterfeit products in the supply chain. He then said that he would just leave a perfectly fine JDM OEM alternator alone. Essentially don't fix what isn't broken because you might end up with something worse. I still bought a new one as I had already done the labor (myself) to pull it out and figured anther $300 wasn't that big of a deal in the grand scheme of things. its not the easiest thing to pull out and put back in, especially with the radiator in place. My old one just sits on the shelf now. I did carry it around in the truck as part of my spares kit for a while but have sense reprioritized what gets packed. Last trip to Moab, I left the spare alternator at home in favor for 2 1/2 gallons of water.

IMO, wither you pre-emptively replace the alternator or not depends on what an alternator failure means to you in terms of dealing with it and the odds of it happening. I'd say the odds of a non-abused (water/mud) alternator failing before 200K are pretty low. If most of the time you are just a phone call away from a tow truck, and you'd have a shop do the work anyway, then its probably not a high priority item to address as PM. If your going to do 8 week backcountry adventures, in your new-to-you 168K mile vehicle, having confidence in its reliability is maybe different calculus.
 
kcjaz said:
I replaced my alternator as part of a 150K overkill baseline of the entire rig. It was easy enough to do as I was replacing the radiator and all of the other things that spin on the front of the engine. I took the old one to a rewind shop to have it rebuilt and keep as a spare. The shop looked at it and told me that while they could rebuild it, it didn't need to be. The guy said that they could just replace brushes and some other parts but he couldn't guarantee genuine Denso or OEM parts. Too many counterfeit products in the supply chain. He then said that he would just leave a perfectly fine JDM OEM alternator alone. Essentially don't fix what isn't broken because you might end up with something worse. I still bought a new one as I had already done the labor (myself) to pull it out and figured anther $300 wasn't that big of a deal in the grand scheme of things. its not the easiest thing to pull out and put back in, especially with the radiator in place. My old one just sits on the shelf now. I did carry it around in the truck as part of my spares kit for a while but have sense reprioritized what gets packed. Last trip to Moab, I left the spare alternator at home in favor for 2 1/2 gallons of water.

IMO, wither you pre-emptively replace the alternator or not depends on what an alternator failure means to you in terms of dealing with it and the odds of it happening. I'd say the odds of a non-abused (water/mud) alternator failing before 200K are pretty low. If most of the time you are just a phone call away from a tow truck, and you'd have a shop do the work anyway, then its probably not a high priority item to address as PM. If your going to do 8 week backcountry adventures, in your new-to-you 168K mile vehicle, having confidence in its reliability is maybe different calculus.
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Thank you sir .
 
HSR said:
Hey, the battery is 9 months old and is in great shape . I went with a diehard platinum AGM.

Thanks !
Click to expand...
You need that high voltage to charge an AGM battery. How are you monitoring the voltage as you drive? If the voltage drops as you drive you might want to get a alternator booster so the battery stays fully charged. If not, it is recommended to put the battery on a charger every month or so to get the battery up to a full charge.

I use one of these Alternator Voltage Booster.


HKB Electronics

The Alternator Voltage Booster was the first of its type on the market and is the only unit available that was has been purpose built for alternator voltage boosting.
www.hkbelect.com
 
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mep1811 said:
You need that high voltage to charge an AGM battery. How are you monitoring the voltage as you drive? If the voltage drops as you drive you might want to get a alternator booster so the battery stays fully charged. If not, it is recommended to put the battery on a charger every month or so to get the battery up to a full charge.

I use one of these Alternator Voltage Booster.


HKB Electronics

The Alternator Voltage Booster was the first of its type on the market and is the only unit available that was has been purpose built for alternator voltage boosting.
www.hkbelect.com
Click to expand...
Trying to not entertain the AGM rabbit hole again - - if the AGM battery has a lower resistance than a normal flooded cell, why does it need a higher charge voltage?
 
AcmeSys said:
Trying to not entertain the AGM rabbit hole again - - if the AGM battery has a lower resistance than a normal flooded cell, why does it need a higher charge voltage?
Click to expand...

Beats me! I just go by what is printed on the battery:

LC200BattInstall4_25APR16_zpsycrarbcp.jpg


HTH
 
HSR said:
Hey, the battery is 9 months old and is in great shape . I went with a diehard platinum AGM.

Thanks !
Click to expand...
Battery discussions often get weird, so I mention this with some trepidation, but I’ll note that I have had many diehard platinum AGM batteries fail in my solar systems and would never buy another for any purpose. If you’re having electrical issues, I would suspect the battery long before an OEM alternator.
 
Yep- And that is the problem. I'm trying to convey this in text and it may not come across but I'll try to cut thru the market'eering since I am stuck at the airport lounge - so I'll try to get this down

I dont know your use case so lets assume normal starting battery. Other applicaitons could vary but the concept is based on physics/chemistry so it doesn't really change outside of the temporal timeframes.

first principle / axiom - volt per volt AGMs recharge faster than standard flooded cells (even if the charge voltage is lower - it is an ohm's law thing)

The listed "cycle service" you show is like a total loss cycle (discharge to like 50% then recharge off a big charger bank - think a backup UPS inverter type service that has an effectively "infinite power" charger system for when grid power comes back on and you want to recharge the battery as fast as technically possible for efficiency reasons). In this application you'd deep discharge and actively monitor the state of charge with a shunt and know exact battery charge status at all times. With this you can do a controlled charge back to near 100% and transition from a very rapid charge rate with 14.8VDC then roll off to the tail/trickle charge at the lower 13.5VDC to prevent boil off for the last ~15% of charge cycle (bulk charge at high amps enabled by the lower cell resistance of AGM). That aint how 98.9% of cars work.

A standard alternator is a constant voltage system (drive the field to the set point voltage +/- the temperature correction and power limit but basically constant voltage). If you bump alternator voltage by cheating the sense signal with a diode you can certainly drive the buss voltage up by 0.7VDC. In a "normal automotive application" the battery is there for the start cycle and then is recharged in tens of minutes (~15% depth of discharge or less). So you are already living in the float charge voltage region of SOC there is no down side to keeping the voltage lower at the OEM setpoint even if you go deeper into the battery state of charge with parasitic loads. The battery will do its thing and recharge faster than the OEM FLA/SLA battery would.

The AGMs are lower resistance so if you don't have a higher voltage bulk charge voltage and just charge at the lower "float voltage" (AKA the stock alternator setpoint) it will recharge faster than an OEM flooded cell would but not as fast as it is capable of recharging (basically inefficient for what the battery could handle but they don't care). If you had a "smart" charger/alternator (a closed loop charge controller) on the car you could ramp up charge voltage and recharge noticeably faster. This higher voltage would be usefull if you did super short trips and never actually drive long enough to let the battery charge but then you'd have a way worse issue if you were on a normal FLA battery in the same use case so that is a bogus use case since either way you'd have dead batteries all the time no mater the battery type. But most cars don't have CL voltage controls so leave the voltage set point lower so you don't boil the battery by over charging. And there is the problem condition- if you set the target voltage higher for a higher charge rate, AKA diode on the sense line and drive up alternator voltage, and then drive long enough to charge the battery you will damage/boil the AGM cells by not rolling back to a lower "float" voltage at the higher state of charge.

The "cycle service" voltage they list is a kinda goofy/contrived spec that really comes back to "maximum charge amps" under some condition that they don't list (I can't find a northstar tech sheet that isn't marketing wonk, so another AGM G27 sheet is below - note that the bulk charge limit is listed in amperage not voltage).

1749839430665.png


Throw a shunt on your battery and see what it is doing for charge rate and what the load actually needs.

Street creds- Designed/serviced/operated properly high draw systems for mobile applications, did chassis/suspension and harness design work for 2 major OEMs, and lived/live off grid on solar/battery inverters (230A split phase service on 22kW of panels plus three generations of battery technology and building out a new system currently)

And I'm out
1749840343328.gif
 
mep1811 said:
You need that high voltage to charge an AGM battery. How are you monitoring the voltage as you drive? If the voltage drops as you drive you might want to get a alternator booster so the battery stays fully charged. If not, it is recommended to put the battery on a charger every month or so to get the battery up to a full charge.

I use one of these Alternator Voltage Booster.


HKB Electronics

The Alternator Voltage Booster was the first of its type on the market and is the only unit available that was has been purpose built for alternator voltage boosting.
www.hkbelect.com
Click to expand...

AcmeSys said:
Yep- And that is the problem. I'm trying to convey this in text and it may not come across but I'll try to cut thru the market'eering since I am stuck at the airport lounge - so I'll try to get this down

I dont know your use case so lets assume normal starting battery. Other applicaitons could vary but the concept is based on physics/chemistry so it doesn't really change outside of the temporal timeframes.

first principle / axiom - volt per volt AGMs recharge faster than standard flooded cells (even if the charge voltage is lower - it is an ohm's law thing)

The listed "cycle service" you show is like a total loss cycle (discharge to like 50% then recharge off a big charger bank - think a backup UPS inverter type service that has an effectively "infinite power" charger system for when grid power comes back on and you want to recharge the battery as fast as technically possible for efficiency reasons). In this application you'd deep discharge and actively monitor the state of charge with a shunt and know exact battery charge status at all times. With this you can do a controlled charge back to near 100% and transition from a very rapid charge rate with 14.8VDC then roll off to the tail/trickle charge at the lower 13.5VDC to prevent boil off for the last ~15% of charge cycle (bulk charge at high amps enabled by the lower cell resistance of AGM). That aint how 98.9% of cars work.

A standard alternator is a constant voltage system (drive the field to the set point voltage +/- the temperature correction and power limit but basically constant voltage). If you bump alternator voltage by cheating the sense signal with a diode you can certainly drive the buss voltage up by 0.7VDC. In a "normal automotive application" the battery is there for the start cycle and then is recharged in tens of minutes (~15% depth of discharge or less). So you are already living in the float charge voltage region of SOC there is no down side to keeping the voltage lower at the OEM setpoint even if you go deeper into the battery state of charge with parasitic loads. The battery will do its thing and recharge faster than the OEM FLA/SLA battery would.

The AGMs are lower resistance so if you don't have a higher voltage bulk charge voltage and just charge at the lower "float voltage" (AKA the stock alternator setpoint) it will recharge faster than an OEM flooded cell would but not as fast as it is capable of recharging (basically inefficient for what the battery could handle but they don't care). If you had a "smart" charger/alternator (a closed loop charge controller) on the car you could ramp up charge voltage and recharge noticeably faster. This higher voltage would be usefull if you did super short trips and never actually drive long enough to let the battery charge but then you'd have a way worse issue if you were on a normal FLA battery in the same use case so that is a bogus use case since either way you'd have dead batteries all the time no mater the battery type. But most cars don't have CL voltage controls so leave the voltage set point lower so you don't boil the battery by over charging. And there is the problem condition- if you set the target voltage higher for a higher charge rate, AKA diode on the sense line and drive up alternator voltage, and then drive long enough to charge the battery you will damage/boil the AGM cells by not rolling back to a lower "float" voltage at the higher state of charge.

The "cycle service" voltage they list is a kinda goofy/contrived spec that really comes back to "maximum charge amps" under some condition that they don't list (I can't find a northstar tech sheet that isn't marketing wonk, so another AGM G27 sheet is below - note that the bulk charge limit is listed in amperage not voltage).

View attachment 3928051

Throw a shunt on your battery and see what it is doing for charge rate and what the load actually needs.

Street creds- Designed/serviced/operated properly high draw systems for mobile applications, did chassis/suspension and harness design work for 2 major OEMs, and lived/live off grid on solar/battery inverters (230A split phase service on 22kW of panels plus three generations of battery technology and building out a new system currently)

And I'm out
View attachment 3928065
Click to expand...
I really apprericaite all the info guys , I may need to read all this a few times to digest all the wealth of knowledge put into this thread !!!
 
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