80 amp vs 100 amp alternator

[pkh540]

I have a 2000 TLC with a bad alternator. Ordered an alternator online but after reading through this forum discovered that the early 100's came with either an 80 or a 100 amp alternator. (And of course I ordered the 80 amp!) Without removing how can I tell which one I have? (Cannot see any part number on mine.)

This weekend I was planning on replacing the timing belt, water pump, hoses, belts, etc. while replacing the alternator but now that I may have purchased the wrong alternator I'm curious if I could use the 80 amp instead of the 100 amp.

I'd really hate to postpone this weekends project if my TLC has the 100 amp version... And paying more than $400 to get one from Toyota is an equally painful thought.

 

[flintknapper]

You can use an 80 amp alternator, but chances are excellent you have a 100 amp on it now (if OEM from factory).

 

[MrChamp421]

You can use an 80 amp alternator, but chances are excellent you have a 100 amp on it now (if OEM from factory).

I think I put an 80 amp in my ’99 LC, but am now having starting issues. If I drive it every day it seems to start ok, but it’s not my daily Driver so after a few days, I need to jump it. Could this be an issue caused by too little amps?

 

[awesomeissquid]

When you do drive it how long are you driving for? Sounds like either short trips are not allowing the battery to fully charge or you have some power draw that is draining the battery.

 

[Malleus]

I have a 2000 TLC with a bad alternator. Ordered an alternator online but after reading through this forum discovered that the early 100's came with either an 80 or a 100 amp alternator. (And of course I ordered the 80 amp!) Without removing how can I tell which one I have? (Cannot see any part number on mine.)

This weekend I was planning on replacing the timing belt, water pump, hoses, belts, etc. while replacing the alternator but now that I may have purchased the wrong alternator I'm curious if I could use the 80 amp instead of the 100 amp.

I'd really hate to postpone this weekends project if my TLC has the 100 amp version... And paying more than $400 to get one from Toyota is an equally painful thought.

Dealer/Partsouq? Your VIN may give you some help; I've never looked a this, so it may be a snipe hunt.

 

[MrChamp421]

When you do drive it how long are you driving for? Sounds like either short trips are not allowing the battery to fully charge or you have some power draw that is draining the battery.

Shorter trips only when all 5 in the family are going to dinner and such (which is generally pretty rare), but mostly for the carrying capacity for luggage and driving 3+ hrs to the coast (even more rare).

But will become the daily driver, 5-7 miles one way to work and back, when my daughter gets her driver license this year.

 

[bubfuji]

A daily driver battery life is 3-5 years. Next time you drive the rig. Measure the battery voltage after you park it and turn off the motor. The immediate voltage should be in the 13v range. Then measure the voltage after sitting for the night. The voltage after sitting overnight should be about 12.5v. Anything less your battery is dying. It happens...

For the alternator: with the engine running. Measure the battery voltage. Should be high 13v to 14.4v. The voltage regulator is designed to produce 14.4 at startup. If the battery is in good shape the running voltage will drop to 13.2 to 13.5v. Because the alternator knows when the battery is fully charged (newer rigs are smarter).

FYI: There are parasitic voltage draws on the battery. The alarm, and ecu pull an infinitesimal amount of voltage. However it is enough to drain a battery over 30-60 days. A regular lead acid battery needs to stay at full charge. Or sulfides will build up on the lead plates inside the battery inhibiting charge/discharge.

Also: If your battery is dying (3-5 years)...Your alternator is working overtime trying to keep the battery charged and the vehicle electrics running. This will shorten the alternator life (voltage regulator usually).

And...and wait for it... battery terminal corrosion...read the signs. Corrosion only on the negative battery post is a sign of under charging, corrosion on the positive post is a sign of overcharging. If the alternator is outputting 13.v to 14.4v and you have terminal corrosion outlined above. The battery is dying.

 

[LandLocked93]

And...and wait for it... battery terminal corrosion...read the signs. Corrosion only on the negative battery post is a sign of under charging, corrosion on the positive post is a sign of overcharging. If the alternator is outputting 13.v to 14.4v and you have terminal corrosion outlined above. The battery is dying.

Ok so this is interesting, had not heard it before. (and admittedly not particularly germane to this thread)
Does it apply to 24v systems as well? My low-side battery neg terminal develops corrosion on the regular. The charge voltage ranges from 25V to 29V, with 29v usually reached after just 30 min or so of driving (RedArc2420).
There is a single constant draw on the system, a Victron 75/15 solar controller. It is not connected to panels most of the time, but remains powered all the time.
I've not had any storage issues as of yet, but the corrosion is annoying.

 

[MrChamp421]

A daily driver battery life is 3-5 years. Next time you drive the rig. Measure the battery voltage after you park it and turn off the motor. The immediate voltage should be in the 13v range. Then measure the voltage after sitting for the night. The voltage after sitting overnight should be about 12.5v. Anything less your battery is dying. It happens...

For the alternator: with the engine running. Measure the battery voltage. Should be high 13v to 14.4v. The voltage regulator is designed to produce 14.4 at startup. If the battery is in good shape the running voltage will drop to 13.2 to 13.5v. Because the alternator knows when the battery is fully charged (newer rigs are smarter).

FYI: There are parasitic voltage draws on the battery. The alarm, and ecu pull an infinitesimal amount of voltage. However it is enough to drain a battery over 30-60 days. A regular lead acid battery needs to stay at full charge. Or sulfides will build up on the lead plates inside the battery inhibiting charge/discharge.

Also: If your battery is dying (3-5 years)...Your alternator is working overtime trying to keep the battery charged and the vehicle electrics running. This will shorten the alternator life (voltage regulator usually).

And...and wait for it... battery terminal corrosion...read the signs. Corrosion only on the negative battery post is a sign of under charging, corrosion on the positive post is a sign of overcharging. If the alternator is outputting 13.v to 14.4v and you have terminal corrosion outlined above. The battery is dying.

This is excellent info, thank you! I will definitely do those tests.

The battery is ≈1-2 yrs old. Replaced that before the alternator because it wouldn’t hold a charge, but it was already between 5 & 6 yrs old.

 

[bubfuji]

A daily driver battery life is 3-5 years. Next time you drive the rig. Measure the battery voltage after you park it and turn off the motor. The immediate voltage should be in the 13v range. Then measure the voltage after sitting for the night. The voltage after sitting overnight should be about 12.5v. Anything less your battery is dying. It happens...

For the alternator: with the engine running. Measure the battery voltage. Should be high 13v to 14.4v. The voltage regulator is designed to produce 14.4 at startup. If the battery is in good shape the running voltage will drop to 13.2 to 13.5v. Because the alternator knows when the battery is fully charged (newer rigs are smarter).

FYI: There are parasitic voltage draws on the battery. The alarm, and ecu pull an infinitesimal amount of voltage. However it is enough to drain a battery over 30-60 days. A regular lead acid battery needs to stay at full charge. Or sulfides will build up on the lead plates inside the battery inhibiting charge/discharge.

Also: If your battery is dying (3-5 years)...Your alternator is working overtime trying to keep the battery charged and the vehicle electrics running. This will shorten the alternator life (voltage regulator usually).

And...and wait for it... battery terminal corrosion...read the signs. Corrosion only on the negative battery post is a sign of under charging, corrosion on the positive post is a sign of overcharging. If the alternator is outputting 13.v to 14.4v and you have terminal corrosion outlined above. The battery is dying

A comment on my comments. Proper grounding, with clean +/- terminals and good clean connections will also have an effect on corrosion

Ok so this is interesting, had not heard it before. (and admittedly not particularly germane to this thread)
Does it apply to 24v systems as well? My low-side battery neg terminal develops corrosion on the regular. The charge voltage ranges from 25V to 29V, with 29v usually reached after just 30 min or so of driving (RedArc2420).
There is a single constant draw on the system, a Victron 75/15 solar controller. It is not connected to panels most of the time, but remains powered all the time.
I've not had any storage issues as of yet, but the corrosion is annoying.

I can not say specifically. Assuming a 24v system charges and regulates as a 12v system would. I would say the same applies. Good grounds and ground cables along with clean +/- terminals and good cable connections are also part of the equation.