My thoughts on spare alternators

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Ricko1966

Full Access Member
Joined
Apr 11, 2017
Posts
4,391
Reaction score
6,506
Location
kansas
First Name
Rick
Truck Year
1975
Truck Model
c20
Engine Size
350
Okay yesterday had a dentist appointment. Downtown KCMO about 70 miles from home. DD ford festiva with a 16valve maxda motor transplant,using a U1R lawn tractor battery,for a battery. Came out of the dentists office,get in the DD hit the key,dim lights,no crank. Push start it drive home no stops other than traffic lights,no lights on,no blower motor etc. Ran 70 miles to my driveway and still running,all on a lawn tractor battery that was to dead to make the solenoid click. Not first expierience driving long distances on just the battery. I've driven 46 miles at night on a fully charged full size battery in a Plymouth Aclaim drove the same Aclaim the next day 80 miles in daylight. Drove a Mazda Pickup IDK how long,real long I was on a several 100 mile trip in the middle of nowhere,bought a second battery made it to my destination,made it back home on 2 fully charged batteries. All of these instances the cars never quit running,and if my DD was an automatic I'd have been better off to have a fully charged battery with me than an alternator yesterday I was lucky I could push start.I remember at least one other instance where I ran on just battery,but it was so long ago IDR the details. people thinking a spare alternator,I'd be more inclined to take a spare battery,cars will run a long time with just ignition on.More than long enough to get you to a parts store
 
Last edited:

fast 99

Full Access Member
Joined
Dec 31, 2021
Posts
1,736
Reaction score
2,387
Location
Spokane, Washington
First Name
Brian
Truck Year
81,85
Truck Model
K20
Engine Size
350
Kind of do that. Some SB came from the factory with 2 batteries, parts are available. I installed a second one in both trucks. Second one is not isolated.

Was handy at the lake when my brother's boat had a dead battery. Took one of mine out.

Most new cars today do not have any extra room under hood. Suppose I could carry one in the trunk, but the DD has an odd size battery. Would have to carry a specific one for it. Do carry good jumper cables.
 

Ricko1966

Full Access Member
Joined
Apr 11, 2017
Posts
4,391
Reaction score
6,506
Location
kansas
First Name
Rick
Truck Year
1975
Truck Model
c20
Engine Size
350
Kind of do that. Some SB came from the factory with 2 batteries, parts are available. I installed a second one in both trucks. Second one is not isolated.

Was handy at the lake when my brother's boat had a dead battery. Took one of mine out.

Most new cars today do not have any extra room under hood. Suppose I could carry one in the trunk, but the DD has an odd size battery. Would have to carry a specific one for it. Do carry good jumper cables.
I know how to isolate them with a common cheap 30 amp relay,depends on second battery use,because 2nd battery only charges at 15 amps.
I meant the carry a spare battery more for the guys that are filling their truck bed before going on a trip. A fresh battery will get you to the parts store,backnon the road in 10 minutes,a spare alternator still leaves you dead until someone stops to jump start you.
 

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
6,204
Reaction score
10,547
Location
Auburn, Washington
First Name
Todd
Truck Year
1986, 1977
Truck Model
K20, C10
Engine Size
454, 350
Of course it’s conditionally dependent, but fun fact, a 5.3 Chevy will run on a fresh battery from Seattle and Vancouver BC and start up again to get to the alternator store. Of course all other electrical draws were turned off.
Now let’s talk about parts store alternators. 1 have a 2 in 7 success ratio with them in the last half dozen years. Would have better luck wiring up a hand crank weather radio than some reman alternators. Lol
 

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
6,204
Reaction score
10,547
Location
Auburn, Washington
First Name
Todd
Truck Year
1986, 1977
Truck Model
K20, C10
Engine Size
454, 350
The real point is, if you’re drivin old cars or bombers like we often do, have to be prepared for some issues. Or some significant delays or tow bills
That’s why the average person can’t handle an old car because any/every little issue is a significant setback to them.
Thank goodness for that or there would be far less new cars sold and far chittier old cars available if everyone was handy.
 

Bennyt

Full Access Member
Joined
May 17, 2019
Posts
1,078
Reaction score
1,543
Location
Surprise
First Name
Ben
Truck Year
1977
Truck Model
C10
Engine Size
350
Also, just a FYI...Used to be you could borrow a battery, start the car, remove the battery and drive without the battery. On a lot of newer cars, you can do some expensive electronics damage if you try that.
 

Bennyt

Full Access Member
Joined
May 17, 2019
Posts
1,078
Reaction score
1,543
Location
Surprise
First Name
Ben
Truck Year
1977
Truck Model
C10
Engine Size
350
The real point is, if you’re drivin old cars or bombers like we often do, have to be prepared for some issues. Or some significant delays or tow bills
That’s why the average person can’t handle an old car because any/every little issue is a significant setback to them.
Thank goodness for that or there would be far less new cars sold and far chittier old cars available if everyone was handy.

The new cars drive me nuts. Fobs, subscriptions, etc. My wife gets a new car every 2-3 years so we always have something under warranty. On her last car every time Apple updated IOS her stereo needed to be reprogrammed. Actually, had to be replaced one of the times. The stereo is like $2k as it controls HVAC, etc. I'd like to buy a new truck but stuff like that scares me as they are too dependent on stuff you can't see with the naked eye. She wants the new Landcruiser or Lexus equivalent but when you see all the screens in the interior, you just know it's a problem waiting to happen.
 

AuroraGirl

Full Access Member
Joined
Sep 8, 2019
Posts
9,311
Reaction score
6,322
Location
Northern Wisconsin
First Name
Taylor
Truck Year
1978, 1980
Truck Model
K10, K25
Engine Size
400(?), 350
Of course it’s conditionally dependent, but fun fact, a 5.3 Chevy will run on a fresh battery from Seattle and Vancouver BC and start up again to get to the alternator store. Of course all other electrical draws were turned off.
Now let’s talk about parts store alternators. 1 have a 2 in 7 success ratio with them in the last half dozen years. Would have better luck wiring up a hand crank weather radio than some reman alternators. Lol
im slightly spoiled because im a girl so lower insurance rates, im no longer in the "high risk" category of new driver, and i Dont have any accidents on my insurance history ever, and I had good grades when in school.

So Im sure my overall rates being low is partially that, but If its the case with other insurers , towing insurance isnt a lot extra per month. I believe its 6-10$ a month to be able to tow my vehicle at least 1 time a month, every month

Thats.. not bad, considering a tow bill here to get home from anywhere is over 100$ during the middle of the day assuming no other crazy situations.

Worth checking to see what your local insurance would cost to include towing coverage. ive used it 4 times since being a new driver. one time was alternator failure and charging system went too low but i was running loads. first issue.

Second was when my first car died for good(subframe dropped, disconnected column),

third was my steering column in oldsmobile aurora SNAPPED at the aluminum collapsing piece that is between the wheel and the intermediate joint (THIS IS WHY YOU DONT BYPASS PS ON A 90s-PRESENT GM. I believe older columns could handle the forces from manual steering a PS car at least for way longer. ) snapped it at Farm and Fleet near home so it wasnt too bad a cost if I didnt have insurance.

4th was when my park avenues rear brake caliper bracket wasnt secured properly by the shop who did brake lines and fluid bleed , locked the wheel up and I had to take my snow tire across a cheese grater to get into a parking lot ;( lol


on the topic of cheap remans, I dont buy many alts from the stores but the cheap brand ford 3g alternator I bought for my f150 failed after a few years (but very few miles, maybe 2k?) because the case halves were pulling apart from eachother (the screws were just shearing out the case) and the bearing was locking up and was deflecting belt a lot. it didnt fully fail but i replaced with a delco-remy rebuild and its been quality.

The New and rebuilt AC delco alts ive bought have been quality, all have been CS130 or AD230 alternator or variants. Solid designs make for harder to **** it up, youd think, but failure seems to be in the parts that even a good rebuilder using would fail. electrical. bearing quality. pulley machining errors. Bad pulley clutch/overruns mechanisms. Overheating. etc
 

AuroraGirl

Full Access Member
Joined
Sep 8, 2019
Posts
9,311
Reaction score
6,322
Location
Northern Wisconsin
First Name
Taylor
Truck Year
1978, 1980
Truck Model
K10, K25
Engine Size
400(?), 350
Also, just a FYI...Used to be you could borrow a battery, start the car, remove the battery and drive without the battery. On a lot of newer cars, you can do some expensive electronics damage if you try that.
considering most cars have logic controlling charging and not simply a diode/resistor set, that logic wants to see a value or set of values to know what to do and how much to do it

Do not run your vehicle, even these squares, without a battery, unless you are very confident in your ability to do so because i can see HEI coils not taking to no battery very well , but thats just me.
 

Matt69olds

Full Access Member
Joined
Jan 8, 2018
Posts
2,390
Reaction score
3,692
Location
Central Indiana
First Name
Matt
Truck Year
81
Truck Model
GMC 1/2 ton
Engine Size
455 Olds
Some batteries have a Reserve capacity rating listed on the label.

Reserve Capacity is how long a fully charged battery can support a constant 25 amp load before the voltage drops below 10.5 volts. Since most modern cars will run on 10.5 volts (obviously you can’t START it on 10 volts) the reserve capacity will give you a ballpark figure on how long the engine will run with a failed charging system.

A stripped down truck with carb, mechanical fuel pump and nothing else would more than likely run all day with no alternator. The ignition system pulls a couple amps at most.


Which got me thinking: Get one of those cheap harbor freight solar panels and strap it to the hood, you could probably run all day, and use the battery at night. Hmm, then you could call your square a hybrid!!!

Cars with EFI, electric fuel pump, headlights, radio, etc wouldn’t run nearly as long. And while the engine may run with low system voltage, more than likely it won’t run well. The transmission probably won’t be happy either.

Last thought: pull a battery cable with the engine running is not a valid test for charging systems, and can easily fry expensive electronics, or worst case blow up the battery. An ignition system only pull a couple amps at modt, obviously a charging system capable of only a few amps isn’t going charge anything. Batteries release hydrogen, anyone familiar with the Hindenburg is well aware of what happens to hydrogen and sparks.
 

AuroraGirl

Full Access Member
Joined
Sep 8, 2019
Posts
9,311
Reaction score
6,322
Location
Northern Wisconsin
First Name
Taylor
Truck Year
1978, 1980
Truck Model
K10, K25
Engine Size
400(?), 350
Some batteries have a Reserve capacity rating listed on the label.

Reserve Capacity is how long a fully charged battery can support a constant 25 amp load before the voltage drops below 10.5 volts. Since most modern cars will run on 10.5 volts (obviously you can’t START it on 10 volts) the reserve capacity will give you a ballpark figure on how long the engine will run with a failed charging system.

A stripped down truck with carb, mechanical fuel pump and nothing else would more than likely run all day with no alternator. The ignition system pulls a couple amps at most.


Which got me thinking: Get one of those cheap harbor freight solar panels and strap it to the hood, you could probably run all day, and use the battery at night. Hmm, then you could call your square a hybrid!!!

Cars with EFI, electric fuel pump, headlights, radio, etc wouldn’t run nearly as long. And while the engine may run with low system voltage, more than likely it won’t run well. The transmission probably won’t be happy either.

Last thought: pull a battery cable with the engine running is not a valid test for charging systems, and can easily fry expensive electronics, or worst case blow up the battery. An ignition system only pull a couple amps at modt, obviously a charging system capable of only a few amps isn’t going charge anything. Batteries release hydrogen, anyone familiar with the Hindenburg is well aware of what happens to hydrogen and sparks.
i had a battery blow up less than 3 feet from me, i am VERY lucky a fender of a tractor separated me from that battery because id be blind or worse
 

bucket

Super Moderator
Staff member
Super Moderator
Joined
Aug 3, 2010
Posts
29,399
Reaction score
25,028
Location
Usually not in Ohio
First Name
Andy
Truck Year
'77, '78, '79, '84, '88
Truck Model
K5 thru K30
Engine Size
350-454
On long trips in one of my older cars, I tend to carry a known good used alternator and also a jumper box. Along with an essential tools kit and other spare parts.
 

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
6,204
Reaction score
10,547
Location
Auburn, Washington
First Name
Todd
Truck Year
1986, 1977
Truck Model
K20, C10
Engine Size
454, 350
The new cars drive me nuts. Fobs, subscriptions, etc. My wife gets a new car every 2-3 years so we always have something under warranty. On her last car every time Apple updated IOS her stereo needed to be reprogrammed. Actually, had to be replaced one of the times. The stereo is like $2k as it controls HVAC, etc. I'd like to buy a new truck but stuff like that scares me as they are too dependent on stuff you can't see with the naked eye. She wants the new Landcruiser or Lexus equivalent but when you see all the screens in the interior, you just know it's a problem waiting to happen.
I guess, conversely, I thoroughly enjoy driving any number of “new cars” when sitting in traffic for a couple hours a day in the rain, or making that weekly road trip across state at 5am, or towing….anything, or the heated seats and wheel when it’s 0 deg outside.
Have had a few infotainment glitches, but not nearly enough to prefer stuffing my @ss in a squarebody every day to do the above vehicular tasks.
The paranoia of new vehicles is not that strong with me.
I also don’t like replacing alternators in a parking lot…or at all on a vehicle I drive regularly.
Edit
Although, I do agree with you that some of that chit is annoying and unnecessary or ill conceived. My new F150 work truck doesn’t function as well as my 8 year old Dodges touch screen controls.
What it will be like in 10-30 years for ability to repair? Idk but I feel like that will work itself out and become the new norm and just fine. Kinda like “damn fuel injection, can’t work on it” argument from 30 years ago.
 
Last edited:

Blue Ox

Turning Diesel Fuel Into Fun
Joined
Mar 27, 2018
Posts
4,988
Reaction score
11,191
Location
LI-NY
First Name
Derek
Truck Year
MCMLXXXV
Truck Model
K20HD
Engine Size
6.2L
Long time ago a friend was driving tow trucks and occasionally he'd be doing a late night job and he'd ask if I wanted to ride along. So one time we go into Queens with an older GMC to pick up a box truck. On the way out he notes that the alternator isn't charging, but we're almost there and it's pretty late, so we forge ahead. We pick up the tow and it's only a few more miles before the lights are getting really dim. Eventually the ignition starts behaving badly. Now we're in Queens in a tow truck that needs a tow truck. Finally, I asked the chauffeur "Why are we towing this truck?" After I explain this a couple of ways he finally says that it has a bad transmission.

"Oh, okay. Do you suppose it has a good battery?" Apparently, you can make it the rest of the way home with a bad alternator and borrowed battery. Good thing I went along. :rolleyes:
 
Last edited:

bucket

Super Moderator
Staff member
Super Moderator
Joined
Aug 3, 2010
Posts
29,399
Reaction score
25,028
Location
Usually not in Ohio
First Name
Andy
Truck Year
'77, '78, '79, '84, '88
Truck Model
K5 thru K30
Engine Size
350-454
I guess, conversely, I thoroughly enjoy driving any number of “new cars” when sitting in traffic for a couple hours a day in the rain, or making that weekly road trip across state at 5am, or towing….anything, or the heated seats and wheel when it’s 0 deg outside.
Have had a few infotainment glitches, but not nearly enough to prefer stuffing my @ss in a squarebody every day to do the above vehicular tasks.
The paranoia of new vehicles is not that strong with me.
I also don’t like replacing alternators in a parking lot…or at all on a vehicle I drive regularly.
Edit
Although, I do agree with you that some of that chit is annoying and unnecessary or ill conceived. My new F150 work truck doesn’t function as well as my 8 year old Dodges touch screen controls.
What it will be like in 10-30 years for ability to repair? Idk but I feel like that will work itself out and become the new norm and just fine. Kinda like “damn fuel injection, can’t work on it” argument from 30 years ago.

I honestly love the older trucks for all of that. I'm perfectly comfortable, about the only thing I would like would be the heated seats in the winter time.
 

Latest posts

Forum statistics

Threads
42,620
Posts
919,302
Members
34,151
Latest member
Fb0067
Top