Dead Battery ruin your alternator - Engineering Explained
- Thread starter StevieC
- Start date
- Status
I'll save you guys 11 minutes of watching: Yes your alternator works harder to charge a battery and heats up a little more, but it is designed to do so.
If you know your battery is low on charge, it is probably better to hook it up to a battery charger over night, but not essential.
It takes 30 minutes of driving to charge a dead battery to 75% charge.
If you know your battery is low on charge, it is probably better to hook it up to a battery charger over night, but not essential.
It takes 30 minutes of driving to charge a dead battery to 75% charge.
Originally Posted by Burt
I'll save you guys 11 minutes of watching: Yes your alternator works harder to charge a battery and heats up a little more, but it is designed to do so.
If you know your battery is low on charge, it is probably better to hook it up to a battery charger over night, but not essential.
It takes 30 minutes of driving to charge a dead battery to 75% charge.
Yes, thank you.
Alternators charge batteries, it puts out power to run the car this is why you can disconnect the negative terminal on an old school car with a working alternator and it will still run that's a test, the excess after running the car (runs off the alternator) goes to the battery, which is only really used to start the car, . take it on a nice long drive.. some not all Alternators are single-wire they need to be revved up past a certain point to excite aka charge however usually hooking a battery up to a wall power source is non-essential.
I'll save you guys 11 minutes of watching: Yes your alternator works harder to charge a battery and heats up a little more, but it is designed to do so.
If you know your battery is low on charge, it is probably better to hook it up to a battery charger over night, but not essential.
It takes 30 minutes of driving to charge a dead battery to 75% charge.
Yes, thank you.
Alternators charge batteries, it puts out power to run the car this is why you can disconnect the negative terminal on an old school car with a working alternator and it will still run that's a test, the excess after running the car (runs off the alternator) goes to the battery, which is only really used to start the car, . take it on a nice long drive.. some not all Alternators are single-wire they need to be revved up past a certain point to excite aka charge however usually hooking a battery up to a wall power source is non-essential.
Last edited:
The temperature measurements were informative... So running a weak battery especially in hot weather beats on the alternator.
Yeah, chicken and egg scenario since alternator slowly going bad can wreck your battery too.
Originally Posted by StevieC
The temperature measurements were informative... So running a weak battery especially in hot weather beats on the alternator.
Would be helpful if it said how much temperature is bad for the alternator components and is there a compounding effect? I.e. the alternator resides under a hot engine bay, so is the extra 24 C for a half hour ruinously detrimental to the alternator life? Will a weak battery even take much a charge and generate alternator heat?
I like most of this guy's videos, but I get irritated when articles don't answer the headline question they pose.
The temperature measurements were informative... So running a weak battery especially in hot weather beats on the alternator.
Would be helpful if it said how much temperature is bad for the alternator components and is there a compounding effect? I.e. the alternator resides under a hot engine bay, so is the extra 24 C for a half hour ruinously detrimental to the alternator life? Will a weak battery even take much a charge and generate alternator heat?
I like most of this guy's videos, but I get irritated when articles don't answer the headline question they pose.
One thing I just recently learned is that an alternator going bad can give you all kinds of "CEL" codes. I had an alternator with a bearing that was getting tight and it ran me ragged trying to fix the codes when all the codes were actually "false."
I only discovered the bad alternator after I had replaced the battery (unnecessary) and I smelled something burning. I took it to my mechanic and he said alternator would charge fine for a while and then it wouldn't charge. Go figure.
I only discovered the bad alternator after I had replaced the battery (unnecessary) and I smelled something burning. I took it to my mechanic and he said alternator would charge fine for a while and then it wouldn't charge. Go figure.
Originally Posted by talest
some not all Alternators are single-wire they need to be revved up past a certain point to excite aka charge
I always rev up to about 2k RPM and let it charge the other battery for a short period of time before I try to fire up the other car. The other party almost always tries to start it as soon as the cables are connected.
I think that if the battery is completely flat, recharging it even for a brief period before starting might be better than trying to start a car with a completely flat battery that is connected to a good one.
Trying to start it immediately, crossing the polarity, letting the positive and negative cables touch when they disconnect it or grounding the positive. I hate boosting people when they try to involve themselves in the process.
some not all Alternators are single-wire they need to be revved up past a certain point to excite aka charge
I always rev up to about 2k RPM and let it charge the other battery for a short period of time before I try to fire up the other car. The other party almost always tries to start it as soon as the cables are connected.
I think that if the battery is completely flat, recharging it even for a brief period before starting might be better than trying to start a car with a completely flat battery that is connected to a good one.
Trying to start it immediately, crossing the polarity, letting the positive and negative cables touch when they disconnect it or grounding the positive. I hate boosting people when they try to involve themselves in the process.
Originally Posted by Gebo
One thing I just recently learned is that an alternator going bad can give you all kinds of "CEL" codes. I had an alternator with a bearing that was getting tight and it ran me ragged trying to fix the codes when all the codes were actually "false."
I only discovered the bad alternator after I had replaced the battery (unnecessary) and I smelled something burning. I took it to my mechanic and he said alternator would charge fine for a while and then it wouldn't charge. Go figure.
Our Acura was acting funny, cluster was acting like a Xmas tree - bad alternator was the reason.
In another vehicle, bad battery was throwing all kind of codes/errors on the cluster.
Definitely, chicken and egg situation.
One thing I just recently learned is that an alternator going bad can give you all kinds of "CEL" codes. I had an alternator with a bearing that was getting tight and it ran me ragged trying to fix the codes when all the codes were actually "false."
I only discovered the bad alternator after I had replaced the battery (unnecessary) and I smelled something burning. I took it to my mechanic and he said alternator would charge fine for a while and then it wouldn't charge. Go figure.
Our Acura was acting funny, cluster was acting like a Xmas tree - bad alternator was the reason.
In another vehicle, bad battery was throwing all kind of codes/errors on the cluster.
Definitely, chicken and egg situation.
Many sensors look for voltages in a range. A bad battery or a bad alternator each can be a cause for out of range voltages. (Also bad grounds.)
When you have many failures at once, start checking things that are common, like voltages and grounding.
When you have many failures at once, start checking things that are common, like voltages and grounding.
gathermewool
Site Donor 2025
Originally Posted by maxdustington
Originally Posted by talest
some not all Alternators are single-wire they need to be revved up past a certain point to excite aka charge
I always rev up to about 2k RPM and let it charge the other battery for a short period of time before I try to fire up the other car. The other party almost always tries to start it as soon as the cables are connected.
I think that if the battery is completely flat, recharging it even for a brief period before starting might be better than trying to start a car with a completely flat battery that is connected to a good one.
Trying to start it immediately, crossing the polarity, letting the positive and negative cables touch when they disconnect it or grounding the positive. I hate boosting people when they try to involve themselves in the process.
If you want to be a good Samaritan, then buy a battery boost-pack.
I experienced the same thing this past summer. I had to tell the guy three times to STOP trying to start the car, eventually reaching a screaming volume of voice before he complied.
Originally Posted by talest
some not all Alternators are single-wire they need to be revved up past a certain point to excite aka charge
I always rev up to about 2k RPM and let it charge the other battery for a short period of time before I try to fire up the other car. The other party almost always tries to start it as soon as the cables are connected.
I think that if the battery is completely flat, recharging it even for a brief period before starting might be better than trying to start a car with a completely flat battery that is connected to a good one.
Trying to start it immediately, crossing the polarity, letting the positive and negative cables touch when they disconnect it or grounding the positive. I hate boosting people when they try to involve themselves in the process.
If you want to be a good Samaritan, then buy a battery boost-pack.
I experienced the same thing this past summer. I had to tell the guy three times to STOP trying to start the car, eventually reaching a screaming volume of voice before he complied.
Originally Posted by maxdustington
Originally Posted by talest
some not all Alternators are single-wire they need to be revved up past a certain point to excite aka charge
I always rev up to about 2k RPM and let it charge the other battery for a short period of time before I try to fire up the other car. The other party almost always tries to start it as soon as the cables are connected.
I think that if the battery is completely flat, recharging it even for a brief period before starting might be better than trying to start a car with a completely flat battery that is connected to a good one.
Trying to start it immediately, crossing the polarity, letting the positive and negative cables touch when they disconnect it or grounding the positive. I hate boosting people when they try to involve themselves in the process.
Take their keys. They have veto power before you hook up any cable, but you get to hook up the cables, too.
Give them the keys back after you've had a few minutes to put a surface charge on their battery.
Originally Posted by talest
some not all Alternators are single-wire they need to be revved up past a certain point to excite aka charge
I always rev up to about 2k RPM and let it charge the other battery for a short period of time before I try to fire up the other car. The other party almost always tries to start it as soon as the cables are connected.
I think that if the battery is completely flat, recharging it even for a brief period before starting might be better than trying to start a car with a completely flat battery that is connected to a good one.
Trying to start it immediately, crossing the polarity, letting the positive and negative cables touch when they disconnect it or grounding the positive. I hate boosting people when they try to involve themselves in the process.
Take their keys. They have veto power before you hook up any cable, but you get to hook up the cables, too.
Give them the keys back after you've had a few minutes to put a surface charge on their battery.
When offering to jump start I always say why don`t we charge your battery for a minute before trying starting and they have always comply.
So far no problems.
So far no problems.
Common sense. If a dead battery at home, charge it on AC charger.
Originally Posted by Donald
Common sense. If a dead battery at home, charge it on AC charger.
Common sense is a super power today... LOL
Common sense. If a dead battery at home, charge it on AC charger.
Common sense is a super power today... LOL
- Status