Thought 145amp alternator enough for additional accessories. Guess not?

[PineyCruisin]

Was hoping someone could give some sort of approximate on how much additional accessory draw I should expect our 145amp alternator to keep up with while driving without draining the starter battery.

Here's why I ask...as an experiment I did the following:

• First thing in morning, before use, battery tested at 12.55 with multimeter
• Drove on parkway, maintaining speed of ~60-65mph, then plugged in a 6.7amp Jackery charger in one ciggie plug, and .5amp GPS, .5amp dashcam, and 35 watt IndelB TB18 fridge in the other. Nothing else was turned on....no headlights, no fans, no radio.
• After 35 minutes of driving at high speeds, we unplugged all accessories and stopped at destination. After 2hrs of resting, battery was at 12.40.
• Did not plug anything back in, nor turn any other accessory on and drove back home. Battery was at 12.6 the next morning.

Even tho it appeared the alternator recharged the battery sufficiently without anything plugged in, I still paid to have the battery and charging system tested to be absolutely certain both were operating properly (both are also brand new). Both battery and alternator passed all tests. I did mention to the service tech beforehand why we wanted system tested so he said they also tested when accessories were plugged in (the refridgerator and the Jackery charger, I'm assuming since they were only things in van at the time and I didn't plug them in for them myself) and said that the battery under this load only reached 12.4--it tested at 13.95 under test load.

The tech said that it appeared the battery/alternator can't handle everything at once. I'm extremely disappointed in that I was hoping to be able to charge the Jackery while driving since we do not have solar panels on the roof (we have portable panels to use when parked). I'm hoping that at the very least we could at least be able to plug in everything else--fridge, GPS, and dashcam while still be able to use headlights and fans as needed. Is this reasonable to expect? This is a conversion van so I was expecting that the system is already set up to handle a butt-load of stuff like TVs with inverters, gaming equipment and stereos (which was actually in the van when we bought it).

Oh! Almost forgot to mention in case it has any bearing--we installed a Blue Sea battery disconnect switch rated at 300 continuous amps on the negative side.

Any thoughts appreciated.

 

[highdesertranger]

first off,
12.55 first thing in the morning is low. sounds like you have a weak battery to begin with.
no matter what you can't rely on your alternator as a sole charging source. automotive alternators are highly overrated. that 145 amp rating was come up with under idea conditions(in a lab) just like solar panels. you will never see 145 amps. alternators are great as a supplemental charge source.

also voltage is a poor indicator of battery SOC(State Of Charge). BTW a 2 hour rest will not cut it, 12 hour minimum.

I wouldn't jump to any conclusions until you are sure you have a good battery. charge it until full and retest after resting overnight. remember no charging or discharging for 12 hours.

highdesertranger

 

[Sofisintown]

Well the alternator is specifically made to charge the battery that runs the vehicle.

Gives the battery enough power to start  the car, move the seats, operate the windows, and power the locks and other micro systems, such as the vehicle  computer.
While running, the battery keeps the lights on, the air conditioning running, fans that cool the motor and miscellaneous pumps, vacuums  and other electric parts.

It is not made to run a household.
It can charge a thing or two while the car is running if there is excess electricity, and if their wattage requirement is low.
You can't can't charge a laptop for instance, if you are driving at night with your lights on and the air conditioning going, the wipers wiping and the radio full blast. There is not enough excess power. You will drain the vehicle battery.

You could possibly install a 'house' battery, that will run your other stuff, and charge the second battery while the car is running.
The second battery has to be isolated, or it can kill your car battery by drawing power when the vehicle is stationary and the house battery  is low.
A Jackery takes forever and a day to charge from the cigarette plug. And it is very unlikely that the alternator can keep your house battery fully charged.
You have to seriously think SOLAR.

 

[jonyjoe303]

what was the voltage of the alternator while driving? it has to maintain 14.4 volt at the minimun, if it is less then that, it's not putting out the 145 amps. All the loads you were using together are insignificant for a 145 amp alternator, unless it's not reaching full output.

On my van it has a voltage meter, I can see the voltage drop when I put a big load like turn on the van AC and it will remain below 14.4 volts while running the AC. If I turn on the headlights and other items sometimes I can hear the fanbelts squeaking as the alternators comes under load but this is just city driving with engine not running at high rpm.

I jumpstarted someones car once and using a multimeter while the car was running notice the voltage was only something like 13.8 volts steady and not going up. I suspect some newer vehicules might not run at 14.4 volts all the time.

 

[PineyCruisin]

I've had my suspicions about this battery. I even brought it up with the tech during this last test (battery was purchased at Pepboys and tested there) and he said he couldn't replace under warranty since it is passing their tests.

Because of this suspicion, we have tested it pretty extensively. One thing we did was disconnect the battery and kept an eye on the voltage over many days and found it held the charge exactly....again when it was disconnected (I'm not going to get into why we installed the battery disconnect...that's another long story). Would this be enough to prove it's good? We primarily have been doing short distance driving lately so not sure if it had a chance to get up to full charge on that day I tested it in the morning at 12.55.

Any other things we can do to test the battery health? Also, if battery is good, it sounds as if I was expecting too much from the alternator in replenishing our electric needs from the battery?

Also, don't know if this is significant but the charging system results--with no load, voltage was 13.96. I thought the magic number is 14.4? Loaded, it was 13.95V.

As for the alternator, I'm looking at the test results and it says "Results cranking normal: Voltage: 10.57, Amps:257" so it almost sounds like the output isn't really tested under the conditions I'm looking for.

 

[PineyCruisin]

what was the voltage of the alternator while driving? it has to maintain 14.4 volt at the minimun, if it is less then that, it's not putting out the 145 amps. All the loads you were using together are insignificant for a 145 amp alternator, unless it's not reaching full output.

During the charge system test, the voltage was at 13.96 with no load and 13.95 under load. The tech didn't bring it up as a problem and I only noticed it when I looked at the test result sheet. Don't know how accurate these digital voltmeter that are included with charging ports but it has read 14.4 on occasion.

 

[PineyCruisin]

Well the alternator is specifically made to charge the battery that runs the vehicle.

Gives the battery enough power to start  the car, move the seats, operate the windows, and power the locks and other micro systems, such as the vehicle  computer.
While running, the battery keeps the lights on, the air conditioning running, fans that cool the motor and miscellaneous pumps, vacuums  and other electric parts.

It is not made to run a household.
It can charge a thing or two while the car is running if there is excess electricity, and if their wattage requirement is low.
You can't can't charge a laptop for instance, if you are driving at night with your lights on and the air conditioning going, the wipers wiping and the radio full blast. There is not enough excess power. You will drain the vehicle battery.

This is why people install bigger alternators in their vehicles. People are able to power winches off their starter battery.

 

[bullfrog]

Has any one done voltage drop tests to insure all cables and connections are good? Even your disconnect switch can cause problems. Are the cables and connections the original stock ones and places? You need to give us all the information as to why the battery cut off switch was installed. I would note people with winches usually install heavy cables to insure a good power flow, you may need to do the same, both positive and negative. This is just a guess but good looking cables can be bad, same with connections, a voltage drop test will tell you for sure, especially since your total out put doesn’t seem to be getting to the battery. Again this is just a guess and an opinion but seldom do manufacturers overbuild and cables size and connection location may be part of the problem in my opinion.

 

[highdesertranger]

"People are able to power winches off their starter battery."

well this is really not true. people who have winches put a dual battery system in. if they are smart.

as far as the battery voltage, I am assuming you have a maintenance free battery? is that true? the alternator is considered good if it's putting out 14.2v right after you start the vehicle. it will quickly drop off into the high 13's. a vehicle alternator cannot put out full power for very long or it will burn out.

I already told you how to test the battery. charge it up to full and let it rest overnight then check the voltage. remember let it rest means no charging or discharging. the tech at Pep boys should have told you they need the battery overnight to test it. that is what we used to do.

highdesertranger

 

[PineyCruisin]

HDR: I used to own a jeep and subscribed to a Jeep forum. These people were adding all sorts of things--xenon lights, winches, huge speakers and subwoofers, etc. Many of them talked about installing high idle output alternators instead of dual battery. Did they really check to make sure the alternator could keep up? Not sure. I wonder sometimes if people are assuming things about what the alternator can do and slowly killing their batteries over time. 

Maybe I misunderstood.....I assumed that you wanted me to test to see if the battery was holding a charge and since I already had done this...many times over many days, even disconnecting it so as to completely isolate the battery just to make sure other things weren't causing a drain. Also it was proved on the test I described above that it held a 12.6 charge overnight because it was tested first thing in the morning after arriving home the afternoon before, meaning it had 18 hrs. sitting idle before measuring voltage. I'm not sure what doing it for one overnight yet again is going to prove but most certainly will if there is something else I need to be looking at. Can you please elaborate?

Yes, it a sealed standard lead-acid battery. I do appreciate the help!

 

[tx2sturgis]

If by chance your vehicle has a current shunt on the negative post this might slightly change the readings you get with other test meters.

Make sure the belt or belts are adjusted properly...a loose belt can cause slippage under load.

Also, some aftermarket alternators and/or voltage regulators can be adjusted.

 

[maki2]

No mystery, you just can't  get enough power out of that undersized alternator to meet you r power needs.

So get a solar panel or use ice for cooling or adapt to eating foods that don't  need refrigeration. Or get a custom built alternator with higher power output installed. Of the choices by far the most expensive is a custom built alternator. The least expensive of them is changing what you eat. But the main point is that you can adapt how you do things as far as supply and demand of power goes. You can choose to supply more power or you can reduce your consumption

 

[PineyCruisin]

Has any one done voltage drop tests to insure all cables and connections are good? Even your disconnect switch can cause problems. Are the cables and connections the original stock ones and places? You need to give us all the information as to why the battery cut off switch was installed. I would note people with winches usually install heavy cables to insure a good power flow, you may need to do the same, both positive and negative. This is just a guess but good looking cables can be bad, same with connections, a voltage drop test will tell you for sure, especially since your total out put doesn’t seem to be getting to the battery. Again this is just a guess and an opinion but seldom do manufacturers overbuild and cables size and connection location may be part of the problem in my opinion.

No, no voltage drop test was done but will certainly look into it. Thanks! The BlueSea did not come with cables so we purchased 4AWG copper cables off Amazon. Was this a bad idea? Do you recommend even heavier than a 4? New terminal bolts were also just installed to ensure good connection (the threads were kinda stripped off one last year and caused our battery to die....this was actually the start of looking into our entire electrical system and it hasn't stopped since). 

Here is my long saga about the battery and charging system, since you asked:

As stated above the first problem occurred with a loose terminal connection that caused the van not to start up in a parking lot a couple times. Also, the battery was not getting charged properly and it died prematurely. After that, we were paranoid about making sure the battery was getting and maintaining a charge. To do that, we got obsessed about checking voltage.

During this time, we noticed that the voltage was dropping over a period of a couple days while sitting idle. We did parasitic draw tests by pulling fuses and couldn't find a bleedin' thing. It was driving me nuts. I was working on the inside of the van a lot at the time and it was only when I had stopped going into the van for a few days did I notice that the voltage did not drop even .01 over 4 days. This is when I put 2 and 2 together -- it had to be the open doors! Sure enough, with any of the doors remaining open, there was a .60 amp draw. With doors closed-- .02 amp. I was able to determine that pulling down the lock-hinges (or whatever they are called) manually when the doors were open would fool the system and  would stop the draw....except the barn doors. There was still a switch that would draw .2amps that we couldn't figure out how to stop when we were parked. Because we do a lot of camping with the barn doors open, a kill switch was installed for those times we were parked for long periods.

Haven't had a problem since with battery drain, except when I go in and out of the car a lot while its sitting in driveway and the disconnect switch is in the open position.

That does make perfect sense about the cables. I also still worry about the resistance caused by the disconnect switch. But, the thing that puzzles me is that the alternator is recharging the battery fine...but then again.... with no accessory load.

 

[Spaceman Spiff]

My 2¢:

First - your added loads are trivial and should easily be handled by the alternator.  Most econoboxes still come with an 80A alternator.

[font=Tahoma, Verdana, Arial, sans-serif]Second [/font]- the tech probably used a handheld battery tester to determine good/bad.  All this tells is if the battery needs warrantee replacement or not.  It gives a poor approximation of battery condition.  
The correct way is to do a capacity÷time test, usually a 10 hour test (but can be 1, 5 or 20 hours).

[font=Tahoma, Verdana, Arial, sans-serif]Third[/font] - the quick and dirty way to test an alternator is to put a large, known load on it and measure its output through the rpm range.  This usually involves putting a large resistor in series with the + battery terminal.  You should have gotten a printout of the RPM vs. output.
The best way is to put it on an alternator tester.

A new 12V LA battery should be 12.7+ volts when rested - can be as high as 13V fresh off a charge.

 

[PineyCruisin]

If by chance your vehicle has a current shunt on the negative post this might slightly change the readings you get with other test meters.

Make sure the belt or belts are adjusted properly...a loose belt can cause slippage under load.

Also, some aftermarket alternators and/or voltage regulators can be adjusted.

Hmmm. That means any testing done is inaccurate? Well, that would be a kicker.

Hubs recently inspected he serpentine and thought it was tight enough, looks good, and not squealing. It was also replaced about 20,000 miles ago. 

Funny you mentioned voltage regulators--I was just reading up on them last night after posting since I don't understand the charging system at all. Still don't understand much but now want to look into that further. Thanks!

 

[highdesertranger]

a big winch can pull in excess of 400 amps. my Warn M8274 has a ratting of 480 amps at full line pull. anybody that is not running dual batteries for that doesn't know what they are doing. plus unlike a starter motor a winch is a contentious draw sometimes for minutes. a winch needs a high amp draw for an extended period of time. there is no alternator that I know of that can keep up with that. custom built stuff usually fails.

sorry about the confusion with the battery testing. actually Spiff is correct about testing. I was referring to how we used to do it in my shop. we would charge the battery until full and then let it sit overnight disconnected of course and test it in the morning. we would check the voltage and then do a load test. high load for a short time depending on the CCA(Cold Cranking Amps).

highdesertranger

 

[PineyCruisin]

Spiff: Looks like I'll have to get a better tests done because none of this was tested at Pepboys. From the test result sheet given to me, it appears everything was tested with only short cranking load in mind. There is a chart given under "Charging System" with the y-axis being voltage (and "Ripple 35mV" label) but have no idea what is represented by the x-axis so do not even know what this is testing. Certainly, no mention about rpms. I'm going to see why this wasn't included with the system test since I specifically asked Pepboys to have alternator tested to see why it can't handle the accessories at high rpms. If not there, I'll have it done elsewhere.

 

[bullfrog]

A simple way to tell if it is the battery is to substitute it with a known good one. It sounds like your battery has been run extremely low several times? Years ago I worked at a Mercedes dealership and fought a disconnect switch for hours. It was a parade car and immaculately clean as was the switch on the outside. The battery had been unable to charge due to the corrosion and when it finally went bad and wouldn’t start they brought it in. After finding the switch which I wasn’t informed it had I tested the battery, it passed but barely. I asked the parts manager to replace it and showed him the test sheet. He said he could not replace it based on the test. He pulled out a large hammer and beat the battery till it cracked around the post and said now I can replace it and gave me a new one! I would recommend you purchase a second battery and insure it is fully charged as well as charging the old battery and having it load tested at someplace like Batteries Plus. Newer vans have many small loads that include interior lighting, computer, radio and etc. Having a house battery that is isolated from the system is a good idea. The less load you put on a battery before fully charging it the better in most cases. I would install the new battery in the vehicle and have the charging system checked including voltage drops. There are discussions on disabling the interior lighting on line if you need to have the doors open so much it discharges there battery. You need to know how many watts you will use on your house system to determine your needs. A monitoring system for the house battery might be a good idea. In my opinion larger cables are always better until they become difficult to run, but that is just me. Once you know your needs the cable size can be determined and how large the system needs to be. Using the vehicles charging system usually takes a good 4 hours of high speed driving to fully charge a battery, not really a good primary system for charging a house battery unless you do drive 4 hours daily. The battery acts as a buffer and storage for power, you may just be running your battery too low for it to recover.

 

[PineyCruisin]

[font=Tahoma, Verdana, Arial, sans-serif]From all the responses, my next plan of attack is to have the following tests done:[/font]

1. [font=Tahoma, Verdana, Arial, sans-serif]Capacity-time test on the battery[/font]
2. [font=Tahoma, Verdana, Arial, sans-serif]Alternator test that is specifically measuring output under load at various rpms.[/font]
3. Measure Voltage drop across the battery/disconnect switch

Thanks so much, everyone! I'll let you know what the results to these are.

 

[tx2sturgis]

Hmmm. That means any testing done is inaccurate? Well, that would be a kicker.

Did I say that? NO I did not say that. What I said was:

"If by chance your vehicle has a current shunt on the negative post this might slightly change the readings you get with other test meters"

And it depends on how and where the measurements are taken.

If your battery does not have that shunt on the negative post, then disregard.