Just havin' a little fun with ya

 

OK, another little update...

Last night, I got the Pathmaker unit mounted (temporarily) and all hooked up to both batteries. I was happy to see that it appears to be in good working order so far. Tonight, I got my accessories hooked up to the aux. battery. I need to put a drain on it so I can verify that the disconnect is working when it should. If the Pathmaker passes the preliminary testing, it will get split into two components - the control board and the relay. From what MNBOY said, Xantrex has verified that it is okay to seperate the two and mount them remotely from one another. So, the control board will go in the cab, and the relay will stay in the engine bay (and get water proofed).

 

I was under the impression that our toyota alternators have external sensing and they can compensate for the 0.6volt drop provided an isolator with a excitation terminal is used. The excitation terminal (the 4th terminal on a 2battery isolator), is connected to the red wire in the alternator harness and 'feeds back' the true battery voltage so that the alternator actually puts out 0.6 volts MORE so fully charge the batteries. Can anyone agree or disagree on this?

Brad

 

I dunno - great question - anyone know? I read/was told that the alt's were internally regulated, and there was no place to hook up the sense wire. That would be great if there was.

OK, while I'm here - another quick update - the control panel on the Pathmaker has been relocated to the cab, and the solenoid has been permanently mounted in the engine bay. I need to get some longer screws to finsih the mount for the panel in the cab... but it's coming along nicely.

 

Its my understanding from talking to the Tech at SurePower that what you say is true, BUT in real world testing using the Link 20 dual battery monitor, I feel the the excitor terminal only see ONE battery, not both. Again I was told by the SP Tech that the isolator sees both batteries. I only use my aux battery 10% of the time, so the reduced charge it gets 90% of the time keeps it full charged and ready to go the other 10%. Of course that is a WAG on my part, but after 2 years of use I never had any trouble. I always thought it would be a good idea to trickle charge the aux battery, but not something I've done yet.

I would sure like to hear feedback, if anyone knows or thinks one way or the other.

BTY the Link20 was loaned to me for about a month and I no longer have use of it.

Keep up the good work there Baja and keep us posted

 

AHA!

Thanks pal will do

(By the way everyone... WAG stands for "wild ass guess"

 

Do you think the results you saw with the Link20 tester could be because of limited current output by your alternator? Additionally differences in battery voltage and resistance (both internal and in the power wires from the isolator to the batteries) will cause a disparity in the charing current. If the stock alternator is barely able to keep the main battery charged, then it is going to have an even more difficult time keeping the aux battery charged.

I'm going to email SP and ask them how the excitation terimal actually works.

Also- about the alternator putting out 0.6volts more to charge the batteries-- does anyone know if this is bad for an alternator to put out more than 14.4 volts??? will it break faster?

brad

 

Brad, Maybe.

The amp & volt reads from the shunt showed I was adding more than the draw was on both batteries.

I was NOT real impressed with the Link20, but I'd sure like to HAVE one. Since I didn't have an unlimited amount of time with it, I just recorded the data. But the Amp-hour Consumption reads could not have been right.

One of these days I'd like to sit down with an elec. eng. and see what could be learned from the records I made.

To see the Link 20 Dual Battery Bank Monitor go to.

www.heartinterface.com

 

Well the voltage at the alternator has to be higher than at the battery otherwise you'd be discharging the battery into the alternator.

I'm not an electrical engineer but I do know a bit about them (I'm a bioengineering grad student)... so if you can figure out a way to post the results or send me the results then I'll be like to look at them.

Brad

 

and I quote:

"On Nippondenso alternators with internal regulators need power to be present on the output bolt of the alternator in order for the alternator to turn on and stay on while the engine is running. The E terminal is an extra diode that is in the forward direction from the E terminal to the A terminal iside the isolator. The sense circuitry is a separate function and is only there to provide the regulator with an indication of what the actual battery voltage is and will allow for the .8 voltage drop across the isolator."

Basically the external sensing of battery voltage and turning the alt on/off are indepedent but are using the same wire for convience. When the isolator is installed, the diodes between the alt and the battery prevent voltage from 'appearing' at the alternator output post. However, the ND alternator needs voltage at the output post to turn on (excite the stator fields?) and so surepower has to provide a connection between the battery and the alternator output post. They do this by using a small diode that allows current to flow from the battery, into the isolator, out the alternator-post and then to the alternator output-post. Surepower instructions say to use the ignition wire that runs between the fuse box and the alternator-- this is the wire the allows the alternator to sense the battery voltage and control the voltage of the alternator accordingly. SP probably recommends this wire because 1) it is switched 12v, so it doesn't disapiate power all the time, 2) it is already conviently located in the alternator wiring harness.

Also- because alternator output is controlled by the voltage on the ign-wire in the alternator wiring harness, the output voltage will be controlled by whichever battery the ign-wire is connected. If you havent fiddled with the wiring, the ign-wire will be connected to the primary/starting battery. Therefor, the alternator can only 'see' the voltage of the primary battery. If the aux battery is completely dead and the primary battery is full then the alternator would turn off because the primary battery is full. However, all that is needed is a bit of a drain of the primary battery (like sparking plugs) and then the alternator will turn on. Since the 'dead' battery has a much lower voltage than the primary battery, it will receive the majority of the current from the alternator. Once the 2nd battery voltage increases (because it is charging), the current will go more to the 1st battery, bringing it closer to the max voltage (14.4 I think) and that will cause alternator output to go down. So the alternator does only 'see' the first battery, but the alternator output is definitely reflective of the state of both batteries.


Hope this helps, it sure helped me.

Brad

 

Brad

Who did you get that from? Who did you quote?

That is helpful. I feel thats what happens, but its sure good to see it in print.

Thanks

Steve

 

The quote is the response to an email I sent to TechSupport@surepower.com.

There wasn't a name signed on the email, but it came from the same address (TechSupport@surepower.com).


Brad

 

Ok thanks.

I had called SP, and talked to the guy. That may have been what he was trying to say. You email had a much better reply, that i comprehend better.

The bottom line is mine has been fine for the last two years, so I'm happy.

 

Steve, if you have the records you got from the link 20 as a computer file, E mail them to me and I can tell you what they mean. I used to do quite a bit of battery and charging system testing and am used to interpreting the data.

The bottom line for all this is that you are correct, even with an external sensing wire you are only getting true voltage from one battery, but it doesn't really matter. Most car and truck systems are charging at about 14.2 or 14.4 volts. Your battery will top out at about 13.6 or 13.8 at full capacity, so the .6 volts drop won't even be noticed. If you know someone that has a good quality battery charger you can check your batteries by disconnecting the wires in the truck and hooking up the charger. My guess is it won't run for more than an hour even with a low capacity charger before showing your batteries fully charged. You can tell a good quality charger if it says three stage charging somewhere in the description.

 

No, all the info is hand written. E-mail me and maybe we can work out something.

steveanita@worldnet.att.net

Since I'm not having any trouble with either battery, this is a real "back burner" project for me. I'm hoping the info will help someone else at some point. Just something on my to-do list, but if you have the time, I'm up for seeing if there is any useful data there.

Thanks for the charger / test info.

I was thinking (if I ever had trouble) I would use a battery load tester and see what kind of loads each battery would handle. This could avoid the risk of mesureing some false surface charge, like I might with a volt meter. I like the charger idea.

 

OK guys, help me understand this.

********
"... The E terminal is an extra diode that is in the forward direction from the E terminal to the A terminal iside the isolator. The sense circuitry is a separate function and is only there to provide the regulator with an indication of what the actual battery voltage is and will allow for the .8 voltage drop across the isolator."
********

OK, so the SP isolator has "sense circuitry" that will indicate the "actual battery voltage" to the internally regulated Nippondenso alternator? Is that what he/she is saying here? He says the sense circuitry is a seperate function - seperate from what?

********
"Basically the external sensing of battery voltage and turning the alt on/off are indepedent but are using the same wire for convience. When the isolator is installed, the diodes between the alt and the battery prevent voltage from 'appearing' at the alternator output post. However, the ND alternator needs voltage at the output post to turn on (excite the stator fields?) and so surepower has to provide a connection between the battery and the alternator output post. They do this by using a small diode that allows current to flow from the battery, into the isolator, out the alternator-post and then to the alternator output-post. Surepower instructions say to use the ignition wire that runs between the fuse box and the alternator-- this is the wire the allows the alternator to sense the battery voltage and control the voltage of the alternator accordingly. SP probably recommends this wire because 1) it is switched 12v, so it doesn't disapiate power all the time, 2) it is already conviently located in the alternator wiring harness. "
*********

OK, so if I understand this correctly, the SP isolator has sensing circuitry that reads the actual voltage from the battery (which one? or both?) and sends this information to the ND alternator via the OEM power wire between the fuse box and the alt?

*********
"Also- because alternator output is controlled by the voltage on the ign-wire in the alternator wiring harness, the output voltage will be controlled by whichever battery the ign-wire is connected. If you havent fiddled with the wiring, the ign-wire will be connected to the primary/starting battery."
*********

So, this ign-wire is the wire mentioned above - from the fuse box to the alternator?

*********
"...Therefor, the alternator can only 'see' the voltage of the primary battery. If the aux battery is completely dead and the primary battery is full then the alternator would turn off because the primary battery is full. "
*********

Does this answer my question above - if the SP sense circuitry sends info to the alt. indicating voltage from one battery or both - looks like only primary battery according to this?

*********
"...However, all that is needed is a bit of a drain of the primary battery (like sparking plugs) and then the alternator will turn on..."
*********

If this is the case, then as long as the engine is running, the alternator is running? The alternator just varies the output according to the charge on the primary battery, so if it is fully charged upon starting the vehicle, only a trickle of output will come from the alternator when only the engine and full-time on board stuff is active (no accessories)? Would this effectively prolong the charge time for the aux. battery, since the depleted voltage on it is not "seen"?

*******
"...Since the 'dead' battery has a much lower voltage than the primary battery, it will receive the majority of the current from the alternator..."
*******

Majority of "how much" current? If the alternator doesn't know the aux. battery is dead, how will it know to put out max current? Will the aux. battery only receive the majority of a limited current?

*******
"...So the alternator does only 'see' the first battery, but the alternator output is definitely reflective of the state of both batteries. "
*******

How can the alt. output definitely reflect the state of both batteries if it only sees the first battery?


I'm not trying to be a stick in the mud - I just want to understand this because I'm kinda confused.

 

Oh yeah, by the way, I finally have the Pathmaker control board mounted in the cab, and the solenoid unit mounted at the firewall in the engine bay. It was a successful surgical separation I will get some pics posted as soon as I can. I have a cover that I made for the control board, that will help protect it, with a "see-thru" hinged face plate to access the controls.

I still need to clean up my wiring under the hood and make it look pretty (as pretty as I can anyway).

 

Wow lots of questons, lets see if I'll be much help. The SP Isolator only read the main (stock) battery's charge. The Denso Alt. is an on-off charging unit, as in all-or-nothing. I think knowing that will help answer all of your other questoins, but I could have missed a few. Let me know, but at any rate I've confused you even more.



Man I kind of bummed at this site. I posted some questons (twice) about manual hubs and didn't get one reply. I would have thought someone would respond, even to tell me I wasn't clear as to what I was asking. (guess I need a whiner e-con here)

 

So, are you saying that as long as the engine is running, the alternator is putting out full power? What keeps the battery from overcharging then?

I don't think I saw the manual hubs post. I have been on the road for awhile so I haven't been around much. Hey folks - we need to get to Steve's manual hubs questions - let's BUMP it.

 

Once the battery is full the alt shuts off. after the battery drains the Alt turns back on. I think the older alternators maight have had current control but thats kind of a waste of fuel. Once the battery is full and you shut off the alt. you are no longer using HP to turn it.

We can email back and forth about this if I'm not making it clear.