Do I need an alternator protection device when switching to Lithium?

[senormechanico]

Originally Posted by john61ct

As a side note, I have yet to find an LFP mode I would use on a bank I care about.

The key attribute for a LFP charge source IMO is user-custom adjustable setpoints, not just a menu of "canned" predefined choices.

John, you remind me of a true story from the 1970's when as an electronics repair tech, I told a new customer his black and white portable TV was not worth fixing. He was a well dressed guy, and I offered him a deal on a new Zenith color portable. He said (and this is a direct quote I'll never forget),

"No thanks, I'm waiting for 3D color TV."


I assured him that even though the new set was a good one and he'd get many years of satisfaction of ownership from it, he'd almost certainly be ready for another TV by the time 3D came out. He was surprised by my comment, and purchased the new TV.


So, John, just jump in to the pool of LiFePo4 ownership. The water's fine.

[Stu Jackson]

Originally Posted by Oceanride007

--Quote (Originally by Oceanride007)---
>>>>>>>>>>>

.........but thinking I may be able to *run a small charger thru a inverter* from LA, if I want more or the other way around.

>>>>>>>>>>>>>>>>>>>>>>>>
---End Quote---

>>>>>>>>>>>>>>>>>>>>>>>


And your issue is?

No issue, just thought that when I first read it because it was standalone with no explanation of using shorepower at the same time.


No issue, no problemo.

[StowawayJoe]

Originally Posted by john61ct

Simpler is better.



Just put a lead batt direct inline with alt output all the time, if that's Starter fine. What is "normal", a simple VSR closes the connection to House based on

Won't this overcharge the lead acid battery? Can you mix battery technologies on a common bus?

[Oceanride007]

A factory installed Alternator would be OK for charging a LA battery any size, but you can't have it connected to in common with LFP.



On charge the LFP will take more from the alternator and at slow revs alternator won't have adequate air flow to prevent the alternator from burning out. (Unless you go to clever Regulator).


On Discharge the LFP battery will be a higher voltage than the at rest LA battery and because the LA battery has losses, you will drain House battery thru the start battery.


Not sure a one way VSR is designed adequately, would want it to close the circuit at >13.2v sensed from LA battery, but stops current from going other way, needs charge limiting as well. Don't know if one is available. John61ct not been around for a while.

[CatNewBee]

You don't need one. Stock alternators just doing fine with LFP, I have 2x 80A Hitachi stock alternators with internal regulation on my 2 Yanmar 40Hp Engines, they are doing fine with the battery isolator FET splitter to charge the start batteries and yeld about 40A each to the 1000Ah massive LFP house battery without getting damaged now for the 3rd year.

But if you have spare money and dont trust the bank, you can buy fancy devices and add them to your alternator in the engine compartment.

There are many different ways to configure your charge system depending on your use profile. Just be consistent.

[Simi 60]

I'll tack onto this thread as it came up while searching and I believe I "may" have a similar issue but without the lithium batts.

We gave a 4 months new 70 amp alt on our 855 cummins
We have a victron Cyrix battery combiner
All has been working fine until a couple of days ago when I noticed walking past the engine that the alternator is still warm, engine is cold and off.

Google led me to believe blown diodes and screwdriver sticks to pulley.
Would/should an alternator protection device have been added to this install?
And what, apart from slowly draining batteries, would be the result of not doing anything for a few months? (boat comes out of water for two weeks then)

I do have a trickle charger lead from the victron inverter/charger that I can connect in minutes.

[Flod]

Originally Posted by Simi 60

I'll tack onto this thread as it came up while searching and I believe I "may" have a similar issue but without the lithium batts.

We gave a 4 months new 70 amp alt on our 855 cummins
We have a victron Cyrix battery combiner
All has been working fine until a couple of days ago when I noticed walking past the engine that the alternator is still warm, engine is cold and off.

Google led me to believe blown diodes and screwdriver sticks to pulley.
Would/should an alternator protection device have been added to this install?
And what, apart from slowly draining batteries, would be the result of not doing anything for a few months? (boat comes out of water for two weeks then)

I do have a trickle charger lead from the victron inverter/charger that I can connect in minutes.

I don’t think you have the same problem. The bms used in lifepo4 setups can suddenly disconnect the battery when its full. Then the alt will go from full power to zero in a fraction of a second, this will blow the diodes and damage the alt. Agm / lead don’t do this. They have high inner resistance when getting charged and quite quickly reduces the amps but will not cut off. You might have overheated the alt or you might have manually switched of the battery main switch during full load or something but you don’t have the same setup issue as the OP

[Simi 60]

Originally Posted by Flod

I don’t think you have the same problem.

I know I don't have the same problem, I said similar.
Similarity being alternator, batteries and diodes.

The bms used in lifepo4 setups can suddenly disconnect the battery when its full. Then the alt will go from full power to zero in a fraction of a second, this will blow the diodes and damage the alt. Agm / lead don’t do this.

I was thinking along the line that the Victron Cyrix combiner will flick from charging starts to charging house in a fraction of a second and surge "may" cook diodes in alt.?????

You might have overheated the alt or you might have manually switched of the battery main switch during full load or something

.

Its a large frame alt in a well ventilated ER and during my 2 hourly ER walk around I put my hand on the alt
Hot, but not ouch hot.
House banks never gets below 80% SOC and it would have had solar assist during the day.
I have never manually switched the batts off so don't think this is the cause.

[Simi 60]

Further to the above post saying.......

Its a large frame alt in a well ventilated ER and during my 2 hourly ER walk around I put my hand on the alt
Hot, but not ouch hot

Changed anchorage this morning (20 minutes run)
No noticeable amps going in so figure it was early solar

Anchor down, checks alt and it is ouch hot.
Shot it with laser thermometer and it was reading 94c

Disconnected alt and taped up cables
Connected trickle charger to starts

There is a noticable pong in the air which could be electrical
But I did start painting the engine several days ago so was initially putting it down to that smelling when hot.

It's worked for 20 weeks so that would imply my bit was ok and alternator fault??

[stormalong]

Originally Posted by Simi 60

I'll tack onto this thread as it came up while searching and I believe I "may" have a similar issue but without the lithium batts.

We gave a 4 months new 70 amp alt on our 855 cummins
We have a victron Cyrix battery combiner
All has been working fine until a couple of days ago when I noticed walking past the engine that the alternator is still warm, engine is cold and off.

Google led me to believe blown diodes and screwdriver sticks to pulley.
Would/should an alternator protection device have been added to this install?
And what, apart from slowly draining batteries, would be the result of not doing anything for a few months? (boat comes out of water for two weeks then)

I do have a trickle charger lead from the victron inverter/charger that I can connect in minutes.

Most likely your alternator is still powered. Do you have an external or internal regulator? In either case the alternator gets it's field voltage through a regulator that is normally activated by the ignition switch, or maybe and oil pressure switch. If that regulator is active the alternator shaft will be magnetic and it will be warm. One possibility is that you stopped a diesel engine with a stop solenoid or pull stop and didn't turn off the ignition. On most engines an oil pressure alarm will sound if you did this.

[Simi 60]

Originally Posted by stormalong

Most likely your alternator is still powered. Do you have an external or internal regulator?
.

No idea
Buys replacement same spec alt, fits it, it works until it doesnt

In either case the alternator gets it's field voltage through a regulator that is normally activated by the ignition switch, or maybe and oil pressure switch. If that regulator is active the alternator shaft will be magnetic and it will be warm. One possibility is that you stopped a diesel engine with a stop solenoid or pull stop and didn't turn off the ignition. On most engines an oil pressure alarm will sound if you did this

Oil pressure alarm is a near deafening horn forcing you to either start or turn switch off so that wasn't it.

[stormalong]

I am guessing that you have an internal regulator on the alternator. In this case check the diagram and find the lead that is energized when the engine switch is in the run position. With the engine switch in the off position there should be no voltage there. If you do have voltage then the switch is bad or there is a wiring error.

If you do not have a multi meter or do not know how to use one just disconnect that wire. If the alternator is no longer magnetic and cools off you have found your problem.

[Flod]

Originally Posted by Simi 60

I know I don't have the same problem, I said similar.
Similarity being alternator, batteries and diodes.



I was thinking along the line that the Victron Cyrix combiner will flick from charging starts to charging house in a fraction of a second and surge "may" cook diodes in alt.?????


.

Its a large frame alt in a well ventilated ER and during my 2 hourly ER walk around I put my hand on the alt
Hot, but not ouch hot.
House banks never gets below 80% SOC and it would have had solar assist during the day.
I have never manually switched the batts off so don't think this is the cause.

No, battery separators separate the battery banks from each other at certain voltages (often low voltage in the house bank) but it doesn’t separate the batteries from the alt.

[lmxr]

Originally Posted by Simi 60

[...]

All has been working fine until a couple of days ago when I noticed walking past the engine that the alternator is still warm, engine is cold and off.

Google led me to believe blown diodes and screwdriver sticks to pulley.

Blown diodes? Could be.. could also be that the installation was messed up. What is connected to the D+ (lamp) of the alternator? If you disconnect all wires on the D+ (with the engine OFF and the engine ignition contact OFF), what voltage do you measure on the wire bundle that previously sat on the D+?


stormalong already gave good advice. You could also try the following:


If you measure a voltage (in the range of the battery voltage) on the D+ cable bundle, then the alternator is getting power from somewhere, which means there are issues elsewhere. On the other hand, if you measure no voltage (< 2 V) then the alternator is powering its field not from the D+ (which does not provide power) but from the B+ (battery positive), which it can only do if its diodes are blown.

Originally Posted by Simi 60

Would/should an alternator protection device have been added to this install?

Any decent system has protections in place such that things don't go south, at least not after four months. Should that protection be in the form of an alternator protection device? Maybe. Depends on your system.

What system do you have? What existing protections for the alternator are there? How is the alternator exactly connected to the batteries? Does the starter battery always stay attached?

Originally Posted by Simi 60

And what, apart from slowly draining batteries, would be the result of not doing anything for a few months? (boat comes out of water for two weeks then)
[...]

I'm not really sure about 'slowly' draining. A field current is in the range of a few A, so it will drain the usual starter battery in about a day.

As your system clearly isn't working as it should and because the issue is related to a critical system (engines of a motorboat), I would strive to resolve the issue before making any trips.

[Simi 60]

Originally Posted by lmxr

As your system clearly isn't working as it should and because the issue is related to a critical system (engines of a motorboat), I would strive to resolve the issue before making any trips.

We have been out here cruising full time for 5 years without seeing a marina

Last time this happened , looking back with hindsight, it was probably 3 months before we noticed.

Non electronic engines and well thought out systems do not necessarily need an alternator to keep the boat going.
Nice to have for night passages, but that's about it, or at least that has been our experience for the past 5 years of full time cruising.

Alternator is disconnected and off the motor in a box.
Engine still starts and runs fine, all systems work as normal.