Sterling "Alternator Lineariser"

[Dockhead]

Charles Sterling is a fountain of creativity.


Here he's come up with a device which will allow an alternator to be connected to a lithium battery system, and which will protect the alternator in case a HVC event suddenly disconnects the alternator (that presumes the primary control previously failed to shut down the alternator via the field wire).


This device also is supposed to allow a B2B charger to be powered by the alternator with no battery in the circuit.


I would have thought that if the B2B charger were designed for this use, it would be able to deal with all this internally, but I guess it's not.


Anyone use one of these? Views?




https://sterling-power.com/products/...-70f-ald-17500

[john61ct]

Originally Posted by Dockhead

I would have thought that if the B2B charger were designed for this use, it would be able to deal with all this internally, but I guess it's not.

99% use cases the alternator still goes to a lead Starter batt, so based on KISS I agree keeping this functionality separate.

I suspect an alternative fail-safe load dump solution could be DIYed very cheaply, but. . .

The no-battery possibility is interesting, but since what 60A is the biggest BB unit, would require stacking multiple ones for those with big alts.

Of course that gives flexibility if split banks are desired, can mix and match current output as the situation demands.

I wish he'd come out with his up-to 240A BB versions already, or at least the 120A.

[john61ct]

Originally Posted by john61ct

I suspect an alternative fail-safe load dump solution could be DIYed very cheaply, but. . .

Besides a little $20 SLA from Amazon that is.

Creative is a good word 8-)

[Dockhead]

Well, adding a battery is not necessarily a solution.


How will a lead battery deal with a lithium charging profile? Not well, methinks.



And for me, with 24v, it would TWO lead batteries, doing nothing but being a "load dump" -- ick.

[senormechanico]

What's in this? It sounds like a filtering system like a big electrolytic capacitor and a relay or two with maybe some winky blinky lights thrown in for effect.


I just now looked at the zoomed in pic. Yup, a big assed capacitor.

[hellosailor]

Almost all alternators still use a field exciter wire. If there's no voltage on the exciter wire, there's no voltage to the field coils, and the alternator makes no output.

It would seem like a simple and obvious thing to fit the high or low voltage disconnect in the battery management system with a simple extra relay (etc.) so that when the battery connection was opened up, the exciter voltage also was disconnected, turning off the alternator entirely.

Or shunting it elsewhere, wherever the designers' whims wanted to go.

Should be an inexpensive retrofit for most folks if they need one.

[rgleason]

John, sorry but what is SLA?
"Besides a little $20 SLA from Amazon that is."


Nevermind, Sealed Lead Acid.
So that would act as a capacitor.

[john61ct]

Originally Posted by Dockhead

How will a lead battery deal with a lithium charging profile? Not well, methinks.

Meh, NBD, why it's called sacrificial.

You're really eliminating all Starters?

[john61ct]

OP stated this is for failsafe protection in case primary HVD mechanism fails to killswitch the VR

[Dockhead]

Originally Posted by john61ct

Meh, NBD, why it's called sacrificial.

You're really eliminating all Starters?

My boat has a luxurious electrical design which includes entirely separate starting systems for main engine and generator, each with its own dedicated alternator, mains battery charger, and starting battery.


This is something lovely which I will not molest.



Anyway they are both 12v, and house and technical systems are 24v.

[john61ct]

Originally Posted by Dockhead

My boat has a luxurious electrical design which includes entirely separate starting systems for main engine and generator, each with its own dedicated alternator, mains battery charger, and starting battery.

This is something lovely which I will not molest.

Which is exactly why Charles designed them that way, require no changes to the existing setup on the source side.

12 to 24V available

https://www.sterling-power-usa.com/S...rycharger.aspx

[tanglewood]

It looks like not much more than a supercap, and even says so on the cover.


Implied in the description is that alternator output to an LFP without a parallel LA or supercap will damage the LFP. So saying the LFP as a filter in place of an LA battery will damage the LFP.


Has anyone heard of issues charging LFP directly from an alternator (assuming proper regulation)? I haven't.

[john61ct]

Originally Posted by tanglewood

Implied in the description is that alternator output to an LFP without a parallel LA or supercap will damage the LFP. So saying the LFP as a filter in place of an LA battery will damage the LFP.

I don't understand that.

> Has anyone heard of issues charging LFP directly from an alternator (assuming proper regulation)? I haven't.

Yes, guaranteed problems with 99% of stock alt setups going into a big LFP bank. Both for the alt, and the longevity of the bank. Then the load dump problem.

Either you

refit the alt setup with a setpoint-adjustable external VR with belt manager - type feature to control current limiting

usually upgrading to higher-output to reduce runtime, thousands of bucks

Or you use one or more B2B.

Then the load dump problem, IMO a $20 lead batt solves that.

[tanglewood]

Originally Posted by john61ct

I don't understand that.

> Has anyone heard of issues charging LFP directly from an alternator (assuming proper regulation)? I haven't.

Yes, guaranteed problems with 99% of stock alt setups going into a big LFP bank. Both for the alt, and the longevity of the bank. Then the load dump problem.

Either you

refit the alt setup with a setpoint-adjustable external VR with belt manager - type feature to control current limiting

usually upgrading to higher-output to reduce runtime, thousands of bucks

Or you use one or more B2B.

Then the load dump problem, IMO a $20 lead batt solves that.

I get all that, but it’s not the problem the liniarizer claims to address. It’s a filter, and Sterling is asserting that unfiltered alternator output will damage LFP.

This filtering is NOT voltage regulation or belt management or thermal management is crappy alternators. It’s about the rectified AÇ output of an alternator. Alternators are 3 phase AÇ, with diodes to rectify full wave to half wave. Connect that to a battery and you get a pulsing voltage and current. On power supplies, filter caps are used to filter the half wave AC into DC with some amount of ripple left over. With alternators, the battery is the filter.

The liniarizer appears to be 90% a filter cap, so it cleans up the alternator output without the need for a battery. As such, it’s now usable to direct power DC devices.

So back to my question, implied is that an alternator direct connected to an alternator is an inadequate filter and will damage the LFP cells. I have never heard of such a problem in practice. In fact, with the very low internal resistance of LFP, I would expect them to be better filters than LA, not worse.

[hellosailor]

tanglewood-
There are companies selling "alternator stabilizers" for the loud car stereo folks too. Same thing.
IF your alternator, with integral or external regulator, is working properly you should only be getting uniform clean DC from it. If you've ever heard "alternator whine" on a car or boat stereo, you know sometimes an alternator is leaking AC.
Take any multimeter, set it to AC, and connect it to the alternator output. You should see no AC voltage if it is working properly. Now also reverse the multimeter leads and recheck--because some multimeters are built in a way that will show AC voltage one way, and not the other, even though in theory both should be the same.

If there's no AC voltage coming through, you don't need that big filter capacitor. If you need the filter capacitor, it is just masking a problem in the alternator.