Sterling "Alternator Lineariser"

[john61ct]

Originally Posted by a64pilot

set the voltage of the alternator to the LFP charge voltage and it would just flow through the lead battery

Nothing "flows through" the lead battery, it just stops accepting any significant current.

> small cheap battery, if you hold it above float voltage, something bad may eventually happen, don’t you think? Or even hold it well below float isn’t good either. Then there is why in the World after spending thousands of dollars on your LFP system, would you cheap out on one component?

So get an expensive one. It really matters not, you are aware of the variables, you make the choice that makes sense **for you**.

IMO if the lead is there **only** to replace this gadget's functionality, cheap is better, easy to put a new one in on a schedule if I were worried.


> Some have said there is no charge at float, that is incorrect, anyone with Solar has seen good charge at float voltage

Means its settings were not adjusted properly.

> it’s not usually until later in the day that bank voltage climbs into absorption level

That is not Float stage, but CC/Bulk, source "striving" to reach the CV/Absorb setpoint.

> ideally a lead acid battery inline with an LFP bank if the charge voltage corresponded to the lead float voltage

That's already the case for lots of normal batts, cheap or pricey.

[john61ct]

Originally Posted by Dockhead

Sure, but even if you can get a lead battery into the picture, how do you make this work?

I see no difficulty with either.

> So if you regulate the alternator for lithium, and connect it to the lithium bank, in order to get the full alternator output into the lithium, what then?

Yes what then? No B2B. What problem are you positing?

> The B2B chargers are not supposed to be used without the first "B"

You mean no battery on the source side? That's what Charles designed this gadget for.

> I thought they had an override for use with regenerative braking.

Not sure what override that would mean. AFAIK there is no interaction between the ECU and the B2B. It is just designed not to mess with those Euro-style efficiency optimizations, while the old-school methods do and thus don't work for those modern vehicles.

While the B2Bs will even work just fine with a Prius, any 12V source.

But none of this has to with the topic, nor even boats.

> In any case, perhaps an easier solution to this would be to use one of Sterling's Alternator-to-Battery chargers, instead of the B2B charger.

Sure, but for me downside is now you are only conditioning that Alt output, rather than being able to use your purchase with any source, perhaps in other contexts decades later.

Plus dunno if user custom setpoints are available as with the BB line.

> If you don't plan to do that much, you could simply run the regular charger (separate for lead since the charging profile is different) via the inverter.

I've always hated that idea in principle, DC to AC back to DC, crazy inefficiency. But people do it. . .

[hellosailor]

Those cheap little $20 SLA's are old standard commodity grade technology by now. They rarely catch fire or explode. In fact, it has probably been 20 years since I had one of them courageously blow an internal fuse link, sacrificing itself to save my computer UPS, and thereby the entire building, during a lightning surge while I was gone for the weekend.
That one was a Panasonic, but I think many if not all of them have the same invisible internal fuse link.
I've used a 17A SLA (free surplus but probably $30 discount new) to jump start a small marine diesel. They're faithful servants, they don't complain much. A real surge protector or spike protector would certainly be smaller, cuter, and cheaper, but it couldn't be more faithful and well-behaved.

[rgleason]

I just read Drop-in Lithium Batteries as suggested.

John wrote:

If you aren't striving for much longevity and if there is a lead battery in the alternator circuit, you're probably fine.

If the internal BMS can isolate without warning, can fry an alt or sensitive load devices. Using high voltages from stock lead charge sources will mean a drastically shortened lifespan.

23 years ago, I installed a ZapStop on my new Balmar Alternator to protect it from frying the diodes when and if someone incorrectly switched the 3-way to Off because I did not have it directly connected to the house bank as is now recommended. The zapstop is still on the alternator and will remain there, as it does not hurt anything.

I still don't know why that would not protect the alternator in the event the drop-in LFP BMS shuts down the battery, but a small SLA battery sounds like a good idea too. Is it the AC ripple that is the issue? I would think you'd want the charge sources connected to the LFP particularly to take advantage of the high acceptance and shorter charge times.

Here Delfin's drop-in LFP with BMS which provides an Alternator disconnect does not seem difficult to accomplish.

Removed the AGM, dropped in the LFP bank in the same box, wired the LFP up to the BMS, ran the ignition wire on the 624 through the BMS port provided, reprogrammed the charge profile of the 624 and Trace and that was it. The LFP bank is wired as the house bank, as was the AGM bank.

[hellosailor]

rg-
"I still don't know why that would not protect the alternator in the event the drop-in LFP BMS shuts down the battery,"
For the same reason that installing a water filter would not protect your engine from overheating.
Huh? Yeah. think about it, the one thing (filter) has nothing to do with the other (heat).
The Zapstop is there to shunt a SPIKE. That's all. If the BMS disconnects the batteries, yes, that may produce a spike (every time a relay opens it creates a spike and proper design includes a clamping diode or other device to absorb that). But more important, when a BMS disconnects the battery, the alternator sense wire is going to tell the alternator "Hey buddy, we're not seeing 14.4 volts here, you'd better ramp up the voltage!" and typically within one minute of that, the alternator is putting out 17 volts and burning itself out--along with all of the electrical devices still connected to it.
Nothing to do with spikes and surges. The Zapstop does *nothing* to prevent a runaway alternator, which is what you get when the batteries are disconnected from the sense lead.
Now, if you have a "one wire" charging system where the sense lead is tied back to the alternator output...you may avert that crisis, but you'll never be charging right anyway. That's a whole other kettle of day-old fish.

[a64pilot]

Flow though or flow around, is irrelevant. The battery functions as a capacitor, and has a lifespan.
SLA or SLAB actually is an AGM battery, nothing more or less.
Do you know what the proper float voltage for one is? If so drive on, or don’t. I guess you could measure an exit signs voltage when power is on, cause that is what most of those things are used for.
I just can’t see the logic in installing a cheap possibly failure prone link in an expensive system is all.

[rgleason]

Originally Posted by hellosailor

rg-
"I still don't know why that would not protect the alternator in the event the drop-in LFP BMS shuts down the battery,"
The Zapstop is there to shunt a SPIKE. That's all. If the BMS disconnects the batteries, yes, that may produce a spike But more important, when a BMS disconnects the battery, the alternator sense wire is going to tell the alternator "Hey buddy, we're not seeing 14.4 volts here, you'd better ramp up the voltage!" and typically within one minute of that, the alternator is putting out 17 volts and burning itself out--along with all of the electrical devices still connected to it.
Nothing to do with spikes and surges. The Zapstop does *nothing* to prevent a runaway alternator, which is what you get when the batteries are disconnected from the sense lead.

Very interesting. What would happen if I were to turn the 3way to "Off" rather than through "off" to the other bank? Wouldn't that be the same thing as the BMS simply disconnecting the LFP batteries?

So the Zapstop is not really fully protecting the alternator!


Also please Note this Delfin post 247:
I also seem to recall that when I bought the Ample Power alternator, it had protective diodes (?) that prevented a disconnect from a destination battery causing any harm, but I can't remember the details....


---Sorry about the off topic diversion.

It is clear the sense/field wire must also be disconnected at the same time as the BMS shuts the LFP down or just before, unless there is some other battery which is also connected, or unless the switch signal automatically connects an LA bank (then the alternator field wire can stay connected).

Thus any good BMS must have this signal.

I can see at some point that we will need to have "dual" program regulators that will switch with a low voltage signal on no/nc contacts.

[rgleason]

Zenor Diode (zapstop) will eventually fail with a disconnection of the battery bank.
hellosailor post #39

Yes, a continuous overload would blow up the diode, or any spike absorbing device. But we're looking to clamp transients that may be on the order of 1000V for a couple of microseconds, and a properly selected diode or other spike protection device should be able to take typically several hundred or thousand hits on that scale. They don't heat up and explode instantly, you need to keep the load on them way longer than one spike incident.

[john61ct]

Originally Posted by rgleason

Is it the AC ripple that is the issue?

Charles uses it to promote this gadget.

IMO only with B2B with no batt on input side, which I've never come across as even a theoretical concept before.

The batt eliminates the issue afaik

[Dockhead]

Originally Posted by john61ct

> In any case, perhaps an easier solution to this would be to use one of Sterling's Alternator-to-Battery chargers, instead of the B2B charger.

Sure, but for me downside is now you are only conditioning that Alt output, rather than being able to use your purchase with any source, perhaps in other contexts decades later.

Plus dunno if user custom setpoints are available as with the BB line.

> If you don't plan to do that much, you could simply run the regular charger (separate for lead since the charging profile is different) via the inverter.

I've always hated that idea in principle, DC to AC back to DC, crazy inefficiency. But people do it. . .

The Sterling A2B chargers have good pre-programmed lead charging profiles. It can also be turned on and off via a remote control. Don't know if they can be programmed for lithium, but that's not how I would use it anyway.



With the alternator regulated for lithium but also connected to one of these charging a lead bank, all of these alternator problems would seem to be solved.


The only thing is you couldn't charge from battery to battery without going through the inverter, and you couldn't shut down the alternator to stop charging the lithium when it's full. I guess it would be easy enough to simply disconnect the lithium from the alternator with a contactor, and since the alternator remains connected to the lead bank via the A2B charger, there would be no danger to the diodes.


This seems to me like a good solution, pretty straightforward, with one minor drawback which would not really be a problem if you're not cycling the lead a lot. And after our tail charge efficiency epiphany, I don't think tail charging a lead bank from lithium battery power is of much use anyway.



Looks to me like the best architecture yet for a hybrid bank where the lead is used just as a reserve bank.

[john61ct]

Sounds good for you then.

I don't spend money anymore on charge sources without user-programmable setpoints.

Want future proofing, even Firefly needs that, and other chemistries will come.

Not sure if mentioned for you to check out

iCharger 4010-Duo

40A max, but takes 24VDC source, can be used for balancing cells, any 12V range, also controlled discharging, load tests etc.