LFP alternator charge, LA-dc2dc in which order

[SOLAR SUPPORT]

Originally Posted by goboatingnow

If you use a dc dc converter mine has controlled voltage out and constant current control

Using both of these especially constant current restricts alternator overproduction you can then decide to charge the battery directly of feed the controlled dc into a more sophisticated battery charger I have both options but I think the dc dc would be sufficient directly.

As of yet the input has survived tests I now have my 500w electronic programmable load with me on the boat to setup more disruptive strategies

With the DC2dc charger, you can only reduce the alternator output current to the desired level. You cannot directly disconnect the alternator charge. If your dc2dc charger can reduce the alternator charge current to a safe level when the target charging voltage level is reached, it may be possible to safely interrupt the alternator charge. Is there a dc2dc device that works this way? Even the smart one needs a smart alternator to safely cut off the charge.

[goboatingnow]

Originally Posted by CaptainRivet

Can you please explain if you connect the DC2DC converter directly to the dumb alternator without external control how do you a)protect the alternator from a sudden disconnect and b)from getting overheated.

That a stock alternator like Mitzi 115A has a working internal temp control is not common, it’s the exception.

You can’t directly buy you can easily on my dc dc units reduce the current or voltage to zero in a controlled ramp

The overheating is not an issue because you just set the current limits within the desired Safe alternator limits. Ie pick a current that prevents overheating

Abrupt shutdown still needs either field disconnect or a ramp down or load divert or alternator protector. In my view simple load dump could be easily developed

Ramp down is simply turning down the current control on the dc dc which lowers the load on the alternator progressively it’s not an abrupt shutoff.

[goboatingnow]

Just to be clear
1 . The dc dc unit allows you to limit the current delivered from the alternator to the lfp keeping it within the safe limits. This is simply a safe currebtbyiu pick there no temperature compensation

The dc dc has a easy remote off on but of course load dump spikes will occurr unless the dc dc settings are ramped down I do have a way to do this but equally I’m adding a protection device to the front of the dcdv to see if it can survive the remotes turn off signal

If the dc dc can survive the remote off is easily incorporated

The other alternative isca simple load.divert and then remote off.

[CaptainRivet]

Originally Posted by goboatingnow

You can’t directly buy you can easily on my dc dc units reduce the current or voltage to zero in a controlled ramp

The overheating is not an issue because you just set the current limits within the desired Safe alternator limits. Ie pick a current that prevents overheating

Abrupt shutdown still needs either field disconnect or a ramp down or load divert or alternator protector. In my view simple load dump could be easily developed

Ramp down is simply turning down the current control on the dc dc which lowers the load on the alternator progressively it’s not an abrupt shutoff.

Could you post a link to your 80A Chinese DC2DC that have current control and ramp down.
The only 2 brands I know having that are Victron and Sterling which are both very expensive.
If it’s that easy a load dump why it’s not done yet?
Sterling has an alternator protect, kina load dump that’s a 1 timer protection if spike is high enough.
That’s why there is a lead involved with DC2DC, it’s simply the load dump and starts your engine car, RV or boat.

[SOLAR SUPPORT]

DC2dc solutions designed for secondary battery charging with alternator require the use of smart alternators. I think these devices are not only produced for use on boats. To fully understand this, it is necessary to know what a "smart alternator" is.

What is a smart alternator? These are alternators produced for land vehicles in compliance with the Euro5-6 emission standard. They work together with the device called ECU (Electronic Control Unit). ECU is an automatic control unit that reduces or increases the power that the vehicle engine transmits to the alternator when necessary. It is sensitive to vehicle acceleration, deceleration or going uphill.

ECU Allows all engine power to be directed to the wheels by turning off the charge during acceleration or climbing. When the vehicle brakes, it contributes to braking by maximizing the charging current. The operation of the ECU for fuel saving prevents the second battery bank from being constantly charged by the alternator in vehicles with a second battery bank such as a caravan. The dc2dc devices used to solve this problem eliminate the input voltage imbalances and continuously charge the second battery bank even if the ECU drops the charging voltage.

But, when the second battery bank in the vehicle is LFP, while the engine is running, the dc2dc charger will need to be turned off when the LFP battery is close to full, or it will need to be turned on again when necessary. How can the dc2dc charger do this harmlessly? Are they designed to work with LA batteries only?

There are standard and special alternators designed for marine vehicles. In order for the standard alternator to work with the devices we know as external regulators, it must be modified. I've heard of an external regulator that doesn't require the alternator to be modified.

Alternators with external regulators are already protected against overheating and therefore do not need dc2dc. External regulators should be able to fulfill the full protection functions required for the LFP battery by controlling the alternator charge, when the LFP battery charge cut-off voltage is adjusted correctly.

[newhaul]

Originally Posted by SOLAR SUPPORT

You can find the schematic below.

Should the existing battery isolator be used or replaced or cancelled? If it is to be replaced, what type of insulator should be used, argofed or mechanical?

Ok just read the whole thread and throwing out all the chaff that doesn't answer the question you asked . The only answer is C alternator FLA DC DC LIFEPO4.
All of the others have issues built into the formulas.
No automatic switch needed no manual switch desired and last the D one does not protect your alternator from a hvd issue . Also puts your fla at risk from psoc issues .

So option C is the only one that makes any sense .

[SOLAR SUPPORT]

I'm sorry, you need to give me good reasons not to trash the [C] option along with the other dc2dc solutions.

[goboatingnow]

We all agree i think the best option is a properly fitted external temperature controlled external alternator controllers , it offers complete safety and adjustability

It’s clearly the best option where budget allows.

Everything after that is a compromise

[newhaul]

Originally Posted by SOLAR SUPPORT

I'm sorry, you need to give me good reasons not to trash the [C] option along with the other dc2dc solutions.

It is the only proper option that was presented . Now there are better options for some but there are budgetary concerns to take into account . For me with a 75 amp internally regulated alternator then a 40 amp b2b makes sense for 2 reasons firstly I already have the alternator . A 40 amp b2b is not expensive and with my fla kept where it is alternator to FLA to b2b to LIFEPO4 . protects my dumb alternator and internal regulator from the possible effects of a HVD event.

[newhaul]

Originally Posted by goboatingnow

We all agree i think the best option is a properly fitted external temperature controlled external alternator controllers , it offers complete safety and adjustability

It’s clearly the best option where budget allows.

Everything after that is a compromise

Best option for some but not all

[goboatingnow]

Originally Posted by newhaul

Best option for some but not all

i do not see what situation would not make it the best option it’s ckesrky superior in all cases

[newhaul]

Originally Posted by goboatingnow

i do not see what situation would not make it the best option it’s ckesrky superior in all cases

Clearly we have been through this before it is the best option for me to use the following
ALT/FLA/DC2DC/LIFEPO4.
It checks off all of my boxes and the dc dc unit I am installing is cheaper to purchase than an external regulator that will send a signal to shut down charging before the HVD event.

But as I said that is best system for my use . Not necessarily everyone

[s/v Jedi]

Originally Posted by CaptainRivet

It’s both, one 12:24 and one 24:12…they are just place holders. Had the same issue with the diagram. So you can charge both ways and 12V starter is always full.

Indeed. I always got complaints that nobody could read the diagrams… I guess they were using a phone and couldn’t zoom in.

I will draw it correctly from here on.

But yes, there is one Orion for each way in the diagram. If you have 12V for house bank as well as start bank then you have the Orion 12-12 doing the correct charge profile for the different chemistries.

For a 24V house bank and 12V start, a 12-24 and a 24-12. I actually have two of each.

[Ballsnall]

Originally Posted by goboatingnow

We all agree i think the best option is a properly fitted external temperature controlled external alternator controllers , it offers complete safety and adjustability

It’s clearly the best option where budget allows.

Everything after that is a compromise

Well, clearly we all don't agree. Your solution is still flawed, you have gone to a lot of expense for very minimal return by using a stock alternator.

Newhaul's solution (ALT/FLA/DC2DC/LIFEPO4) is simple, cheap and effective for the vast majority of boats with a stock alternator and will produce very similar real world output at a fraction of the cost and complexity.

Put the money saved in a bigger LifePo4 bank, a much better ROI in my opinion.

For boats that require it then do it right and get a high output alternator with all the bells $$$ and whistles $$$ and not try and milk a stock alternator.

[newhaul]

Originally Posted by Ballsnall

Well, clearly we all don't agree. Your solution is still flawed, you have gone to a lot of expense for very minimal return by using a stock alternator.

Newhaul's solution (ALT/FLA/DC2DC/LIFEPO4) is simple, cheap and effective for the vast majority of boats with a stock alternator and will produce very similar real world output at a fraction of the cost and complexity.

Put the money saved in a bigger LifePo4 bank, a much better ROI in my opinion.

For boats that require it then do it right and get a high output alternator with all the bells $$$ and whistles $$$ and not try and milk a stock alternator.

How about spend all that extra money saved wrt special alternator belt kit and external regulator ., on improving solar capability .

I am considering an improvement by adding 2 200 watt panels for just over 300 they are only 1480mm long by 680mm wide. So not any wider just longer by 18 inches than current 100 watt pair . Will give me 300 watts at 24 volts tto charge my 12v lfp via my mppt .