80A Alternator and 'drop in' LFP?

[mitiempo]

Originally Posted by Scrimma

Tha la for that! I had read that before, but I guess I should explain why I'm still confused. If my Hitachi will get warm very quickly as my lithium will try and draw 80A constant out of it, then my alternator will begin to drop it's output to protect itself...that means my alternator will not continue to charge my batteries based on that info correct? To me, that sounds as if my alternator will just become useless shortly after starting the engine when it heats up too much. Does that mean due to alternator voltage dropping, that there is in fact no risk to the alternator itself? It will simply get warm and decrease it's output and not be over worked?! (Allbeit ineffective at charging the LFP as a result...)

I will have plenty of solar and also a generator to put amps back into the batteries. I just need to upgrade my charger to lithium algorithm capable...?

First of all realize that your (or any other engine supplied) Hitachi alt is really only designed to replenish a start battery. It was not designed for deep cycle battery charging. Lfp is the worst kind of deep cycle work for an alt assuming a larger bank as it will accept just about all you can throw at it.

Many Hitachi and similar alts have been destroyed in short order when owners changed to AGM batteries without any other charging changes. Lfp is worse.

If you add an external regulator (Balmar MC-614 for example) and derate it to half its output it will still get too hot - it will just take a bit longer.

Better to get a good aftermarket alt from Balmar or other company and the external reg that can be adjusted for voltages, derating, etc.

[tanglewood]

Originally Posted by Scrimma

Thanks for the tip. Although I would assume these B2B would only be flowing current and in one direction when under power when the engine is running? I'm no electric wiz, and not sure how that would work, but seems like something that would be in place in these expensive electronics?

Don't assume. The flow of power is unchanged, flowing from the start battery to the house battery, with the alternator charging the start battery.


Some devices have the smarts to only turn on when the power source voltage rises high enough to indicate a charger is active. The Sterling product may do that, but I wouldn't assume.

[john61ct]

Yes nearly every DCDC only works while the charge source is active, voltage elevated, no need for a separate VSR.

Sterling gives a manual start option, but very rarely used.

Since Starter is Full, the flow is from the Source not from the Starter, in effect the latter is just a buffer, energy does not flow "through" it.

[NahanniV]

Originally Posted by Scrimma

My question is, how 'DROP IN' are lithiums these days really? And will my alternator need regulating to say 60A to avoid overheating? How would I go about regulating that?

If your alternator has an internal regulator it will most likely protect itself from overheating by limiting output.
External regulators need to have a (usually optional) alternator temperature sensor.

If your alternator will overcharge the lithium batteries is another question.

[CapnBazza]

Originally Posted by Scrimma

Haha yes it can turn into a science experiment rather quickly. Moving onto my boat with the wife is definitely about having a coldicoldie on a hot day and exploring all the ocean has to offer, rather than fretting about every little detail. It's good to hear your set up is going well. Ill have 660w of the highest efficiency panels on the market pushing up to 50A and regularly 40A+ from the MPPT to the batteries so I will depend on alternator changing very rarely. I would need to upgrade my battery charger though if I wanted to run the portable generator as it's old school and cannot be programmed for lithium.
I wonder how long is ok to run my Hitachi 80A alternator at 100% before it starts to do damage to the alternator...
I can in the mornings before the sun is up, having to leave an anchorage and therefore running the engine for a good 30mins or so. Or, potentially more if we need to motor out a long ways.
As long as my alternator knows not to overcharge the lithium if I have to motor for an hour or 2 when the batteries are close to topped up....thoughts?

Sorry mate, I can’t help you with Hitachi alternators. Mine is an 80amp Bosch and the longest I have motored in one stretch would be about 30 hours. The alternator is connected to a Yellowtop engine battery, then, through a VSR to the house lithium batteries. Dead simple, dead easy, just gotta check our supply of shiraz now .....

[john61ct]

The overtemp protection on stock alts effectively stops charging.

A specialized external VR like Balmar MC-614 is required to maintain the voltage setpoint, and lower the load by derating current only.

[NahanniV]

Originally Posted by john61ct

The overtemp protection on stock alts effectively stops charging.

A specialized external VR like Balmar MC-614 is required to maintain the voltage setpoint, and lower the load by derating current only.

I now have two different first hand experiences with stock alternators charging lithium batteries.
One an ancient Leece-Nevil and the other a Bosch.
Both limited their output when warm.
They did not stop charging.

current and voltage are linked by ohms law.
You can not maintain voltage while derating current.
You can not maintain current while derating voltage.

The problem I see with the internal regulators is that they can overcharge Lithium if you are motoring for a long time or the batteries are already full; You need some mechanism to handle that. The Balmar regulator can do that.

[NPCampbell]

There have been "drop-in" auto and motorcycle batteries for almost 10 years now. When I bought my motorcycle in 2012 the best weight reducing mod for the money was a lithium battery drop in (it saved 7 pounds). However, the BMS at the time sucked and bricking protection was iffy. I'm glad I didn't I didn't get one as I have left my lights on a half dozen times. However ,the batteries now typically have discharge, overcharge, temperature and bricking protection as well as cell-to-cell balancing built-in.

In autos, it works with the existing alternator and is proven. In your scenario with mixing battery technologies, and inverter/alternator/generator ... I dunno.