Am just finishing my first season with solar/lithium batteries and it’s been a 
revelation.  
Few chargers I found have a lithium setting, you can use a lead acid setting.  
My shore power charger is set for agm and is connected directly to the agm 
start battery and the LiFePo house bank. 
The shut down risk typically discussed is that alternator over voltage can 
trigger the BMS’ protection. As you suggest the dc:dc charger addresses this.
Your second paragraph loosely describes my setup and it works great.  

Project is detailed here- 
http://cncwindstar.blogspot.com/search/label/Solar%20and%20Batteries?m=1

I need to write a summary as there are a few learnings.  175 w of solar with 
the mppt controller plus the 220ah lithium batteries worked better than 
expected and I never used shore power.  Awesome!

One thing to consider is the maximum charge current that you wish to see 
provided to the house bank by the alternator/DC:dc charger.  My renogy combo 
unit limits dc:dc charging to 25a.  The spongelike LIFePo batteries can accept 
more and even my little alternator can deliver more.  (At the price of 
heat/load)   It isn’t conclusive to me that the overall system performance 
would improve, however it is something to be aware of.

Dave 33-2



Sent from my iPhone

> On Sep 14, 2021, at 9:27 AM, Della Barba, Joe via CnC-List 
> <[email protected]> wrote:
> 
> 
> My batteries are about shot and I am thinking of going to lithium batteries. 
> I have to say I thought I knew this stuff and it seems massively confusing 
> with a ton of directly contradictory information. One big issue seems that if 
> the BMS disconnects for any reason, that will do a lot of damage to your 
> alternator and perhaps other equipment too. Add to that my regulator does not 
> have a specific lithium setting, I would need to get into the custom menus 
> and try and make one.
> What seems to be the best bet is just to connect the alternator to the start 
> battery and use a DC-DC charger to charge the lithium bank. Some of them also 
> take solar input, so that saves me buying a solar controller with lithium 
> settings, which is something else I don’t currently have.
>  
> Joe
> Coquina
> Thanks to all of the subscribers that contributed to the list to help with 
> the costs involved.  If you want to show your support to the list - use 
> PayPal to send contribution --   https://www.paypal.me/stumurray  Thanks - Stu
Thanks to all of the subscribers that contributed to the list to help with the 
costs involved.  If you want to show your support to the list - use PayPal to 
send contribution --   https://www.paypal.me/stumurray  Thanks - Stu

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