8 replies to this topic

[pollux]

i connected a Battleborn Lithium battery with a Blue Sea ACR7610 on my 2015 Eagle. The voltage of 100% state of charge of Lithium should be 13.6V. 

 

The ACR will stay connected with the car battery above 12.75V.  The voltage of 100% charge of the car lead acid battery is 12.7V, yet this voltage of 12.7v is only 17% of the lithium battery charge. 

 

My question is if ACR is connected and both not being charged, will it slowly drain the Lithium to equlibrate with the car battery until it reach 12.7v and disconnect the ACR?   what other battery separator is better?

[kmcintyre]

If you are using the trucks alternator to charge your battleborn, you are going to want to get a DC-to-DC charger.  The LifePO4 batteries will eventually damage your trucks alternator.

[Vic Harder]

yes, the batteries will equalize.  

[rando]

This is kind of a tricky configuration.    Yes your ACR will stay connected until the voltage drops to 12.75V, which generally won't happen with the lithium battery.   However, the lead acid won't really drain your lithium battery unless there is a load on the lead acid.  The resting fully charged voltage on the lithium battery is about 13.2-13.3V, and it will pull the lead acid up to this voltage.  This would be the equivalent of a very mild float charge to the lead acid battery, but unless there is a load, there is almost no current flowing.

 

What will happen is that your lithium house battery will end up providing the power for the parasitic loads that would normally be on the trucks starting battery.   If you don't have solar or a shore power charger, over time this will discharge the lithium battery until the ACR cuts out, then it will discharge the starting battery, but we are typically talking many weeks to months for this to happen.   If you do have solar, then no big deal the solar will more than offset the parasitic loads, and both your batteries will be happy.    I am using the 7610 Si-ACR, a standard starting battery, lithium house battery and 160W of solar.  I have not seen an issue with this configuration. 

 

If you want to avoid this situation, Victron makes a battery isolator with set points appropriate for lithium: 

https://shop.pkys.co...ner_p_7358.html

[rando]

If you are using the trucks alternator to charge your battleborn, you are going to want to get a DC-to-DC charger.  The LifePO4 batteries will eventually damage your trucks alternator.

 

This can be true, but is not strictly true.   If you have an alternator with a higher voltage output, and large diameter wires running to your lithium batteries, then they can draw too much current from the alternator and shorten it's life.   However, with a smart alternator, or with smaller diameter wires (such as the stock FWC 10 AWG wiring) this won't be an issue as the alternator output will not be high enough and/or the resistance in the wiring will be enough to limit the current.   

 

As an example on my 2016 Tacoma (smart alternator), even with 6 AWG wiring to the camper my 150 Ah lithium only draws a max of about 12A, and typically more like 8 - 10A from the alternator.   I did end up implementing a DC-DC charger using my MPPT solar controller, but that was to increase the current to the lithium battery. 

[pollux]

i check with the battery monitor, the ACR is connected with car battery and draining the lithium (when >13v) about 0.2A to the car battery. 

 

Today i replaced the ACR with the LI-BIM 225 battery separator, which disconnects with the car battery at 13.5V.

Now the battery monitor shows 0A.

[rando]

Are you sure you want the LI-BIM 225? It will reduce the charge from your alternator by 60%.   I know on my Tacoma the charge from the alternator was a bit anemic to start with (~8-10A),  with this installed you only get ~4A or so. 

Edited by rando, 29 October 2020 - 02:08 AM.

[pollux]

Are you sure you want the LI-BIM 225? It will reduce the charge from your alternator by 60%.   I know on my Tacoma the charge from the alternator was a bit anemic to start with (~8-10A),  with this installed you only get ~4A or so. 

 

The Li-bim 225 is said to have a charge mode of 15 minutes charging and 20 minutes break. i will measure the amperage someday.

 

I think i will rely more on my 300w solar panels to charge the battery. 

[rando]

The Li-bim 225 is said to have a charge mode of 15 minutes charging and 20 minutes break. i will measure the amperage someday.

 

I think i will rely more on my 300w solar panels to charge the battery. 

 

Yeah, that is what I meant by reducing the amount of charge by 60%.   It also won't allow your solar to charge your truck battery.