Firefly AGM start battery and Battleborn house bank

[docrn]

I liked my Firefly AGM’s but needed more Ah in the house bank so I took advantage of Battleborn’s Black Friday sale and picked up 4 100Ah 12v LiFePO4’s. I’ll keep my FF engine start battery and the plan was to get a DC-DC charger for charging it but after rechecking the charge parameters for both the FF and the BB’s I’m not sure why I’d bother doing that. I think I could just charge everything with the lithium settings on the charger, charge controllers, voltage regulator on the alternator. Can someone explain why this might be a bad idea?


Charge voltage range BB = 14.4-14.6. FF = 14.4
Bulk/absorption BB = 14.2-14.6. FF = 14.4
Float BB = N/A. FF= 13.4-13.5 (not required on a reg basis).

Edit: no “lithium” setting for the alts Balmar MC-614. Looks like just an AGM setting...

[rgleason]

Go to Rod's Marine How to website to see the correct programming for LifePo
https://marinehowto.com/programming-...age-regulator/

[docrn]

Originally Posted by rgleason

Go to Rod's Marine How to website to see the correct programming for LifePo
https://marinehowto.com/programming-...age-regulator/

Thank you!

[Randy P]

I’m converting my FLA house bank to Battle Borns but keeping my FLA engine battery. I’ve had very good response and advice from Battle Born via email. They respond quickly. Suggest you contact them via email or phone.

[rgleason]

[QUOTE=docrn;3288326

Charge voltage range BB = 14.4-14.6. FF = 14.4
Bulk/absorption BB = 14.2-14.6. FF = 14.4
Float BB = N/A. FF= 13.4-13.5 (not required on a reg basis).

Edit: no “lithium” setting for the alts Balmar MC-614. Looks like just an AGM setting...[/QUOTE]


Your MC-614 is an older one, but it can be set for charge of Lithium, see How to Marine detailed article on this. You do not want any temperature compensation or float, but see what Rod has written.


As you know, FF require several full charges (time) to recover capacity. This type of charging will completely damage LFP.

[Adelie]

With LiFePo what not just start off the house bank?
Get a little emergency lithium jump starter pack from Costco for $40 in case you Opps the the house bank too low.

[smac999]

Originally Posted by Adelie

With LiFePo what not just start off the house bank?
Get a little emergency lithium jump starter pack from Costco for $40 in case you Opps the the house bank too low.

Not only would I have a start battery. But also a back up agm house bank for when the lithuim or bms fails.

No way would I ever have a single lithuim bank. Have seen too many fail.

[Randy P]

My understanding of LFP is that they may not have enough CCA to crank the starter motor, but they do have plenty of power to handle deep discharges over longer periods of time. Again, think an email or call to Battle Born would answer this question.

My set up has solar panels to charge the LFP house bank, and I’m thinking about running the MPPT controller positive to the central post on my 1-2-All-Off battery switch so I can use the MPPT to charge the engine battery, which is FLA, not LFP. I’m also thinking I can use my small inverter (600W) to power my plug in Victron IP67 120V/25A battery charger. The inverter is powered off the LFP battery bank. All of this is applicable when I’m away from my AC pedestal and either at anchor or docked away from any AC power.

[smac999]

Originally Posted by Randy P

My understanding of LFP is that they may not have enough CCA to crank the starter motor, .

the cheap ones with built in BMS have current limits around 50a.

so a three battery bank will have a max draw of 150a. not enough to start. you'll trip the BMS and lose all power on boat.

[sailorboy1]

I seriously, make that incredibility seriously, doubt a FireFly battery used as a start would EVER require a recovery charge.

[Pitchondesign]

Originally Posted by docrn

I liked my Firefly AGM’s but needed more Ah in the house bank so I took advantage of Battleborn’s Black Friday sale and picked up 4 100Ah 12v LiFePO4’s. I’ll keep my FF engine start battery and the plan was to get a DC-DC charger for charging it but after rechecking the charge parameters for both the FF and the BB’s I’m not sure why I’d bother doing that. I think I could just charge everything with the lithium settings on the charger, charge controllers, voltage regulator on the alternator. Can someone explain why this might be a bad idea?


Charge voltage range BB = 14.4-14.6. FF = 14.4
Bulk/absorption BB = 14.2-14.6. FF = 14.4
Float BB = N/A. FF= 13.4-13.5 (not required on a reg basis).

Edit: no “lithium” setting for the alts Balmar MC-614. Looks like just an AGM setting...

You've got the right idea. The reason for the dc-dc charger is the charge times are very different for lithium and agm. Lithiums charge fast, agm is slow. If on the same charger, it will keep the voltage high for the agm, while damaging the fully charged lithiums.

[rgleason]

Originally Posted by sailorboy1

I seriously, make that incredibility seriously, doubt a FireFly battery used as a start would EVER require a recovery charge.

So you are just accepting the gradual reduction in capacity.

[sailorboy1]

Originally Posted by rgleason

So you are just accepting the gradual reduction in capacity.

No and I will post it later. But if you think the batteries need this .4C all the time you dont understand. But a start battery hardy needs charging at all.

[rgleason]

Don't bother, you misrepresent what I said.

He asked:

I’ll keep my FF engine start battery and the plan was to get a DC-DC charger for charging it but after rechecking the charge parameters for both the FF and the BB’s I’m not sure why I’d bother doing that. I think I could just charge everything with the lithium settings on the charger, charge controllers, voltage regulator on the alternator. Can someone explain why this might be a bad idea?

He suggested charging his FF with a Lithium charge routine and wanted to know why it might be a bad idea.

Sure the FF doesn't need much charge as a start battery, and it will probably last all summer with no charge at all. However its total capacity will gradually decline without several full charges.


Yes the FF charge routine will ruin his LFP.
and the LFP charge routine will not fully charge his FF.

Originally Posted by sailorboy1

No and I will post it later. But if you think the batteries need this .4C all the time you dont understand. But a start battery hardy needs charging at all.

[Adelie]

Originally Posted by Randy P

My understanding of LFP is that they may not have enough CCA to crank the starter motor, but they do have plenty of power to handle deep discharges over longer periods of time. Again, think an email or call to Battle Born would answer this question.

My set up has solar panels to charge the LFP house bank, and I’m thinking about running the MPPT controller positive to the central post on my 1-2-All-Off battery switch so I can use the MPPT to charge the engine battery, which is FLA, not LFP. I’m also thinking I can use my small inverter (600W) to power my plug in Victron IP67 120V/25A battery charger. The inverter is powered off the LFP battery bank. All of this is applicable when I’m away from my AC pedestal and either at anchor or docked away from any AC power.

Originally Posted by smac999

the cheap ones with built in BMS have current limits around 50a.

so a three battery bank will have a max draw of 150a. not enough to start. you'll trip the BMS and lose all power on boat.

BattleBorn indicates:
100A continuous,
200A for 30sec.
Higher loads for 1/2sec.

2 or 3 BattleBorns should be fine for starting larger engines, 1 or 2 for medium sized, and 1 or small.

https://1t1pye1e13di20waq11old70-wpe...-Cut-Sheet.pdf