Hybrid lead/LifePo4 Battery Bank Manager System

[CaptainRivet]

Hi all,

I just came across this thread about a device called Battery Bank Manager System that claims that with this you can simply add a LifePo4 with its BMS to a lead battery bank and don‘t have to even change chargers or modify alternator plus optimizing the charge for both battery type.
https://www.emilyandclarksadventure.com/bbms
Technical doc:
https://www.emilyandclarksadventure.com/bankmanager

What do you think about that?
At the first look that seems genius and solves a lot problems at ones incl. never sitting in the dark if your LifePo4 disconnects.
You still need a BMS for the LifePo4 but in this configuration it seems you really just need a simple one that disconnects LCV and HCV.
Do I miss something important…most likely otherwise he would sell them like crazy.

[CharlieJ]

Note that this concept is non-compliant with ABYC E-13 or ISO/TS 23625.

[CaptainRivet]

Originally Posted by CharlieJ

Note that this concept is non-compliant with ABYC E-13 or ISO/TS 23625.

and why? lead and LifePo4 get just merged when at the exact same voltage, so no current in rush.

non of the ABYC or ISO thinks about the way he chosen here making sure no current inrush can happen by managing the merging based on voltage. that is the reason ABYC tells you you not to connect FLA with LifePo4. it happens due to different voltages of the chemistry but if you take care of it like he did that feasible in my eyes.

Terry, Jedi... what do you think?

[goboatingnow]

It’s a “ mechanism. “ personally why not use a dc dc converter.

[CaptainRivet]

Originally Posted by goboatingnow

It’s a “ mechanism. “ personally why not use a dc dc converter.

I use a DC to DC too.
I just find this concept very interesting as you don’t have to change anything and having the lead always parallel means you never sit in the dark when LifePo4 gets disconnected and you don‘t need a complex switchover and warning process.
Also cheap BMS like Daly just cutting off at LCV or HCV is enough.
The most simple way I am aware of in adding a LifePo4 in my eyes and getting the starter float charged by LifePo4 is a good way of always having it charged properly.

[wholybee]

This concept comes up on various forums. In short? Why? You are not getting the best features of each chemistry; you are getting the worst. You have heavy lead battery, a Peurkurt effect, dangerous out gassing, expense of Lithium.

The only application that it _might_ be smart (and even then its a big maybe) is in a large storage application where you have lots of space, not weight restrictions, and a large investment is lead batteries you would like to hold on to for a few more years. That application is not a boat.

[CaptainRivet]

Originally Posted by wholybee

This concept comes up on various forums. In short? Why? You are not getting the best features of each chemistry; you are getting the worst. You have heavy lead battery, a Peurkurt effect, dangerous out gassing, expense of Lithium.

The only application that it _might_ be smart (and even then its a big maybe) is in a large storage application where you have lots of space, not weight restrictions, and a large investment is lead batteries you would like to hold on to for a few more years. That application is not a boat.

Why do you get outgassing and peukert effect, ok yes if your lead bank is very big and LFP very small. But eg if you add that to the typical catamaran setup where one hull you have a typically 300AH combined service/starter lead bank and starter on the other hull that makes sense.
If you parallel that to eg 560AH of lithium to that 300AH lead and put a big load eg inverter, 90% of the energy will be taken out of the Lithium unless the LFP is not connected which happens mainly during the night. And even if LFP it’s not connected the big load will be dragging the voltage of the lead down and the LFP will be connected and taking over the big part of the load. So puckert effect is not noticeable and gassing is 0.
YouTube channel Offgrid garage tested that batteries with even different chemistry surprisingly balancing the load between them well and LFP having the very low resistance takes over a huge part. Same during charging.
It has not only the worst, some of it yes (as always compromise) but also have advantages as you sit never in the dark, You don‘t need all that security stuff, new chargers or MPPTs and if you add eg EVE or Lishen cells with a Daly or JDK BMS that are cheaper then good AGM or cheaper LFP drop ins why not? Sure not going that route if you add expensive Winston or battleborn…
Yes it’s not a highend setup but simple and cheap add on of a lot capacity and current delivery to add a big inverter for eg electric galley.
And if the lead dies scale down to 150 or 200AH as you have the LFP, not a bad backup with 30kg additional weight and most will have the lead starter in both hulls anyways.

[smj]

A friend did this, added a 100amp lithium to his 4 6v golf cart batteries. He says the lithium keeps the lead acid at about 13.4v so drastically cuts back on the lead acid cycles making them last much longer. I know nothing, just passing on his experiences with Emily and Clark’s BMS.

[Pete7]

Originally Posted by smj

A friend did this, added a 100amp lithium to his 4 6v golf cart batteries. He says the lithium keeps the lead acid at about 13.4v so drastically cuts back on the lead acid cycles making them last much longer. I know nothing, just passing on his experiences with Emily and Clark’s BMS.

Just coming to the end of season two with a hybrid LFP and FLA bank. We get the best of both worlds for minimal cost. LFP gives us the ability to use heavy load electrical devices yet recharge quickly. Disconnecting the LFP when we leave the boat, the FLA charged by solar runs the bilge pump if its ever needed.

Works well, delighted we made the switch.

Originally Posted by CharlieJ

Note that this concept is non-compliant with ABYC E-13 or ISO/TS 23625.

That's okay, Capt R and I live in free countries

[CaptainRivet]

Originally Posted by smj

A friend did this, added a 100amp lithium to his 4 6v golf cart batteries. He says the lithium keeps the lead acid at about 13.4v so drastically cuts back on the lead acid cycles making them last much longer. I know nothing, just passing on his experiences with Emily and Clark’s BMS.

Interesting, another different purpose to use it but that is only paying of if you get grade b or c cells 100AH for cheap plus the BBMS is 380$ on top.
In my eyes used for that purpose it’s riding a dead horse…

[smj]

Originally Posted by CaptainRivet

Interesting, another different purpose to use it but that is only paying of if you get grade b or c cells 100AH for cheap plus the BBMS is 380$ on top.
In my eyes used for that purpose it’s riding a dead horse…

Adding 2 more 6v would have cost about $400. He added a Chins 100 amp lithium for $300, probably equivalent to the 2 6v so he’s out an additional $280 for the BMS.
Pretty much a crap shoot at that point for me.

[CaptainRivet]

Originally Posted by smj

Adding 2 more 6v would have cost about $400. He added a Chins 100 amp lithium for $300, probably equivalent to the 2 6v so he’s out an additional $280 for the BMS.
Pretty much a crap shoot at that point for me.

That chin has at best 80AH…truly a crap shoot.
If spending 300, get 4x100AH calb cells and a JDK bms…then later add 4 more instead a lead. That would be a step by step approach keeping one lead and parallel 2p4S the calb cells for a small system on eg a small sailboat.

[smj]

Originally Posted by CaptainRivet

That chin has at best 80AH…truly a crap shoot.

If spending 300, get 4x100AH calb cells and a JDK bms…then later add 4 more instead a lead. That would be a step by step approach keeping one lead and parallel 2p4S the calb cells for a small system on eg a small sailboat.

Test showed the Chins 100AH actually getting 104AH not 80

[CaptainRivet]

Originally Posted by smj

Test showed the Chins 100AH actually getting 104AH not 80

Who tested it? With 5A draw or with 40A? Just looking at the specs I would run…100AH calb cells are definitely better by far.

[smj]

Originally Posted by CaptainRivet

Who tested it? With 5A draw or with 40A? Just looking at the specs I would run…100AH calb cells are definitely better by far.

As I said, it’s a friends project and he’s very satisfied.
Thanks for the info on the other cells, if and when I decide to make the change I’ll keep that in mind.