LiFePo house battery

[Cargile]

Thought this would be simple but not as far as finding help. Maybe I am making it more complicated then it is? I want to change my house bank, 2 6v golf cart batteries to 1 100 AH LiFePO battery w BMS. My 50 year old trailer trawler has a 35 amp Prestolite alternator (original). The starter battery is a 900 CCA lead acid battery turning over a Ford 302 gasser. Charging current from the alternator is managed by a Blue Seas ACR. I believe my 2 bank 10 amp Guest Marinco charger will not work with LiFePo batteries so I am prepared to buy a charger and whatever for LiFePo battery. Also not sure if the Blue Seas ACR can manage the two different battery types. Also not sure if the alternator is up to speed for the job. On other sites I have been told to get a Renogy DC-DC charger and it will handle the lead acid starter and the LiFePo house. That, I believe covers charging with the alternator as a power source underway. Charging on shoe power/genset is another topic I will look at later. In short, I guess I am looking for a list of equipment and a wiring diagram. Sweet Jesus a wiring diagram would be nice. Thanks

[Ka_sea_ta]

It appears that you currently have a system that meets your needs. Unless there is an environmental reason to change battery chemistry from FLA to LPO it appears your not gaining any increased capacity as a couple 225 AH GC batteries should have a little more usable energy then the 100 AH LPO.

If you want to go to the LPO battery a dc to dc charger is the best way assuming you have a single engine and alternator. Loose the ACR, feed the existing charging sources into the FLA starting bank and wire the house loads into the LPO bank, the let the DC to DC charger charge the LPO battery.

With your proposed setup I don't think your gaining much, as it doesn't take advantage of LPO batteries

[SteveK]

Ka sea ta
Does the DC2DC charger have an off switch if the engine is not running so the full start battery does not continue to charge the house bank?

[Iggy]

Originally Posted by Ka_sea_ta

It appears that you currently have a system that meets your needs. Unless there is an environmental reason to change battery chemistry from FLA to LPO it appears your not gaining any increased capacity as a couple 225 AH GC batteries should have a little more usable energy then the 100 AH LPO.

If you want to go to the LPO battery a dc to dc charger is the best way assuming you have a single engine and alternator. Loose the ACR, feed the existing charging sources into the FLA starting bank and wire the house loads into the LPO bank, the let the DC to DC charger charge the LPO battery.

With your proposed setup I don't think your gaining much, as it doesn't take advantage of LPO batteries

Yep!

[Cargile]

Originally Posted by Ka_sea_ta

It appears that you currently have a system that meets your needs. Unless there is an environmental reason to change battery chemistry from FLA to LPO it appears your not gaining any increased capacity as a couple 225 AH GC batteries should have a little more usable energy then the 100 AH LPO.
If you want to go to the LPO battery a dc to dc charger is the best way assuming you have a single engine and alternator. Loose the ACR, feed the existing charging sources into the FLA starting bank and wire the house loads into the LPO bank, the let the DC to DC charger charge the LPO battery.
With your proposed setup I don't think your gaining much, as it doesn't take advantage of LPO batteries

Thanks for the advice/help but......power available currently falls short of needs. Also the boat has a port list. I believe it is the 150 lbs of lead acid batteries I added in the aft port engine space. Plan is to remove them and move the house battery forward maybe 6 feet and mid ship to a space now vacated by a removed holding tank. You assumed 225 AH batteries. They are 110 AH. Optimistically I am looking at a 50% increase in available power with LiFePo. I have been looking at DC to DC chargers. Thanks fore the suggestion. So, a post puberty Airman 1st Class has access to and has published national defense top secret info and I am having a hell of a time finding an electrical wiring diagram for a recreational boat system? Go figure. Frustrated in Florida.

[sunchaser]

Marine How To website May offer some guidance.

Given your 35 amp alternator expanding the battery bank capacity seems a challenge. Possibly you’re short of charging capacity rather than battery capacity at this point.

Did you remove or relocate your holding tank?

[Ka_sea_ta]

Originally Posted by SteveK

Ka sea ta
Does the DC2DC charger have an off switch if the engine is not running so the full start battery does not continue to charge the house bank?

My only experience is with the Victron Dc to DC charger, and the input voltage level that the unit will turn on is configurable when setting the unit up. So yes the charger will only turn on when the source battery voltage reaches a user determined level.

[SteveK]

Originally Posted by Ka_sea_ta

My only experience is with the Victron Dc to DC charger, and the input voltage level that the unit will turn on is configurable when setting the unit up. So yes the charger will only turn on when the source battery voltage reaches a user determined level.

'source' battery being the start battery? This remains my yet to be satisfied concern. The DC2DC from start to house, the start bat being depleted when at anchor for a couple days.
If 'source' is the house bat, then no worries.

Here is where I am at with LifePO4
Found the ALT saver to protect ALT from a BMS shutdown. Charge LFP (without external reg) from Alternator, then DC2DC to start battery.
Inverter charger to house too. Almost sold on the upgrade.

[Ka_sea_ta]

Originally Posted by SteveK

'source' battery being the start battery? This remains my yet to be satisfied concern. The DC2DC from start to house, the start bat being depleted when at anchor for a couple days.
If 'source' is the house bat, then no worries.

Here is where I am at with LifePO4
Found the ALT saver to protect ALT from a BMS shutdown. Charge LFP (without external reg) from Alternator, then DC2DC to start battery.
Inverter charger to house too. Almost sold on the upgrade.

I probably didn't explain the turn on voltage for the dc2dc charger clear enough. The turn on voltage for the Victron dc2dc charger that I have can be set via the app to turn on only when there is a charging level voltage on the the source battery (I.E. 13.5 v) once the charging level voltage is removed the dc2dc charger turns off and isolates the source battery. This is similar to an ACR but not bidirectional... In other words your start battery is isolated from house battery once the charging sources are removed from the start battery.


I wouldn't use a stock regulator to charge a LPO battery bank without an alternator temperature sensor at minimum. In addition the charging characteristics of a internal regulator are not optimal for LPO. At minimum for a LPO bank I think a programmable external regulator with alternator temp sensing is prudent. A dc2dc charger from your port engine could help to reduce the charge time for LPO bank....

[SteveK]

Originally Posted by Ka_sea_ta

I probably didn't explain the turn on voltage for the dc2dc charger clear enough. The turn on voltage for the Victron dc2dc charger that I have can be set via the app to turn on only when there is a charging level voltage on the the source battery (I.E. 13.5 v) once the charging level voltage is removed the dc2dc charger turns off and isolates the source battery. This is similar to an ACR but not bidirectional... In other words your start battery is isolated from house battery once the charging sources are removed from the start battery.

OK, I can see that now, as long as start bat voltage is below set point it will not drain into house.

Originally Posted by Ka_sea_ta

I wouldn't use a stock regulator to charge a LPO battery bank without an alternator temperature sensor at minimum. In addition the charging characteristics of a internal regulator are not optimal for LPO. At minimum for a LPO bank I think a programmable external regulator with alternator temp sensing is prudent. A dc2dc charger from your port engine could help to reduce the charge time for LPO bank....

Using a stock internal regulator is not ideal but it is workable as long as other charging sources top up the battery later. The LFP does not need to be charged to 100% every time as needed by FLA.

I do not know of a alternator temp sensor that will work with internal regulator, is there one?
These are the roadblocks to making the move to LFP, too many other working parts need to be replaced or added to.

[Cargile]

Originally Posted by sunchaser

Marine How To website May offer some guidance.
Given your 35 amp alternator expanding the battery bank capacity seems a challenge. Possibly you’re short of charging capacity rather than battery capacity at this point.
Did you remove or relocate your holding tank?

Thank you. On my list of potential gear so far: WIRING DIAGRAM, LiFePo 100 AH battery, Renogy DC to DC charger, Victron Smart Battery Protect, 70 amp alternator w external regulator w temp sensor and a WIRING DIAGRAM.
The holding tank, head and all plumbing was removed an replaced with a Nature's Head.

[MacPhid]

Am I the only one that thinks its ridiculous that the latest bleeding edge battery technology can't be connected to any system without major upgrades and hardware replacement? Could the BMS not simply be programmed for the installation type and be good to go? I mean, they're smart enough to know when to disconnect due to over voltage, under temp, over temp, over current but can't figure out to reduce input current when they reach full charge? I'm hoping the next generation batteries are smarter than this generation.

James

[Simi 60]

Originally Posted by MacPhid

Am I the only one that thinks its ridiculous that the latest bleeding edge battery technology can't be connected to any system without major upgrades and hardware replacement?

It can be depending on how your boat was set up

We set ours up 7 years ago with big solar and a Victron multiplus with Genset attached.
No on engine charging

When the AGM died and we went lifepo4, it was 20 minutes to reprogramme the multiplus and solar mppt charger to suit

We still have no on engine charging
To much drama for us to bother with.

[Simi 60]

Originally Posted by SteveK

.


Using a stock internal regulator is not ideal but it is workable as long as other charging sources top up the battery later. The LFP does not need to be charged to 100% every time as needed by FLA.

I think the point he might be getting at, and I could be wrong is a big battery bank be it Lifepo4 or AGM will take many hours to charge at 30 or 40 amps.

We killed off 2 large frame alts connected to AGM simply because the alt ran flat out for as long as the engine ran.
A couple of hours may have been ok, but we do 8+ hours often enough that it was a killer.

My way of thinking is a DC to DC charger will cause the alt to do the same

[SteveK]

Originally Posted by Simi 60

I think the point he might be getting at, and I could be wrong is a big battery bank be it Lifepo4 or AGM will take many hours to charge at 30 or 40 amps.

We killed off 2 large frame alts connected to AGM simply because the alt ran flat out for as long as the engine ran.
A couple of hours may have been ok, but we do 8+ hours often enough that it was a killer.

My way of thinking is a DC to DC charger will cause the alt to do the same

Bolded, yes I have that same thought.

Killed two Alternators charging AGM? I wonder if it was due to the size of the bank you have, smaller bank AGM maybe OK for same ALT.
A lot to digest.

[Delfin]

Originally Posted by MacPhid

Am I the only one that thinks its ridiculous that the latest bleeding edge battery technology can't be connected to any system without major upgrades and hardware replacement?
James

Not exactly accurate. I had to make zero modifications to my system to shift from 1380 ah 24vdc AGMs to 600 ah LFP. I elected to add additional charging capacity to take advantage of LFPs ability to absorb peak current until virtually full, but that was optional. Everything else in the system used to maintain the AGMs remained the same. If you have an existing system that isn't quite up to the task of effectively maintaining an LA bank (like having internally regulated alternators), then sure, if you want to upgrade you should address those deficiencies but that has nothing to do with LFP needing something special.



There seem to be two falsehoods regarding this technology that just don't seem to go away:


1. You can't install LFP without major changes to an existing system.

2. LFP is more dangerous than LA.

[SteveK]

Originally Posted by Delfin

.............. If you have an existing system that isn't quite up to the task of effectively maintaining an LA bank (like having internally regulated alternators), then sure, if you want to upgrade you should address those deficiencies but that has nothing to do with LFP needing something special.

Originally Posted by Delfin

There seem to be two falsehoods regarding this technology that just don't seem to go away:


1. You can't install LFP without major changes to an existing system.

So which is it?

[mvweebles]

Originally Posted by Cargile

In short, I guess I am looking for a list of equipment and a wiring diagram. Sweet Jesus a wiring diagram would be nice. Thanks

Two diagrams are attached.

Given the relatively small size of your system (one G24 FLA for start; and one (or even two) 100AH LFP batteries), you may want to look at Van installs as this is extremely common. Both Renogy and Australian company RedArc (HERE) make a popular DC-DC charger, though the big benefit is they also have an MPPT built-in so can integrate solar charging into the system (solar isn't required to make these work, but heck, even a 50W panel would be helpful). Both have an integral relay so the Blue Sea ACR is no longer needed. Note RedArc has a 20A and 25A output so would protect your 35A Alternator. Smallest Renogy is 30A. I believe they both split the power between two feeds so if you have solar and alternator on a 50A DC-DC charger, solar is limited to 25A; alternator is limited to 25A. But if only alternator, then it gives full 50A.

Despite the RedArc being 2x the cost of Renogy ($550 vs $260), I would strongly recommend against Renogy - their tech support is worse than bad: on the rare instance when they do respond, the information is often incorrect. A good question for them (RedArc tech support) is whether you could keep your existing battery charger, but place on the FLA start battery and use the DC-DC charger to convert to charge your LFP. I don't see a reason why it wouldn't work, but would pay to ask first. Or you could buy a LFP-capable charger and place on your house-bank which would also charge the start battery via the DC-DC charger.

Note, the overall system changes beyond installing the DC-DC charger would be near zero byond crimping new lugs in the positive cable to the house battery (assumes there is existing circuit protection). The ACR can be left in place, or you could remove it and use those connections for the DC-DC charger. So while the RedArc is $550, nothing else is needed.

Attached is a diagram of the RedArc. Hope this helps.

Peter

EDIT - also attached the Renogy wiring diagram since OP asked for a wiring diagram (Renogy Install Manual HERE). Assumes alternator output is connected to the start battery. Install is identical to the RedArc. I have the 50A version of the Renogy product installed in my camper van that I purchased prior to a disasterous DOA event with a Renogy inverter, thus my admonition about Renogy. The Renogy product works fine, but I would never take a chance on Renogy again.

[Iggy]

I have the same setup on my boat as the van for the past year and so far so good. I lucked out for the fact that the last owner install 120A alt with an external regulator, a Balmar. Which I highly suggest with temp sensor.

I reading other post about burning out Alts. I bet there was no temp sensor to back down the Alts. Maybe one could not be added.

This setup is very easy to do. Just be sure that the Alt sense wire and the charging wire is mover over to the starting bank if not already. Than install your DC to DC charger. I used two Victron chargers that total 60A on a 800A bank. Remove the ARC/VSR if one is used.

As a precaution and for Cargile, I installed two remote battery switches. My switches are in the engine compartment. Not too hard to get at but if the batteries BMS's shuts down in 3 or 4 seconds I can run off that starting battery. Also this protects that Alt since its only seeing the starting bank and DC to DC charger. One switch kills the house bank and the other parallels the house loads not LFP bank itself since that switch is off. These switches were already there and most likely we all have them. A starting bank switch, a house bank switch and a parallel switch.

Keep in mind that 60A of charging may seam low, but. LFP batteries charge 2 to 4 times faster than AGMs generally speaking.

Now did I do a Major Upgrade, I don't think so. Upgrading the ALT running LFP or AGM is not a bad thing. More so if using AGMs due to the longer charging times. So that may need to be done anyways.

[Delfin]

Originally Posted by SteveK

So which is it?

Sorry to confuse you Steve, so I'll try to be more clear.


If your existing charging system is put together with zip cord and an alternator from a '56 DeSoto, you have other problems to fix before you think about LFP.


However, if said system doesn't suck, and has the gear found on 95% of all trawlers (like smart regulation, adequate wire size, fuses, etc.) then the idea that you have to make major changes to install LFP or buy dc to dc chargers to make LFP work is an opinion generally offered by people with little knowledge of the subject.


That help?