Charging options for boat Lithium house bank and AGM engine bank

Simi 60

Solar Enthusiast
Our Victron multiplus has a port in it to run out wire to starts for a 4 amp trickle charge

We have no alternator on the engine, too expensive and problematic to use as a charging source for house bank imho.
And, has been proven not to be needed to maintain starts.
 

Fusion is the future

Solar Enthusiast
Our Victron multiplus has a port in it to run out wire to starts for a 4 amp trickle charge

We have no alternator on the engine, too expensive and problematic to use as a charging source for house bank imho.
And, has been proven not to be needed to maintain starts.
A good engine alternator is NOT at ALL problematic , in reality it is very easy if you have the right stuff .
And a blessing for a house bank , a lot of A/H in a short time
 

Simi 60

Solar Enthusiast
A good engine alternator is NOT at ALL problematic , in reality it is very easy if you have the right stuff .
And a blessing for a house bank , a lot of A/H in a short time
It was working fine just doing the starts
Using a vsr to charge house banks killed it off
And I wont be spending another $500 on an alternator + $1000 getting a mc624 balmar or similar fitted.
 

Fusion is the future

Solar Enthusiast
It was working fine just doing the starts
Using a vsr to charge house banks killed it off
And I wont be spending another $500 on an alternator + $1000 getting a mc624 balmar or similar fitted.
What you are willing to spend has nothing to do with your statement of technical problematic .
And indeed you have to spend between 800 / 1200 bucks for a complete Balmar kit, but your 3000 bucks Lithium house bank is it worth !
 

noenegdod

Solar Addict
Our Victron multiplus has a port in it to run out wire to starts for a 4 amp trickle charge

We have no alternator on the engine, too expensive and problematic to use as a charging source for house bank imho.
And, has been proven not to be needed to maintain starts.

Although I do agree with with Fusion is the future that they really are not problematic if done properly, if you have enough solar to do away with the parasite, for sure, do it!

I have a multiplus as well and assumed the 4a trickle charger only worked when plugged into shore power. Does it work when not plugged in?

Also, is that the only charge source for the starting/engine system? You must be diesel fueled with an old non ecu engine if it is because the electronics and the ignition system on a gasoline engine consume more than 4 amps.
 

Simi 60

Solar Enthusiast
What you are willing to spend has nothing to do with your stament of problematic .
And indeed you have to spend between 800 / 1200 bucks for a complete Balmar kit, but your 3000 bucks Lithium house bank is it worth !
But it only works when the engine is running so there are days and days or longer at anchor with no input from that expensive box.

With an already installed 2.5kw of solar I get silent trouble free daily power in without running the engine and an already installed 7.5kva genset provides more charge than the alternator with minimal fuel burn on days without sun.

For the price of that balmar setup I can get another 2.5kw of solar onboard.
 
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Simi 60

Solar Enthusiast
I have a multiplus as well and assumed the 4a trickle charger only worked when plugged into shore power. Does it work when not plugged in?
We have not been plugged in anywhere for over 5 years so I'd say yes.
Also, is that the only charge source for the starting/engine system? You must be diesel fueled with an old non ecu engine if it is because the electronics and the ignition system on a gasoline engine consume more than 4 amps.
855 Cummins, hit it with a stick simplicity.
 

Fusion is the future

Solar Enthusiast
But it only works when the engine is running so there are days and days or longer at anchor with no input from that expensive box.

With an already installed 2.5kw of solar I get silent trouble free daily power in without running the engine and an already installed 7.5kva genset provides more charge than the alternator with minimal fuel burn on days without sun.

For the price of that balmar setup I can get another 2.5kw of solar onboard.
850 Cummings 300KW, you must have a motor boat, more room for solar, and a gen set, why did you say that not directly.
You have no need for a good alternator .
But on a sailboat it is a complete different situation special if you are a long distance sailing and spending time on the hook .
Than is a Balmar the best solution, it is not use space up like a gen set, it is a big amount cheaper than a gen set, a way easier to install.
and 2,5 KW solar on a sailboat is not possible or it must be a 100 footer, but that will have also a gen set or 2 .
Solar is perfect, but useless in a 48 hour storm , radar on and all the other goodies, run the main engine for an hour of 2 while motor sailing and you stay in bussines .
And in a storm it not a bad idea to have some prop power anyway, all depending on course , wind and so on, i like to have some water flowing around the rudder .
and another 2,5 KW solar on your boat for lets say 1200 bucks must be realy a beautifull instaltion of quality realy an eye catcher , sarc off !
Show us a picture.
But you do not need an other alternator that is now clear .
 
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Simi 60

Solar Enthusiast
850 Cummings 300KW, you must have a motor boat, more room for solar, and a gen set, why did you say that not directly
I didn't realise it was a requirement, the op never made mention of sail until several posts in.
But on a sailboat it is a complete different situation special if you are a long distance sailing and spending time on the hook .
Previous sailing catamaran we had was outboard powered
Had enough solar and AGM onboard to run small refrigeration and instruments
And a small rarely used Honda Genny for rainy days.
Wed stay out several months at a time on that.

and another 2,5 KW solar on your boat for lets say 1200 bucks must be realy a beautifull instaltion of quality realy an eye catcher , sarc off !
Show us a picture.
9x 250 watts of tier 1 company panels going up 5 years ago
$60 each with 9.5 years of a 10 year warranty remaning
Down below they run though a midnite classic 150 mppt $800 on eBay from US

That S/S frame at back of pic now covered in shadecloth can take another 4 panels and there is space fwd of the funnel/ mast for another 6 panels
 

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Fusion is the future

Solar Enthusiast
I didn't realise it was a requirement, the op never made mention of sail until several posts in.

Previous sailing catamaran we had was outboard powered
Had enough solar and AGM onboard to run small refrigeration and instruments
And a small rarely used Honda Genny for rainy days.
Wed stay out several months at a time on that.


9x 250 watts of tier 1 company panels going up 5 years ago
$60 each with 9.5 years of a 10 year warranty remaning
Down below they run though a midnite classic 150 mppt $800 on eBay from US

That S/S frame at back of pic now covered in shadecloth can take another 4 panels and there is space fwd of the funnel/ mast for another 6 panels
Thanks, it is not a requirement but it would avoid confusions.
Nice , space enough is it a Barge? , just one remark i would not cross oceans with your solar panels, i know they are widely used because the are cheap ( you bought them darn cheap ) but they will be damaged on a solar bridge as mostly used on sailboats
There are a much better quality on the market these days for long range sailboats, and on a sailboat you need more than one charger controller .
If you read my profile you can see what i have installed at home .
I sailed on a sailboat from La Paz Mexico trough the Panama Chanel with one 250 W panel and 3 old regular batteries , no gadgets, only an auto pilot and a handheld gps , old paper charts, no fridge and we stayed out for 6 days, filling up the BIG cool box with ice bars, meat, beer, ones in the 4 a 6 days
Of coarse it is possible but is it safe and always fun ?

If i recommend here something i will recommend the best to my knowledge .
 

Simi 60

Solar Enthusiast
Thanks, it is not a requirement but it would avoid confusions.
Nice , space enough is it a Barge? ,
No, its an ex commercial fishing trawler converted to a full time cruiser
just one remark i would not cross oceans with your solar panels, i know they are widely used because the are cheap ( you bought them darn cheap ) but they will be damaged on a solar bridge as mostly used on sailboats
And how will they be damaged exactly?
They have already seen multiple 40+ knot and an 80+knot storm with hail
I sailed on a sailboat from La Paz Mexico trough the Panama Chanel with one 250 W panel and 3 old regular batteries , no gadgets, only an auto pilot and a handheld gps , old paper charts, no fridge and we stayed out for 6 days, filling up the BIG cool box with ice bars, meat, beer, ones in the 4 a 6 days
Of coarse it is possible but is it safe and always fun ?
Well you didn't die and neither did I so I guess it was safe enough
As for fun, we had plenty
But now comfort is important as well
 

Fusion is the future

Solar Enthusiast
No, its an ex commercial fishing trawler converted to a full time cruiser

And how will they be damaged exactly?
They have already seen multiple 40+ knot and an 80+knot storm with hail
That would be a STURDY boat what can HANDLE a lot .
Than are you panels from a better quality than i thought, normally the really cheap ones has weak glass and bad sealing.
The hail tells a lot, the wind a lot less because they are mounted flat on a roof and and not on an open solar bridge .
Trough not avoidable litle movement on a solar bridge also functioning as dingy lift , storage, the sealing will fail after time, but you do not have that problem.
 

wwwtractor

New Member
I know my RV is not a sailboat but I have a related question. I have 300 Watts of solar panels with Victron 100/50 Controller and 400 Amp Hour Shunbin house battery in 24 foot Airstream Interstate GT RV on a Mercedes Sprinter 3500 van. Looking for maybe three recommendations for about 100 Amp Hour LiFePO4 starting battery for the diesel engine which I can connect to the Shunbin with toggle switch for a total of 500 Amp Hours of LiFePO4. I have been using an AGM charging profile from my Magnum Inverter/Charger which seems to be working and doing an monthly desulfurization routine to kick the voltage up enough to balance the LiFePO4 battery. I also have a 30 Amp LiFePO4 charger to use when plugged into shore power.

So far I have noticed the Weize, Antigravity, Chins, and Ampere Time all running around 100 Amp Hours in a Group 8 automotive form factor (13x6.5x8). It seems that some manufacturers are aiming more at the automotive market now.

Does anyone have any experience with a similar system? Why would going total LiFePO4 kill my alternator? I see about 30 Amps of charging with the engine running currently. Current battery BMS limits charging to 50 Amps and discharge to 100 Amps.

I would like to replace the AGM starting battery with lithium. Thanks for your help.
 

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wholybee

Solar Addict
LiFePO4 is not a good battery for starting, for a variety of reasons. Starting is high current, but low discharge. In other words, you may need a 750CCA staring battery, but it only needs to be about 25Ah. Starting batteries basically sit fully charged until you need them, and that will shorten the life of a LifePO4 battery. The staring current will be higher than what most BMS's are capable of. It can be made to work, but with no advantages over lead. You also would not want to connect and disconnect a starting battery that is at a different state of charge than the house battery, excepting if the purpose is to charge the starting battery from the house battery.
There are 2 potential issues with the alternator. The first is the current. Your BMS may "limit" current to 50A, but what it really does is stop charging if it goes over 50A. It doesn't hold it there allowing charging to continue at 50A even though it might otherwise go higher. Because LiFePO4 will suck up as much current as you can give it, your alternator will run wide open with as much current as it can, until it either cooks itself to death, or if it has an internal temp sensor throttles itself back to cool off. Many newer alternators do this. Many common older alternators do not.
The second alternator problem is what happens when the BMS does shut off charging? When the BMS shuts off charging, there will be a voltage surge, which can be hundreds of volts, that can fry the alternator, and most everything else in you van. In simply terms, the alternator is still trying to produce power, and all of the sudden it has nowhere to go. Keeping a lead acid battery in the system will prevent this.
You do not want to be using a desulfurization charge on either AGM (unless it is the Lifeline brand) or LifePO4. LiFePO4 really should only be charged with a charger made for LiFePO4, because the float stage on lead acid profiles will overcharge and shorten the life of a LiFePO4 battery.
All of this said, I do know of a few boats that have a single large LiFePO4 battery that is used for both starting and house. DIY from cells, not drop in batteries, and they use an expensive REC BMS that can handle the large current. They also use expensive externally regulated purpose built alternators with temperature sensors. I would not recommend that setup for most installations.
 

noenegdod

Solar Addict
LiFePO4 is not a good battery for starting, for a variety of reasons. Starting is high current, but low discharge. In other words, you may need a 750CCA staring battery, but it only needs to be about 25Ah. Starting batteries basically sit fully charged until you need them, and that will shorten the life of a LifePO4 battery. The staring current will be higher than what most BMS's are capable of. It can be made to work, but with no advantages over lead.

The majority of the issues you have presented above have nothing to do with the battery chemistry itself and the discharge rate issue is easily accounted for.
Discharge rate:

If you have one 280AH battery the continuous discharge rate is 280ah. Its peak is higher but lets just work with 280. This means that if you have 3 strings of 280ah batteries, you have met the current requirements of the starter without exceeding the continuous discharge rate of the battery.

Keeping the battery full to start the engine:

Continuing along now with needing 3 strings to meet the current requirement, What is the voltage of a fully charged LA battery? What is the voltage of a lifepo4 at 50%? You dont need to keep a (edit: lifepo4) "starting battey" at full capacity, so not an issue. Also, 3 strings of 280ah batteries at 50% has way more than enough current available to start an engine

The BMS current issues has several work arounds including but not limited to having one bms on each string would provide enough current if you had 4 strings. Connecting the starter through a contactor to the battery around the bms (push a button to close the contactor, cranking the engine to start it and then releasing the button to open the contactor.)

You also would not want to connect and disconnect a starting battery that is at a different state of charge than the house battery, excepting if the purpose is to charge the starting battery from the house battery.

Why not? The voltage difference between the two banks is small enough that current isnt crazy enough to cause an issue. Especially when connecting LA and lifepo4.
 
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wholybee

Solar Addict
The majority of the issues you have presented above have nothing to do with the battery chemistry itself and the discharge rate issue is easily accounted for.
Discharge rate:

If you have one 280AH battery the continuous discharge rate is 280ah. Its peak is higher but lets just work with 280. This means that if you have 3 strings of 280ah batteries, you have met the current requirements of the starter without exceeding the continuous discharge rate of the battery.

Keeping the battery full to start the engine:

Continuing along now with needing 3 strings to meet the current requirement, What is the voltage of a fully charged LA battery? What is the voltage of a lifepo4 at 50%? You dont need to keep a (edit: lifepo4) "starting battey" at full capacity, so not an issue. Also, 3 strings of 280ah batteries at 50% has way more than enough current available to start an engine

The BMS current issues has several work arounds including but not limited to having one bms on each string would provide enough current if you had 4 strings. Connecting the starter through a contactor to the battery around the bms (push a button to close the contactor, cranking the engine to start it and then releasing the button to open the contactor.)



Why not? The voltage difference between the two banks is small enough that current isnt crazy enough to cause an issue. Especially when connecting LA and lifepo4.
Well, first, the question was about replacing an AGM starting battery with a 100Ah drop in, not building a bank capable of starting an engine. Even so, using 12 280Ah cells, plus a BMS capable of 750-1000A, is a really expensive alternative to a $150 AGM. Yes, it will work, though. But holy cow, you are suggesting an 840 Ah LFP battery to do what an 80Ah AGM will do just as well.

I personally know of several installations that have foregone a separate starting battery and use LifePO4 for starting as well. I think this is an unusual outside case. They are large LFP banks, with expensive and relatively complex BMS systems. They are well designed and the owners really knew what they were doing. I don't generally recommend giving up a separate staring battery, and where the starting battery is separate, I don't recommend LFP.

This is a staring battery, it sits fully charged, not because it *has* to, but because that is what it does. The engine starts, the alternator then fully charges the battery (which happens quickly, as starting doesn't use very many Ah), and it sits there until needed for starting again. If it was a dual purpose starting and house bank, that wouldn't be the case, but that also wasn't what the question was about. It was specifically about a starting battery.

How do you know the voltage difference isn't great? What is to stop someone from connecting the two banks when one bank runs dead, the BMS protects it at 10.5 volts, and the other is at 14+ volts? That actually seems a likely scenario, "oops, all my stuff just turned off, I better connect the second battery!"

I stand by my answer, LFP is a poor choice for a starting battery.
 

noenegdod

Solar Addict
Well, first, the question was about replacing an AGM starting battery with a 100Ah drop in, not building a bank capable of starting an engine. Even so, using 12 280Ah cells, plus a BMS capable of 750-1000A, is a really expensive alternative to a $150 AGM. Yes, it will work, though. But holy cow, you are suggesting an 840 Ah LFP battery to do what an 80Ah AGM will do just as well.

I personally know of several installations that have foregone a separate starting battery and use LifePO4 for starting as well. I think this is an unusual outside case. They are large LFP banks, with expensive and relatively complex BMS systems. They are well designed and the owners really knew what they were doing. I don't generally recommend giving up a separate staring battery, and where the starting battery is separate, I don't recommend LFP.

This is a staring battery, it sits fully charged, not because it *has* to, but because that is what it does. The engine starts, the alternator then fully charges the battery (which happens quickly, as starting doesn't use very many Ah), and it sits there until needed for starting again. If it was a dual purpose starting and house bank, that wouldn't be the case, but that also wasn't what the question was about. It was specifically about a starting battery.

How do you know the voltage difference isn't great? What is to stop someone from connecting the two banks when one bank runs dead, the BMS protects it at 10.5 volts, and the other is at 14+ volts? That actually seems a likely scenario, "oops, all my stuff just turned off, I better connect the second battery!"

I stand by my answer, LFP is a poor choice for a starting battery.
If you are answering a specific question outside of the OP then it would be beneficial to the rest of us who are engaging for you to actually quote that question in your post so we know what it is you are talking about.

Now that you have given me enough information to understand what you are talking about, lets get on the same page.

Im not a proponent of lifepo4 for a "starter battery". I dont think it is a good idea from either cost or function to replace a LA battery with a 100ah drop in lifepo4. Not smart from several perspectives. BMS turns off charging and destroys your alternator, and, holding the battery at a full SOC are the two biggest issues IMO. Never mind that the starting current far exceeds the current a 100ah lifepo4 battery can repeatedly supply.

So, engine electrical system needs something in the system to save the alternator. The only practical and cost effective solution I am aware of is to leave a lead acid battery in that system, but, it does not have to be a standard size LA battery, it doesn't even have to be big enough to start the engine. It just has to be big enough to absorb the field windings collapsing. The vast majority of the energy to start the engine can be provided by the house batteries as described in the post you quoted above. Yes, of course the house battery has to be big enough to supply the current with out exceeding the max current ratings of the battery so that is a limitation.

You appear to have thought I am suggesting that a person should replace the lead acid starting battery with a drop lifepo4 battery capable of starting the engine. I agree, that wouldnt be a smart idea and neither would continuing to think that that is what I was suggesting.

This idea seems to be something that people have a hard time getting their heads around. Many of us have a house battery that is big enough to supply the current to start an engine. It is not complicated to integrate the house battery into the vehicle electrical system to provide starting current so you can all but eliminate the LA battery from the system while providing isolation for the the alternator and provide it protection from the issues associated with trying to charge lithium batteries.

Lets be clear. In what I have suggested, the house battery is the "starting battery" . It will not be kept at full voltage by the alternator as it will be isolated from the vehicle system by a DC-DC or some other means. The LA battery will be kept at electrical system voltage and is there for the sole purpose of protecting the alternator. It is no longer the "starting battery" as it is simply too small to do the job.

So, as long as the house battery is big enough to provide the current, lifepo4 makes a fantastic "starter battery".

As for connecting two batteries at different SOC:

 
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wholybee

Solar Addict
If you are answering a specific question outside of the OP then it would be beneficial to the rest of us who are engaging for you to actually quote that question in your post so we know what it is you are talking about.
Sorry about my negligence. I was responding to the post directly above mine, you are right I should have quoted it.

You appear to have thought I am suggesting that a person should replace the lead acid starting battery with a drop lifepo4 battery capable of starting the engine. I agree, that wouldnt be a smart idea and neither would continuing to think that that is what I was suggesting.
We agree.

This idea seems to be something that people have a hard time getting their heads around. Many of us have a house battery that is big enough to supply the current to start an engine. It is not complicated to integrate the house battery into the vehicle electrical system to provide starting current so you can all but eliminate the LA battery from the system while providing isolation for the the alternator and provide it protection from the issues associated with trying to charge lithium batteries.
This a common approach I support. A common trend though, is that someone gets an idea "LFP is awesome, let's get rid of all the LA batteries and make them all LFP." Without some careful engineering, that is tough to do and usually not worth it. It is much easier and much more practical to just keep the LA battery. There are some well-engineered (and expensive) systems that do it. Using a BMS that can communicate with an alternator regulator to control current and either change charging stages or turn off the alternator altogether prior to a disconnect.

Let's be clear. In what I have suggested, the house battery is the "starting battery" . It will not be kept at full voltage by the alternator as it will be isolated from the vehicle system by a DC-DC or some other means. The LA battery will be kept at electrical system voltage and is there for the sole purpose of protecting the alternator. It is no longer the "starting battery" as it is simply too small to do the job.

So, as long as the house battery is big enough to provide the current, lifepo4 makes a fantastic "starter battery".

As for connecting two batteries at different SOC:

Yes, I have seen that. I don't have fast enough internet to watch it again at the moment, but if I recall, there was very little current at "normal" states of charge, and that terminal torque made a huge difference. But, when one battery was quite low, and the other quite high, current did increase dramatically as the bolts were torqued.
 

noenegdod

Solar Addict
Yes, I have seen that. I don't have fast enough internet to watch it again at the moment, but if I recall, there was very little current at "normal" states of charge, and that terminal torque made a huge difference. But, when one battery was quite low, and the other quite high, current did increase dramatically as the bolts were torqued.
Yes, properly torqued fasteners made a difference and to be fair, he was running current between cells with a voltage difference of ~1 volt vs batteries with a potential difference of 3 or 4 volts for a 12 volt system and obviously a lot more for higher voltage systems.
 
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