Starting a big diesel with lifepo4

[CaptainRivet]

Originally Posted by Phil_Fr17

I looked up what this device was and didn't know. It has to be said that I don't do developing any more and wouldn't be comfortable with it. Is there any data or typical set-ups for using it?
Interesting, in any case.
And I completely agree with you about the performance and capabilities of LTOs. As for the price of LTOs, I was stuck on the price of 45 Ah Yinlong cells, which cost over $87 excluding tax and shipping... Hence my slightly biased comparison with lead-acid batteries.
But I also think that lead batteries are no longer really in the running when there are batteries to replace.

Which device you need to look up?

45AH are degraded, in best case B grade, 50AH Yinglong LTO cells. They don't produce 45AH and the 50AH are their worst cells, problematic as not very stable and a lot production defects. The round cells are produced in 30A,40A and 50AH, heard they will stop making the 50 one.
Best cells are the 40AH, cheaper and extremely stable and reliable...we tortured them like crazy far outside the parameters and they still worked fine.
For a starter bank the 40AH B-grade from a good source that match them are totally fine, they mostly have around 37-38AH but because you charge them in parallell with Lifepo4 they will be 85%SOC=33AH. You don't want them to charge to 15.6 (means using a DC2DC to charge them above 14,4V) as they act as backup for your Lifepo4 house too and this 4AH don't matter at all. But they can still do 10C constant so 400A....
the 7lV8 from Corvette Z06 has a 3500W starter and my buddy has the 40AH B-grade which work fine since 8 years, he has a 4kw stereo in there too and the LTO is the only battery....

[CaptainRivet]

Originally Posted by CapsizedVeteran

None of what you said has anything to do with the mosfets in the BMS handling transient currents from inductive loads.

Your capacitor won't change anything for the mosfets in the BMS either. Only that helps get a bigger or a 2nd one but as long as you don't want to use house as starter you don't need. For an emergency start from.the Lifepo4 the existing BMS will most likely work without issue.

How big is your windlass? Normally smaller then the starter, so the surge currents are no issue for the BMS mosfets.
But they are an issue for your chartplotter and radar, especially the newer ones were they saved on filtering of power supply/input voltage...and i gave you a smart solution for that.

[SOLAR SUPPORT]

Originally Posted by CaptainRivet

Current is like water, it takes the way of the lowest resistance and thats the lifepo4 so you can be sure that 500-600A amp comes to 95% from the Lifo4 but yes your 2 BMS parallel can handle that. With an oszi you can see that.

You connected both batteries to starter...so cables are already there, just disconnect the lead as its contraproductive, keep it with a 1/2 switch as backup. By the way how did you isolate them from each other???
If that would help, it would be done long time ago by a lot of people but it isn't....we tested that 15 years ago in competition car stereo paralleling lead and LFP (with a lot lab equipement like oszi) the results where as i told you, short high peaks come only from LFP and when big loads and lead sags the LFP need to deliver the load and support the sagging lead means double stressed.

Pay attention to the video link I sent. Watch the video in slow motion. This short video consists of two parts. Firstly, it is 306A measured when starting the engine with only LA battery. The second measurement shows the 126A current measurement through the lead acid battery when the Lifepo4 bank and the LA battery are connected in parallel.

During operation, the Lifepo4 bank and LA battery load distribution are 180A and 126A respectively. It means that when the engine is started, the load distribution is 41% LA, 59% Lifepo4 bank. This has nothing to do with the Battery Isolator.

[CaptainRivet]

Originally Posted by SOLAR SUPPORT

Pay attention to the video link I sent. Watch the video in slow motion. This short video consists of two parts. Firstly, it is 306A measured when starting the engine with only LA battery. The second measurement shows the 126A current measurement through the lead acid battery when the Lifepo4 bank and the LA battery are connected in parallel.

During operation, the Lifepo4 bank and LA battery load distribution are 180A and 126A respectively. It means that when the engine is started, the load distribution is 41% LA, 59% Lifepo4 bank. This has nothing to do with the Battery Isolator.

Did you start the engine with the lifepo4 alone? will most like be in the 230A range and not 306A.
Load sharing in operation is different then the short peak with 500A+ as eg lead is too slow so lifepo4 takes over which you can only measure with an oszi...which we done 15 years ago.

You have absolutely no add value, lfp and BMS can handle the full starter load which is lower with lifepo4 alone and engine will most likely start faster.

Do you have a curcuit diagram how you wired both for charging and discharging. Interested how you prevent that the lfp support the lead in discharge.

I have VolvoD2-50F with 150h and start from 1088AH bank, operation is 180A and ot starts on below 2sek.
BB hull lead 2x110AH needs 260A and about 3sek to start.

[SOLAR SUPPORT]

Originally Posted by CaptainRivet

Did you start the engine with the lifepo4 alone? will most like be in the 230A range and not 306A.
Load sharing in operation is different then the short peak with 500A+ as eg lead is too slow so lifepo4 takes over which you can only measure with an oszi...which we done 15 years ago.

You have absolutely no add value, lfp and BMS can handle the full starter load which is lower with lifepo4 alone and engine will most likely start faster.

Do you have a curcuit diagram how you wired both for charging and discharging. Interested how you prevent that the lfp support the lead in discharge.

I have VolvoD2-50F with 150h and start from 1088AH bank, operation is 180A and ot starts on below 2sek.
BB hull lead 2x110AH needs 260A and about 3sek to start.

I have never started the engine with the Lifepo4 battery bank alone without the LA crank battery. If you do this, the current drawn from the Lifepo4 battery during the first start of the internal combustion engine may be slightly lower since the Lifepo4 voltage will be higher during the first start. The measurements seen in the video were made via the cable connected to the - pole of the LA engine battery.

I have the standard electrical equipment of a Bavaria® sailboat (2007). Lifepo4 service and LA engine batteries are charged from the alternator using the standard type argodiode battery isolator connection. I use a manually operated battery switch to connect the + poles of the Lifepo4 Service and LA engine batteries when necessary. Are you saying that starting the engine directly from the Lifepo4 service battery without the LA engine battery will reduce the current load on the Lifepo4 bms?

[CaptainRivet]

Originally Posted by SOLAR SUPPORT

I have never started the engine with the Lifepo4 battery bank alone without the LA crank battery. If you do this, the current drawn from the Lifepo4 battery during the first start of the internal combustion engine may be slightly lower since the Lifepo4 voltage will be higher during the first start. The measurements seen in the video were made via the cable connected to the - pole of the LA engine battery.

I have the standard electrical equipment of a Bavaria® sailboat (2007). Lifepo4 service and LA engine batteries are charged from the alternator using the standard type argodiode battery isolator connection. I use a manually operated battery switch to connect the + poles of the Lifepo4 Service and LA engine batteries when necessary. Are you saying that starting the engine directly from the Lifepo4 service battery without the LA engine battery will reduce the current load on the Lifepo4 bms?

Its not only the higher voltage, its also a much lower resistance means ramp up is faster and therefor less current needed overall but especially in the ramp up.
Yes it reduces the inital load on the BMS significantly. The moment you parallel them the lifepo4 is delivering current to starter during starter operation also to support its higher voltage sag and at the same time operate starter.
I suggest you rewire that 1+2 switch and then you decide yourself which battery to use for starter, for lifespan of starter its the lifepo4.
But be aware the starter introduces spikes and noise in your house power curcuits which your senstive electrics doesn't like.an issue you have now too with paralleling them.
How to solve that smart i posted above.

Just a side note, thats a lot start current in operation for that little D1-30 and 5sek to start from beep a long time. Are you in a very cold area, then ok. Otherwise indicates someting is wrong there, glow plug? Did a Compression test? How many hours? Bad or corroded connection: Did you measure voltage at starter to see voltage drop to terminal?

[SOLAR SUPPORT]

I see, I will try a cold start test with the Lifepo4 bank after removing the LA battery connection. But I will need to keep LA battery connected to battery isolator to ensure the possibility of an accidental Hvcutoff action of the Lifepo4 bank.

[CapsizedVeteran]

Originally Posted by CaptainRivet

Your capacitor won't change anything for the mosfets in the BMS either. Only that helps get a bigger or a 2nd one but as long as you don't want to use house as starter you don't need. For an emergency start from.the Lifepo4 the existing BMS will most likely work without issue.

How big is your windlass? Normally smaller then the starter, so the surge currents are no issue for the BMS mosfets.
But they are an issue for your chartplotter and radar, especially the newer ones were they saved on filtering of power supply/input voltage...and i gave you a smart solution for that.

A large capacitor will change absolutely nothing for the currents and voltages the mosfets on the BMS are seeing? I'm not sure how you could come to such a conclusion but I'd be happy to be the test subject for it. I can check both the current and voltage that's hitting the batteries with an oscilloscope both before and after installing a large capacitor to see what difference it actually makes for the BMS. I'd be happy to post up the results of it so people could see how things work in the real world instead of just talking theory.

[wholybee]

Some considerations that are overlooked. First, and perhaps most important, starters are no wound for 12V. They are wound to operate at the _lower_ voltage considering voltage sag. So they are really wound to operator at around 10V. So if you are starting with and LFP, you are using up to 40% more voltage than what they are wound for, and that is very significant.

This added voltage does not translate to less current. The voltage current relationship assumes the same amount of power is being output. (VI=W) But with the starter motor, with a higher Voltage the motor will spin much faster, and spin the engine much faster. More Watts are output from the motor, and thus the Voltage increase did not result in less current, it resulted in more Watts.

Starting the engine with LFP will most certainly start the engine much easier and faster, due to the 40% extra voltage. However, if the engine doesn't start quickly, if the injectors need primed or whatever, you might damage the starter or melt the wires faster than you would with lead acid.

Overall, LFP would start an engine better than Lead-Acid, just don't let yourself crank a not starting engine for a long time.

[lateral]

Wow, this is indepth, just what I need as I am contemplating finally installing my windlass. I have replaced the FLA 460Ahr house with 8 CALB LiFePO4 230Ahr cells in 4S2P config, with 2/JBD 200A bms's 8mnths ago- Excellent.
Currently charged with just the alternator via MC618 regulator/argofet and occasionally top off with Pronautic 1250P & balance with lab power supply. Suits current sailing. keeping batteries <80/20% except on TB. Tedious, so have a 5A active balancer (for above 3.4V.) thats about to go in.
My start battery is a 14yro SLA that refuses to die, but it must be near given age. Lithium charge is set to 14.2V so that must be enough.
I was seriously thinking of bypassing BMS and hooking windlass direct to LFP via contactor even though JBD 200A are supposed to be 200A continuous.(Or 365A for 30secs.) My reluctance to go through FETS stems from the fact that if I experience a disconnect on one of the banks the full load goes to the other. My starter is 1200W (On 3GM30 yanmar) I have to replace starter at some stage, so perhaps there is a replacement that would serve both starter & windlass & complement current DIY install. LTO, proprietry LFP, big SLA? Cheers for any comments. (I do have components to isolate electronics from back emf etc) Oh, and would my fluke clamp with inrush, not give accurate initial start current?

[CaptainRivet]

Originally Posted by lateral

Wow, this is indepth, just what I need as I am contemplating finally installing my windlass. I have replaced the FLA 460Ahr house with 8 CALB LiFePO4 230Ahr cells in 4S2P config, with 2/JBD 200A bms's 8mnths ago- Excellent.
Currently charged with just the alternator via MC618 regulator/argofet and occasionally top off with Pronautic 1250P & balance with lab power supply. Suits current sailing. keeping batteries <80/20% except on TB. Tedious, so have a 5A active balancer (for above 3.4V.) thats about to go in.
My start battery is a 14yro SLA that refuses to die, but it must be near given age. Lithium charge is set to 14.2V so that must be enough.
I was seriously thinking of bypassing BMS and hooking windlass direct to LFP via contactor even though JBD 200A are supposed to be 200A continuous.(Or 365A for 30secs.) My reluctance to go through FETS stems from the fact that if I experience a disconnect on one of the banks the full load goes to the other. My starter is 1200W (On 3GM30 yanmar) I have to replace starter at some stage, so perhaps there is a replacement that would serve both starter & windlass & complement current DIY install. LTO, proprietry LFP, big SLA? Cheers for any comments. (I do have components to isolate electronics from back emf etc) Oh, and would my fluke clamp with inrush, not give accurate initial start current?

If you still want a starter bank, i suggest LTO 30AH or 40AH Yinglong cells in 1p6S with an active balancer, no BMS needed. Cells can be grade B, as long as they work is sufficient, don't need to waste money here on top notch cells. A good alibana or aliexpress offer will do.
As you have already a regulared alternator simply connect them parallel to Lifepo4 with the argofet.
Advantage of LTO is they don't care at all which state they are floated or kept as long as above 10%SOC. And with charging parallel they are only charged to 85%SOC which is perfect for starter.

Or spend no money on new batteries, put LVC at 3.0V. In this case with FETs BMS i would simply bypass BMS and connect starter directly with a 175-200A breaker.
When lights go out at 3.0V disconnect you still have enough juice in the bank to start the engine 40xtimes. Nothing happens if you don't operate it and if something is wrong the breaker trips and disconnects. A breaker and not a fuse as you see it quick and can reconnect quick compared to a fuse.
And well in emergency can decside to better ruin the bank then ending up on a rock.

The fluke clamp is not quick enough to measure the first ms where you get biggest inrush current but double what the fluke measures and you have the inrush.

[SOLAR SUPPORT]

Originally Posted by lateral

Wow, this is indepth, just what I need as I am contemplating finally installing my windlass. I have replaced the FLA 460Ahr house with 8 CALB LiFePO4 230Ahr cells in 4S2P config, with 2/JBD 200A bms's 8mnths ago- Excellent.
Currently charged with just the alternator via MC618 regulator/argofet and occasionally top off with Pronautic 1250P & balance with lab power supply. Suits current sailing. keeping batteries <80/20% except on TB. Tedious, so have a 5A active balancer (for above 3.4V.) thats about to go in.
My start battery is a 14yro SLA that refuses to die, but it must be near given age. Lithium charge is set to 14.2V so that must be enough.
I was seriously thinking of bypassing BMS and hooking windlass direct to LFP via contactor even though JBD 200A are supposed to be 200A continuous.(Or 365A for 30secs.) My reluctance to go through FETS stems from the fact that if I experience a disconnect on one of the banks the full load goes to the other. My starter is 1200W (On 3GM30 yanmar) I have to replace starter at some stage, so perhaps there is a replacement that would serve both starter & windlass & complement current DIY install. LTO, proprietry LFP, big SLA? Cheers for any comments. (I do have components to isolate electronics from back emf etc) Oh, and would my fluke clamp with inrush, not give accurate initial start current?

400Ah capacity drop-in 2p4s LFP battery bank. Two BMS have a total capacity of 300A. It can provide 600A maximum peak current for 10 seconds. I cold-started my VP D1-30 engine directly with this LFP service battery today.

I am sharing the slow motion video recording link below. The initial operating speed of the motor and the maximum observed current remained unchanged. The only difference is that all the current is drawn from the LFP bank, because at this time the + terminal of the LA battery is not in place.

When the LFP battery bank and the LA crank battery were connected in parallel, the load of the LFP battery was reduced by 41%.

I have been using my 1000 Watt Lewmar windlass with my LFP service batteries for a year without any problems. The 1000W DC motor of the windlass operates at high speeds before the three-stage transmission. Since the torque required for the first movement of the windlass is much lower compared to the first movement of the diesel engine, the peak current drawn from the batteries is lower.

https://youtube.com/shorts/pTUauz9OX...2fHY_pVC0YVGh3

[lateral]

Thanks CR & SS for your replies.
Firstly CR,
I love the specs of the YinLong LTO/LIFePO4 hybridism, and your methodology, but alas here the current regs suggest no electrical certification for a start battery of Li chemistry. These are cloudy rules but not sticking to them could result in being booted from marina. I have three switch emergency setup so if required can switch to lithium bank, but thru the BMS's. To bypass bms would make that five switches. Which is too open to operator error. So, dunno whether to look for an inspector that sees the merit in embracing superior chemistry or just comply. Not an urgent decision and I WILL use my emergency switch over rather than risk the boat or some one else's.

SS, Good vid, thanks. I believe the volvo starter is 2000w right? Mine is 1200 so bit of headroom there. Also my windlass is 800w. Your experience is valuable. What brand/model BMS's do you have?
I like your 4s2p setup for safety reasons.
Ok, so scenario: lead starter bat is dead. You NEED to start your engine. For some reason your 4s2p bank #1 bms trips because of overload or whatever. Immediately your Bank #2 has double the current and trips. Now you have no starter or house until reset? If i have misconstrued, apologies.
I believe (but must check) direct parallel LA to LFP is not legal here, so thats out. I think my head can deal with windlass thru BMS'S at less than 400A inrush. But will do a test run on circuitry thru a scope first. (bypassed.) Awesome, thanks!!

[SOLAR SUPPORT]

Originally Posted by lateral

I believe the volvo starter is 2000w right? Mine is 1200 so bit of headroom there. Also my windlass is 800w. Your experience is valuable. What brand/model BMS's do you have?
I like your 4s2p setup for safety reasons.
Ok, so scenario: lead starter bat is dead. You NEED to start your engine. For some reason your 4s2p bank #1 bms trips because of overload or whatever. Immediately your Bank #2 has double the current and trips. Now you have no starter or house until reset? If i have misconstrued, apologies.
I believe (but must check) direct parallel LA to LFP is not legal here, so thats out. I think my head can deal with windlass thru BMS'S at less than 400A inrush. But will do a test run on circuitry thru a scope first. (bypassed.) Awesome, thanks!!

Lewmar pro1000 windlass has 700w motor and VP D1-30 has 1100w motor. It took an Internet scan to be sure. When I opened the Dropin LFP batteries, I saw that there was a Dally 150A bms inside. My LFP service and LA engine batteries are separated by the battery isolator. The battery isolator provides assurance against possible accidental Hvcutoff action during charging from the alternator. I'm not sure if the same safety will continue if LTO batteries are used instead of LA.

What harm could a switch that temporarily connects the LFP service batteries directly in parallel with the LA crank battery do to the system when the LA battery is insufficient to start the engine? You use this switch for paralleling batteries only in emergencies. Once signs of weakening of the LA crank battery are observed, we need to replace this battery as soon as possible.

I would like to remind you that when using the windlass, as everyone knows, the engine must be running at this time and the energy received from the alternator provides great support to the electrical system. Your LFP bank is ok with this support when your windlass works.

[wholybee]

Originally Posted by SOLAR SUPPORT

Lewmar pro1000 windlass has 700w motor and VP D1-30 has 1100w motor. It took an Internet scan to be sure. When I opened the Dropin LFP batteries, I saw that there was a Dally 150A bms inside. My LFP service and LA engine batteries are separated by the battery isolator. The battery isolator provides assurance against possible accidental Hvcutoff action during charging from the alternator. I'm not sure if the same safety will continue if LTO batteries are used instead of LA.

What harm could a switch that temporarily connects the LFP service batteries directly in parallel with the LA crank battery do to the system when the LA battery is insufficient to start the engine? You use this switch for paralleling batteries only in emergencies. Once signs of weakening of the LA crank battery are observed, we need to replace this battery as soon as possible.

I would like to remind you that when using the windlass, as everyone knows, the engine must be running at this time and the energy received from the alternator provides great support to the electrical system. Your LFP bank is ok with this support when your windlass works.

You should check the specs of the Daly BMS. Depending on the specific 150A model, the 150A rating is continuous, with a max intermittent discharge of 500A. A good friend of mine has been using a 100A Daly for several years with his windlass. No problems. An 1100W windlass is only 85A continuous. With high current of a couple hundred Amps for only a few seconds.

And yes, the engine should be running, giving you another 50-100A depending on your alternator.

And, the BMS will protect itself if current truly is too high.