Electrical system load measurements?

[imiceman44]

I'm in the process of swapping my trailer over to lifepo4. In the process my trailer needs an upgrade to the charger as the voltages used on lead acid only gives about an 80% charge. Need to be about 14.6v for most of the bulk charging or you wont ever get a full batt.

It's ok, LifePo batteries actually have a lower life if you do not let them get all the way full or below 30%.
90-95% is best.
As long as you have an alternator there to charge it all the time it's not a problem.
The last 10% of charging takes longer and generates too much heat which kills the battery prematurely.

 

[dyeager535]

1 question I have. How well will the charging systems work on lifepo4. If not what mods needed.

There's a lot of back and forth on this. There are a few things to work through. Charging voltage, and the disconnect. As stated they have (basically) an on-board computer (BMS) that controls charge/discharge, among other things, to prevent damage to the cells. These batteries generally don't "ramp down" the charge current as they top off however. They may be pulling 50 amps charging (could also overload the alternator from draw), and once full, the BMS immediately stops charging. To the alternator this looks like the battery has been disconnected, which theoretically can spike system voltage enough to damage components. There are plenty of people out there who have run them as-is without destroying the alternator or electrical components, I don't particularly want to risk all my electrical components to try it out. BMW has been doing this for years apparently, however that's a system built for lifepo4. I suspect the reason we haven't seen all the controls/components integrated to ensure ability to charge off any system isn't technology, but cost. Heat isn't related to charging really, but the lifepo4's also have a temperature threshold, 140* is the upper end typically seen. For short term testing or remote mounting not an issue, but it is a consideration. I suspect the battery temps underhood approach that.

It's generally recommended to run a two battery system for vehicles, with an SLA for starting and lifepo4 charging.

So your concern is that a lithium pack will not need as many Ah to get the required CCA, hence the reduced run-time without an alternator?

How often does this really happen? If you really want extended run-time, swap in a 6.2. They can run all day with no alternator as long as you keep the lights off.

Not really. The main reason for wondering the actual running load was to be able to run without the alternator just to see if a lifepo4 would be viable for a vehicle starting battery and perhaps as an emergency spare (or jump starter), without risking the electrical components from the expected voltage spike as the BMS disconnects. Actual cranking amps is what I'd need to know to get one with a BMS that will handle the starter load. We are talking ~4Ah for the starting batteries I'm looking at, so run time won't be long in the truck. I just don't think we are far from lifepo4's as automotive starter batteries, and if I can play around with the lifepo4 in the truck as a side benefit, why not? The quality and price of lead acid batteries seems to be getting worse and worse, while lifepo4's have gone the opposite direction. Something like a 30% decrease in price over a year with far more expansive options in the same time. In doing just a little math, even a 100Ah battery won't run the truck long if using the blower, electric fans, etc., so certainly not practical to run without an alternator. And yes, starting over, the 6.2L would probably be my choice for a powerplant.

It's ok, LifePo batteries actually have a lower life if you do not let them get all the way full or below 30%.

I hadn't seen that stated before, what I've seen is that lower depth of discharge means more life. But it's pretty darn linear, one 90% discharge is nearly the same as two 45% discharges. https://pknergypower.com/lifepo4-high-rate-vs-standard-discharge/

With a cycle life of "just" 2000 100% discharges, you'd get a lifespan of 5.5 years discharging it completely every day.

 

[dyeager535]

Making one work in place of lead-acid relies on a BMS. The ones you buy have it built in. https://www.amazon.com/TYKOOL-Firep...Bilt-Generator/dp/B0DK1M4V8B/ref=sr_1_1_sspa? If rolling your own, you'll have to add some kind of BMS. For a car, you can get more voltage just by putting a diode(s) in the sense line. A lawn tractor is typically a pretty poor charger, with voltage varying a lot with engine speed. You can probably verify ahead of time it's able to make 14V or more.

Which if anyone else is looking at the lifepo4's for starter batteries in things like lawn tractors, the companies selling the batteries don't seem to understand that onboard charging of the battery is how the SLA works in those applications. I even had to ask one company advertising these about it. They say compatible with X Y and Z applications, but that's not really true. The batteries aren't going to charge...they are likely to run flat eventually. You'd need a standalone lithium-compatible charger. They aren't much, and I'd assume a lawn tractor would probably run for many many hours on 4-8Ah, (and indefinitely as long as they didn't need restarted) but they are absolutely not a drop in, in the truest sense.

Many of the problems you will see people talk about are *likely* from the misunderstandings of how these batteries charge, and the fact that the lifepo4 manufacturers aren't explicit about the charging requirements.

 

[Blue85]

We are talking ~4Ah for the starting batteries I'm looking at

Is part of your goal to move from a new lead battery at $160+ to a $100 or less lithium motorcycle battery? I don't think anyone is going to recommend it for the application.

There are lithium batteries sold as automotive starting batteries and they contain the electronics to keep the battery at correct SoC and prevent the "no battery" scenarios. You already know they are expensive. What I don't know is if you can get that kind of controller as a separate unit that can play nice with whatever random BMS ends up being paired with it.

 

[dyeager535]

Is part of your goal to move from a new lead battery at $160+ to a $100 or less lithium motorcycle battery? I don't think anyone is going to recommend it for the application.

There are lithium batteries sold as automotive starting batteries and they contain the electronics to keep the battery at correct SoC and prevent the "no battery" scenarios. You already know they are expensive. What I don't know is if you can get that kind of controller as a separate unit that can play nice with whatever random BMS ends up being paired with it.

No, a 4Ah battery for a sole battery is a bad idea IMO. I've driven a fair distance without an alternator on the lead battery, something with ~4Ah doesn't give much time if you want to run the electric fans and headlights, along with the ignition system. As a comparison, it looks like ~20Ah is about what you'd expect to be able to pull out of a starting battery if you had to, without destroying it.

The expensive starter batteries hold no sway for me. The cost benefit isn't there. At those prices the capacity isn't enough to make them interesting for storage and starting. But if the 4Ah theoretically should start the truck, I'd like to test that out. The ultimate destination for the battery is a lawn tractor, but if it will start the truck in a pinch, it has additional potential utility. The lower the starting current required, the cheaper the battery.

 

[Wes Harden]

I may be able to play with some Noco NPL20 or 30's.
Many have been returned as "defective" I suspect incompatible charging systems. Many are being used in pwc durt bikes etc.

 

[imiceman44]

No, a 4Ah battery for a sole battery is a bad idea IMO. I've driven a fair distance without an alternator on the lead battery, something with ~4Ah doesn't give much time if you want to run the electric fans and headlights, along with the ignition system. As a comparison, it looks like ~20Ah is about what you'd expect to be able to pull out of a starting battery if you had to, without destroying it.

The expensive starter batteries hold no sway for me. The cost benefit isn't there. At those prices the capacity isn't enough to make them interesting for storage and starting. But if the 4Ah theoretically should start the truck, I'd like to test that out. The ultimate destination for the battery is a lawn tractor, but if it will start the truck in a pinch, it has additional potential utility. The lower the starting current required, the cheaper the battery.

If you're thinking of using small batteries like this, I have a couple of 11ah in LifePo I could give them a try, and I have one I think 18ah or 20ah.
I use those for my kids electric cars.

I do also have a couple of deep cycle 280ah that I am using for my solar emergency power system that I want to see at one point how they would do in a truck application

 

[imiceman44]

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They are based in Seattle WA

 

[imiceman44]

Dakota Lithium DL+ 12V 135Ah Heated Dual Purpose LiFePO4 Battery

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This is their automotive battery, built to be in a truck. It's still expensive but compared to other batteries that people have been putting in their off road trucks costing $5-600 or more I guess it's comparable for 11 years warranty and the lower weight and longer full voltage discharge rate.
I am not there yet but I'm close.
If it drops to under $1000 I might

 

[dyeager535]

I may be able to play with some Noco NPL20 or 30's.
Many have been returned as "defective" I suspect incompatible charging systems. Many are being used in pwc durt bikes etc.

Those are pretty darn capable batteries. If I was getting one of those free and the only component I was really worried about frying was the alternator, I'd drop it in and see what happened lol.

The 30 is $200 on their website, that's more than most alternators people run on these trucks.

 

[Blue85]

The big lithium batteries are gaining popularity with overlanders, based on being able to run all the toys while camped and still start the vehicle. Plus, it's a crowd that seems to like spending money . In my mind, 2 batteries still makes way more sense, but for some rigs, that means the 2nd battery is in interior space. Since hydrogen gas (and sulfur stink) would push you to a lithium in that location it starts to make sense to do1 big lithium.

In this case, a 2nd battery is another option to extend potential run-time. It sort of doubles the problem of the short life of new batteries, but if the replacements are alternated by about half the life, it's mitigating that in another way.

 

[dyeager535]

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This is their automotive battery, built to be in a truck. It's still expensive but compared to other batteries that people have been putting in their off road trucks costing $5-600 or more I guess it's comparable for 11 years warranty and the lower weight and longer full voltage discharge rate.
I am not there yet but I'm close.
If it drops to under $1000 I might

If the only motivation for DL is USA made, probably want to dig in more. There are apparently a lot of posts about problems with their support, and extreme skepticism that their components aren't Chinese made. It sounds like most every lithium cell on the planet is coming from China. Depends what drives your motivation, there really aren't a lot of high amp hour lifepo4's designed for vehicle starting. You figure a decent lifepo4 100Ah battery is in the $200 range, adding $500 or so isn't a huge stretch for an even larger battery that will pull duty as a starter.

https://www.thehulltruth.com/boating-forum/1274084-dakota-lithium-issues-help-please.html

I'm confused about what differentiates a marine starter from vehicle. The only thing i can think of that might be different is what heat it's exposed to, but this is down to $530. Funny that they say 1000CCA, but nowhere that I see do they show the actual BMS surge numbers, which is always shown with lifepo4's destined for golf carts and what not. They mention alternator charging, are marine alternators different than automotive?

https://www.litime.com/products/12v-140ah-dual-purpose-marine-starting-battery

I don't see anywhere how they address charge current. Voltage is oft-mentioned, but these batteries will accept a charge rate usually of 100A+, that will have a lot of alternators maxed out, which is not a good thing for any length of time.

As a starting battery with a decent size alternator (100A or more) it's probably not much of a concern as the only charge typically imparted is to make up for the starter. But dual purpose, where the battery may be down 50-75Ah, that would put a significant load on the alternator for a prolonged period if the battery isn't somehow internally regulated to not draw more than a specific amount of amps.

I'm just not sold that the potential problems using lifepo4's in vehicles have been addressed properly by the aftermarket yet.

 

[Wes Harden]

Marine vs automotive is fire suppression. No sparks/arching in the engine compartment.

 

[dyeager535]

Marine vs automotive is fire suppression. No sparks/arching in the engine compartment.

Functionally are they any different though? I would expect manufacturers would love to get us to put as many of their products in as many vehicles as we have, so to single out marine starting as being ok, but not automotive when the BMS will clearly handle the starter draw, confuses me.

If anything I'd expect marine to be heavier duty in most regards.

 

[imiceman44]

If the only motivation for DL is USA made, probably want to dig in more. There are apparently a lot of posts about problems with their support, and extreme skepticism that their components aren't Chinese made. It sounds like most every lithium cell on the planet is coming from China. Depends what drives your motivation, there really aren't a lot of high amp hour lifepo4's designed for vehicle starting. You figure a decent lifepo4 100Ah battery is in the $200 range, adding $500 or so isn't a huge stretch for an even larger battery that will pull duty as a starter.

https://www.thehulltruth.com/boating-forum/1274084-dakota-lithium-issues-help-please.html

I'm confused about what differentiates a marine starter from vehicle. The only thing i can think of that might be different is what heat it's exposed to, but this is down to $530. Funny that they say 1000CCA, but nowhere that I see do they show the actual BMS surge numbers, which is always shown with lifepo4's destined for golf carts and what not. They mention alternator charging, are marine alternators different than automotive?

https://www.litime.com/products/12v-140ah-dual-purpose-marine-starting-battery

I don't see anywhere how they address charge current. Voltage is oft-mentioned, but these batteries will accept a charge rate usually of 100A+, that will have a lot of alternators maxed out, which is not a good thing for any length of time.

As a starting battery with a decent size alternator (100A or more) it's probably not much of a concern as the only charge typically imparted is to make up for the starter. But dual purpose, where the battery may be down 50-75Ah, that would put a significant load on the alternator for a prolonged period if the battery isn't somehow internally regulated to not draw more than a specific amount of amps.

I'm just not sold that the potential problems using lifepo4's in vehicles have been addressed properly by the aftermarket yet.

Well this the first time I hear of this but then again I wasn't looking.
I bought my first few in 2020 and I haven't needed anything.
I did however have the same issue this guy had with some batteries I had for my ridgid 18v that sat for 3 months and died.
I was able to revive them but it wasn't easy.
I actually took them apart and bypassed the BMS and charged them with a 12v charger low amp for a day and they started taking a charge through the BMS.
But that was easy because they are bolted together.
Automotive batteries are sealed and they do need to be periodically charged or used to stay alive.
I will be digging more into it because the only reason I went with them vs a Chinese company is for the warranty.
I have had trouble with warranty from a Chinese company so I figured if they are based here I have a better chance.
I have bought lifepo4 batteries from cheap Chinese companies and from better Chinese companies as well as DL and the finish is indicative of cost.
Also the warranty on Chinese batteries is max 5 years.
Only time will tell.
The cheap Chinese battery I got for my boy's electric car died within 2 years.
No chance in warranty so I moved on to a different company and we will see how that goes

 

[CyberSniper]

The truck in my avatar (TBI350) took 14 amps to idle but I don't remember at what voltage. I do remember it being fairly relative to the voltage because the voltage regulator in the alternator would randomly choose about 12v to 14.5v and the current draw would fluctuate also. I can't remember, but a significant portion of the load was the electric fuel pump. So, I'd say that the consumption is more of a power thing than a current thing.

 

[dyeager535]

Well this the first time I hear of this but then again I wasn't looking.
I bought my first few in 2020 and I haven't needed anything.

Will Prowse (of DIY solar fame) has taken a ton of batteries apart. He's not the only one that disassembles them of course, there are a couple more I'm familiar with that regularly disassmble them. From what I've seen, a battery manufacturer that is good today can be terrible tomorrow, or the opposite. A lot of the battery companies have pretty poor ratings for customer service. Seeing what I have with SLA starting batteries and customers bringing them back for being dead when its a charging issue and so on, and lithiums needing a different charge than SLA, I'm sure the LifePo4 companies deal with a lot of problems that are customer induced. I'd be inclined to ignore them after awhile too, truth be told lol.

I think buying the no-names would be questionable. But people seem to enjoy tearing them apart, at this stage just search youtube with that battery name and I'm sure you'll find a disassembly video.

Have you been running them in vehicles as starter, or for other applications?

Of course now that the LifePo4's seem to be nearing "perfection" of the tech, we are probably on the cusp of another change, I've seen the sodium ones and lithium titanium or something like that being advertised as the latest and greatest. But with LifePo4's being in the $150-200 range for 100Ah, for storage capacity and lifespan they are already arguably better than SLA's, anything that comes out promising better is going to have to be even cheaper.

Just need affordable ones that play nice with the charging systems. Really all we are lacking.

 

[dyeager535]

The truck in my avatar (TBI350) took 14 amps to idle but I don't remember at what voltage. I do remember it being fairly relative to the voltage because the voltage regulator in the alternator would randomly choose about 12v to 14.5v and the current draw would fluctuate also. I can't remember, but a significant portion of the load was the electric fuel pump. So, I'd say that the consumption is more of a power thing than a current thing.

Mine is consistent 14.3-14.4V regardless of load or engine speed. I am certain there is something "wrong" with the alternator, it didn't always run that, but it hasn't gone crazy and cooked my battery yet, so I'll leave it be. It may be ideal for the LifePo4. I'm torn on testing that, it's nice having an alternator where things don't dim/slow down at idle. But this SLA is probably nearing its end of life.

If the system is drawing minimum (say) 14A, how much of a spike will there really be when the BMS shuts down?

Additionally, if the alternator isn't charging at idle (due to voltage being below what the battery needs), the occurrence of any spike will be greatly reduced.

I've seen some LifePo4's that are BMS-limited to 30A charge, with a decent alternator that wouldn't be too taxing for even a moderately powerful alternator. Given the fact LifePo4's don't generally change voltage significantly as they discharge, they would actually probably do very well keeping things like electric cooling fans and heater/AC blowers going at a constant speed at idle, even as the alternators output drops.

 

[Wes Harden]

Have noticed some new vehicles, Jeep, coming with ab Aux battery. Haven't researched why, it is a small battery normally AGM LA type.
The starting batteries normal FLA or AGM.

 

[imiceman44]

Will Prowse (of DIY solar fame) has taken a ton of batteries apart. He's not the only one that disassembles them of course, there are a couple more I'm familiar with that regularly disassmble them. From what I've seen, a battery manufacturer that is good today can be terrible tomorrow, or the opposite. A lot of the battery companies have pretty poor ratings for customer service. Seeing what I have with SLA starting batteries and customers bringing them back for being dead when its a charging issue and so on, and lithiums needing a different charge than SLA, I'm sure the LifePo4 companies deal with a lot of problems that are customer induced. I'd be inclined to ignore them after awhile too, truth be told lol.

I think buying the no-names would be questionable. But people seem to enjoy tearing them apart, at this stage just search youtube with that battery name and I'm sure you'll find a disassembly video.

Have you been running them in vehicles as starter, or for other applications?

Of course now that the LifePo4's seem to be nearing "perfection" of the tech, we are probably on the cusp of another change, I've seen the sodium ones and lithium titanium or something like that being advertised as the latest and greatest. But with LifePo4's being in the $150-200 range for 100Ah, for storage capacity and lifespan they are already arguably better than SLA's, anything that comes out promising better is going to have to be even cheaper.

Just need affordable ones that play nice with the charging systems. Really all we are lacking.

I am using the batteries for all kinds of things.
The big 280 amp are for storage from my solar emergency power system, I do want to try them on my big rig on starting to see how they do.
They are not cheap but I snatch them when they go on sale below $500.
I got 2 so far for $450 each.
The other smaller ones run my electric scooter, my boys electric cars, my emergency lights and I have used one to start a motorcycle.
Car is next to get more info on how they fare