Keeping Lithium runs at limited charging HO current or without.

[Oinkypig 10+ year member]

Here is the dilemma, safely protect the alternator with a valid charging current. Avoid an over-current draw at low RPMs to ensure the alternator doesn't overheat while charging lithium. PRACTICALLY making a static charging state limited and mandatory for lithiums at the expense of largely discharging lithium while at load. As a result, its detrimental to substantially load lithium itself, moreover due to the power draw from audio. I have yet to manage a dummy load to the alternator and find out the exacts..BUT finding a happy dynamic between the alternator charge current off a 250 amp alt and discharge current is the ultimate goal here..
The 250 HO setup runs to a 300ah lithium axillary separated by nvx bir500 amp relay isolator from two starters, both 55ah AGM optima blue tops. Only needed, if only suitable, to solve parasitic voltage drop of lithium and AGM...:{. I would like to look for solving the low resistance of the lithium drawing too much current at idle and crippling the alternator for starters.
One way of charging is a DC to DC charger for all intents and purposes is meant to charge a standing lithium bank that isn't currently on any load, particularly a massive equipment wattage draw. If at any moment, or lack thereof, the discharge current doesn't exceed 40 amps of the DC to DC charger due to car accessories and audio amps then it may just do its job and charge the lithium battery, even for an instant.....
Low and behold there's another way of reaching a higher limiting charging state as well... The two AGMs and the lithium battery may be run in parallel, but all the audio equipment is wired directly to lithium. So let's go in between with really my only other option. To rely on an external victron BMS that can electronically limit the charging current to the lithium battery from 0-125 amps. Between it and the audio equipement is the lithium powering the whole darn system(dont forget AGMs are also in parallel being also limited to 125amps to rest of the system too). So without burning the alternator coils, what is a recommended charge current for a traditional AGM system vs lithium system that draws anywhere between 500-5000 watts at any given moment, especially working in tandem, in this case? And how can i ensure that the lithium battery doesn't just drain excessively now with a limited charge capacity too?!
Because the NVX isolator relay wires the AGM and lithium in parallel with a BMS going to the lithium that powers all the audio equipment, the lithium can only ever be able to reach a max 125amp charge current of the alternator AND similarly any needed draw from the two AGMs wired in parallel for POWA.
Victron Energy Battery Management System 12/200
Victron Energy Battery Management System BMS 12/200 | Northern Arizona Wind & Sun (solar-electric.com)

Should I just run the relay isolator to connect all batteries in parallel and run wires from Every amp or audio accessory straight off the lithium bank? If the car audio system averages a discharge of 1000-2500 watts constantly but only charges 125 amps continuously, how would the lithium battery ever get a charge? Run it with BMS locked at 80/125amps or without and find out how the alternator handles the heat?
The upside to all this limiting current is that my starter batteries should always work but the downside is limited current reaching the audio equipment.switchback to letting lithium take the blunt force..... split the amp load between the two battery banks? Lithium powers the high side and AGM powers the low side, vice versa or just Let the lithium bleed dry and recharge with LiFePO charger with car off?

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[adulbrich 5,000+ posts]

What lithium battery do you have?

 

[Oinkypig 10+ year member]

Heres my stance on the choice between LTO and LiFePo. Its that LTO, done the right way, would need 16+ volts to be externally regulated and are not very cost-effective at price per capacity. LTO, although pricey, I can understand achieve up to 5C charge and discharge, albeit at lower temperatures and that is a plus as well. The cells Im looking at are 300ah prismatic LifePo with low temp cutoff + 200/250 amp discharge 4s Daly BMS. So lets assume it's 300ah with a 250a BMS discharge at 0.83C or 250 amps, Or at best a 35ah Yinlong LTO discharge at 5C is 175amps. Wouldnt underestimate LTO as it may not cause alternator overheating and not require pricey accessories to maintain properly.
edit: The added two AGMS wired in parallel may also just have added enough resistance with a lithium battery in place to maintain an ideal current output without damaging the alternator and pulling excessive amps at low RPM. I might not need to limit a charge of 125amps because LiFePo can handle 1C charging rates(above alternator rating) but I feel the need to understand the scenario that causes pulls of 0.5C to 1C at idle RPM, and how the alternator reacts. SO IF LiFePo is maintained on an hourly(hopefully only daily needed) basis with 14+ volts fully charged and is not engorged with extended power draw, the alternator shouldn't heat up drastically, if only momentarily, and not melt the coils.
It would seem to me that I just turn down to lower volume at idle, gauge the lithium voltage, monitor the current output of the alternator. The victron BMS does all that while running on bluetooth and digging a little deeper might actually have the possibility of turning off the limit on charging the lithium battery, which i can do when above idle. it would help to know a way to use a contactor or solid state relay to open the circuit of the charge limiter above idle RPMs and close it at idle...... Keeping DC motor cool is a problem.. I will need the information from a chrysler/dodge PCM of the jeep jk 250HO external regulator to be able to maintain ideal temperatures by lowering current output. If it works as it should, i neither need the victron BMS nor BMS-limit current charge to a lithium battery. if the chrysler/dodge pcm regulator doesn't moderate properly then it would need an external regulator to limit output and maintain temps.. Here... found some super duper sales articles 1. Protecting your alternator when switching to lithium – Liv Sailing 2. Adding an alternator to your lithium-ion battery setup requires a bit of planning.... (pkys.com)

 

[adulbrich 5,000+ posts]

Are you worried about frying your alternator because the batteries are pulling too much, or frying the batteries because the alternator is supplying more current than they can recharge with?

In either case, the batteries are only going to be "pulling" from your alternator when the amp is "pulling" from your battery bank.

If your amp is constantly drawing way more current than your alternator can provide, your alternator is going to burn out. Stock alternators are not designed to put out their max current ratings all the time. They're designed to be able to run all the vehicle's stock accessories, and keep the car running. That's it. Regardless of what batteries you choose, your alternator is going to go out if it's constantly loaded down. I'm assuming your 250 amp alternator is aftermarket though. What brand?

If you're concerned about the batteries overcharging, don't skimp on the amount in your battery bank. If you have 250 amps of current supplied from the alternator for one battery bank, the bank would theoretically be able to take in that 250 amps of current. If you added another bank in parallel, the current would be split to roughly 125 amps per bank, assuming they don't have another issue causing uneven balancing, like one bank being much older than the other.

All that being said, if you watch voltage drop and don't have the volume cranked, you could probably get by with one bank until you were able to save up and add a second.

 

[Oinkypig 10+ year member]

This is what im worried of How to not blow up your Alternator when charging Lithium - YouTube
I need some help understanding what you stating is According to this demonstration What happens when you charge and discharge a LiFePO4 battery at the same time? - YouTube
1. If the power draw is under the rated (<250) amp alternator current output than, power is provided by the alternator
2. IF the current draw is above 250 amps, the additional needed electricity is pulled from the batteries?
Whenever and as long as a lithium battery is under full state of charge <14.4-14.6v the BMS would set the lithium cells onto a charging state and lithium take as much current as possible... Which is why most solutions are either a battery management bms THAT limits current all together no matter the RPM or involved an external regulator that drops current/voltage accordingly when an alternator reaches high temperatures.
My proposed system would have either/ both external regulator and victron BMS. The AGM and lithium are seperated by 125 amp limit current fuse and probably offers more protection than absolutely needed. This would mean exceeding the lithium discharge rate would correlate with additional power draw of a max 125 amps allowable from the alternator AND the AGMs.
Or could I wire the equipment to the AGMs that arent being current limited by the alternator and could perform as a buffer/capacitor between the equipment and lithium energy storage. I can either use the lithium as the immedate power source when needed up to 250-300 amps as well as additional 125 amps fused with parallel AGMs. Or use the lithium as a reserve energy source for the AGMs with the 125fuse still in place. See the problem? There is a parallel connection but theres a darn 125 amp fuse in the way,
Any recommendation for compatible external regulator that regulates under temperature?

 

[Slo_Ride 5,000+ posts]

Jesus y'all sure do like to type.

 

[adulbrich 5,000+ posts]

Not sure if he had a speech problem, or it was just his accent, but the guy talking in the alternator video annoyed the shit out of me. He pronounced R's with an "ah" sound instead of an "arr" sound.

From the alternator charging video, a few things can be noted. Yes, you could set up a complex alternator and battery monitoring system, which chokes your alternator when it gets warm. This would protect your alternator. However, this "fixes" things the same way that Jayquan fixes his dimming Crown Vic headlights by throwing in a BOSS capacitor from Walmart. The headlights are no longer dimming because the amp isn't able to draw as much current. The headlights are fine, but he's going to fry the amp. If you choke off your alternator current, you're moving the problem somewhere else. The amp will still draw power from the electrical system. This will be supplied more from your batteries, as shown in the radio video you linked. This will draw your batteries down. Being in a lower state of charge, they will want to draw more current from your alternator when the amplifier load stops, so they can recharge. If you don't allow your choked alternator to recharge your batteries, you'll basically just be constantly wearing down on your batteries without allowing them to fully recharge.

If you're willing to spend a bunch of time and money on a complex monitoring system, just get a bigger alternator (or add another), and double your battery bank. This is the only way to "solve" your problem of having an amp that draws more than your current electrical system can supply.

I would not bother with the temperature controlled external regulator. You can get smaller "overdrive" pulleys for your alternator that will allow it to spin faster at idle. That being said, it will spin faster all the time. If you've got a lead foot and like to run around at high rpm, it's not good for the longevity of your alternator bearings. If it's just something you puts around in and listen to while parked in a parking lot, an underdrive pulley may be a good option.

I would say pick one type of battery and stick with it. Don't mix AGM and lithium. I don't even recommend people mix standard lead acid batteries and AGM batteries. A lithium battery bank in the trunk is perfectly capable of starting your vehicle. An AGM up front and several in the back would probably be a viable option. Adding different battery chemistries and isolators just adds complexity to the system. Battery chemistries don't always play nice together.

 

[adulbrich 5,000+ posts]

Jesus y'all sure do like to type.

You should see some of the academic literature I'm using to write my research paper on microbatteries. Motherfuckers type a page to explain the advantage of a solid polymer electrolyte in lithium batteries. Shit's essentially less volatile than organic liquid electrolyte.

Also, just wasted like 20 minutes on this while I should be studying for my production systems exam.
:crap:

 

[Slo_Ride 5,000+ posts]

Yahtzee

 

[adulbrich 5,000+ posts]

Every time I hear yahtzee, I always think of the Third Reich

 

[Slo_Ride 5,000+ posts]

Every time I hear yahtzee, I always think of the Third Reich

Ummmm that's Nazi. Lol. Man I haven't played Yahtzee in forever. Used to love that ****

 

[adulbrich 5,000+ posts]

Ummmm that's Nazi. Lol. Man I haven't played Yahtzee in forever. Used to love that ****

Yes, they sound the same. I wonder if Hitler ever played yahtzee

 

[Slo_Ride 5,000+ posts]

Yes, they sound the same. I wonder if Hitler ever played yahtzee

Yahtzee no, but he may of played a similar form of it.

 

[adulbrich 5,000+ posts]

Yahtzee no, but he may of played a similar form of it.

You're right, he couldn't have. Unless he played really did escape to Argentina

 

[Slo_Ride 5,000+ posts]

Hell yeah