Problem running a lithium battery with built in BMS

[JHZR2]

This is the battery. It works great except for the issue with my 16v spike.
https://dakotalithium.com/product/d...fd7a3wSh218KxIHZJppxHeD7BjEvitw583rCYW35_q-I9

You know you have a spike based upon alternator excitation controls. You know the bus will cut out to prevent abuse. What else is there to know? Program out the alternator scheme, disable it, or run agm.

The primary use for LiFePO4 12v batteries is ups and trawling motors. Not sli.

Can one be made the handles the L di/dt voltage spikes and all the rest, sure. Some may actually even have active components in them. But that’s a major undertaking, and introduces other reliability and integration considerations…

 

[Stumpalump]

You know you have a spike based upon alternator excitation controls. You know the bus will cut out to prevent abuse. What else is there to know? Program out the alternator scheme, disable it, or run agm.

The primary use for LiFePO4 12v batteries is ups and trawling motors. Not sli.

Can one be made the handles the L di/dt voltage spikes and all the rest, sure. Some may actually even have active components in them. But that’s a major undertaking, and introduces other reliability and integration considerations…

I am going to say you are correct. These lithium batteries in all flavors that claim they are for automotive or cranking are not ready for prime time. Optima is coming out with an Orange top lithium battery so I sent their tech line a question and got this back.

 

[BrendanC]

I am going to say you are correct. These lithium batteries in all flavors that claim they are for automotive or cranking are not ready for prime time. Optima is coming out with an Orange top lithium battery so I sent their tech line a question and got this back.

View attachment 267422

run two or three in parallel

 

[jetman]

I removed dual 50#each in parallel agm batteries and alternator and installed dual 7#each in parallel 12v https://www.golithium.com/product-page/12v batteries in my race car.
Work great. No issues.

 

[barryh]

I expect the regulator to converts the alternator output to a smooth DC, clean unwanted spikes.
Based on this, shouldn't the regulator be inspected?

The regulator doesn't smooth the DC output. What the regulator does is switch the rotor current on and off rapidly such that it limits excitation of the rotor to the level necessary for the alternator to deliver the desired voltage output. It's the battery that smooths the DC and it's the disconnection of the battery by the lithium BMS that cause the spikes as without the battery in circuit there is nothing else to do the smoothing. That's why people are suggesting a large capacitor which would smooth the rectified AC in the same way that a large capacitor does in every other AC to DC power supply.

 

[nobb]

It really depends on the vehicle. On modern vehicles, often times the 15 - 16V voltage spike is a designed feature acting as a pseudo regen braking by using the alternator to capture energy to the battery.

Using a lithium battery with it's own BMS is a bad idea because the battery might cut itself out as overvoltage protection, which is worse for the car because without the battery as a buffer the voltage spike on the car electronics will be even more severe.

The suggestion to use MOVs would not work because MOVs are designed to be self sacrificial intended only for emergency surges (not continuous).

 

[bonjo]

not sure if I entirely agree with you.
First a rectifier is used to convert the 3 phase AC from the generator to DC (unregulated with ripples) then the regulator smooths out this DC for supply to the ancillaries.
The proper operation of this is what I was questioning.
A long time ago, I noticed my headlights would sometimes become very bright for a minute then go back to normal. I had to change the regulator to solve this.
Cars nowadays have Rectifier & regulator in one unit

 

[barryh]

First a rectifier is used to convert the 3 phase AC from the generator to DC (unregulated with ripples) then the regulator smooths out this DC for supply to the ancillaries.

I would have to see a circuit diagram to understand what you are saying here. The only regulator that I've seen that might have a smoothing function is the crude total loss systems once used 50+ years back on some motorcycles.

On more recent systems the regulator controls the average current through the rotor windings in order to vary the excitation of the rotor and hence voltage output. In this case the regulator can't have a smoothing function. The battery provides the smoothing.

Example of a very old motorcycle total loss system.

Example of a more modern system with the regulator controlling rotor current to vary the output voltage.

 

[meep]

give mechman alternators a call. they’re the name in aftermarket specialty alternators. i have a 370 amp from them with probably 100k miles on it and no telling how many idle hours running my sound system or 3k inverter. i can highly recommend idle my truck at 1500rpm and run my inverter hard until the cows come home.

You get into some pretty cool stuff - enjoy your posts!!!

 

[Fitter30]

16.5 lb race car batteries
https://www.google.com/url?q=https:...8QFnoECA4QAg&usg=AOvVaw3hg950dy-JJ2rHpXTprJgc

 

[bonjo]

I agree on newer vehicles the two functions are combined in one "block".
I can also see from the diagram, the output of the "rectifier" is directly connected to the battery which may be where the confusion lies
The rectifier should also divert excess current to ground rather than the battery.
An oscilloscope on the battery terminals would shows us what is there for certain.
Perhaps having spikes on the so called DC voltage supply in modern cars alternator/rectifier/regulator design design featrure

 

[oilboy123]

I was going to post about a Noco Lithium power sports battery. I wanted to replace a flooded battery on a 2 year old generator. It is already leaking acid on the terminals.
But now I'm afraid to.......... I don't want a spike in my electronics on an inverter generator. So back to my first thought, AGM.