Alternator delete consequences

[EcoCivic]

Originally Posted by Ecky

LiFePO4 would not explode. That chemistry doesn't melt down, it tends to just... fail. Loses capacity, loses cranking amps, etc.

I've run it down a few times in winter and jumped it, before I figured my wiring out. On the truly cold days I brought it inside to warm up before charging but it *has* been charged, probably slowly, a little below freezing. Couldn't tell you exactly what goes on having supercapacitors in parallel but my educated guess is that the battery's internal resistance must limit charge rate somewhat, and the caps handle transient loads.

Well that's the kind of battery I should get then. I don't want the battery to turn into a bomb if the alternator regulator goes bad and it way overcharges or something. Honestly I am a little afraid of Li Ion and Lipo batteries

[Piotrsko]

While they tend to not "explode", they will vent a low vapor point highly volital organic solvent when they get hot/overcharged, possibly from the electrodes shorting.

When they are frozen, the same solvent becomes incapable of moving electrons.

Over discharge typically results in the electrodes warping or being saturated with "oxides" much like flooded lead acid, but cant be recovered.

[redpoint5]

Yep, I destroyed a $45 LiFePO4 by over-discharging. It happened very quickly. I had my Acura engine off, but the ignition on, and was testing various accessory draws when the car rapidly showed signs of low voltage. By that time it was too late and the battery had puffed up. I removed the puffed up cell and the remaining 3 are probably in decent condition, but I don't have a use for a 10v battery at the moment.

[teoman]

If you have a boost converter an 2 energy storage mediums (caps and battery or 2 batteries), you can set whatever voltage you want.

[redpoint5]

I don't have a boost converter and wouldn't build a project that has one unless there was no other way to accomplish the task. I'm about simplifying things where possible.

I'll probably use my 3s LiFePO4 for testing purposes. Still curious how efficient the battery is at accepting a charge compared to lead acid. Was going to compare charging from 80% to full with LiFePO4 and lead acid to compare charging efficiency. Lead acid is extremely inefficient as it approaches full charge, which is where it spends most of its time.

[teoman]

It depends on your objectives.

Mild hybrid completely alternator free with constant voltage and you really do need some electronic wizardry.

[Ecky]

Originally Posted by teoman

It depends on your objectives.

Mild hybrid completely alternator free with constant voltage and you really do need some electronic wizardry.

I'm running alternator-free right now with my LiFePO4. On my Insight the hybrid system has been removed, but I repurposed the electric motor as a 3 phase electricity source to power a Meanwell power supply which supplies a constant ~13.5v. Capacitors take care of transient load. I can't imagine there are much more efficient ways to generate and store electricity in a car.

[jjackstone]

Below is a link to a DIY lifepo4 battery. The video is about building the battery cheaply and protecting the battery. He is building it for solar charging but it wouldn't be too hard to make mods for using it in a car. I'm assuming you would be charging the pack externally since this thread is about an alternator delete.

https://www.youtube.com/watch?v=O94aEaa6d1A

I've been watching this kid's videos for a while now. He pretty well knows his stuff. If I were worried about over discharging a pack I would stick a voltmeter gauge on it and run it to where I could monitor while driving. Additionally I might connect a beeper that would sound at a certain level of discharge.

JJ

[EcoCivic]

Originally Posted by jjackstone

Below is a link to a DIY lifepo4 battery. The video is about building the battery cheaply and protecting the battery. He is building it for solar charging but it wouldn't be too hard to make mods for using it in a car. I'm assuming you would be charging the pack externally since this thread is about an alternator delete.

I've been watching this kid's videos for a while now. He pretty well knows his stuff. If I were worried about over discharging a pack I would stick a voltmeter gauge on it and run it to where I could monitor while driving. Additionally I might connect a beeper that would sound at a certain level of discharge.

JJ

To clarify, I am not talking about completely removing the alternator and driving off battery power on a daily basis. While it would be very nice to be able to completely get rid of the alternator and just run the electrical system off of batteries, that would not be practical for me for a lot of reasons. For one thing, I don’t have hundreds of dollars for a super large battery pack. However, I will certainly consider these ootions when I need to replace the battery.

If I was going to completely remove the alternator, I would need a battery pack with enough capacity to run the car for probably about 2 hours minimum with the electrical system loaded before the batteries start to die.

I frequently drive 30 minutes each way to the store, and I need to be able to use accessories without killing the battery. I am the kind of person who plans for the worst case scenario. For me, that would mean I am about 30 minutes from home, I get stuck in traffic at night in the rain, I have at least the AC on, headlights on and wipers on. The last thing I would want would be in a situation where the battery is dying, and I need to have the car towed home because the batteries are dead or will be damaged by continuing to drive.

[redpoint5]

Lol, and I'm the opposite; an optimist expecting best case scenario. That's why I'm usually late to things, and sometimes run out of fuel. I could probably stand to be a bit more pessimistic and be pleasantly surprised when things go better than anticipated.