MkngStffAwesome
Active member
Humm rather interesting..
Destroying Alternators
- Thread starter MkngStffAwesome
- Start date
Humm rather interesting..
Lol. Holy crap. Let me be the first to say - what a janky test rig and completely idiotic mode of testing. First of all - most alternators have at least a 3:1 step up and are not designed to run at 1,500 rpm at anything close to full load for any length of time. They even double down on it be saying their test is, "Above a typical speed of an engine running at idle." Secondly, the small alternator has two strikes against it - it's only a 70 amp alternator (i.e. tiny, by today's standards) and a Citroen. Need I say more? Of course it'll overheat. You're well out side the design parameters for the alternator. The Balmar is at least visibly larger, but also designed for more severe service as it's a marine unit (I realize that's not what saved it; but rather the field controller, but still...)
And then there's their "load" - it looks like someone just cleaned out their lightbulb box. For a company that actually claims to manufacture something, that actually made me laugh out loud. I won't even talk about the 3 or 4 rib belt on 6 rib pulleys or the welding that looks worse than my daughter's stick welds from when she was 10.
And finally - when charging lithiums of any chemistry, you'll need to current limit the output anyway. Now, if you're well inside the charging C rate, then perhaps you'll need to protect the alternator, but why in all that's holy would you do it by reducing the output of the alternator? What about the car's ECU, fans, and all the other electrics and electronics? Wow. And they do intend for this to be run in a car, based on the end of the video.
No wonder the comments are turned off. These clowns are something special. And the really sad part - they have over a half million views.
And then there's their "load" - it looks like someone just cleaned out their lightbulb box. For a company that actually claims to manufacture something, that actually made me laugh out loud. I won't even talk about the 3 or 4 rib belt on 6 rib pulleys or the welding that looks worse than my daughter's stick welds from when she was 10.
And finally - when charging lithiums of any chemistry, you'll need to current limit the output anyway. Now, if you're well inside the charging C rate, then perhaps you'll need to protect the alternator, but why in all that's holy would you do it by reducing the output of the alternator? What about the car's ECU, fans, and all the other electrics and electronics? Wow. And they do intend for this to be run in a car, based on the end of the video.
No wonder the comments are turned off. These clowns are something special. And the really sad part - they have over a half million views.
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PS - I'd just like to add one more thought. I'm running a LiFePo4 DIY car battery now. And because I don't try to run idle at 400 rpm, or use a 70 amp alternator (I use a 170 amp unit), I have precisely zero problems. And when I first installed the battery, I intentionally installed and ran it at a very low state of charge, just to see if it would start the car and how it would charge. It did just fine, once I remembered to connect the alternator...
MkngStffAwesome
Active member
I actually thought it was quite good.. at making a point..
My car has a alternator of about that output (less i think).. It's small because the car is small.. it will also idle rather slowly in an attempt to save petrol... not at 400rpm though..
I think the main point that i took away from it is... you need to consider the implication of the additional load you'll be putting on the alternator and not to kill it...
You have a huge car so i assume adding 40amps extra to the alternator maybe no big deal to your car.. but adding that same 40amps to mine would be a huge mistake...
My car has a alternator of about that output (less i think).. It's small because the car is small.. it will also idle rather slowly in an attempt to save petrol... not at 400rpm though..
I think the main point that i took away from it is... you need to consider the implication of the additional load you'll be putting on the alternator and not to kill it...
You have a huge car so i assume adding 40amps extra to the alternator maybe no big deal to your car.. but adding that same 40amps to mine would be a huge mistake...
It's hugely flawed. Measure your car's crank pulley and alternator pulley and calculate the ratio. Then look at your engine's idle speed and figure out exactly what your alternator's rpm is at idle. My crank pulley is 6" and my alternator pulley is 2" and my idle speed is about 850 rpm (those are stock pulley sizes and stock idle speed minimum is 750 rpm). That means, even completely stock, my car's minimum alternator speed is 2,250. However, alternators are typically rated at 6,000 rpm. So a 70 amp alternator is 70 amps at 6,000 rpm. Not 1,500 rpm like those idiots were trying to show. Remember the integral alternator fan needs rpm to work.
Most alternators are rated for a minimum of 1,800-2,000 rpm. In fact, some alternators cut out below that. That's because the integral fan is designed to cool the alternator, and if you're below the minimum, and pulling virtually the maximum load the alternator's rated for (in which case, the alternator's undersized anyway), then of course it will overheat. Might you need a bigger alternator if you're putting in lithium batteries? Yeah, of course. But the same holds true if you put in an electric radiator cooling fan (if your original one was mechanical), if you put in an electric water pump, if you put in a much larger fuel pump, etc, etc. I did all those things, which is why I ditched my stock 100 amp alternator for a 170 amp unit. Lithium batteries are no different load-wise than any of those; additionally, as you get closer to the max state of charge for the input voltage (which is different from max state of charge for the cells), current drops off dramatically anyway (you end up in the constant voltage area of the charge cycle).
You have a very good point - we must be aware of the electrical loads we place on our alternators, and upgrade when it's appropriate. But those guys are just either intentionally deceptive or morons.
Most alternators are rated for a minimum of 1,800-2,000 rpm. In fact, some alternators cut out below that. That's because the integral fan is designed to cool the alternator, and if you're below the minimum, and pulling virtually the maximum load the alternator's rated for (in which case, the alternator's undersized anyway), then of course it will overheat. Might you need a bigger alternator if you're putting in lithium batteries? Yeah, of course. But the same holds true if you put in an electric radiator cooling fan (if your original one was mechanical), if you put in an electric water pump, if you put in a much larger fuel pump, etc, etc. I did all those things, which is why I ditched my stock 100 amp alternator for a 170 amp unit. Lithium batteries are no different load-wise than any of those; additionally, as you get closer to the max state of charge for the input voltage (which is different from max state of charge for the cells), current drops off dramatically anyway (you end up in the constant voltage area of the charge cycle).
You have a very good point - we must be aware of the electrical loads we place on our alternators, and upgrade when it's appropriate. But those guys are just either intentionally deceptive or morons.
Also - Lol at the "huge car" comment. The LTD feels downright tiny tooling around here. I feel like I'm sitting on the ground, and even "small" cars now outweigh it and tower above it. My daily is a 2021 Jeep Grand Cherokee (it's a lease and my third one - the price is right and it's perfect for my work needs; at under $400/month, zero maintenance costs over the life of the lease and being a tax write off, well, it's kind of a no-brainer); but it's shorter than the A6 Audi it replaced. Both cars outweigh the LTD by quite a bit - the Jeep is supposed to be around 4,800 lbs and the Audi was likely at least 3,800. My car weighs about 3,200-3,300 - I really need to weigh it again without the Whipple, with the new-ish chrome moly tubular K member and much lighter exhaust. It may actually be under 3,200 lbs without me in it.
Installing a larger alternator is one of those almost no-drawback propositions. Except for expense, it's usually pretty easy to do and costs virtually no performance penalty, but increases capacity. What's your car again? I'm fairly positive we could find a larger capacity alternator for it.
Installing a larger alternator is one of those almost no-drawback propositions. Except for expense, it's usually pretty easy to do and costs virtually no performance penalty, but increases capacity. What's your car again? I'm fairly positive we could find a larger capacity alternator for it.
SkylineUSA
New member
There is some very good info in the video that I was unaware of. Thanks for sharing!!!!
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SkylineUSA
New member
The loading difference of the batteries.
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That part is, at least, accurate. And I think MkngStffAwesome's point. I wonder if there's an affordable, off the shelf current limiting solution that's more elegant than a giant power resistor...
But in my LiFePo4 setup, I don't seem to have any issues. I really should try discharging the battery and measure the current flow to get some data points.
But in my LiFePo4 setup, I don't seem to have any issues. I really should try discharging the battery and measure the current flow to get some data points.
Load on alternators: I can certainly understand the worries of car owners of european small hatch backs and small sedans. They usually do not plug 300W led lightbars and 5t whinch to their non 4x4 eco vehicle on board power BUT: there is a very much alive stereo fanatics community in europe who fill their trunks with amps and glass popping sub woofers. I would simply check out what they have done to run their multiple kW equipment in a hatch back 
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MkngStffAwesome
Active member
Maybe you should take a step back and just look at the point they are making which is .. lower the alternator rpm lower the output power and lower the cooling.. This might be ok in a completely stock car because the alternator is oversized but if you massively increase the load it can be very bad.
On my car i can read the alternator current and % via OBD2 and it's simply impossible to run it at 100% for any length of time. HOWEVER when i connected up my AC inverter and turned on my Heat gun it ran the alternator at 100% at idle. Interestingly the idle will increase i believe.
Another thing to consider is that at idle the engine bay temps will be at their hotest which is bad for the alternator.. Also load has probably increased due to a radiator fans. My car has a transversely mounted engine with the alternator on the back of the engine and the radiator is also mounted off to one side of the engine bay so the rad fan does not help the alternator temps.
The premise of us running the alternator at 100% all of the time it's probably incorrect though. If we were running a 12v system with a massive battery to power the e-Turbo then this MIGHT be a problem .. However i believe thus far everyone on this forum is using another high voltage pack to power the E-Turbo and charging this pack from the 12v system. The charger can then limit the power pulled from the 12v system to not overload the alternator.
Something like the below you can adjust the output current and therefore the input current and therefore the load on the alternator.. However this can't be adjusted based on RPM which is what you'd like to do. For me i have already assumed i'll need RPM from the engine and a mosfet to turn the charger off when E-boosting and when the engine is off so i can just PWM the charger to reduce the charge current at low RPM... For me with a small alternator pulling 30-40 amps is probably a horrible idea.
https://www.aliexpress.com/item/1005001314801794.html?spm=a2g0s.8937460.0.0.9e7c2e0eIwF4nl
Alex are you able to load test this charger.. i see people say it doesn't get anywhere near 40A and gets extremely hot.
On my car i can read the alternator current and % via OBD2 and it's simply impossible to run it at 100% for any length of time. HOWEVER when i connected up my AC inverter and turned on my Heat gun it ran the alternator at 100% at idle. Interestingly the idle will increase i believe.
Another thing to consider is that at idle the engine bay temps will be at their hotest which is bad for the alternator.. Also load has probably increased due to a radiator fans. My car has a transversely mounted engine with the alternator on the back of the engine and the radiator is also mounted off to one side of the engine bay so the rad fan does not help the alternator temps.
The premise of us running the alternator at 100% all of the time it's probably incorrect though. If we were running a 12v system with a massive battery to power the e-Turbo then this MIGHT be a problem .. However i believe thus far everyone on this forum is using another high voltage pack to power the E-Turbo and charging this pack from the 12v system. The charger can then limit the power pulled from the 12v system to not overload the alternator.
Something like the below you can adjust the output current and therefore the input current and therefore the load on the alternator.. However this can't be adjusted based on RPM which is what you'd like to do. For me i have already assumed i'll need RPM from the engine and a mosfet to turn the charger off when E-boosting and when the engine is off so i can just PWM the charger to reduce the charge current at low RPM... For me with a small alternator pulling 30-40 amps is probably a horrible idea.
https://www.aliexpress.com/item/1005001314801794.html?spm=a2g0s.8937460.0.0.9e7c2e0eIwF4nl
Alex are you able to load test this charger.. i see people say it doesn't get anywhere near 40A and gets extremely hot.
Yeah, you're probably right. I'll console myself with the fact they turned comments off for probably this very reason. Moving on - I did do some math, and in my case, a typical dragstrip pass should drain about 1ah from my packs; so in other words, recharging a single pass isn't that demanding. I'm actually not even worried about charging in-car for my use case, but I can see why many people would be. I have modified boost converters like this before actually. I've built lights for work (1kW tungsten lights converted to 100 watt high CRI LEDs running off 12 volts - I use these sorts of boost converters (600 watt rated) to make the dimmers). Basically, I removed the multi-turn pots and replaced them with external pots supplemented by external fixed resistors on either side of the pots to keep the voltage (or current, it's been a long time - I don't remember which, if you really want to know I can pull one apart and tell you, but I don't think it matters) in a specified range. You could do something similar with an RPM window switch where below a certain RPM you're limiting the current with one preset pot and switched to another at higher RPM for more current.
To answer your other question - no, I haven't had a chance to test that boost converter yet. I've been finishing up the second pack when I've been finding scraps of time here and there and am at the point where all that's left is installing the cells and the balance board. Between work, life and dealing with family members passing away (I'm being concise, not flippant - just today we've had our 6th death in the family in less than a year; but only 1 was unexpected, and none from covid) it's been difficult. I do have all the parts for the load tester as well; I'm just trying to find the time. In a sense this is a kind of therapy - I really enjoy making this kind of stuff and it lets me forget the misery my daughter and I have been through in the last year. Probably also explains why I've had such a strong visceral reaction to the video. My general rule of thumb when dealing with chineseum electronics is to cut their ratings by at least a third, and usually you'll be ok (thus the 600 watt boost converters in 100 watt lights). I really don't expect this thing to do more than about 600-800 watts or so. But since most of the time you'll just be topping off the batteries (never charging them from less than maybe 75% SOC), it should work fine. The easiest way is just to test it in situ. The way approach projects like this is I get the key parts working, and then upgrade/tweak as necessary. I never try to do everything in one fell swoop - it can get overwhelming.
To answer your other question - no, I haven't had a chance to test that boost converter yet. I've been finishing up the second pack when I've been finding scraps of time here and there and am at the point where all that's left is installing the cells and the balance board. Between work, life and dealing with family members passing away (I'm being concise, not flippant - just today we've had our 6th death in the family in less than a year; but only 1 was unexpected, and none from covid) it's been difficult. I do have all the parts for the load tester as well; I'm just trying to find the time. In a sense this is a kind of therapy - I really enjoy making this kind of stuff and it lets me forget the misery my daughter and I have been through in the last year. Probably also explains why I've had such a strong visceral reaction to the video. My general rule of thumb when dealing with chineseum electronics is to cut their ratings by at least a third, and usually you'll be ok (thus the 600 watt boost converters in 100 watt lights). I really don't expect this thing to do more than about 600-800 watts or so. But since most of the time you'll just be topping off the batteries (never charging them from less than maybe 75% SOC), it should work fine. The easiest way is just to test it in situ. The way approach projects like this is I get the key parts working, and then upgrade/tweak as necessary. I never try to do everything in one fell swoop - it can get overwhelming.