Upgrade Batteries Or Alternator?

[066]

Hi, my name is Dylan. Thanks for looking at my thread.

Im trying to make sure I take the right next step with my electrical system.

First, the truck is a Powerstroke diesel. Stock dual (lead acid) batteries and a 130a alternator. Big 3 already done with 1/0 welding cable.

Im powering 2 CT Sounds 1500.1 (strapped at 2ohm ~1700 watts) and a JL 600/6 (4 and 2 ohm loads ~500 watts)

At full power, voltage is dropping like a hammer (<13). At my normal-high listening level, voltage is fine but my lights still dim.

Batteries are fairly new so I’d prefer to do the alt first.

Which one will give me the best result though?

Click to read more...

 

[dragon.breath 10+ year member]

I would go for the alternator.

 

[066]

Thanks. I’m looking at a 320a or 370a Mechman. I only want to do this once but would I be just as good with a 320a? I think this system will be pretty permanent for me. That adds 190a for my 2200 watts.

 

[hispls 5,000+ posts]

I’m looking at a 320a or 370a Mechman.

It is extremely unlikely that any of those 300A+ alternators will truly make 300A+ outside of very briefly on a test bench, but Mechman is a trusted brand for aftermarket high performance alternators so I'm sure you'll get your money's worth with him, Singer, Excessive Amperage, Ohio Generator, etc.

 

[mat3833 10+ year member]

Alternator is the cheaper/eaiser route and will probably be fine. Just remember that any 300a+ alt will not make much power at idle unless it's a "special" one(aka Hairpin, 6 phase, few other terms). Alternator and 2 quality AGM would be better, but push you into the realm of a Lithium battery swap for cost.

Matt

 

[066]

Thanks.
Here’s the description for the 370a

The Elite series offers the highest possible amperage and durability available in a large case alternator. 6 phase technology combined with massive twin rectifier assemblies and 12 diodes makes these alternators totally durable for daily use, while still maintaining 200+ amps at engine idle speeds.

And for the 320a


The Elite series offers the highest possible amperage and durability available in a "direct bolt in" large case alternator. 6 phase technology, combined with massive twin rectifier assemblies and 12 diodes makes these alternators totally durable for daily use. This alternator will crank out 200+ amps at engine idle speeds, while producing 320+ amps at full operating temperature.

Maybe I need to ask what the 370 produces at full op temp. Wonder why they left that out.

 

[066]

Anybody know if showtime electronics is a legit site? They have the 370a for 519 vs 599 MSRP

 

[066]

Mechman seems like the only option out of all those brands. Dc power makes one and a couple other brands. Think I’m settled on Mechman.

 

[Wesseat]

Anybody know if showtime electronics is a legit site? They have the 370a for 519 vs 599 MSRP

I have bought xs power agms and a superbank from showtime.. They were a little cheaper than everybody on xs power stuff and was an authorized retailer.. Quick shipping too. I would buy from again.

 

[HardofWhoring]

I have a Mechman that's been working great for me. When searching for an alternator, there are 2 things you need to know. Amps at idle (which will be close to your idle), and rpm for full output. Any alternator company that can't give you those numbers, then walk away. The difference between a mechman and a cheap ebay alternator is Mechman will do around half at idle, and full output around 2200 rpms. A cheapo 300 alt is going to do less at idle than your factory 130, and won't do full output until over 3K rpms. If you aren't sure what your cruising RPMs are, then see where those are at and if it works. Mechman individually tests their alternators, and not only gave me those numbers but an actual printout of the overall output curve, and it produced a little more than rated.

Sounds like you are planning for 2200 watts on those two amps. 2200 / 14.4v = 152.7 amps. If your stock is 130, then you are at 282 amps needed. 320 will be plenty and give you a little extra room, for other electronics.

If you turn on your AC, your lights, turn signals, even brake lights, plug in some USBs, and try to get your electronics going (high beams, bed lights, etc.. ), then play your stereo at full volume, and your lights dim right away, then your battery can't keep up. If you play it for an hour and your voltage starts dropping over time, then your alternator can't keep up.

For almost every vehicle even stock, the big 3 will help. If you do that and your battery is still questionable, something I actually noticed an improvement on were with those $5 plated battery posts, (my truck went from cranking about 2 seconds to start, to about 1/2 -1 second start). If that is an option, spend the $5 on better posts and see if that might do it. If your grounds are good, and it still won't keep up, then you probably need a better battery also.

 

[2023 LTZ]

Very true about the spec sheet being available. Quality units are bench tested to be w in spec and show real unit results.
One more thing to consider is rpm refers to the alternators rpm. Mine is 3:1 so 1000 on my tach means 3000 on the alternator.

 

[JW266]

Smaller pulley will give you more juice at idle. As long as your tensioner has enough adjustments or you might have to modify or build a new bracket

 

[mat3833 10+ year member]

I have a Mechman that's been working great for me. When searching for an alternator, there are 2 things you need to know. Amps at idle (which will be close to your idle), and rpm for full output. Any alternator company that can't give you those numbers, then walk away. The difference between a mechman and a cheap ebay alternator is Mechman will do around half at idle, and full output around 2200 rpms. A cheapo 300 alt is going to do less at idle than your factory 130, and won't do full output until over 3K rpms. If you aren't sure what your cruising RPMs are, then see where those are at and if it works. Mechman individually tests their alternators, and not only gave me those numbers but an actual printout of the overall output curve, and it produced a little more than rated.

Sounds like you are planning for 2200 watts on those two amps. 2200 / 14.4v = 152.7 amps. If your stock is 130, then you are at 282 amps needed. 320 will be plenty and give you a little extra room, for other electronics.

If you turn on your AC, your lights, turn signals, even brake lights, plug in some USBs, and try to get your electronics going (high beams, bed lights, etc.. ), then play your stereo at full volume, and your lights dim right away, then your battery can't keep up. If you play it for an hour and your voltage starts dropping over time, then your alternator can't keep up.

For almost every vehicle even stock, the big 3 will help. If you do that and your battery is still questionable, something I actually noticed an improvement on were with those $5 plated battery posts, (my truck went from cranking about 2 seconds to start, to about 1/2 -1 second start). If that is an option, spend the $5 on better posts and see if that might do it. If your grounds are good, and it still won't keep up, then you probably need a better battery also.

Good info here. Only issue is you didn't take into account amp efficiency, and listed 14.4v to get your amps. Kinda nitpicking but still important.

Proper math should be somewhere around 85 percent efficiency for a class D, and 13.5v for lithium battery or 13v for AGM. You can use 12v as a bottom line worst case.

2200x1.2= 2640

2640/13.5=195.

You can also just add 20 percent to your final number to take into account efficiency.

152x1.2=182.4a at 14.4v

Otherwise, great info!

Matt

 

[2023 LTZ]

This is the sheet on my alternator. I would guess if I wanted a different output than 14.8 I could have it. True, it may only make peak power under limited circumstances but the proof is in the pudding. Or rather it’s on the spec sheet.
This one was hand made in AZ.

 

[066]

Thanks for all the replies, everyone. I ended up with the 370a Mechman. Showtime ftw.

I just installed the alt and got a smoke show. Melted a wire when I turned the key. I don’t suppose anyone has an idea what the problem is?