[PSUBS-MAILIST] 48VDC generator

Wed Sep 12 16:10:03 EDT 2018

 Alan,The alternator in you car has an internal regulator to prevent overcharging the battery.  If an alternator does not put too much current into your car battery then why would it put too much into your submarine battery.  Yes the motor draws say 100 amps but it is drawing from at least 4 batteries but likely 8.  So the draw is minimal per battery and likely less than the typical demand in your car.  If you put two 24 V or 4 12  alternators directly to the batteries, it is the same as your car.  The leads are still short to the controller.  
I also like the idea of a outboard motor on the back of the sub, in fact E3000 can accommodate that with the flat top on the sub and the great stability.  You can put a couple lawn chairs on the deck with an umbrella and enjoy a trip on the lake lol.Hank
    On Wednesday, September 12, 2018, 1:44:23 PM MDT, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 Hi Hank,I am not sure of the electronics involved. Just cautioning Brian toresearch it as there are a few things that indicate it's not as simple asjust wiring a generator output straight to the batteries. You mentioneda regulator. If he pumps more amps in to the batteries than their ratedcharging rate then they could get too hot & off gas. Also (repeating myself) you would have a long length ofwire carrying DC from the generator to the motor controller if the generatoris sitting in the inflatable tender. In the article I quoted last week, an electric motor & controller builder of 30 years doesn't recommend over 1ft in length. (you can have a long length from controller to motor)They do say that the battery can act as a large capacitor so connecting the wiring straight to that may help with the associated voltage spikes, but again youwould need some sort of charge regulation.Just know my 48V rectifyer & charger weren't cheap, & the rectifyer is only40 Amps. I am not sure how many amps Brian's generator puts out. Cheers Alan

On 12/09/2018, at 11:42 PM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Alan,I am not getting what the problem is.  A car driving down the road with all the lights on and heater and stereo and wipers etc is probably drawing 40\50 amps with one single battery.  If you use automotive alternators as I suggested with internal regulators, it will be the same as driving in your car.  The sub has multiple batteries that can be powered with multiple alternators that are cheap.  Hank
    On Wednesday, September 12, 2018, 12:57:34 AM MDT, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 Brian,you could but hybrid cars do both. It's just a matter of delving in tothe technology & knowing what's required to make it happen.However if you are just powering your motors from a generator youmay as well just use an outboard motor that is designed for a marineenvironment to push you along. ( have you got one on your yacht)Alan

On 12/09/2018, at 5:47 PM, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Alan,        That's very interesting.  I guess the issue is that the batteries can only accept so much current depending on what state of charge they are at.  If the motors are using that power then it's not a problem but the power needs to be regulated.  Maybe another way would be to isolate the batteries while using the remote power. Brian 

--- personal_submersibles at psubs.org wrote:

From: Alan via Personal_Submersibles <personal_submersibles at psubs.org>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
Subject: Re: [PSUBS-MAILIST] 48VDC generator
Date: Wed, 12 Sep 2018 12:49:33 +1200

Brian,in this video the guy is just charging a battery bank off a generator.He has a massive blue capacitor & electronics in the system.https://m.youtube.com/watch?v=1CvYcCUZqOII don't know enough to advise you, only to warn you that it might notbe that easy & needs a bit of investigating. The current would need to beregulated to the batteries. My 48V 40A rectifier cost me NZ $800-.Carsten may know a bit about this with his diesel electric sub.I would be interested in what you find out.Alan

On 12/09/2018, at 10:22 AM, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Alan,        Maybe I could just put an appropriate sized one way diode so current does not flow to the batteries.  Maybe there is some other device that would be better for such a sizeable current rather that a diode however. Possibly the generator people would have the answer for this. Brian 

--- personal_submersibles at psubs.org wrote:

From: Alan via Personal_Submersibles <personal_submersibles at psubs.org>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
Subject: Re: [PSUBS-MAILIST] 48VDC generator
Date: Wed, 12 Sep 2018 07:39:02 +1200

Brian,it could be complicated. I was going to suggest having a switch toswitch from charging the batteries to running the motors, as youmay need to restrict the amps going in to the batteries dependingon their rating. However you may recall me posting about keepingbattery to controller wire length short to avoid large voltagespikes in DC systems. You would have a very long wire length fromthe generator to the motor controller carrying DC. A battery can actlike a large capacitor to absorb voltage spikes, so maybe it doesneed to be incorporated in the system. It may be that you need an AC generator & a rectifier nearer the motor controller. Voltage spikesfrom the motors could be a problem but I guess your motor controllertakes care of this. Some motor controllers have regenerative breakingthat feeds power from the motor as it slows down, back to the battery.This is probably not a problem with a sub as you wouldn't get backemf like you would from a car running down hill, however I test mymotors from a 48V rectifier & they advise to turn off regeneration onmy motor controllers in case it wrecks the rectifier. There should be a lot of information available as off grid people combine generators, battery banks & other forms of power generation.Cheers Alan

On 12/09/2018, at 5:17 AM, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Hank,    I remember you talking about that,  I was thinking of getting a dedicated 48 vdc generator and hooking into the battery bank through the hatch and then disconnecting to submerge. Brian 

--- personal_submersibles at psubs.org wrote:

From: hank pronk via Personal_Submersibles <personal_submersibles at psubs.org>
To: Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org>
Subject: Re: [PSUBS-MAILIST] 48VDC generator
Date: Tue, 11 Sep 2018 11:34:06 +0000 (UTC)

 Brian,That was my plan at one time also, I was going to use alternators with internal regulators.  It should work, but I am not sure how long the alternators will last if they are not sized correctly.Hank
    On Monday, September 10, 2018, 11:20:59 PM MDT, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 Hi All,                     Does anyone know what's involved in linking a 48 volt dc generator to ones 48 Volt drive system?   Is it as simple as connecting to the batteries?  If the generator senses a voltage draw then it engages, this is how most generators are set up .  Seems like there's got to be some sort of protection for the batteries so they don't see too much voltage.   I was thinking of having a 48 V dc generator in an inflatable secured to my deck and feeding my motors for surface transit.  Then once at the dive site leave the inflatable floating at the dive site.   Brian  _______________________________________________
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