[PSUBS-MAILIST] 48VDC generator

Tue Sep 11 20:49:33 EDT 2018

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=1CvYcCUZqOI
I don't know enough to advise you, only to warn you that it might not
be that easy & needs a bit of investigating. The current would need to be
regulated 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 to
> switch from charging the batteries to running the motors, as you
> may need to restrict the amps going in to the batteries depending
> on their rating. However you may recall me posting about keeping
> battery to controller wire length short to avoid large voltage
> spikes in DC systems. You would have a very long wire length from
> the generator to the motor controller carrying DC. A battery can act
> like a large capacitor to absorb voltage spikes, so maybe it does
> need to be incorporated in the system. It may be that you need an 
> AC generator & a rectifier nearer the motor controller. Voltage spikes
> from the motors could be a problem but I guess your motor controller
> takes care of this. Some motor controllers have regenerative breaking
> that 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 back
> emf like you would from a car running down hill, however I test my
> motors from a 48V rectifier & they advise to turn off regeneration on
> my 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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