RE: [PSUBS-MAILIST] 36V verses 24V

["James Frankland" <james@guernseysubmarine.com>]

Hi Scott.  Just in responce to this question.

>I don't understand the K-350 plans as how to get the power from the pods to the hull.

Im actually doing my pod vents and electrical through hulls tomorrow.  I'll take a load of pics as i do it.

The plans show some old electrical penetrator which i dont think you can get any more.  I couldnt find it anyway.

but the important point is that the wiring definitly does not go through the vents.  They need to be shut up for diving, otherwise if you spring a leak in a pod, it would flood up into the cabin.  You need proper penetrators regardless of your choice of voltage.

I'm using a design by Alec Smyth which i suspect is similar to Dans.  There are 2 per pod (for positive and negative).  1 replaces the aft vent, a second is added conveniently placed in between the next set of ribs, and finally the front vent is as per the plans.  I believe thats why Dans boat looks like he has 3 vents, but its probably the same as mine, 1 vent forward, and 2 penetrators.  (or he has 2 vents as per the plans and 1 multi penetrator - i dont know)

I havent got this bit finalised yet, but Im using 24v MinnKota motors so i will probably have 2 banks of batteries wired up independantly with switches so i can change from port (power the whole boat), starboard (power the whole boat) or both (power the whole boat).  I will probably carry a spare battery inside also.

Kind regards
James



36volt:

Advantage - More effecient power

Advantage - Has ability to provide more thrust (good in current or dangerious situations)

Advantage - Last longer and won't overheat as likely

Disadvantage - Need second tru-hull (from pod to hull) because of gauge of wire

Disadvantage - difficult to charge because of 12V and 36V both in pod

Disadvantage - more money for wire and parts



12volt:

Advantage - Easyier to wire (no need for extra tru-hull

Advantage - Easy to charge

Advantage - Costs less

Disadvantage - Less effecient power

Disadvantage - Less thrust (not 100% sure will have enough power, snoopy is 12V and works, but it is smaller sub)

Disadvantage - Won't last as long, possible overheating in extreme situations



I am stuck in between a rock and a hard place as what to do. I want to do the 12volt, but am worried it won't have the power I need. I don't understand the K-350 plans as how to get the power from the pods to the hull. I assume you run it through the aft battery vent and actually vent with the forward vent. The blueprint only showes 2 vents per pod, yet I noticed on Persistance there is a 3rd tru-hull. That is one of the 3 main issues. The second is how in the world does the charging work with a 36V and a 12V in the sub. I can only think the way to do this is either have a 36V charger and a 12V charger or take all the batteries out and charge them separately. The 3rd issue is will a 12V system have enough power to run the motors with enough thrust for a K-350? I heard that Snoopy is all 12V and manuvers fine, but Snoopy is a K-250. I am pretty much at a stand still till I get this problem solved. The next step is attaching the battery pods, but I don't want to do that if I need a 3rd tru-hull.

Any help is greatly appriciated.

Thanks,

Scott Waters



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