T-Pain Is On A Boat: Re: [Electric Boats] Beginners Guide

Thursday, June 18, 2009

Re: [Electric Boats] Beginners Guide

Keith,

I just got a chance to look over your new site - great job!

As we both know, there is a lot of "beta testing" involved in setting up an electric drive system. The components don't always work so well together and the manufacturer's tech info is often sketchy, irrelevant and sometimes just wrong. (like the MARS PMAC rpm per volt data).

Here's something I learned along the way about charging and battery banks that could save someone else grief. Feel free to incorporate into your website if you think it's appropriate.

Often a battery bank is tapped for a lower voltage than the whole string provides. For instance in a string of (4) 12v batteries supplying 48v to the motor you might connect one of the batteries to a 12v distribution panel to supply power for lights, stereo, GPS, etc. This works fine but it means that one of the batteries will be discharged down lower than the other three. This is not a problem IF that 'special' battery is charged independently but putting one 48v charger on the whole string will not fully charge the lower battery.

Wiring a Link 10 meter or other battery 'fuel' gage can cause this same problem, even though their power usage is measured in milliamps. In the case of the Link 10 the instructions (and their tech support) say to wire a 12v or 18v power supply directly to the battery bank so the meter is always powered as it can be damaged if the wrong wires are powered up first. This works fine BUT that small 25 ma current is being drawn from just part of the bank 24/7 and adds up to a significant ah drain over several months. Without independent charging the bank will slowly get unbalanced.

Another solution is to use a motor voltage to 12v transformer and power all 12v loads off the transformer. This means the 12v loads are shared equally by all the batteries. This adds a couple of hundred dollars to the cost of the system but little weight or complexity.

A third solution is to use a separate 12v battery with its own dedicated charger just to power the house loads. This is much heavier and may be either cheaper or more expensive depending on the quality of the house battery and charger used. You also have to remember to plug in two chargers.

Denny

PS: Thanks for the link to my website.

----- Original Message -----
From: aweekdaysailor
To: electricboats@yahoogroups.com
Sent: Sunday, June 14, 2009 3:34 PM
Subject: [Electric Boats] Beginners Guide

Lately I've found myself and others answering the same questions a lot, and one of the reasons of course is that, while a ton of information is available here, it's somewhat daunting to get at (if Yahoo's group search is even working which seems spotty at best). Many of the answers are buried in long, intimidating threads containing much debate and little resolution.

With that in mind, and somewhat based on earlier FAQ efforts - I threw together a Beginners Guide. It's got a lot of my own, possibly incorrect, opinions and observations, so I didn't want to represent it as an FAQ for this group. But it's there, and might be a convenient resource to point the NOOBs (newbies) at vs repeating the same responses to the group.

http://sites.google.com/site/electricboating/Home

Not complete by any means, but a good start I think. If anyone wants to contribute a specific section please contact me offlist. In particular I think there is a crying need for parts lists and suppliers so if anyone can provide documentation on their installation that would help.

-Keith

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