Engine Start Video / Real World Data

Maine Sail · #1 (**permalink**) 10-03-2008

Hi All,

I saw a need for something often debated but rarely ever clarified.

Many sailors/boaters often believe that you need to switch back and forth between your house bank and your start bank or as I prefer to call it, "emergency bank" of batteries for engine starting.

The truth is you don't! Switching back and forth from bank 1 to bank 2 only leads to eventual human error, as has been reported here all to often, and you will, in due time, fry your alternator diodes with a mental lapse or via a crew member asked to switch banks.

The reality is that your system should be wired to prevent this but that is another subject for another day and most will never get this far down the project list.

I am simply trying to prevent any more fried diodes with this video!

Another mis-truth that is often perpetrated amongst sailors is the absolute need for a "starting" type battery to start your small diesel engine.

This video will show why it is not necessary to use a thin plate high CCA rated battery to start a small auxiliary diesel engine. The max load when starting my engine, a four cylinder 44hp, is 132.5 amps for less than two seconds. Any deep cycle marine battery you can find will have a LOT more than a 130+/- CCA, CA or MCA rating.

Start batteries don't, and won't, generally last as long as a true deep cycle battery so pound for pound deep cycles generally cost less in the long run.

You no longer need to be affraid to use deep cycle batteries for your starting/emercency bank or to start your engine using your house bank. I've always started my engine on my house bank

. Hopefully this video will give many of you piece of mind around the subject of starting and how little it actually consumes.

What Happens When My Engine Starts Video (LINK)

Or click the photo:

Stats:

Engine - 2003 Westerbeke 44B, 44hp four cylinder diesel (marinized Mitsubishi).

House Bank - 2 Group 31 batteries 120 ah rated each / 240ah bank

Glow Plugs - They consumed between 30 and 56 amps for about 8-10 seconds.

Starter - Max draw of 132.5 amps for about two seconds.

Battery Monitor - Xantrex XBM

sailingdog · #2 (**permalink**) 10-03-2008

Halekai-

You must have been really bored this week.

Maine Sail · #3 (**permalink**) 10-03-2008

Quote:

Originally Posted by sailingdog

Halekai-

You must have been really bored this week.

Actually I made the video in June but finally was able to add the text and save it last night a two in the morning!!

It's been on the to-do list for a while.

Who knows, if I had not had insomnia you may have never seen it.....

Stillraining · #4 (**permalink**) 10-03-2008

Quote:

Originally Posted by MaineSail

if I had not had insomnia

Ah..ha...........So thats why you called me.......

I take back all the nice things I said about you...

Maine Sail · #5 (**permalink**) 10-03-2008

Quote:

Originally Posted by Stillraining

Ah..ha...........So thats why you called me.......

Freakin' expense report had me all riled up....!

artbyjody · #6 (**permalink**) 10-03-2008

Good post - convincing enough I am gonna rid my starter battery (well use it as an emergency - as in pull it from a storage location and hook it up when need be) and have two sets of house batteries instead...

sailingdog · #7 (**permalink**) 10-03-2008

LOL... good think you don't have a scrip for Ambien.

xort · #8 (**permalink**) 10-04-2008

I have 3 banks. One engine start, one genset start and house bank. I've been thinking the genset battery could also be the engine start battery with house as backup.

erps · #9 (**permalink**) 10-04-2008

Quote:

Another mis-truth that is often perpetrated amongst sailors is the absolute need for a "starting" type battery to start your small diesel engine.

Start batteries don't, and won't, generally last as long as a true deep cycle battery so pound for pound deep cycles generally cost less in the long run.

While I don't believe that starting batteries are absolutely required, I also don't think they're a bad idea. If deep cycle batteries were a good choice for starting engines, they would be in all our cars.

From what I've read, a starting type battery has a lower self discharge rate than the heavy duty wet cell deep cycle batteries. Starting batteries are also cheaper than deep cycle batteries and in my experience, starting batteries last a long time, when not deeply discharged. So, if you have a two bank setup and just run off your house bank all the time for engine starts and everything, you may find that your emergency bank is dead if you went with a deep cycle battery instead of a starting battery because of self discharge. That kind of defeats the whole purpose.

I doubt there is one best setup for all boats and their conditions. Just like everything else, there are compromises. Just as the standard 1-2-both battery switch works perfectly fine, you can spend all sorts of additional money to protect your system from yourself. you could also sail with a woman who always asks "did you switch the battery switch back over?" but I'm not sure that saves any money. Our boat has two banks, each with their own alternator.

theartfuldodger · #10 (**permalink**) 10-04-2008

I'm wondering if this post is plagarism, seeing it was reported being composed by another chap on another site verbatim, and as for deep cycle verus normal batteries it all depends on ones preference and personal knowledge and experience. I have a question if a battery is dead ,dead flat will it still show 12 volts on a meter.