alternator connection to primary battery bank

[Jon W]

I started with 300A then switched to 250A, but don't remember why.

Side note - great sailing yesterday.

[KWKloeber]

Thanks Jon and Noah

All good information.

Kk

[J_Sail]

Ken,
Now that I know what Jon was referring to I think I can answer, as I was the person on the other end of many of those communications, having assisted both Noah and Jon in their redesigns.

The 250 vs 300A question wasn't one of controversy, just matching the wire size and fusing to the particular needs during a complete electrical system redesign. Jon was leaning towards (and eventually settled on) AWG 1 wiring for both house and reserve batteries. With the routing (through engine compartment) and insulation temperature, the most appropriate fuse for that gauge was 250A. We discussed that Noah was installing an inverter on his boat that spec'd heavier wiring and a 300A fuse. Jon concluded that he would not likely add a large inverter in his future. Thus, for Jon's application AWG 1 and a 250A fuse was appropriate.

Jeremy

[KWKloeber]

Jeremy

Makes perfect sense.  Thanks!

Ken

[hwd]

Ken et al:  Great discussion and a lot of help!....My next step is to determine an estimated energy budget and to make a drawing of the plan.   For the next year I'll be continuing to anchor out for 1-2 nights at a time, followed by plug-in and re-charging with my 30 amp Charles charger (2005) at the marina.  After that I plan to begin cruising the ICW with more time at anchor (1-2 weeks between marina tie-ups and plug-in charging).

My immediate (proposed) plan is to connect my 55 amp alternator (4 AWG cable and 100 amp fuse, sound OK?) to my existing house bank (4 golf cart batteries, 12 volt, 400 Ah) and install a new start/reserve battery with an echo charger.  I'll disconnect the alternator cable from the starter motor, but keep the existing 1 AWG cable running from the existing battery switch (B connection) to the starter motor.  The start/reserve battery will be located under the starboard settee outboard of the hot-water heater just forward of the galley counter.  The house bank is located in the same space, inboard of the hot-water heater and just forward of the galley sink.  House bank and start/reserve batteries will each have a 300 amp fuse (within 7 inches of + terminal) and be connected with 1 AWG cable to the existing battery switch (1 and 2 connections, respectively).
Does this sound, OK?     

Any suggestions on what type of 12 volt start/reserve battery I should use that will be compatible for charging with the golf cart batteries?

Harry

 

[Kyle Ewing]

Harry,

I used an Optima 34M (blue) battery for my dedicated starting battery connected to an EchoCharge.  I mounted it on the hull behind the engine on the starboard side of the stuffing box.  I went with the Optima because it's sealed meaning there's no water to add (or check) and doesn't have to be mounted flat, which simplified installation.  It's shorter than other batteries (<8" tall) so it fit.

Most importantly, the Opitma's charging voltages are similar to what the EchoCharge and Xantrex TrueCharge 40 provide.  The TrueCharge 40 float charge is 13.5 volts on warm setting.  The Optima 34m Blue needs 13.2-13.8 float charge and a 13.3-15.0 volt alternator, source https://www.optimabatteries.com/en-us/bluetop-dual-purpose-deep-cycle-and-starting/34m.  This is compatible with the Trojan T105s I had at the time (13.5 float voltage).

If memory serves me correctly, I used a 250amp breaker similar to Blue Sea series 285 (Defender no longer carries the exact part) on the starting battery and have never had a nuisance trip.  My engine is the M25XP.

I put it in in 2008 and the only problem was a failed Echo Charge in 2013.

Hope this helps.

Kyle Ewing
Donnybrook #1010 (1990)
Chicago

[Dave Spencer]

Excellent choice by Kyle to go with the Optima my opinion.  Although certainly not the most economical one if that is a factor.  I would love to have a nice, light, maintenance free Optima 34M as my starting battery as it would provide lots of margin.   But our starting loads are relatively low (as is my budget) and almost any automotive battery will do the job if you start off the starting battery and charge it via an echo charger.  I think some may have even used a lighter garden tractor battery for starting... I'm not that brave.   We are starting relatively small engines (compared to car or truck loads) and we don't have to worry about cold starts since the engine is unlikely to be started in conditions below 0C.  Attached link provides  more information - lots of discussion and great information on this subject.  http://c34.org/bbs/index.php/topic,8331.msg58621.html#msg58621

[hwd]

Kyle and Dave,
Thanks for the great suggestions on a starter battery!
Harry

[Jon W]

I used a group 24, 650 CCA, 80ah maintenance free lead acid. Your layout fwd of the galley must be different than mine. The stbd water tank uses all of that space on my boat.

[KWKloeber]

Harry,  Thanks,

I think that the wagooon may be before the horse.  You choose based on the budget, so why decide on a the wiring before the budget? It literally takes (elapsed) hours, not days of time, to do a budget.  I suppose you can fly by the seat, if there's a hurry to do "something immediately."    But you don't know the Alt voltage setpoint, whether it can be adjusted, etc...... is it 55a or 51a (thought that's what you had said,) not that it's any big deal.  Another thing I always think about when opening the wallet for anything is, "What do I NEED now vs what do I WANT now?" 

My boat has had a 1-2-B-O switch, a start battery and a house bank, no A.C.R., echo, x/y/z, or m/o/u/s/e, since 1984.  So a somewhat  loaded question, do you NEED? or WANT? an echo?  I just manually know what my battery status is, and do it manually.  KISS.  RC's done testing to show that the AH draw to start a diesel is peanuts, motoring out of the slip replaces it for me.  If my #1 needs more, then I can manually control that.   Maybe you prefer to be hand's off and leave it all to automation, which is fine also.   But, JTSO, it's always good to think about the easiest, KISS, alternative to anything/everything (especially on a sailboat.)

So, ........ what is the thinking behind an echo at this point in time?

What kills a battery is charge/discharge cycles and heat.  A start battery has LOW LOW LOW charge/discharge cycles, naturally (especially if it's a reserve battery.) You don't need anything fancy for a start battery, it's not a power boat bouncing around where you want heavy-duty plates, so it's a matter of resources to buy the best name, or less cost and replace maybe more often.  I had sworn by DieHards for years and years -- yah know what?  I have a Wally*Mart battery in my "other (non-floating) vehicle" and it starts every time, 10 deg below zero or 100 deg above.  And Wally*Mart for my floating vehicle start battery.  And it cost a whole bunch less than a top name brand, and it carries the SAME warranty.   If my "other" vehicle was an RV and I needed a battery that was subject to high charge/discharge cycles, that would be an altogether different story. 

I'd put in the highest cranking amps you can fit and afford in a reasonable value battery line, rather than the highest price-tag battery with maybe lower cranking amps because of what you can afford.  No perfect answer, JTSO to KISS.

ken

connect my 55 amp alternator (4 AWG cable and 100 amp fuse, sound OK?) to my existing house bank (4 golf cart batteries, 12 volt, 400 Ah) and install a new start/reserve battery with an echo charger. 

what type of 12 volt start/reserve battery?

Harry

[Noah]

I had the same puzzlement as Jon-- confused as to where you plan to place your "start/reserve battery". I can't imagine the location "behind your house bank on starboard side". No free space there on my boat . Behind house bank is water tank then cubby hole storage behind settee backrest cushions. ???