1987 MK 1 Electrical System Upgrade - Feedback Requested

[Noah]

Jon- was going to communicate offline but decided it was worth a group posting/discussion. I would recommend your (maint-free) starting/reserve battery be "buried" in aft cabin or beside engine, instead of in main salon, for a number if reasons. Here are some.
1. Shorter cable run.
2. Your second considered location, in salon, is prime accessable storage space--don't waste it on battery.
3. Limit weight forward of mast (OK, this is probably of minimal consideration).

[Ralph Masters]

I put my start battery under the berth in the aft cabin tucked in on the starboard side of the stuffing box. Real short run for the cables.

[Joe Holmes]

For what it's worth, I put a start battery on a shelf in the bottom of the port hanging locker between the head and the nav station.  Very easy to access and short cable run. Also mounted the ACR in there.

[Jon W]

A quick note about my boat - the refridgerator compressor is installed at the end of the stbd water tank underneath salon. This area is not really available for storage. Quick measurements show the space is comparable to under the aft berth for mounting a group 24 battery. The battery box will not have the top in either case because of limited height. The difference in the salon area is better access with no gymnastics to get to it, and a group 27 could be installed which is ~1/2" lower in height.

Did a little why-why-why exercise - Asked why the increased length of the negative? Why put the shunt and negative busbar in the OEM battery compartment? By moving the busbar and shunt to the board the echo charger will be installed, I shorten length of the negative to the reserve and the main engine ground. Result is voltage drop now ~4% compared to ~3% if under the aft bunk. This is based on my length estimates which I've erred on the long side. Another plus is the Echo Charger to the reserve is now ~10 feet shorter and connects directly to the reserve positive post.

The attached is a better visual to see the considered battery location. It will be under the corner covered section where the outboard long cushion back of the table meets the short forward cushion end of the table. There will be a 2-4" gap between the end of the battery box and the refridgerator compressor. I moved busbar, shunt, and battery graphics around in the attached schematic to give a better visual if interested.

Right now nothing to lose since everything ordered is for installing under the aft bunk. If I go this route, the extra wire can be used for the electric windlass. Won't hurt to try.

Jon W.

[Noah]

Jon- guess I should have come over and looked at your boat before conjecturing. I should know that no too boats are the same. I am surprised at your reefer compressor location. Most are under the helm seat, I believe. I suppose I could really shake it up if I recommened that you also MOVE the compressor out of that prime real estate space, too!!!

[Jon W]

Reserve battery question before I buy -

I've found a group 24 RV/Marine battery described as Maintenance Free Deep Cycle, DC24MF, Group Size 24, CCA 650, Amp Hours 80. One brand label is Centennial, the other brand label says Battery.com 619. Price difference between the two is $10.

Any issues with this type battery rating starting the Universal M25XP and being a temporary back-up for systems in an emergency? Thanks.

Jon W.

[KWKloeber]

Jon,

Have you studied mainesail's posts on 12v " deep cycle" batteries, power used for starting (ie a "starting type" battery)?

When I first got P.I. I put in a new 24, and I wasn't happy with the oomph -  so went to a 27.

kk

[Roc]

I have a West Marine group 24 labeled as a maintenance free "starting battery" that I use as a reserve, and not everyday starting.  My house bank (4 golf cart batts) is for house loads and all the time starting.  The WM 24 starts the M35B with no problem.

[Jon W]

Hi Ken, I have read the deep cycle vs starting and starting amp draw threads. The start draw tops out with a momentary 132A. Seems 650 CCA's will cover the need. Wondering why your group 24 didn't have enough power?   Jon W.

[KWKloeber]

Jon,

Everything was
OEM, and I hadn't had the benefit of all the experience with the cty and universal electrical issues and all the good online stuff (pre Al Gore).  The 4 awg cables were a major contributor.

That said, as I've said to you before a one-time purchase/upgrade is often well worth the cost - especially if it's for 'emergency' use.  I now use 3 gp 29a or 31s.

kk

[Roc]

If I remember correctly, the WM battery I have comes in different CCA's.  I bought the higher of the two.

[J_Sail]

My two cents - quality matters enormously and it's hard to ensure quality when buying a battery from a company that just buys the cheapest ones they can get and slaps their own label on them. Specs only matter to the extent that the product actually meets them. I would stick with well-known brands, and even then some of them are re-labelers (but at least they have a larger reputation at stake).

If the battery is in a relatively accessible area and not too heavy, then buying an inexpensive one and replacing it more frequently is an option, but even then, you need to be able to trust a reserve battery to be there for you when you need it.

That said, Costo can be a good source in your area.

P.S. For a reserve battery you do NOT need to use a Marine or Deep Cycle model. They are fine, but absolutely not necessary.

[mainesail]

Some will find this interesting..

How To Murder Batteries In Half A Year

[Roc]

I have (4) golf cart 6 volt batteries as the house bank which also starts the engine.  Bought them at Sam's Club for about $75 each in 2009.  They still are being used.  They are marked "Energizer" brand and in the small print Johnson Controls seems to be the manufacturer.  I also have a WM starting battery, group 24 as a reserve battery.  I believe it's the 650 CCA model.

[Ekutney]

Jon,

I like the details you added to your drawing, very useful.  I am looking at rewiring and plan to use a very similar configuration.  Could you provide a copy of the drawing in original format because I lose resolution when I tried to print a hard copy and have trouble reading some of the details.  It would save me time instead of starting from scratch to modify per my exact configuration.  Also do you have a key for the numbered items in circles?

I lived in SD during the 80's while stationed at North Island, loved the year round sailing weather.

Thanks much,