Adding A Starting Battery

[starfishblaabla]

Hello

I have just purchased Catalina 30 mk. 3 with two batteries (group 27) under the starboard settee. Both in good condition

I would like to add a new starter battery for the engine and make the two batteries the house bank

The engine is a universal 23 hp
Any recommendations on where and what battery will best suit and fit
Many thanks

[Adelie]

I used to think a starting battery was a great idea but my thinking has changed.

The biggest impetus has been the increasing economy of solar, even if I completely run down the house bank, if I wait awhile solar will bring it back enough to start the engine.

Secondly if I add a battery to the house bank I'm helping to extend the life of the house bank as long as I don't up my consumption to compensate. If I still draw the same amount out daily on average then with a bigger bank 3 things happen:
1. Each battery experiences a slower draw rate and consequently provides more capacity, literally something for nothing.
2. With a bigger bank the daily depth of discharge is less so you increase the number cycles the batteries will survive.
3. I'm less likely to run the batteries down too far to start the engine.

Additionally I am avoiding the secondary costs of charging the starting battery. Doing so requires a second alternator, a battery combiner, an echo charger or a separate solar panel and regulator.
If I were going to go with a starting battery I'd get a small 1-5w solar panel with a very low capacity regulator. Starting an engine uses a bit less than 0.1a-hr. Even if it is hard starting it will only use 1a-hr. The small panel can recharge that in an hour or so. How many time per day do you start the motor? The small panel method has the advantage of completely isolating the starting battery from the house bank, keeps the starting battery topped up even thru extended periods of disuse and is pretty cheap.

If you are prone running the house bank down too far to start the engine then yeah starting battery is a good idea.

Otherwise add a battery to the house bank and reap a bunch of secondary benefits.

I only know the layout of the original Cat30 so I can't advise you on where to put an additional battery.

If you get a starting battery get a real starting battery. FLAs are the best bang for the buck. If you add to the house bank then match the existing batteries for maker and chemistry.


A house is but a boat so poorly built and so firmly run aground you would never try to refloat it

[Adelie]

Originally Posted by Adelie

I used to think a starting battery was a great idea but my thinking has changed.

The biggest impetus has been the increasing economy of solar, even if I completely run down the house bank, if I wait awhile solar will bring it back enough to start the engine.

Secondly if I add a battery to the house bank I'm helping to extend the life of the house bank as long as I don't up my consumption to compensate. If I still draw the same amount out daily on average then with a bigger bank 3 things happen:
1. Each battery experiences a slower draw rate and consequently provides more capacity, literally something for nothing.
2. With a bigger bank the daily depth of discharge is less so you increase the number cycles the batteries will survive.
3. I'm less likely to run the batteries down too far to start the engine.

Additionally I am avoiding the secondary costs of charging the starting battery. Doing so requires a second alternator, a battery combiner, an echo charger or a separate solar panel and regulator.
If I were going to go with a starting battery I'd get a small 1-5w solar panel with a very low capacity regulator. Starting an engine uses a bit less than 0.1a-hr. Even if it is hard starting it will only use 1a-hr. The small panel can recharge that in an hour or so. How many time per day do you start the motor? The small panel method has the advantage of completely isolating the starting battery from the house bank, keeps the starting battery topped up even thru extended periods of disuse and is pretty cheap.

If you are prone running the house bank down too far to start the engine then yeah starting battery is a good idea.

Otherwise add a battery to the house bank and reap a bunch of secondary benefits.

I only know the layout of the original Cat30 so I can't advise you on where to put an additional battery.

If you get a starting battery get a real starting battery. FLAs are the best bang for the buck. If you add to the house bank then match the existing batteries for maker and chemistry.


A house is but a boat so poorly built and so firmly run aground you would never try to refloat it

A house is but a boat so poorly built and so firmly run aground you would never try to refloat it.

[roverhi]

If you don't have an engine start battery, losing the house bank for whatever reason leaves you without a way to start the engine. Doesn't matter whether you have a load of watts of solar power as you still can't crank the engine until the batteries recharge, if they can be recharged, which will take hours even in midday with full sun. Had a bad cell in the house bank but hooked up to shore power didn't notice it. Needed to start my engine right now to keep from running aground but the batteries didn't have enough juice to crank the engine. Fortunately only had to spend one night aground before I could sail back to the marina. I was in the process of making a battery mount for the engine start battery so didn't have the backup I needed.

You will probably only need a fairly lightweight group 24 battery for the engine in your boat. You can charge on the both switch though risk running both batteries flat if you lose in either bank. Best to only use the both switch for charging when connected to shore power. The engine start battery needs to be charged for short periods of time as even though the amperage draw is high the duration is usually very short. Recharge time will be quick so switching to start battery just for starting the engine and then a short period of time while running the engine will normally keep it charged. The rest of the time, run the boat on the house bank for recharging them. A splitter takes care of battery charging automatically but the most efficient kinds are expensive. A battery monitor gauge will let you keep track of each bank and charge them optimally. No need for separate alternators or solar panels to keep each set of batteries charged unless you want the backup. Just a little attention on your part will keep your batteries happy.

For longevity with lead acid batteries, get a remote fill set up for your batteries. Makes it super easy to keep the fluid levels at the correct level so you'll actually do it. IPC Eagle Single Point Battery Watering System for Small Size Batteries

[Sailuke]

What do you have for deep cycles? id say add a group 27 starter and then get two 6v golf cart batteries and hook em up for 12v. i did this on my Catalina 27 and i haven't been as happy with my power as i am now. No 12v deep cycle can compete with 6volt flooded golf cart batteries in terms of lifespan and capacity. and i have no problem starting my 18 horse diesel with them, hell, they start it faster than my starting bat! The only downside is that they're flooded, but its actually not that hard to deal with flooded batteries. Just be sure to check out this article on how to orient them properly.

Installation & Orientation of Flooded Batteries Photo Gallery by Compass Marine How To at pbase.com

[S/V Alchemy]

Originally Posted by Adelie

I used to think a starting battery was a great idea but my thinking has changed.

The biggest impetus has been the increasing economy of solar, even if I completely run down the house bank, if I wait awhile solar will bring it back enough to start the engine.

Secondly if I add a battery to the house bank I'm helping to extend the life of the house bank as long as I don't up my consumption to compensate. If I still draw the same amount out daily on average then with a bigger bank 3 things happen:
1. Each battery experiences a slower draw rate and consequently provides more capacity, literally something for nothing.
2. With a bigger bank the daily depth of discharge is less so you increase the number cycles the batteries will survive.
3. I'm less likely to run the batteries down too far to start the engine.

Additionally I am avoiding the secondary costs of charging the starting battery. Doing so requires a second alternator, a battery combiner, an echo charger or a separate solar panel and regulator.
If I were going to go with a starting battery I'd get a small 1-5w solar panel with a very low capacity regulator. Starting an engine uses a bit less than 0.1a-hr. Even if it is hard starting it will only use 1a-hr. The small panel can recharge that in an hour or so. How many time per day do you start the motor? The small panel method has the advantage of completely isolating the starting battery from the house bank, keeps the starting battery topped up even thru extended periods of disuse and is pretty cheap.

If you are prone running the house bank down too far to start the engine then yeah starting battery is a good idea.

Otherwise add a battery to the house bank and reap a bunch of secondary benefits.

I only know the layout of the original Cat30 so I can't advise you on where to put an additional battery.

If you get a starting battery get a real starting battery. FLAs are the best bang for the buck. If you add to the house bank then match the existing batteries for maker and chemistry.


A house is but a boat so poorly built and so firmly run aground you would never try to refloat it

I will continue to have a start battery that is charged solely by the echo charger off the large house bank. The rationale is that the main switch can make that starter battery the emergency house bank should the house bank need service or be otherwise disabled. Basically, all charge sources go to the house bank, and the start bank is kept very close to 100% for emergency purposes.

It was interesting the other day to start the diesel from the house bank.

[Cheechako]

an Echo charger or similar device to automatically charge the start battery is a good idea and makes life simple. There are many types around that work fine, some are only $50. Most any decent start battery should work with the little diesel as Barnakiel indicates.

[guyrj33]

Roverhi described the ideal setup, an asymmetric battery bank.
Small starting battery and large house bank. This is the system I've been using on our Pearson 10M for 20+ years.

[skipgundlach]

Just one observation to the effect that starting batteries are designed to deliver massive amps for a short time; house batteries are designed to deliver small amounts of amps for a massive amount of time.

Despite my L16s being fully charged they won't spin my starter nearly as fast as my standard type 29 starting battery.

As a matter of routine, I use 'both' to start, and for however long I'm motoring, keep it there, charging both batteries (treating my 740AH L16 bank as one); my starter and windlass are on a combiner so won't deplete with the house bank, but I put the switch to house, anyway, whenever we're not actively charging. We use alternator or Honda2000. Despite my having wind and solar which are entirely sufficient in perfect conditions, I don't trust those conditions to be present all the time. Case in point was having a guest aboard one day, and then going off the boat for two more days. Each was cloudy and still. I came back the following afternoon (total 4 days sun and wind, whatever was available) to a bank down to 35% (-548AH). That's the lowest by far it's ever been. Honda for a tankful got it back up to -211AH, and when we returned this morning, it was -335AH.

But that was the house bank, only. As I'd put the selector to house, the windlass and start batteries (unused) were unaffected.

So, my recommendation would be to separate your house and start battery with a combiner, AND get a start battery for a specific. Whether you change your type for the house battery (to a true deep cycle such as the T-105/Golf Cart, which are commonly discharged to 20% and recharged, again, overnight, in commercial applications) whenever it's time to renew would be a separate decision, of course. Ditto the discussion (not germane to this question, really) of whether FLAs represent the best bang for the buck against other LA types or the newer types, some of which are relatively maintenance free, but take entirely different charging sources/methods...

L8R

Skip

[ramblinrod]

Originally Posted by starfishblaabla

Hello

I have just purchased Catalina 30 mk. 3 with two batteries (group 27) under the starboard settee. Both in good condition

I would like to add a new starter battery for the engine and make the two batteries the house bank

The engine is a universal 23 hp
Any recommendations on where and what battery will best suit and fit
Many thanks

The first question to consider is, "Do I have sufficient house bank reserve capacity to serve my needs, when disconnected from shore power?

If you will be running refrigeration without shore power for any length of time, the answer is likely, "No". If your have low loads when away from the dock, the answer is likely "Yes".

If "No" I would recommend increasing the house bank size instead, and adding considerable solar. (For all batteries that are not ventilated outside the occupied space, I recommend AGM, and if some are AGM, all other batteries connected in that bank need to be AGM.)

If "Yes" and you already have a 1/2/B/OFF switch splitting the two existing batteries, you can change that so the switch isolates the new start battery from the now combined 2 battery house bank. If you do not have a switch already or you wish the combining of batteries for charging to be automatic, I recommend using an ACR instead of the switch.

Batteries store hazardous materials and sufficient energy to cause personal injury or vessel damage, if handled or wired incorrectly. If you are not completely familiar with marine electrical standards, and sound battery handling practices, I recommend hiring a "Card Carrying" Certified Marine Electrical Technician. (No card, no touching my boat.)