Batteries in Catalina 30

[Edward 14244]

I recently purchased a 1988 Cat30 and am trying to understand the electrical bits. She has two batteries and the standard 59 amp alternator on the universal 25x diesel and a solar panel charging the no1 battery. The original owners manual tells me to switch the battery switch on 'ALL' to start the engine and keep it there, but that you can charge each battery separately (but doesn't give any further details). A previous owner has inserted a manual note advising to start and run engine on battery 1, and switch to '2' when the engine is not running (clearly suggesting to use '2' as house battery, there is a 12v fridge etc)That's where I am confused and I have the following questions (I noticed a similar thread in the archives, but didn't quite understand the answers...):1) when switch is on '1', does engine charge battery 1 only and NOT battery 2? 2) if so, shouldn't one charge on 'ALL' and switch to '2' when the engine is not running, to keep '1' charged for starting the engine?3) The manual warns not to change from 1 to 2 or all whilst the engine is running - is that one of those 'catch-all' warnings or has it substance?4) Is the standard 59 amp alternator a multifase one - I think not: is there any danger of overloading when motoring, and therefore cgarging, for extended periods?Hope you don't mind I pick up an old thread - but this bugs me no end...!thanks for any help,Edward.

 

[Ron]

i'm told

I am told:1. When it is on it is only charging that battery that is an isolator switch2. Yes to that question3. It could cause damage as a current is going through the battery4. ugh unknown.my two cents on what I have been told by my electrician guy

 

[Rob 1981 Cat 3019642]

about #3...

I tend to motor for long periods of time. Therefore, after about 15-20 min. of motoring, I switch to battery 2 and turn on the fridge etc.I have never had a problem switching while the engine is running. (Although I've only had the boat a year!) I believe the only problem would occur if you switched it to the off position.Happy sailing!-Rob

 

[Stu Jackson]

Trace the wires and don't depend

on vague and unspecific instructions that you don't understand.Every boat is, eventually, wired differently.You NEED to find out how your's works.Trace the wires, make a diagram and figure it out.StuPS This is really important safety stuff, and ONLY you can find that out.

 

[Gary Kunkel]

Battery use

We also have a 1988 Catalina 30 w/ two batteries and the std alternator (running off a Universal M25-XP). We use two Trojan deep cycle batteries. We use the "both" position to start the motor, keep it there whenever the motor is running, then switch to either battery "one" or "two" after the motor is stopped. Actually, I use position one on odd-numbered days and two on even-numbered days as I imagine that sort of randomly discharges the battery we're running on when the motor is off. This has worked well for years.Regards,Gary Kunkel

 

[Big Windy]

Off

What ever you do, do not switch the selector to "Off" while the eng is running.

 

[Joe]

Battery comments

Gary's post is right. You should separate the batteries to "1" and "2" when there's no charging current, otherwise the stronger battery will discharge into the weaker until they are equal. If you have an ISOLATOR installed between batteries then you won't have to worry about switching them out of parallel ("all") because this device prevents one battery from discharging into another.Also, take heed to Bert's comment. Don't pass the switch through the "off" position while the motor is running. Someone else can offer a good explantation why...just don't do it.The voltage regulator (or whatever controls the alternator's output) will prevent overcharging the batteries, the same as your car. Finally, take Stu's very important advice. Make a wiring diagram of your system. Examine and identify all components and tag each wire and connection if they haven't been already. Remember that factory systems on older boats may have been modified by their owners over the years. A basic book like "The 12 Volt Bible" by Miner Riperton (?) will help you understand and troubleshoot your system.

 

[Edward 14244]

Thank you

Thanks to all for your valuable input, it makes things a lot clearer. I bought the '12 volt doctor' booklet today and will be crawling all over the boat this weekend with a notepad making diagrams . I might even go for a sail if I have any time left...But seriously: I agree this is an important safety issue and I feel I am now on the right track. Thanks again.

 

[Bill5763]

Nice little test provided

the previous owner did not wire the radio directly to the battery.Sort of goes back to making a diagram to know exacty what you are dealing with.

 

[Bill N.]

Look for additional devices

Edward,Don't assume the previous owner written comment represents the latest wiring changes (I know mine doesn't, as I have a 88 cat 30 #5279 and have done lots of electrical upgrades).Also look for either a 'isolator' or a 'battery combiner'. That might explain the previous owner's written comment (as the norm is to start/run the engine on 'both/all', and then after stopping the engine, turn it to 'house' bank).The 'battery combiner' is more probable as the 1988 Catalina 30's wiring does not lend itself well to installing an 'isolator'. Also the 'battery combiner' is better anyway, as there is no voltage loss across the 'isolator' diodes (note: the combiner does need a disabler switch if used with a battery charger with seperate outputs for each battery bank).Also look for the very important factory/vender recommended owner installed upgrade to the charging circuit which re-routes the alternator output directly to the starter battery post, eliminating the altenator's output running thru the harness rubber plugs and a very long trip to the batteries via the cockpit engine panel (see upgrade info at attached link).Don't forget to also review www.catalina30.com for lots of additional information as well as other older catalina model's websites (e.g. 27, 34, 36 -- find them via www.catalinayachts.com 'links').BTW, regarding your question #3, the factory alternator will undercharge deep cycle batteries. You can confirm this by taking a hydrometer reading after doing alot of motoring.Hope this helps.