Charging System Question

"Newbie here asking a question

"Newbie here asking a question. Been lurking on this forum for a while and have an issue that I'd like some help with.
We have a 1984 Carver with twin Crusader 220's. I'm running two 12v engine batteries, and twin 12v house batteries with a shore-power charging system feeding all 4 batteries while docked. I'm also running twin battery isolators. This was all rigged by the previous owner.
When running and docked away from our marina, the house batteries run-down pretty quickly. Apparently while under-way they are not receiving any charge from either engine alternator.
Here's my question: Is this normal? Should one engine charge house batteries while the other charges engine batteries, or not? I can't find any reference in my owners manual for this.

Thanks one and all for your help. This is a fresh-water boat (Lake Michigan) and only used on the weekends.

Mike"

Is it normal?
Kinda hard to s

Is it normal?
Kinda hard to say based on the info provided. I would say you can make it much better but we need to hear/see the details to help find the problem areas.

There was a recent post on the crusader board about just this topic. suggest reading it and then figure out exactly what you have on your current setup.

"Apparently while under-wa

"Apparently while under-way they are not receiving any charge from either engine alternator.

This is easy to measure. You need to put a dc voltmeter on the house system. Get readings with engines off and then running at 1500rpm.

And you can do that in the sli

And you can do that in the slip.

Jeff

"Thank you gentlemen. I will g

"Thank you gentlemen. I will get back to the boat this week, list/document the wiring from batteries out and back and re-post.

I was told that the previous owner was a senior engineer at GM in Detroit who was afraid of battery failure and over-compensated. But I'm not sure the system is installed correctly."

"Michael,
Knowing the battery

"Michael,
Knowing the battery size and types will also be helpful. Let us know what type of alternators you have as well. Two OEM alternators are not going to do much in trying to charge four batteries, especially if they are all different types."

"Another item that would help

"Another item that would help would be your 'use patterns'. For example, turning on the shore power charger for an hour and then heading out won't put much energy back into the batteries."

"Ok, back to the boat today -

"Ok, back to the boat today - 2 1/2 hour drive each way.
4 batteries, Size 27 12v. Two for the engines, two for the house.
On the engine batteries - we have heavy cables (#2) running from each battery to the starter and a smaller cable (#8) running from the battery to the isolater's.
On the Starboard side, we have a #2 cable and an #8 wire running through the bulkhead to the battery switch. ON the Port side, this combo of wires is disconnected - laying loose under the engine mount.
Alternators appear to be of standard (65 amp) size.
"Use Pattern" is that it stays connected to shore power through the week while we are away with minimal draw on house systems - frig, batt charger, and pumps. On the weekends while on board, we use the various systems as needed.
While cruising, the only house accessories we use are the frige, VHF radio and GPS. I routinely get a "low battery" warning on the radio after 3 or 4 hours of cruise.
I'm thinking that over the winter - I have some re-wiring to do. DPO issues plague me forever. (Darn Previous Owner)"

"Winter layup is probably the

"Winter layup is probably the best time to resolve the dPO issues....believe me, they exist on new boats, too.

The #8 wire running to the switch puzzles me. If it is the charging wire, no need for it to go thru the switch.

There are plenty of how-to articles on the www for doing this right; suggest researching on a rainy day until you find one that "clicks". Figuring out your needs, in amp-hours, is a first initial step. Then you can figure your total need and then make sure your 'use pattern' and alternators support it along with the shore power connection.

Last recommendation is to make your own schematic and then keep it current as you improve the system. I keep the 'master' at hope and keep the current, as-built on the boat. I can tell you the functions and locations of each wire and its terminal block on mine, except for one item....I still haven't found the diode that lets the NAV light switch power the ANC lamp, and that's after many years....one day I'll find that little guy!"

"Also, after you lock down you

"Also, after you lock down your use patterns you may find that you need to use dedicated house batteries that are truely deep cycle and can provide the amp-hours you need while away from dock. All this separately controlled and switchable. You also need to keep in mind that if you do decide to change the type of house batteries (i.e. from wet cell to AGM or Gel) you may need to upgrade your house charger to one that can charge multiple types all at once."

"From my wiring re-design 2 ye

"From my wiring re-design 2 years ago, I had learned it is so much easier to use ALL the same type of battery and not mix. The text (Nigel Caulder) says to even look for batteries that were made all on the same batch to maintain consistency. I did not do that but all my group 31's are Gel, same model, same brand. We do have a 2500 w inverter/charger using 3 batteries and the others are just for the engines but when we are underway, they all get charged by both engines. Frankly, it works very well"

"Have a similar problem. Two b

"Have a similar problem. Two batteries are hooked together in parallel, and one of them is always low on water. Looks like I'll have to match a pair of them somehow.

Jeff"

"Al, sounds good but your stoc

"Al, sounds good but your stock alternators may not be charging your gel batteries correctly (i.e. bulk and adsoption charging amounts/rates, float voltage, etc.). Their lifespan may be shortened as a result. I don't know the exact details of your system and I not trying to speculate on yours. Usually when it comes to batteries I try to tell people that different battery types have different charging profiles. As such you must take into account the way you plan on charging them - at dock and under way. Everything needs to be compatable. The problem you commonly run into is the older boat electrical systems were designed with standard wet cell starting batteries in mind. New technology batteries (AGM and Gel) do not make good direct replacements because the old charging systems won't provide the correct charging rates and levels for the newer types, which can in some cases ruin a several hundred dollar battery. So the bottom line I tell most people is if you upgrade the batteries then you probably need to upgrade the house charger and in most cases the alternators as well."

"Greg..

VERY GOOD POINT....

"Greg..

VERY GOOD POINT....That is where my research has really paid off. I had never known about all of those facets of a battery until I had to start looking for these batteries. The company I work for has a huge battery company we work with so I had bent the ear of one of their tech guys and we had done those cipherin things back then. My ac/dc system was completely torn out and re-designed by a marine electrical engineer down in Fla. HIs design was terrific and he was super supportive and was on the phone with me several times as we were laying out cable and other stuff.

Bulk, float and absorb rates had all been figured in for the alternators and then the inverter/charger was programmed to provide those same elements...AND ( this I love) I did it with a freakin' telephone handset.

My batteries are on their third full season and so far (knock wood) Things are really good. You are absolutley correct and these variables NEED to be calculated in. Not an inexpensive deal but certainly well worth the effort and time.

By the way: those (7) batteries weigh in about about 85lbs each and we had to seal up a few areas and re-distribute the weight so we were not listing to one side all while providing an non-explosive atmosphere"

Awesome Al! Sounds like you d

Awesome Al! Sounds like you did it right. Nice job. What alternators did you wind up using?