Batteries / Battery Charger

[Viper]

QR_BBPOST....KM its a 12 volt thruster and the two starter batteries (900 CCA) are wired in series....

I'm sure KM's point is that if you wire two 12 volt batteries in series, you would get 24 volts. I think you mean they are wired in parallel.

QR_BBPOST....Viper the owner manual also states: "...While the engines are running, their alternators generally supply enough power to replace the power used by the boat’s 12-volt equipment..".....

Ya that's a given. What I was pointing out was that while we are always concerned about having "smart" chargers maintain our expensive batteries, and rightly so, we seldom worry about them not being charged by "smart" alternators or "smart" add-on charge regulators. If we're so worried about the "smart" charge patterns and switching the house charger to the correct battery type setting which is a few tens of a volt difference to accommodate proper charging requirements for the battery type specs, why aren't we just as concerned with how they are being charged by the dumb alternators who's charging won't be accurate to tenths of a volt? They are nowhere near that accurate yet on a long run and in a fully charged state, they're being charged by an alternator output that is way off the required spec for hours or days.

[denpooch]

Comments much appreciated.

[km1125]

QR_BBPOST Yea COOLER that's it.
KM its a 12 volt thruster and the two starter batteries (900 CCA) are wired in series.
...

OK, maybe you're getting the terms "parallel" and "series" mixed up. If two batteries are wired in series, they would total 24VDC. Now, you could hook a 12V thruster to either the first battery or the second battery, but you're not getting any advantage of the two batteries hooked together, so I'm not sure why you'd do that. If they were in parallel and the thruster was a 12VDC unit, you'd get the capacity of both batteries.
If the two batteries are really in parallel, what you'd really want is a high-capacity relay between then that is activated when you use the thruster. Then the two batteries would be isolated and be charged independently

QR_BBPOST....If you're recharging them independently, then it's perfectly OK to have different battery types....

I'm not sure I'm following but I might be reading it wrong. Unless you have a very expensive charger where you can program a different battery type for each bank, or are using multiple charges, all the batteries on the boat being maintained by the same charger with multiple bank outputs should all be the same type so the (single) charge curve setting suites all the batteries hooked up to that charger.

Having said all that, what do we do about the charging characteristics when the batteries are being charged by your conventional alternators that don't have settings for different battery types?
There are smart alternator charger systems out there now that are becoming more popular due to the higher costs of some battery types but very few people upgrade this part of their charging system when upgrading to expensive batteries.

Yes, if they were different types your charger would have to be able to have independent settings for each output, or you'd have to use two chargers.

I think the issue with the alternators is just a length-of-time thing. If you were to run the same batteries on your engines for 1000 hrs, that would typically be years of usage for the average recreational boater. Plugged into and sitting on shore power, those same batteries would get that charge in a couple of months. If the charge voltage was off and what was causing the batteries to go bad, it would take years with the engines and months with the charger.

[denpooch]

KM, I am assuming that indeed the thruster batteries are in fact wired in parallel. This is the first time I am hearing the term 'high capacity relay'. I did google it and see a bunch of them on the market but cannot discern what exactly they would do for me in my application.
I believe that the thruster - two battery 'bank' - is providing extra power/quick recovery when I engage the thruster.
If you don't mind explaining in a bit more detail, how does the relay change or enhance that function? Thanks.

[km1125]

A 'high capacity relay' is just like a starter solenoid or one of the "emergency start" solenoids that you'd put between your two main batteries. It's just a relay that can take large amounts of current.

If your thruster needs the current from two batteries to satisfactorily run, then paralleling the batteries makes sense. However, that complicates charging, as now they do need to be the same type and similar age/capacity. You really don't want to parallel two different batteries and leave them connected because one will affect the other one unless they are in a constant state of charge. And even then, one of them will 'trick' the charger into providing a voltage that's not the best for the other.

The solution to those kind of issues is a "high capacity relay" that you only enable (activate) when you need both batteries connect, like you would when you're using the thruster. The rest of the time the batteries are disconnected and can be charged independently. This is made very easy if you have an "on/off" switch for your thruster, as it could also activate the high capacity relay.

If the only reason the two batteries were combined is because there were both weak then maybe just by replacing them you don't need to combine them anymore?

[Midnightsun]

This setup must be common in later years as mine is the same from the factory.

2 group 31, 1000 cca batteries weed in parallel do both port engine and bow thruster. Another identical bank does starboard engine and stern thruster and finally a single group 31 deep cycle for house which I upgraded to dual L16's in series.

All this gets charged while on shore power via a 60a 3 bank charger. The alternators are hooked up to each engine bank and manage the house bank through two rather large combiners.

Finally there is the lone generator battery which is on it's own getting charged either through the generator alternator or an independent 10a shore power charger. Never looked into it but pretty sure there is no wiring to charge this lone battery via one or booth of the main engines.

[denpooch]

Thanks folks.

[denpooch]

Follow up on the Charles 5000 charger switch.
I did remove the chargers off of the port port side engine compartment and there is a switch behind the window indicator. It was set to 'gel' type battery. I changed the 50 amp switch to 'AGM' setting and the 30 amp generator battery charger switch from gel to lead acid. I sprayed a little electronic connection cleaner and moved the switches up and down a few times. My 2005 vintage (black and orange graphics on the face of the unit) had the switch. There are some models that cannot be altered. The tech person at Charles Industries proved very helpful.

[89Convert]

OK, here comes the newbie, just bought my 89 3227 in May. I never really gave batteries much of a thought until yesterday. I was having a compression test being done before a tune-up and the mechanic said the battery/s were dying down during the test, maybe batteries or charger or both? I checked the batteries and they are only 3 yrs old. So I read the manual about battery operations (section E1-3) and learned about starting the motors with one-battery at a time and switching back and forth. Does anyone do that? I always leave switch on All.

[tomschauer]

I switch from 1 to 2 and back to 1 every week, or at least try to remember to do so.
The problem with keeping the switch to all is if you are on the water and you drain your batteries, you have done just that, drained all the batteries and need to call for start or tow unless you have a genny with a separate battery that will fire up and run your battery charger for a couple hours so you can start the engines.