Battery Setup - 1998 405 Aft Cabin

[Mikwallace]

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QR_BBPOST And how does the Generator battery get charged?

Two ways....One, if you have the on board charger connected....two, the genny charges its own battery while it is running. This is why some of the ways these boats are set up is complete overkill with the generator battery size. In reality these are just small equipment engines that require only around 250 cca to start depending on your genny size (hp), also of course this will not apply if you have a diesel genny.

Horror of horrors, I just had two start batteries in parallel to start the mains, to this bank I connected the generator so it started off the same bank, thereby eliminating the generator battery ( more room ). Now this may rub some folk the wrong way but it worked just fine and while the generator was running it was charging the mains start battery bank.

Now your on board charger probably has the capability to charge three banks, it doesn't have to, check the wiring for that.

Now that’s food for thought!! My on-board chargers will charge 3 batteries each. The OEM charger was replaced by 2 Xantrex chargers. I can’t answer why, but that’s the way it is. And there’s a charger wire for each battery. Even the 3 batteries connected in parallel. I’ve got to research the Xantrex manual/website and read how they recommend to connect parallel batteries. It doesn’t seem logical that each battery would be connected to its own charger wire since the batteries are connected parallel??

But if you had both engines and the generator running, did the alternators compensate for multiple charging sources?

[bud37]

QR_BBPOST It doesn’t seem logical that each battery would be connected to its own charger wire since the batteries are connected parallel??

The charger only needs to be connected to each bank ( not each battery ), a bank being any number of batteries connected together to produce 12 volts in your case.

There really are many ways to do this , charging relays/isolators etc etc.....but simply you have two battery banks....one for start and one for house which you can control manually quite easily. Now that said , unless the previous owner has wired something different. Take your time .

There is some good experience to rely on with G36 having the same boat.

How big ( what model) are the xantrex chargers ?

[km1125]

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QR_BBPOST And how does the Generator battery get charged?

...... This is why some of the ways these boats are set up is complete overkill with the generator battery size. In reality these are just small equipment engines that require only around 250 cca to start depending on your genny size (hp), also of course this will not apply if you have a diesel genny.

Horror of horrors, I just had two start batteries in parallel to start the mains, to this bank I connected the generator so it started off the same bank, thereby eliminating the generator battery ( more room ). Now this may rub some folk the wrong way but it worked just fine and while the generator was running it was charging the mains start battery bank. ...

Totally agree on the "overkill" on the genset battery sizing in almost all situations. I don't like the idea of tying it to the main starting batteries as I do think they should be independent systems. But I ALWAYS wondered why folks aren't using common 'motorsports' batteries for the gensets. If they can reliably start 160HP PWC engines they should have no problem with a ~20HP genset. And if it was a little bigger diesel you could just put two motorsports batteries in parallel!!

Now that’s food for thought!! My on-board chargers will charge 3 batteries each. The OEM charger was replaced by 2 Xantrex chargers. I can’t answer why, but that’s the way it is. And there’s a charger wire for each battery. Even the 3 batteries connected in parallel. I’ve got to research the Xantrex manual/website and read how they recommend to connect parallel batteries. It doesn’t seem logical that each battery would be connected to its own charger wire since the batteries are connected parallel??

But if you had both engines and the generator running, did the alternators compensate for multiple charging sources?

THe issue is not with the how the batteries are connected, but how the charger isolates the three different outputs. On some chargers, each output is isolated, so you'd need all three outputs connected to the same bank (whether all three wires go to the same posts, or one pair on each battery doesn't really matter), because the charger provides, say, 10 amps PER OUT for a 30 amp charger. Other chargers just use diodes to isolate the output, so they're just taking a 30 amp output and splitting to three feeds. Any ONE set of wires or the COMBINATION OF WIRES can pull all 30 Amps.

Another thing to think about the way your batteries are setup. Because the charging systems for each engine are tied together in the 1/2/all switch, you should get in the habit of alternating which engine you start first, and then checking the voltage (WITHOUT the shore power or generator powering the shore-power charger), so you know that EACH engine is providing charging power. Once you have both engines running, you don't really know if both charging systems are working because they are tied together.

[Mikwallace]

QR_BBPOST

QR_BBPOST It doesn’t seem logical that each battery would be connected to its own charger wire since the batteries are connected parallel??

The charger only needs to be connected to each bank ( not each battery ), a bank being any number of batteries connected together to produce 12 volts in your case.

There really are many ways to do this , charging relays/isolators etc etc.....but simply you have two battery banks....one for start and one for house which you can control manually quite easily. Now that said , unless the previous owner has wired something different. Take your time .

There is some good experience to rely on with G36 having the same boat.

How big ( what model) are the xantrex chargers ?

The chargers are Xantrex True Charge2 - 40amp.

Reading on the Xantrex web site, it appears there’s a real overkill on my 12vdc setup. I don’t know why it is setup the way it is; however, I do believe it is incorrect. In fact the second charger is not even required. The TrueCharge2 40a will charge three banks of batteries. It should NOT be wired to each battery within the parallel setup I have on Bank 1! The Xantrex chargers may be setup in parallel with optional Xantrex panel, but mine is not. As I read the info on the Xantrex website, the 40amp charger shares the 40 amps over the three banks. So if output 1 from the charger only needs 5 amp, but output 2 needs 10 amps, in theory output 3 could get the remaining 18 amps if required.

In my scenario, since I already have the 2 chargers, I might use Charger 1 on bank 1 by itself since there’s 3 batteries in parallel. So, only 1 output from Charger 1 would be connected to one battery on Bank 1, charging all three batteries within that 3 battery parallel bank. Then use the second Xantrex charger for Bank 2 and the Generator battery.

And a few of you recommended the BMV battery monitor. Xantrex has a battery monitor as an option for the True Charge2 chargers. I’ve not price comped, but will research. However the remote battery monitor will only monitor one charger so I could not monitor all 3 banks if using the aforementioned setup with 2 chargers. I could monitor all 3 banks from the monitor if I connected only one charger to the three banks as the charger is designed to do!

Thanks for all your input!

[g36]

Here's the victron battery monitor , i upgraded my last victron to this one a few years ago. This one has bluetooth so I can monitor my house bank state of charge and starting battery voltage on my phone when I'm lazy or look at the guage too. Its handy to check on charging amps while house bank charger or engines are running and watching altenator output . Im not monitoring the genset battery its not that big deal imo. ...https://www.victronenergy.com/battery-m ... -712-smart

[Viper]

Whenever you connect a house charger to a generator battery and other banks, you need to ensure the charger continues to work while the generator is running. Some will shut down when they see a conflicting charge such as the charge output from the generator itself. If this happens in your case, the generator battery would be okay as it'll still get charged by the generator but your #2 bank wouldn't get charged. The same would happen to the banks being charged by the engines while they're running at the same time you have the generator running and powering up the chargers while under way. This isn't a problem for most chargers but some had this problem, Xantrex True Charge was actually one of them.

[km1125]

If I'm reading everything right, the below diagram is how you're wired now, without the charging connections. I don't know if you really have a ground buss, but all the negatives should be wired to a common point. That could be that they are all tied to the engine blocks, or individually tied together with cables.

When you have several batteries connected in parallel, it's best to arrange the load and charging connections with the positive on one end of the "string" and the negative on the other end of the "string" so that the jumper cables between each battery cancel out with voltage drops so each battery sees the same loads and same charging. If you put both the connections (positive and negative) on just the first battery, then the other two batteries see slightly less load and slightly less charging. How much that matters determines on a lot of things like the actual currents and wire sizes and quality of the connections, but there will be a difference.

Boat_battery_wiring_diagram_multiple_batteries.jpg

[Mikwallace]

FOLLOWUP -

What an afternoon!! KM1125, your diagram is much more organized and neater than mine; but here goes.

After all your comments and reading the Xantrex website and the operator manual for the Xantrex TrueCharge2 charger, I re-organized all my batteries. I had an assortment of 1000mca crank battery, 675cca and 750cca Deep Cycle mix. Two of the batteries had been overcharging and boiled the acid (one battery was very low and I topped it off with Distilled Water, the other OK but messy). I removed all 5 batteries and boxes, cleaned them using baking soda on the exposed acid and dried everything before installation (what a mess).

Here's what I finished with:

Bank 1 - three 750cca Deep Cycle Batteries parallel
Bank 2 - One 1000mca Start Battery
Generator - One 675cca Deep Cycle Battery

I connected Bank 1, Bank 2, and the Generator Battery to ONE Xantrex TrueCharge2. The charging wire for bank one is run to the center battery of the three batteries. The Xantrex is a 40amp charger and will run three banks. The second XantrexTrueCharge2 is unplugged and not in use. I'll try this for a while and see how it goes. If it doesn't work, I can either split a bank to the other charger or PARALLEL the chargers and they'll provide 80amps. But I think 40amps will be sufficient. We'll see.

I've ordered the Xantrex TrueCharge2 Remote Panel. It allows you to monitor and control battery charger performance from the panel. It's an easy connection via phone cable, just gotta figure out where to mount it. The DC/AC panel cabinet is full.

KM1125, I can easily switch the GROUND on Bank 1 as you mentioned. Which does make sense, too.

If I were to guess, I'd say the original setup was two batteries on bank 1, and 1 battery on bank 2, and the Genny battery isolated. All those ground cables look the same age and are tied together. It appears as if a third battery was added to bank 1. I can't begin to rationalize why there's two battery chargers?? All the batteries are 2021 models.

I'll let this age for a while, then connect the Inverter. I'm also looking at the Xantrex FreedomX 1000w or 2000w Pure Sine Inverter, but that's down the road, or should I say river? The FreedomX has an auto transfer switch built-in. All the correct wiring is already in place. I'll just have to do a little research to see how to include the coffee maker in the circuit if I go with the 2000w inverter. And take a look at the DC C/B between the batteries and the Inverter for correct size. -ANOTHER PROJECT-

Thanks for everyone's input!!

Here's my PDF diagram:

Battery diagram 2.jpg

[bud37]

I don't see a ground to the stbd engine on start bank. #2.....there needs to be a ground cable joining the port and starboard engine grounding studs together, not thru the batteries. On bank #1 the positive cable should come off one end and the neg off the other end of the bank like km mentioned. Check where your bonding wiring is connected to the ground side......There should be some bus bars down there.

The control panel is ok, but if you want to monitor battery use /draw and charge rate accurately at the bank you will need a monitor with a shunt.....maybe something for later.

Here is a good read on many topics related to boat electrics....covers some of your questions.

https://marinehowto.com/category/electrical/

[Mikwallace]

QR_BBPOST I don't see a ground to the stbd engine on start bank. #2.....there needs to be a ground cable joining the port and starboard engine grounding studs together, not thru the batteries. On bank #1 the positive cable should come off one end and the neg off the other end of the bank like km mentioned. Check where your bonding wiring is connected to the ground side......There should be some bus bars down there.

The control panel is ok, but if you want to monitor battery use /draw and charge rate accurately at the bank you will need a monitor with a shunt.....maybe something for later.

Here is a good read on many topics related to boat electrics....covers some of your questions.

https://marinehowto.com/category/electrical/

Yes, there's ground wires going from port to starboard engine and generator to starboard engine and ground to bar. all the OEM grounds are intact/unchanged. I just didn't draw them in the diagram as it's confusing enough as drawn. I was really focusing on the setup and which batteries ran what.

Thanks for the link. There's a wealth of info there. Those articles should be pinned somewhere. GOOD INFO!!

Thanks!!