Battery Charging and Misc Questions

W

Westie

New member
Hi there,

I am struggling to understand my battery setup and standard use. I thought I would turn to the experts again to bail me out...

I have two brand new AGM cold cranking batteries and I understand that they are independent to each engine. When I'm drifting or at anchor without the outboards on, I'm completely paranoid that I will drain a starting battery and not be able to turn the engines over. I'm only running the MFD and maybe lights so I know the draw is minimal and my concern is simple paranoia but I only have ~15 hours of experience on the boat and thought I should ask.

My manual says use of the in-board charger is "highly recommended" when connected to shorepower at all times. However, I found a manual on-line and I don't recall seeing the same recommendation. Note - I do select "off" for both batteries when charging. I'm now wondering if the manual is saying to use the charge with shorepore (as needed) and not as a general practice; is this just poor manual writing???

Question 1) do you charge when connected to shorepower at all times?

Since my battery's are both cold cranking, I have been thinking about installing a house battery to prevent concern with extended use. I hope to do a few overnights soon. I'm also planning to install downriggers which will increase the surge but will likely install on one of my cold crank batteries.

Question 2) For those with twins, what is your battery setup?

Lastly, all hard wired components (e.g. bilge, wallas) are connect to battery 1 (starboard).

Question 3) If battery 1 was fully drained, can I start the starboard engine if I select position "2" on the battery selector for starboard? I'm 99% sure this is possible but can find it in the manual.

Thanks as always.
 
Boat wiring is highly dependent on the dealer who installed the batteries and engines and not so much on the factory. Hence the details in the manual from the factory are less than clear. I can't answer your specific question since it's unclear how things are wired. On my tomcat, there's one battery and one switch for each engine with no cross over between them. One of the start batteries is used as the house battery (not the way I would have set things up). I carry a set of jumper cables in the event I need to start one engine from the other battery. I do have voltage monitors for each battery so I can keep track of what is going on with them. That would be one recommendation I would make regardless of how your boat is wired - put in a gauge to keep track of voltage and current draw from each battery. From that you will very quickly learn how much draw you have under your typical operating scenarios and whether or not you really need to worry much.

As for the charger, anytime I'm hooked to shore power, the battery charger is running. Keeping the batteries topped up will extend their lifespan.
 
It sounds as if you have no connection between the batteries. My 2006 Tom Cat came with a house battery--and I added several more. I had one house on each side (as well as the starting battery). I put a VSR (Voltage Sensitve Relay, also known as ACR) between each start battery and each house. This allows the start batteries to be charged first, and when the voltage reaches 13.7 volts, then the house begins to charge. When you shut down the engine, and the voltage is less than 12.7 volts the relay isolates the start battery--thus no worry. You can do this with one battery. Depending on what engine you have, there may already be a second isolated battery charging circuit.

It is possible to run down the battery by accident--so I always use a separate house battery. There is also another very good reason, the separate house does not subject your electronics to voltage spikes and low voltage when engine starting.

The charger should be hard wired to your batteries, so it makes no difference if they are on or off. You should at least charge the batteries on a regular basis. The charger tops off the batteries, which may not be done with the alternator, and is better for the batteries. Sometimes the Guest chargers fail, and I have almost always upgraded them, to larger size, and better quality.

The Wallas does specifically say to be attached to the battery terminal. We have ours to the switch--about 2 feet from the battery, with heavy cable between, and no issues. Bilge pumps should be on an "on" battery, or hard wired.

Roger's jumpers will work. I always have a heavy cable (heavier than the jump start cables, with a "on/off" switch between the two batteries. in some setups, this has been a relay and a momentary push button switch.

Without seeing your setup, or photos, diagram, I would not know if #2 would start--most likely it will.

Set up for Tom Cat--two engine start, two house, VCR between the engines and house each side. two bank charger will work with this, but at least 10 to 20 amps--not 5 amps--should be good 3 stage charger. Switch to combine the start batteries. Switch to combine house batteries. All electronics to one house battery, Refer to the other house battery.
 
Definitely absolutely add a house battery.

My practice is to always hook up to shore power and let things charge, although I've been out as long as 5 days with no shore power and I've not had a power emergency. We have all LED lights and turn off all electronics when over-nighting away from the dock. I always turn off the twin engine start batteries when settling in for an evening away from the dock. Even if the house battery discharges, I know that my crank batteries will get me going.
 
Thanks for the info. Im wondering if I should test the "independence" of my wiring by setting both batteries to "1" and then "2" and starting each outboard independently. That would tell me if I can crank both outboards if on one battery was drained. I have attempted to trace the wires but it's well above my electric knowledge...

I think I'll add one house and VCR to battery 1 and run electronics and lights. I don't like the idea of using my starter as is. I'm fishing most of the time so I don't think I need too much house battery support.
 
Looking at this reference: Battery Basics, I would think that AGM batteries can serve as deep cycle as well as starting batteries. The reference mentions holding discharge to 50% DoD, which is the same as any lead-acid deep discharge battery.

So, it may be that instead of adding batteries, you might just need to figure out how to interconnect the existing ones. Use one to start an engine, wait until the charge voltage comes up then start the other. Use the other battery as a house battery. Then hook them in parallel while the alternator charges both.

I always charge the batteries while hooked to shore power and the battery switch is always ON, feeding the house circuits. Also, I have a good 3 stage battery charger. The Guest doesn't meet that description.

Open to other opinions.

Boris
 
One thing I would strongly recommend to anybody leaving their batteries hooked to an onboard charger for long periods of time - MONITOR THE CHARGING VOLTAGE. I left mine on a 3 bank 15 amp. charger over the winter. The charger literature declared that it dropped to float mode or 13.2 volts after reaching full charge. IT DID NOT - both my start and house battery had to be replaced. It was charging at over 16.5 volts. I took it back and had it replaced twice under warranty. Both units when I brought them home and hooked them to my truck battery(fully charged) immediately pushed the voltage up close to 17 volts. It was a Nautilus charger - all of them faulty right out of the box. I finally took it back and requested my money back. Right now I am only using 1 amp maintainers for extended periods and even then I have them on timers that only come on for 2 hours a day. I have checked the voltage on them and it is within float charge perimeters.

This is not to say that a good onboard charger is not a good thing. If you use a lot of ah from your house battery one night and have shore power the next - then definitely a good onboard charger is a good thing. Trying to charge a depleted house battery with my 1 amp maintainer would not be a good thing. The initial(bulk) charge rate for say a 100ah house battery should be at least 10 amps.

Regards, Rob
 
Rob hit on a subject I alluded to--that is the quality of the battery charger. I have had it with the Guest Chargers--every one I have owned has failed in some way--no output, or too high an output (as Rob had). I leave my RV plugged in, and it stays at 13.2 volts…..

There is a whole other issue, and that is pulse plate desulfators: PulseTech, Battery Minder, Power Pulse etc. These keep battery plates from accumulating sulfate crystals, which is one of the major causes of battery failure. I often will leave one of these on the battery for long periods of time, especially if the battery has not been under ideal conditions. For example the batteries I used at Powell, will be on pulse technology chargers for the next few months. I cycled these batteries thru 50% of their capacity daily. I should get much better longevity out of the batteries, by using a pulse charger.
 
Hi Westie!
Here in my 2nd season I haven't yet figured out all the nuances of my boat's battery rigging...Rogerbum is right, as usual, that it's the rigging dealer who designs it.
Dr Bob is right on in pointing out that YOUR 110V ONBOARD CHARGER WILL BE CONNECTED DIRECTLY TO YOUR BATTERIES; this makes wire tracing easier knowing that. Everything else (x Wallas/bilge pumps) should be connected at the battery switches. I would expect a 'Combined' (Blue Seas term) or BOTH (Guest/Marinco term), not '2' to parallel (combine 2 12v batteries into one great big 12v battery, with the disadvantage of the weaker one 'pulling down' the stronger one).
Do you have a 110/12v fridge? that would be your biggest 12v draw when out; generally they will automatically switch to 12v when you disconnect from shore power UNLESS you turn down the themostat (in the fridge) to the OFF position (or pull it's 12v fuse on your fuse panel).
You can manually do the same switching a VSR does, but if you forget to 'un-combine' at destination you can run down both house and eng batteries and thus be hosed.
A smart rigger will rig your windlass (a real 12v power hog) to an engine start battery under the theory (generally correct) that you'll always have an engine on when running the windlass 'hog'.
Agree whenever connected to shorepower, have your 'smart' 110v onboard charger 'on'...as Dr Bob said, it's the only thing hardwired to your batteries and thus 'immune' to your battery selector switch. Agree with replacing any Guest charger or Galvanic Isolator at the first sign of any excuse to do so. PS... I was drafting while Dr Bob posted the above re Guest products...combined I guess we have, what, 90 years trailer boating experience?
I have 3 identical Sears Marine Platinum (re-branded Odessey gp 31 105 AH) deep cycle batteries...S and P start and one house (which gets the use, since the Yami's each start within 2 seconds and each is charged by it's S or P engine @ 30 amps at cruise). Conventional rigging would be to have the Port engine have an Accessory (house charging wire) to the House battery via the Port eng battery switch, but I haven't been able to trace that yet...you can check all this with your digital voltmeter with the switches/engines/charger on or off. You don't want BOTH engines to have a House charging wire since the engine voltage regulators would be competing against each other and only one would 'win'; and you don't want a VSR between BOTH engine start P/S batteries and single house battery (if you have one like me and not 2 like Dr Bob) for the same reason.
Put pics in your album of the battery switches; see my beautiful Blue Seas panel and delightfully clear "bilge pump--24h" with yellow LEDs in my album.
The 255 is elegantly designed...but not simple. It will take you years to figure out how all the systems work on your boat, and that's half the fun. PM me with any questions, and have FUN!
Cheers!
John
 
Thanks for the advice. That book sounds like a sound investment for me.

I do know my charger is directly wired to the batteries.

Sounds like I will need to replace the charger and isolator. Any suggestions on which to purchase?

I have a long list of items I still need before I would consider my boat rig for use. I would like to add these items so I can prioritize.
 
I use a Mastervolt chager and have been happy their products. Victron Energy also makes a good line of chargers. I have not tried their cheaper "blue line".

For the VSR (ACR is the same) , Blue Seas or BEP both make great marine products.

Many of us also monitor the state of our battery banks. I got a buy on a Link, but Victron is a very good way to go. (VMP 700 --one bank, or 702, monitors second bank voltage). This measures the amount of energy used, the amount put back into the battery and voltages.

We have all sorts of ways to spend your money!….none of these are essential, and we all managed before these came along with manual switches.
 
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