Batteries, the Battery Switch and the Onboard Charger

[Pat Anderson]

OK, there are some specific questions at the end, I'm sure all of you know the answers but I don't. At home Daydream is plugged into AC that powers the onboard Guest 5/5 charger all the time, since the manual says it is both a charger and smart battery maintenance system. We discovered at the 40th Street Ramp that our starting battery was dead before we went out for an overnighter last Saturday (that one is detailed in a different thread!), so we started the BF150 on the Parallel setting on the battery switch, then when the motor was running, we set the battery switches to Parallel off and Start on and House on. We have Optima gel cell batteries, one dedicated to starting and two dedicated to the house, with a Voltage Sensing Relay (VSR) on the battery switch. So while we are running, I assume we are charging the starting battery. We anchored up, and enjoyed a lovely evening, night and the next morning. We turned the refrigerator off to protect the house batteries, basically we were only using a couple of lights and the Wallas. When it came time to leave, we ran the Honda 2000i through the shore power connection for an hour to put a little charge on the batteries. The starting battery had a little power but not enough to start the BF150, an we again switched to Parallel, but now of course the house batteries were a bit more depleted. The engine did start but we had an anxious moment for sure. Now, I will pull the starting battery and have it tested, but assuming it is no longer taking a charge, as appears to be the case, my first question is - is the VSR preventing the house batteries from getting charged at all when the starting battery cannot be charged up to the switch over point (13.7 volts or something like that)? That is what the battery switch manual seems to say, that it won't charge the house until the starting battery has a full charge. Is this affected by the switch settings, say Parallel should result in both starting and house batteries getting whatever charging is going into the starting battery, correct? Or is the Parallel setting just sucking juice out of the house batteries into the presumably defective starting battery? Do these questions even make any sense?

[sportner]

Yes Pat, they don't make sense. But I am glad its you trying to explain the problem and not me. I do wish you luck and look forward to the correct solution.

[thataway]

Some depends on where the VSR is set and the float voltage of the charger. Ideally the VSR is set at connect at 13.7 volts, and disconnect at 12.7 volts. (this combines the start and house batteries). The battery charger should be hooked up to the start and house batteries (two outputs). When the charger goes over 13.7 volts as in the bulk charge phase, it will combine the batteries. But if it does not go into bulk and stays on float (typically 13.3 to 13.5 volts) it may not combine the batteries. Irregardless; both batteries should be charged when the charger is on. The major reason for the combiner (VSR) is when charging from the engine. The engine charging voltage will be about 14.4 volts, and the batteries should be combined via the VSR--without using the parallel switch.

There is some danger in switching the batteries from one positon to parallel or another when the alternator is charging. If the output of the alternator is left open, the diodes will be blown. Thus you should not have to fool with the switches when using a combiner.

The battery charger at 5 amps each will take hours to charge--at least 10 to get enough for a start charge. The way around that is to either install a considerablly charger --for example a 30 amp charger will bring the battery from 50% discharged to 90% discharged in about an hour and a half. But the 50% discharged battery should still start the engine. You can also carry a automotive battery charger for use in an emergency to either boost the charge or as a more rapid charger, but not for perment mounting.

Most likely the starting battery is bad and not holding a charge. Best to put it on a good charger and take it up to full charge, then load test.

I like to resolve all of these difficulties by having a digital volt meter on the dash, with a switch which allows me to moniter the voltage of each battery (Blue Seas volt meter: 8235-single battery with a 6 position Radio shack rotary switch is what I use--you can spend a little more money and buy the 8251 which has alarms and measures 3 batteries.) There are other meters such as the Link systems or just a digital volt meter which can moniter the state of the batteries.

I like to check all batteries before I start the engine, when running and when using the batteries at anchor. This way there are no surprises. Sitting at the helm and turning a switch makes this quite easy and thus is done on a regular basis. We also like to keep a small battery completely isolated for an emergency start battery--even a garden tractor battery will start a C dory 22 engine. You can also carry one of the multipurpose boaster's which have jumper cables.

[Pat Anderson]

Thanks, Bob - what I get from this is that the VSR is not preventing the house batteries from getting charged, they are always getting charged by the separate outputs from the Guest to each side, starting and house - the VSR only kicks in to combine them when the start battery goes over 13.7 volts? I assume the same is true for charging from the alternator? I guess I could have hooked up the Honda 2000i to the house batteries directly by the provided charging cable, that I think charges at 13 amps instead of 5. My solution probably will be to do as you suggest, pull the battery, put it on a conventional charger and see what we get - not sure how to "load test" but I can sure take it to Les Schwab! Also I will probably get a completely separate marine battery in one of those dedicated battery cases that have the appropriate connectors, keep it on a small maintenance charger all the time at home, and take it with me as an emergency backup to start the motor in dire cases. Not sure I have the savvy to rig up all the battery monitoring stuff at the helm, but I do have a Radio Shack digital volt meter, and I will be more diligent to see what I have before departing home in the future...

[tom&shan]

[thataway]

Pat, Correct.

I had looked at the Optima and then reviewed the various forums and decided against them. Some folks have had really good experiences, but there are others who have had the problem with premature deaths. I assume that they can be charged as an AGM battery--that is a 14.4 volts.
(I find several places which state that Optimas can be charged up to 15 volts--this is a bit higher than most AGM's are susposed to be charged at)

There are a couple of sites which show premature failure if the batteries are deeply discharged (over 55% discharge)--although they are advertised as being able to be deeply discharged multiple times.

When load testing a battery, it is taken to full charge, then a specfic load (usually 1/2 of the cold cranking amps for 15 seconds) is put on the battery and the voltage measured again.

There pulse desulfators and battery conditioners. These work on AGM batteries as well as lead acid batteries. I have used these to restore sulfated or batteries which had been abused. (Battery minder--I leave them on the RV batteries)

[Bad Boy]

I have had two instances where the Optima red top batteries went unexplicably dead on two separate boats. After researching, I decided to try the very expensive Odyssey batteries.

[flapbreaker]

Pat, can the Honda 150 be rope started? It might be worth learning how to do that rather than lugg a spare battery around. Just a thought.

I doubt this is the problem but I urge you to check that the VSR is wired correctly. Mine was wired backwards from the dealer. Took half a year to figure out what was going on. Les Schwab checked the batteries and to my surpise they were fine. Thought for sure something was going on with them. My problem was the house batteries though. Anyway just check to see if the alternator cables go where they should, that the house battery cable actually goes to the house side and the same for the starting battery. Good luck.

[rogerbum]

[mikeporterinmd]

Putting in a large smart charger is a nice option. It takes a fair amount of
work though. The wires for a 30 amp charger are substantial unless the
batteries are really close to the charger. Not much point in installing a high
output charger and using skinny wires and hence getting a voltage drop
at the battery. Some chargers have remote mount displays which also
function as voltage meters. When I tried to start my Wallace last nght,
there wasn't much doubt as to why it wouldn't fire up...11.5 volts. Charger
was not connected...

Mike