Battery trouble, so I ran an experiment.

[Stu Jackson]

Originally Posted by jeepbluetj

yup. But the OP still needs about another 25 hours of charge no matter what.

Pull the batts. Put em on a charger in your garage. equalize the flooded ones. Then do a timed discharge and see what you got left. You may be fine, you may be hosed. I had the RV batts down to zilch once and they're fine now (2x GC6's)

90 min of charge is nothing if you're talking 400AH of battery on something like 30 or 40A charger.

Yup. Good advice.

[Dymaxion]

Your lead acid batteries are likely sulphated up from prolonged discharge, plenty of battery chargers out there that will recover a sulphated battery but as someone said, split the bank apart and do one at a time. Allow 24hrs for each battery on recovery/charge. If you're charging directly off your generator its not likely to have desulphating capability, nor push out more than 15 amps anyhow. Time to price a small solar panel system, 40-80 watts. With a pwm controller you'll find them for about the same price as ONE of your gel cells. Cheap insurance for next time. Time to reseal the mast boot too I'd guess. ☺

[socaldmax]

Originally Posted by pesarsten

I have to ask, Is the Honda eu1000 a pure sine output generator or a modified sine output? I had problems using a large boost charger with an eu1000 and thought it was due to the output. If it is modified sine, then his charger output would be degraded wouldn't it?

He's using an EU2000, not a 1000. They're pure sine wave inverters.

I think your problem was the fact that it was an EU1000, which puts out only 900w continuous. This isn't enough to even run a toaster, about 1/2 of what it takes to run a 1,000w microwave (they need 1,800 to 2,000w to produce 1,000 to 1,100w of RF), 1/2 of what it takes to run an 1800w blow dryer...

you get the idea. I doubt it could support most 30 or 40A battery chargers.

[andyft]

I have a 1000 watt generator connected to a 40 amp charger and 2 100ah batteries, works fine.

[vmattiola]

Lots of great input, thanks for everyone's ideas/opinions and dealing with my ignorance here on the topic.

From what I gather, a few things:

1 - Definitely not enough charge time. Got it. In truth, the Honda ran out of gas at 90 mins so I basically said, well...experiments over then....since that was the last of my gasoline on board. (take a free swing for that one)

2 - My Beta Marine 90hp diesel has a 100A alternator. For certain that is the more effective charging option. In reality, I was replacing a coolant water vent cap anti-siphon fitting at the same time...so diesel was de-commissioned. I'll use her today for charging and burn diesel instead of gasoline.

3 - I need to isolate both my battery banks. How I do this? I'm not really sure at the moment, but I'll figure it out. Right now they feed into the battery switch at 1 and 2, independently, and I just always kept the switch on BOTH. Perhaps they're already isolated? (another free swing here) I bought the boat with the system set up as-is, so I'm trying to learn it all now and stay afloat at the same time...

4 - I should get a hydrometer instead of my multimeter. But won't this only allow me to test the specific gravity of my old batteries, not the newer gels? The last time I used a hydrometer was organic chem lab in college, but I could probably figure it out again. Is this critical though? Why is a meter not effective enough? I'm in St. Maarten and not sure where I can even buy one.

Questions:

How do I calculate how long I need to charge for? I was going to use some of your sample calculations as reference, but it'll differ for my diesel alternator.

Should I just go for 24hrs of charge and let the smart charger do it's thing?

How do I calculate what my solar needs are?

[vmattiola]

By the way, who added "men" as a tag to the thread??

[Sailmonkey]

Well, first gel and flooded batts have very different charge requirements, what one thrives on kills the other.

Does your 100 amp alternator have an external regulator?

What size is your shore power charger?

Running the engine to charge could still take 10 hours to get a full charge.

You may need to equalize the flooded batts, but the gel will not like this treatment.

You isolate and charge one or the other by turning the switch to 1 or 2, unless a PO has played a cruel joke.

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[Adelie]

Originally Posted by socaldmax

. . . I doubt it could support most 30 or 40A battery chargers.

40a at 12v is 480w. even with 50% efficiency loss in the charger the EU1000 should still be able to cope just fine.


A house is but a boat so poorly built and so firmly run aground you would never try to refloat it.

[Dymaxion]

Check the tops of your batteries, if they're sealed up no way to get a hydrometer into them to test charge level. Sounds like your banks are already separated, eyeball/trace the wiring if you can to double check. Verify that charging voltage reaches each bank independently and that the two banks aren't somehow connect via your boats charging system. If the switch 1/2/both has been properly wired it should be. Check with multimeter at alternator itself and see what voltage is, likely 14.1 or so. Then stick meter on each bank and make sure one is seeing the 14.1 while the other is 12.7 or similar. That will verify bank separation. I'd still separate to individual battery to do the recharge using your smart charger, one at a time.
For solar requirements start by reading the amperage rating on you bilge pump, likely 3-4 amps minimum. Then figure out how many hours you expect it to run between battery charges. Hah, good luck with that. How long did it run to empty the bilge when you got back after the 1.5 months is a first cut, a poor one. Now you have a poor estimate on amp-hours consumed per flooded bilge pump out. So how many times would that happen between engine runs? Yada Yada, eventually you'll get to amp-hours per day required. Then shop for a panel that will match that, on a cloudy day, dirty panels, obscured by sail cover, boom etc. Fun, non? Far more knowledgeable folks than I have put great solar info online, hope someone posts a link. Add in some other loads like masthead lights while at it.

[Dave22q]

Maybe my experience will help. I recently had to replace my 400AH AGM house bank. I installed the new gr 31 batteries on my boat and let my Promariner 30a charger do its thing on shore power. I monitored it closely because I feared a charger problem. Voltage went up on a straight line over more than 24 hours peaking at 14.7 v. Then it dropped abruptly to the float mode at 13.4 v and held there. (There were a few 12v items drawing power throughout). Based on this I think you need to allow for a lot more charging time on your boat.

[W3GAC]

Somehow you all got sidetracked over the 'traditional' generator/ charger topics, but he clearly doesn't have enough time to properly charge the bank on generator/ charger power. If there ever was a good application for solar charging...THIS IS IT! Even a modest solar panel working on sunny days would get/ keep the battery bank to full charge. I believe that should be our universal recommendation to keep a boat's batteries topped off that's moored/ anchored unattended for what may be long periods of time.


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[Stu Jackson]

Originally Posted by W3GAC

I believe that should be our universal recommendation to keep a boat's batteries topped off that's moored/ anchored unattended for what may be long periods of time.


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Maine Sail has be "preaching" this for at least the past five years for anyone on a mooring (i.e., no shorepower).

The cost of a panel and a controller and wiring is less than a bank of batteries, which WILL die if left to self discharge.

Simple stuff, but, like crappy wiring harness connectors, completely ignored by altogether too many skippers.

[nigelmercier]

Originally Posted by Adelie

The generator putting out 13a at 120v becomes 130a at 12v...

Huh? Some confusion I think.

[Cheechako]

You need a good long charge to determine anything. At 13.5 amps you're not putting much in in 90 minutes. Once you do a long full charge, disconnect all batteries from each other and let them sit over night. Measure the voltage on each one in the am. They should be 12.40 or higher. Right after charging, if one battery is hot to the touch, it's likely shorted.

[boeing1]

batteries flat, thing you might have another drain on you batteries or getting more water in other that rain water. just a thought....