Batteries and Alternater Charging

[barfwinkle]

Hello to all

Well I have been fighting my batteries for several months now and yesterday I decided to take 'em out and replace them. So I took them out and one battery was 5 years old (GP 27) and one was 4 yrs old last November (Gp 24). I had them tested and the guy said there was nothing wrong with them. All cells were fine! So puzzled as to why they wont hold a charge for very long (and I have minimal load on the when not actually sailing and using the autopilot) I put them back in.

My neighbor at the marina rebuilds antique cars for a living and I discussed this with him and he asked if my alternator belt was tight. I told him that it was as tight and an old "fan belt" would be on an older car engine. He told me I might need to tighten it more because alternator belts require more tension than fan belts in order to achieve max output. Thus implying that the batteries have been undercharged for some time. Could this be so?

I have the Yanmar 1GM (7.5 hp) and the alternator is a 35 AMP output. The batteries have been maintained fairly well, but truly seem to be weak? I dont have a marine charger, but I am thinking about fixing that and putting a two bank 120v charger on board.

My questions then become

1 - how tight does my belt need to be (it has 3/4" play when depressed)

2 - suggestions for a two bank charger for a 25D

3 - where have others installed the charger?

[Ed Haley]

I had them tested and the guy said there was nothing wrong with them. All cells were fine! So puzzled as to why they wont hold a charge for very long

There appears to be something else going on here that is either a failure to charge or a discharge somewhere. If your batteries tested fine after being charged by the alternator, then check for a discharge somewhere. There may be a wiring problem somewhere that is causing a direct discharge. Maybe some electronic device is grounding out.

I know it sometimes takes a long while to find a wiring problem but if you know how to use a VOM maybe you can track it down sooner. There are lots of places to look for sure.

[Bob L]

Hello to all
I had them tested and the guy said there was nothing wrong with them. All cells were fine!

barfwinkle??

What did the guy do to test the batteries? Just measure the voltage? Check the specific gravity?

I know my batteries don't charge up to well with my automotive type alternator but charge fine using a 3 stage charger at shore. I bought a refurbished truecharge 20 2bank 20 amp charger for $150 direct from xantrex. I've been very happy with it.

Bob

[barfwinkle]

barfwinkle??

Its a long story Bob But I kinda like it!

And to the batteries. We (he) just hooked up a electric gizmo that he said "tested" both the charge status and cell condition. We didnot open the batteries and test the fluid. But I specifically asked if the cells were okay and he said yes. And after all I had two new batteries in my cart and he told me I didnt need them. He did tell me that my alternator propably didnt had the ump to fully charge the batteries with just 35 amp outpout.

Can they be tested under load and get different results?

I just had another thought. My battery leads (cables) are OEM and very flexible. Is it possible that due to their age they might be losing a considerable amount of charge due to their inefficiency?

TIA[/quote]

[Bob L]

Bill (who may have lost something overboard on the way to Bermuda?),

You can check the cables if you have a voltmeter. A digitial one may give you more precise measurements. With the cables attached to the battery, measure the voltage at the battery and at the end of the cable. That difference is the voltage loss indicating the resistance of the cables. (You could just measure the resistance of each cable with the meter). I forget how much voltage drop per foot for given gauge cable, but I think you can find that on the web or in a marine catalog pretty quickly. If your cables are losing more than they should, then you'll know.

If your batteries are lead acid and you can measure the specific gravity, it would probably be wise to get something in the automotive section of a hardware store that would tell you the specifici gravity. Then you'll really know the state of the charge.

You can also measure the voltage at the battery (and at the alternator) when the engine is running at some adequate rpm to see if the alternator is putting out enough voltage to adequately charge the batteries.

There is also the possiblity of sulfation which would impede your batteries from fully charging. Many battery chargers have an equalization charge option that will help to desulfate the plates. This sometimes makes a big difference, particularly in older batteries.

Bob

[Phil Shedd]

Barfwinkle

I think you should first get your alternator tested to see what it is putting out. While it is out you may go to a auto parts store UAP or the like and let them see it . They may have some thing the same size but more output. Should be a lot cheaper than the high output type.

The other suggestion was to test for a small short or power leak. Use a VOM meter and check across the battery leads . With all switches off there should be a open circuit. Make sure all switches are off then turn on battery selector switch. You should still read an open circuit unless there is some thing direct to battery( ie pump ?). If the there some reading on the meter start looking at what is connecter to the battery before the selector switch. Try that it may help.

Phil

[Mark Yashinsky]

Your first comment on "the batteries wont hold a charge" needs more details. Wont hold a charge when not using the boat and/or when using (what on) the boat??? Do you even know if the batteries have a (full) charge to begin with? How??? This is a sailboat, so are you running the engine for say 5 minutes to get out and 5 minutes when you come back in while you have say lights, stereo, VHF, etc draining the batteries??? On the other hand, 4-5 years on regular lead acid batteries is not shabby at all in terms of getting your moneys worth. Verify the rest of your system and maybe just replace them both. Do you hear any squealing from the alternator belt?

[barfwinkle]

Thanks for all the input folks. And to answer a few questions, generally if I am on the boat during the winter (not too much sailing going on) I'll be at the slip listening to the stereo (cd player), maybe the vhf on but just listening to local traffic, and that's about it. I use a AC light & oil lamp and very limited use of capin DC lights. Before the night is over I'll have to switch batteries or run the engine.

I kinda agree with Mark in that the usage I have gotten out of these two batteries is pretty stinking good which is why I took them out to replace them. However, I have other areas where I can spend those dollars if these batteries are still good.

The only thing wired directly to the battery is the stereo and it is only for powering the battery on the radio to maintain memory settings. I'll check next time I am at the boat for "leakage" and see what I get.

Bob when you install a battery charger do both batteries need to be the same group size (I know they should be the same type with regards to Flooded, AGM, Gel etc..)?

Thanks to all for the comments and I'll keep working on it.

[Kurt]

Where do you leave the battery selection switch when the boat is left unattended? The switch should not be left in the 'both' position.

[barfwinkle]

Kurt

If I do that then the batteries will be dead when I return because the pilot light will be on.

[Bob L]

Bob when you install a battery charger do both batteries need to be the same group size (I know they should be the same type with regards to Flooded, AGM, Gel etc..)?

Not as far as I know. I have a one group 27 and one 31, each connected to its own output from the charger. Most charges have a switch that does the appropriate charging for AGM, Gel, or plane old lead-acid batteries. The truecharge's switch applies to all outputs.

When I leave Magdalena for a while (like going home to Wisconsin), I unplug the radio so the 7 mAmps doesn't run down the battery its attached to.

Bob

[Bob L]

Bob when you install a battery charger do both batteries need to be the same group size (I know they should be the same type with regards to Flooded, AGM, Gel etc..)?

Not as far as I know. I have a one group 27 and one 31, each connected to its own output from the charger. Most charges have a switch that does the appropriate charging for AGM, Gel, or plane old lead-acid batteries. The truecharge's switch applies to all outputs.

When I leave Magdalena for a while (like going home to Wisconsin), I unplug the radio so the 7 mAmps doesn't run down the battery its attached to.

Bob

[Bob L]

Bob when you install a battery charger do both batteries need to be the same group size (I know they should be the same type with regards to Flooded, AGM, Gel etc..)?

Not as far as I know. I have a one group 27 and one 31, each connected to its own output from the charger. Most charges have a switch that does the appropriate charging for AGM, Gel, or plane old lead-acid batteries. The truecharge's switch applies to all outputs.

When I leave Magdalena for a while (like going home to Wisconsin), I unplug the radio so the 7 mAmps doesn't run down the battery its attached to.

Bob

[Bob L]

Bill,

As far as I know, you don't have to have the same batteries. I have a one group 27 and one 31, each connected to its own output from the charger. Most charges have a switch that does the appropriate charging for AGM, Gel, or plane old lead-acid batteries. The truecharge's switch applies to all outputs.

When I leave Magdalena for a while (like going home to Wisconsin), I unplug the radio so the 7 mAmps doesn't run down the battery its attached to.

Bob

[Bob L]

Bill,

As far as I know, you don't have to have the same batteries. I have a one group 27 and one 31, each connected to its own output from the charger. Most charges have a switch that does the appropriate charging for AGM, Gel, or plane old lead-acid batteries. The truecharge's switch applies to all outputs.

When I leave Magdalena for a while (like going home to Wisconsin), I unplug the radio so the 7 mAmps doesn't run down the battery its attached to.

Bob