Battery problems -- seeking ideas

[Sanders]

The batteries on my H37c are exhibiting strange symptoms, and I am looking for suggestions and ideas. (I checked the archives...)House batteries and the separate charging battery are more than three years old. The two house batteries are wet cells, fairly standard marine design, with a warranty of 36 months.The charging battery appears to be a standard truck-type, the same age, but a sealed "maintenance free" type (not AGM).(A battery isolater is mounted to protect the starter battery from being drained by the house bank, and I suspect the isolator is not working properly.)The house bank will take a full charge, either from the alternator or the dockside charger. But 12 hours or so of routine at-anchor use and they begin to fade quickly (from 13.2 to 10 or less.. This in not under a heavy load, just a few lights.) The charging battery just recently began rapid decline of power, in some cases from 13+ to 10.2, even when the battery is turned off. It has happened as quickly as within one hour. Sometimes when I turn the starter battery on the power reading increases, but it drops back rapidly. (Which indicates, I think, the system is tapping into the house batteries.)The first suggestion I received was that all three are probably old and need replacing, which I am willing to do.My concern is that is something is wrong with the system, I might just be feeding new batteries into a bad situation.Any suggestions for trouble-shooting?I have no doubt the house batteries need replacing, and from what I understand the sealed starter battery tends to fail rapidly once it ages.Could a wiring problem with the isolator create a failure like this?Can I damage a new battery if I install them, or can I put in the new batteries and monitor them closely to see if a simple replacement solves the problem.(And, if you want to suggest a good electrician in the Bay Area, I am all ears...)The alternator appears to be working properly and feeding power into the system, but that won't help if i can't get it cranked to start!Thanks for your ideas...Sanderss/v Good News

 

[Rick D]

Good News.... Not

Make sure the connections are clean an bright. Otherwise, I suspect it's just old age for both the house and starting. That's about all I ever got before they got tired. (I spent good bucks on some Trojan golf-carts this time, so I better get more than three years.) Anyhow, there are certainly many skilled amp-heads on this board who will, I'm sure, offer up some testing hints. Good luck, Rick D.

 

[Ed A]

yes

that answers most of your questions. remove the batteries and take them to a battery shop to be tested. that will save you a lot of trouble guesing. if you have a charger at home charge them up before you take them to be tested. they will load test them and be able to tell you whats what. the your in a position to evaluate the rest of it.

 

[Ed Schenck]

Timely question.

You are right to investigate before installing new batteries Sanders. Ed A. is right, haul them out for testing. Even old batteries should not drain that quickly with a few 2 amp lights burning. You really need an ammeter to watch the draw as soon as you turn on the battery switch.And lose the isolater. Wire the battery switch so the two banks never see each other. Keep the starter battery charged for starting and never use it for anything else. If you are worried that the starter battery will be forgotten when charging then add a combiner. I am wired this way and my gels are six years old. They read 13.5 at the END of the weekend.

 

[Ed6885]

Isolator

I agree on losing the isolator...I disagree on the switch...Replace the isolator with a battery combiner....No loose as with an isolator, and it still keeps your batteries from seeing each other...It allows your batteries to charge, and keeps them apart...We have our house bank, and start battery wired this way and have been very pleased with the way it all works..Also a Link 10, nice item for watching your house battery situation...Good investment..EdS/V MYST

 

[Gene G]

End of life

I am sure that your batteries have hit the end of their life. 3 years is about all you can expect from them.All the above suggestions are good ones. I have 6 golf cart batteries. The first set lasted 7 years. They still had some life, but were obviously getting tired, so I put a new set in about a year ago. I highly recommend them.My first choice would be 2 alternators. My last choice would be an isolator. Just a tad above the isolator would be the switch, which WILL leave you stranded one day.

 

[Seattle Scott]

Sander, just checking in with you and the

rest of the posters. If the charging system is working properly the voltage at the terminals will be 14+ DCV when charging. Right?A fully charged 12 volt battary should show a terminal voltage around 12.7 DCV. Right?A fully charged cranking battary will drop down to 10-11 volts while cranking but if in good shape will jump back to the 12+ range as soon as cranking is stopped without starting engine/alternator. If the engine starts then you should see voltage on the terminals again in the 14+ range. Correct? Scott

 

[Sanders]

Scott: Yes

That sounds like what I would look for as normal.The abnormalcy came when I simply watched the voltage drop rapidly without doing anything (from 13 down to 10.2).No load, and the battery switch in the off position.My plan now is to head back to the marina Sunday night, pull the starter battery and have it tested Monday.And then, probably, I will buy a new starter battery.If it gets much more complicated than that, I'll call an electrician. (The first one I talked with is not available until mid-July. Business is very good.) I'll deal with the house batteries later.ThanksSanders

 

[Ed A]

some thing that comes to mind.

maybe you have a high resistance joint. or a loose joint that heats up and increases resistance an there by would comsume lots of energy?