House Battery Bank Questions

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junaido

I have a house bank of 4 Trojan Mileage Master 6V batteries of unknown age.  I think there is a Xantrex battery charger. Recently I noticed the cabin lights get dim after 3-4 hours of use when boat had no shore power. The Link 20 battery monitor shows green lights but when I check voltage it's about 10V. After leaving the charger on for a few days, I turned it off, turned everything off that could draw current (Link 20 still showed 0.1A current for some reason), after a day the fully charged house bank was down to 9.9 V with nothing on. When I put a multimeter on the 4 batteries, two of them show 5.5 V and two show 4.5 and 4V respectively. Is there any way of milking some more life out of these batteries by getting rid of the weaker two batteries? In case I need to replace, the Interstate Golf Cart batteries at Costco are about $100 whereas the Trojan batteries run about $300 at the local battery store. Both have roughly the same amp hours, 210 vs 225 AH. Are the Trojans really 3 times better? Any other 6V battery recommendations? Thanks.
1986 #105, std. rig,  M25, Everett, WA

KWKloeber

#1
Possibly some helpful info you can use:

https://groups.io/g/Catalina30/message/108544

Rod Collins really likes USBatteries - calls em the Trojan Killers.

You might want to load test the batteries.  Is there no date code on them or serial no.?
Twenty years from now you'll be more disappointed by the things you didn't do, than by the ones you did.
So throw off the bowlines.  Sail away from the safe harbor.  Catch the tradewinds in your sails.
Explore.  Dream.  Discover.   -Mark Twain

waughoo

I would say that if your cabin lights brings 4 Trojen batteries down to 10v after only 3 or r hours of use, them batteries are cooked.  As a last ditch hail Mary, you could check the electrolyte in all the batteries.  It is possible that all the water has been cooked out of them.  Pull the caps and add distilled water to bring them up to the proper level.

After you've checked that, do a load test and start shopping for batteries.
Alex - Seattle, WA
91 mk1.5 #1120
Std rig w/wing keel
Universal M35
Belafonte

pablosgirl

I would not mix old batteries with new ones.  I run 4 GC2's from Advance Auto Parts. They go for ~$100 each on sale. I have 6 years of heavy use on them and they are still going.  I do check the water level at least once a month.  Letting the water fall below the top of the plates damages them and reduces capacity.
Paul & Cyndi Shields
1988 hull# 551 Tall Rig/Fin Keel
M25XP

Stu Jackson

The 0.1A draw on the Link 20 could well be the parasitic load of the Link unit itself.  Yes, when have you checked the water levels?  Have you used a hydrometer on the cells?  It does sound like your bank is toast, because of the voltage sag and no results when charging.  In addition to water levels, have you checked to see if any batteries have their cases bulged?  Please do not continue to charge this bank unattended because it sounds like a potential for a catastrophic event: charging dead batteries that could have internal faults is a possible route to a literal blow up.  Individual choices in new batteries can vary all over the place, but in the end the choice is usually over cost and quality, you can't get low cost with high quality.  Maine Sail's experience is priceless.  Lots also depends on how you intend to use your boat:  i.e., weekend warrior vs. long term cruiser/anchor out for long periods. 
Stu Jackson, C34 IA Secretary, #224 1986, "Aquavite"  Cowichan Bay, BC  Maple Bay Marina  SR/FK, M25, Rocna 10 (22#) (NZ model)

"There is no problem so great that it can't be solved."

junaido

#5
I should have mentioned, batteries had been topped off with distilled water before all these readings. No bulges in batteries but I think the time has come to replace. I have yet to spend a night at anchor so I think I will probably go with the cheaper option. When I turn on the charger it shows 8 or 9 amps going into the battery bank. This continues to drop off steadily to about 1A after several hours.
1986 #105, std. rig,  M25, Everett, WA

Roc

If your battery charger can go into the equalization process, you should try to do that.  I just bought (4) Duracell golf cart batteries at Sam's Club to replace the "Energizer" ones I bought there back in 2009.  The one's I just bought are EGC2 replacing the GC2 from 2009.  $135 each.   20 amp hour rate 230. 
Roc - "Sea Life" 2000 MKII #1477.  Annapolis, MD

KeelsonGraham

Quote from: pablosgirl on March 18, 2022, 08:07:35 AM
Letting the water fall below the top of the plates damages them and reduces capacity.

This got me thinking. What happens to wet cell batteries if you're on the same tack for a couple of days? Unless you go against the normal advice surely a good part of the plates will be uncovered when the boat is heeling??
2006 Catalina 34 Mk II. Hull No:1752. Engine: M35 BC.

KeelsonGraham

Quote from: junaido on March 18, 2022, 01:51:33 PM
I should have mentioned, batteries had been topped off with distilled water before all these readings. No bulges in batteries but I think the time has come to replace. I have yet to spend a night at anchor so I think I will probably go with the cheaper option. When I turn on the charger it shows 8 or 9 amps going into the battery bank. This continues to drop off steadily to about 1A after several hours.

I have the same problem. Last weekend, after a 9 hour charge, my four T105s were down to 50% after 4ah of draw. I did a hydrometer test on two of the batteries which revealed some totally discharged cells in both of them. I didn't bother checking the other two. They all have to be replaced.
2006 Catalina 34 Mk II. Hull No:1752. Engine: M35 BC.

Steve McGill

Assuming you have the space in your battery location the proper orientation for the battery cells are to have them running port to starboard, not bow to stern. This will help minimize the plates being uncovered.

Good luck,

Steve
CLARITY 1988 #588 TRWK (sold 8/2023 after 17 yrs)
Chesapeake, Herring Bay, MD