Battery Charging

[Nereussailor]

I purchased four 6 volt golf cart batteries last year for my Hunter 30 house bank. After one year, one of the batteries won't hold a charge. Everyone states that all of the batteries in the bank need to be the same age, type and voltage. Does this mean that I have to replace all four of the batteries in order to get my house bank back? The other three batteries are still in great shape and have about a 90% charge. What's the best rout to take? Dave

 

[Steve Dion]

one of the disadvantages of the setup.

Dave:That is one of the dis-advantages of this setup. You can break the bank up by using two of the batteries for a starting bank and then purchase 4 more batteries for the house bank.Before you replace any batteries be sure that you have a good charger. Something like a Xantrex smart charger.You may also want to contact the battery mfg and see if they are willing to replace all of the batteries in the bank (you never know until you ask).What brand of batteries are you dealing with?Have you thought about some of the large Trojans (370 amp/6v). This would only require 2 batteries in the bank vs 4!

 

[Rick D]

I'd Try It

I'd certainly try replacing the one. At just one year, the others should not be too aged. I would sure do as Steve suggests and try to get a warranty replacement. But, if you cannot, you are only gambling the cost of one battery, a fair bet in my book. Rick D.

 

[Don]

Might depend on what the problem is

I have the same type bank of 6- 6V T 125 Trojans. If one of mine went bad, I'd first try to find out if it's just one bad cell (by using a hydrometer). If that's the only issue, given the bank is new, I'd just replace the one bad battery. What you have been told about using a "matched set" is correct but they are relatively new so adding one brand new battery (which has likely been sitting on the shelf a while) isn't a big deal.I'd also try to find any problems in the system so as to avoid doing this periodically - a good charger as Steve said is the first priority. It's not uncommon for a battery to have a bad cell regardless of the service it is in so if everything checks out okay, chalk it up to one bad battery.

 

[Nereussailor]

battery

All of the cells in the one battery are the same when using a hydrometer. (1.12) and the multi meter reads 5.54. The charger I'm using at home is a basic 6 volt auto battery charger.I keep an eye on it all day when charging. The one on the boat is a Xantrex Truecharge. I bring the batteries home for the winter to keep them in heated storage and charged. I will contact the manufacturer to see if a warantee replacement is possible.Don,I'm not sure what you mean by "a problem in the system". Wouldn't there be a problem with all of the batteries if there was a problem in the system? They are all connected together.Dave

 

[Don]

cell density sounds good

What I should have said is a problem in the wiring - like a bad connection. A bad connection would normally result in constant under-charging of the battery WITHIN the bank. What baffles me is that the cellls test good.If the hydrometer tests good and the battery won't hold a charge, I'd take it back to whomever you bought it from, have it load tested and ask for an exchange presuming it fails.

 

[Tom Spohn]

Your Multimeter

reading of 5.54 is roughly equivalent to 11.08 volts if they were 12 volt batteries. According to the chart this means a dead battery. (ie. less than 10% left.) A fully charged 12 volt battery should read 12.7 volts and one that is 80% charged reads 12.5 volts. Halve these values for your batteries. I assume you have checked the water levels in the batteries. If they are going dry you may be overcharging them with your home setup. Marine batteries will do better on a three stage charging system. For home storage a very small one will suffice.I would make sure they are all filled. Replace your home charger with a three stage unit and let them charge. Then take readings on them separately, and take any bad ones to the dealer for load testing. If it fails the load test try to get a warranty replacement or buy new if you have to. If only one battery is bad you can probably add a new one to the setup without harm. If they are all bad I would suspect the charger, especially if they are drying out.

 

[Nereussailor]

batteries

After buying a new battery charger for home use, I charged them again and found that after they sat for 24 hours, the multimeter read 6.48 on two batteries. The other two read 6.54 and 6.55 does this sound right? I replaced the battery in the multi meter and came up with the same. The specific gravity was around 1.15 in the first two, which would still make them dead, unless my hydrometer is screwed up too. The hydrometer isn't a quality one.

 

[Ross]

If you were measuring the voltage with an analog

meter instead of a digital you wouldn't read a difference.Try this ; connect a small load to each battery, say about one amp, and let it perc for 24 hours and read the voltage again. This would give you a 24 amp-hour draw and would be more diffinitive than just reading the open circuit voltage on a freshly charged battery.Edited for typo's

 

[Don]

hydrometer

check it my testing water - if it reads correctly, the hydrometer should be pretty accurate.