My 6V House Batts

[Tom.B]

Hey Y'all,

While I work out the electrical charging system upgrade on Skinny Dippin', I found I needed to completely rebuild the battery tray. So I have pulled the house battery entire bank (running mostly on the charger and starter batt) and took the time to test and see if these 3 year-old Sam's Club 6V galf cart batteries even need replacing.

I pulled out the multi-tester:

Right off charge - 6.69V

After 24 hrs.***** - 6.36V

After a week***** - 6.31V

I was able to get my brand new hydrometer to test most of the cells before the cheap piece of crap broke on me.

All cells read in the close neighborhood of 1275 (or is that 12.75?)

I'm checking out Calder's book and if I am reading it right, after a week they are still at 100% charge. But his book is a lot more 12V oriented. I suppose I really need to get a 20A load tester, but I was just wondering if y'all can make heads-or-tails of this information?

Thanks!

Tom-


-- Edited by GonzoF1 on Friday 2nd of March 2012 09:15:01 PM

 

[Daddyo]

Going by voltage they sound good to me. I've been using the Sam's Club 6v for years and have never had a problem. Ten on our current boat to which I'm getting ready to add ten more where I pulled out one of the gensets. Eight on the last boat.

 

[BruceK]

Ed Sherman`s book says for a 12v battery, 12.6v up, on an open circuit test, is full charge; halve that. Specific gravity in a fully charged battery is 1.260-1.280. My recollection is wet lead/acids off charge drop 1% a day(sounds too much);yours do better. 3 out of 3 so far.

* Do you trickle solar charge them? Good result after 3 years. BruceK

 

[FF]

"My recollection is wet lead/acids off charge drop 1% a day(sounds too much)"

NEW good not abused batts in normal temperatures may loose 1% per day ,

end life or abused batts will loose closer to 3% or 4% per day , that's when most folks recycle them.

 

[timjet]

I'm going to add a engine start bank for my electrical system, see understanding my genset alternator thread below.

Is the reason you are using 6v instead of 12v because of the smaller size? If I use 6v I'll need 4 batteries or 2 12v batteries. Is one really better than the other?

And whatever batteries I go with can my battery charger differentiate between wet cell and AGM's. I currently have 4 AGM's for the house bank with the battery charger setup for AGM's?



-- Edited by timjet on Saturday 3rd of March 2012 07:00:02 AM


-- Edited by timjet on Saturday 3rd of March 2012 07:01:06 AM

 

[Tom.B]

TBH, I don't take care of them much at all. For their entire life they have been on an 80's era 30A Newmar charger 24/7 that really cooks them. I keep the water topped off, but literally... That's it and that's what is puzzling.

Tim... the reason I have 6V is because that's what came with the boat 2.5 years ago. ;-) But if I had to do it over, for the time being at least, I would do the same. The batteries sit on the port "table" and it would be a BEAR to get a 4D or 8D up there. Cost too. These batteries are only $80 each to replace and seem to last a while... apparently.

(Damn... woke up this morning with a headache. OUCH!)

Tom-

 

[Larry M]

Tom: To me the batteries sound OK, maybe showing there age but nothing I would worry about.* When you get ready to take off, then change them out.*

 

[Tom.B]

I do have a new charger that will be installed in the next few weeks. It's an Iota 55Amp that can float charge and equalize them regularly.

I suppose this is a great opportunity with these older batteries to really watch and learn about them as they age so I can identify the warning signs with the next set.

 

[Forkliftt]

TBH, I don't take care of them much at all. For their entire life they have been on an 80's era 30A Newmar charger 24/7 that really cooks them. I keep the water topped off, but literally... That's it and that's what is puzzling. :::itto here on an old Lewmar 50 amp. I am waiting on your Iota installation. I have saved a link to their site already. I keep the charger off till we get to the boat, then I always turn the blower on first at the panel, then the charger- to be sure the batteries are holding up.

 

[rwidman]

The open circuit voltage of a battery isn't going to assure you that they are OK. They can have a satisfactory open circuit voltage but not be able to supply the current they are rated for. You need to load test them. You can take them to any battery store and have them load tested or you can buy your own load tester.

 

[RT Firefly]

Greetings,
I got a swell load tester at Harbor Freight on sale for $22.

 

[Tom.B]

Like this?

http://www.amazon.com/Schumacher-BT-100-Battery-Load-Tester/dp/B000AMBOI0 (new tab)

This is a 50/100 Amp. Since amp/hours are based on 20A load, wouldn't make sense to have it test uner 20A conditions? Just askin'.

 

[RT Firefly]

Greetings,
Can't remember the load base but when applied, gives CCA or some such in the 100's range. It does test both 6v and 12v batteries. Looks VERY similar.

 

[rwidman]

RT Firefly wrote:
Greetings,
I got a swell load tester at Harbor Freight on sale for $22.

Yes, I got one too.

http://www.harborfreight.com/100-amp-6-volt-12-volt-battery-load-tester-90636.html

*


-- Edited by rwidman on Saturday 3rd of March 2012 06:13:13 PM

 

[Fighterpilot]

San's just pick up the Duracell line of batteries. Don't know if the 6volts are the same as before or not but I am going to give them a try. I believe the entire line up is made by Penn. Going to Parallel the 34s for start. Both types will fit in existing battery boxes.

 

[Tom.B]

I want to try the load test first. If they pass, I am just going to add two more 6V's to the collection and go with it for 660A/hrs for the season. May swap the starter for a lead-acid that I can add water to (current one is sealed) and it will be a 12V Series 31 size. I am having to rebuild the battery tray and have added quite a bit of space to it.

 

[Forkliftt]

Tom
Be sure to look into mixing old and new batteries. It may not be a problem if your current 6V s are in good condition- but the general rule I have always heard is that a new battery will drop to the voltage of the older battery, and this process repeats itself over and over if you have a defective battery till it goes dead. This may not apply to your case.

 

[Tom.B]

I bought a 130A load tester from O'Riley's Auto Parts and tested of of my batteries last week. all of the 6V GC batteries showed "Weak" and the specific gravity was borderline at 1250-ish, so I suppose they are NOT in as good a condition as I first thought. So, at some point in the NEAR future (and once I get some new connectors and battery monitor going), we are going to do a full "plugs-out" test at the dock and see what sort of results we get.Then, based on that, I suppose I will replace them with new when funding allows.

FWIW... Here is the new battery tray I finished last week. (just in case you missed it in the last thread :-D ) I can now hold 6 golf cart batteries and a group 31 starter battery)


tray by GonzoF1, on Flickr

 

[FF]

If I use 6v I'll need 4 batteries or 2 12v batteries. Is one really better than the other?

Usually the 6 v are much better at Deep Cycle use , a house bank.

The plates are thicker and there will be a space at the bottom of each cell for sloughed off lead.

There is frequently more space in the case with less insulation per cell at 1/2 the voltage.

LEAD is what makes the battset work , so usually the heaviest set is the best set.

Also many 6v golf carts can be had with "flag" terminals , rather than the round peg.

 

[timjet]

FF wrote:
Usually the 6 v are much better at Deep Cycle use , a house bank.

*So what would you recommend for engine start batteries. I know the thinner plates of a start battery supply more amps, but are more amps vs the longivity of a deep cycle battery better in a engine start application.

 

[JD]

timjet wrote:FF wrote:
Usually the 6 v are much better at Deep Cycle use , a house bank.

*So what would you recommend for engine start batteries. I know the thinner plates of a start battery supply more amps, but are more amps vs the longivity of a deep cycle battery better in a engine start application.

*Yep!

 

[FF]

The best is to use deep cycles for the house and starts for starting.

Almost no amps are used for most starting , and should someone crank too long , the starts will stop giving juice , as the plates get covered with bubbles. Wait 5-10 min and you can have another attempt or two. Good safety feature.

However I have been on boats with NO start batt set. BUT it was a sail boat with tiny 35hp engine and HUGE house set.

The voltage for starting depends on plate surface area , where starts excel, but with close to 1/4 ton of house batts , the surface area of the deep cycle batts was enough.

Always best to use a hammer on a nail , rather than the hydrometer!

Starts to start , 6v golf carts for the house, DONE.

 

[timjet]

Thanks guys for clarify this.