12v Golf Cart Battery Question

[BFL13]

Sorry, don't have enough internet access at the moment to do a proper search, so I thought I'd ask here 🙂

Talking with a local guy today who seems to know his stuff. He gave me a tip that the local golf course has carts that use four 12v batteries for their 48v instead of six 8v batts.

He says these 12v batts are Trojans and they have about the same AH as a pair of 6s. If so, they must be about 150 lbs each!

Does anyone know of such a thing? The place that supplies them is near, so I will check it out next week. The real tip, is he said they often swap out batteries with the golf course and you can get two-year old ones of these for $60 each!!! Apparently the hippy off-grid solar types around here snap these up in large quantities.

If this is all true, I am thinking it would be fun to get one and do a desufation routine on it and so forth and it would be like having another pair of 6s for as long as it keeps going. ????

[mena661]

You're already pigging out on Ah so not sure what else you could do other than my previous suggestion. :B It almost seems that you can have too much battery AND solar in some situations. With our camping style, it works out to just one cycle per trip. Maybe you could shoot for that. Probably not possible given your space for batts. Maybe you can up your solar so you will charge up in a day or two.

If I were camping more than just 3-4 days, I'd still go for one cycle per trip even if I had to use solar to get there. The thing is if I have cloudy days then that throws off my cycle per trip goal. If I add more batts then I don't need solar.

[BFL13]

pianotuna wrote:
Hi BFL13,

Center tapping with the greatest capacity in the middle is a "second best" solution to equal length cables to a load buss bar. The outer batteries will degrade slightly faster.

Putting one twelve volt jar at each end would be my very last choice. They won't charge or load well at all, so I'm glad you can't do it.

Now that the two old 12s have proven out ok at about 250-260AH the pair, I am going with leaving them in the middle with centre tapping for convenience of wiring mostly.

But now I am worried I have too much battery. ISTR it was 2Oldman who reduced from six batts to four because he could never get six full in the daylight provided even with his large amount of solar.

If I go with six batts and even with shallow discharges, I can see how they would never get fully charged and be living somewhere underwater at neutral buoyancy at 90% or somesuch and sulphating.

In winter at 40F with no solar though, it might be possible to do a three day weekend and get home without doing a recharge until home with so many batts on line.

I am stewing about what to do for the next seven weeks here on "summer" routine. Leaning towards just having the 12s and leaving the 6s to sit fully charged with a shot of solar once in a while to keep them honest.

So, Peanut Gallery, what would be the way to go with this "embarrassment of batteries" I have somehow got myself into?

Thanks.

[BFL13]

Thanks, PT. Yes, while camping even on solar, I don't think I get to true full. So it doesn't matter if one gets to 97% and the other only to 95%

BTW, only a month and a couple weeks to go here and then solar goes back in the garage till next April, so I just sold the two 100w panels and my second 20amp controller to a guy here, and am now back to just the Sharp 130w on the swivel.

Last year that is all I had and it was plenty as long as it was mounted so I could move it around during the day. So now operating with the two mystery 12s and the 130w panel 🙂 Four 6s now having a holiday.

[pianotuna]

Hi BFL13,

No, the extra resistance (yes I know it is small) causes a slight voltage drop. So you have a choice of over charging the middle battery and getting the charge "just right" for the other two, or charging the middle battery "just right" and having the other two a smidgen under charged.

Does it matter? Perhaps not. Especially for a person such as yourself who separates the banks and fully charges when you get home after a trip.

I preferred to balance in the first place so that I would not have the issue to deal with. (but that is MY rubber ducky, LOL)

[BFL13]

I don't charge them separately while camping even when on solar, but only at home or when equalizing on solar when camping if I ever did that if needed. So the downstream batts would get less share of the daily charge whatever that is, but if we get to Float on solar early enough they would all get done before dark?

[pianotuna]

Hi BFL13,

Charging separately would keep the banks from degrading. I was not aware you did that.

[BFL13]

I don't understand why the outer batteries would degrade faster if they are getting the easier ride. I would still be bringing each pair to 100% separately whichever way I do it.

The pair of 12s right now has the highest capacity at est 243, with the Interstates at 232 and the Exides at 226.

( I don't know why the Exides don't like this routine I am on. Maybe they spend too much time at 14+ volts on solar. smk is always going on about too much time in the controller's absorption stage for storage. The controller is timed for two hours, but while camping and running high amp loads after dropping to Float, it keeps getting knocked back into Absorption for another two hours. The Interstate GC2 XHDs love it though)


The 12s are now wired up in the centre position, and my pos load wires won't reach farther out, so the easiest quick job is just link a pair of 6s on each side of the 12s.

Maybe work the heck out of these 12s and then toss them and go back to my four 6s like nothing ever happened?

So far, I can't tell the diff on the two 12s from the four 6s. They take inverter loads like the kettle at 90a no prob. eg. I will get them back up to "full" and then switch off solar and run them down to 50% est again and get another est capacity.

[Old___Slow]

BFL13


Some of us folks (me) are not up to speed with knowledge concerning the 'smart gauge' That one flue over my head. Is it possible to post a picture? If not, okay. The proper hook up is a problem with the mixing of batteries for RV use, or any use, me thinks.

Roy B ~ has posted some useful detail I printed, even then I get lost when he shows leads going to an Blue Sea 9001e (off-batt1-batt2-both) me thinks, one batt is good:)


EDIT: Just looked up the Blue Sea 9001e ~ If I ever I have two battery banks, this would be my way to go. Thanks to Roy B for the info' and posted diagram in another RV. Net thread. We are all family on the forum, right?

[pianotuna]

Hi BFL13,

Center tapping with the greatest capacity in the middle is a "second best" solution to equal length cables to a load buss bar. The outer batteries will degrade slightly faster.

Putting one twelve volt jar at each end would be my very last choice. They won't charge or load well at all, so I'm glad you can't do it.

[mena661]

Guess I can strike Exide from the list. That's such BS that they're bad already. Are they out of warranty? On topic! I'd put the good 6's in the middle and put the lesser batts on the outside. Such a great idea, glad I thought of it. And you're welcome!

[BFL13]

I agree with the three 12s in this case. Last time I had three 12s I just treated them as a pair, with loads on the outer ends. I think this gives the middle batt an easier ride?

So with one pair of 6s perhaps getting shaky (some black stuff in hydrometer if do four sucks a cell, but clear if only do one suck per cell---which is what I do now, so they look good--out of sight, out of mind) although seemingly at full capacity, and one pair in excellent shape,

I was thinking of putting the good pair of 6s in the middle with loads on that, with a pair of batts on either side as "downstream" so those two pairs on the outer ends get an easier ride and the good pair of 6s in the middle takes the weight.

I can't add one 12 to each end with the four 6s in the middle due to compartment sizes. Has to be either a pair of 6s or a pair of 12s in the middle of the three pairs.

[pianotuna]

Hi mena,

Thanks--I'd do it as in my original post then, treating the pair of t1275's as one large 12 volt source, and connecting the three large 12 volts a la #3 at smartgauge.

[mena661]

pianotuna wrote:
Hi,

If on the other hand the t1275 end up as 243 amp-hours each, then just wire as #3 as per the smart gauge site for four 12 volt jars.

T1275's are 150Ah each when new.

[pianotuna]

Hi,

If on the other hand the t1275 end up as 243 amp-hours each, then just wire as #3 as per the smart gauge site for four 12 volt jars.