Golf Car BATTERIES at SAMS?

Re: Golf Car BATTERIES at SAMS?

mshen11 wrote: »

so wait... you are saying we can mix... but just dont go below 20%?

Actually Bill is saying there will be a mix - even when you start with brand new batteries. It is impossible to manufacture a battery so that every cell is absolutely identical and will remain so throughout the life of the battery. It is even more impossible that any two cells from two different batteries will be identical, regardless of date of manufacture or how good the quality control is. To start with, these variances are inconsequential. The older the batteries get, the more/deeper they're cycled, the greater the differences become. As this happens the effect of one "weak" cell has on the others increases. As Bill mentioned, the worst case scenario is actual reversal of polarity of one cell - which will ruin the rest of them in short order.

Re: Golf Car BATTERIES at SAMS?

mshen11 wrote: »

ah thanks. another point i dont understand is how/why will a dead cell reverse polarity. what exactly does that mean?

Electro-chemical magic!:p

Basic battery chemistry: one plate is made of a metal with a (+) charge, one with a (-) charge (electron balance of the metal). Stick 'em in acid, connect a circuit between 'em, the electrons start to flow from one to another. Push current 'backwards' across the plates and the electrons go back to where they were (recharged).

When you do this in the real world, the chemical nature of the plates changes. In a FLA battery the acid is sulfuric, which is why when you re-charge and boil off the water component (hydrogen and oxygen) you're left with sulphur which bonds to the plates - "sulphation". This is also why the plates (lead/antimony) break down over time (or sometimes suddenly with catastrophic results). The positive plates are usually the first to go, because they attract the oxygen molecules - leading to oxidization of the metal.

If you discharge a battery too much, too many electrons flow across and the make-up of the plate changes from metal having a (+) charge to having a (-) one (and vice versa).

Fun, eh?

Re: Golf Car BATTERIES at SAMS?

mshen11 wrote: »

thanks for the laymen description... everything makes sense except the last paragraph.

isn't it like a magnet - sure the polarity changes but why cant you change it back?

Theoretically you can. But it's like trying to change rust back into steel. Simply applying voltage won't do it. Remember batteries actual produce voltage as a result of the chemical reaction; they don't store it. Applying voltage back to the battery will reverse some of the process, but not all of it.

This is the same problem as a heavily sulphated battery refusing to release the bonded sulphur even though you crank the voltage to it. There are battery desulphators which claim to work by applying pulses to the plates to knock the sulphur off, but they have their detractors as well as proponents.

Eventually all batteries fail because the chemical reactions inside are only reversible to a certain degree. Each 'cycle' of a deep cycle technically takes the battery's capacity down a bit, and every time it's recharged it does not come back to 100%. This loss is miniscule until you add it up over several thousand cycles.

Trying to explain this in terms anyone can understand - and it's getting a bit wonky.:p

Re: Golf Car BATTERIES at SAMS?

bobdog wrote: »

Apparently Sam's buys batteries from various manufacturers close to their distribution centers and then re-labels them. At least I've read that on this list before. Mine aren't Eveready, but something else.

Edit: Mine are Interstate re-branded

Mine are Interstate not re-branded, and one of them failed in the first year (collapsed plate). This is the first time I've had a catastrophic battery failure ever. Doesn't give you confidence. But the point is, when you buy a "house" brand you have to do a bit of digging to find out who really made them. Besides that, they are not necessarily made to the same standards as one with the manufacturer's name on it (this happens a lot in industry).

For the money and as TRAINERS I think you can't beat 'em. If I mess up, I'm out $65. If I buy a Trojan right off the bat, and then mess up? I'm out a lot more.

True enough, provided you understand going in that there is a possibly greater potential for premature failure. If you buy cheap batteries and they last and last and last ... smile and know you're lucky!

As far as marine vs GC...some might say it's a tough choice, but for someone who actually OWNS a boat and has used them, they are not IMHO useful for RE systems. Just my 2 cents.

100% agreement there!

Re: Golf Car BATTERIES at SAMS?

mshen11 wrote: »

a few battery questions now that i have real batteries!

* if the plate collapses, would that be reflected right away in the specific gravity or voltage (which one)?

The first thing you'd probably notice is a voltage drop: two plates touching eliminates their ability to produce electricity (shorted). Even this may take a while to show up.

* i took a look at the inside of the battery (peering through the energizer watering hole)... the plates looked warped/crooked/ridged. is that normal? i am guessing it is because all my batteries looked like that. what does a collapse plate look like?

This is normal: the ridges add strength to the plate structure. Lead/lead oxide is pretty soft stuff, even when 'reinforced' with antimony or other substances. You won't actually be able to see a collapsed plate or sulphation through the fill hole.

* i recharged all night until float... after waiting 5-10 mins the water inside was still bubbling a little - looked like mosiquitoes in the pond. thats normal right?

Yes. The Bulk & Absorb cycles will cause quite a bit of 'bubbling' - that's actually the electrolytic process converting water to hydrogen & oxygen (the bubbles). Float voltage doesn't do this as much, but some bubbling may still occur - it takes a while for the process to "slow down".

* how much water do i add into the battery (specifically tghe sams club battery). no instructions or labels or markers telling me where to stop watering

Usually it's to the bottom of the fill tube. That's hard to explain in words, but look at the level when you first get the batteries - it should be about there. Under the caps there's a bit of plastic tube that's part of the top of the battery. It will probably have slits in the sides. The water should come up to the bottom of this tube. Another way of looking at it is "enough to cover the plates (roughly) + 1/8". Do not over-water; it dilutes the acid and reduces capacity.

* the specific gravity (temp adjsted) after float [10mins wait] with no equalization on 9/09 batteries were ~1290 is that normal? or did i do something wrong? also the spec gravity varied between batteries - varies up to 0004. is that normal?

The important thing with new batteries is to charge & equalize to begin with. Let them rest (it's hard to get a good SG reading while bubbles are still forming) for about 3 hours, then read. Take that as your base number: the thing to compare all future readings to. The truth is, SG varies from battery to battery and location to location, to say nothing of the difficulty of reading a hydrometer down to 0.004. Up here all my SG readings are 0.050 low due to altitude.

* also battery temperatures varied by quite a few degrees celcius
* during equalization... is it normal to have this musty smell in the air?

Don't sweat the small stuff. A few degrees Celsius measured how? And how many is "a few"? Variations in batteries are always present. The "musty smell" is probably you breathing in hydrogen sulphide gas, which is present in small quantities above batteries of this type.

btw i my setup is 2/0 - one set of battery is 3ft... 3 sets of battery at 4ft to the buss bar; 2 interconnects are 6awg; 2 are 2/0 - all 1ft. thats not recommended but it doesnt hurt anything right? during charging max amp through any of the wires were 20A which is much lower than the max current the wires supports
i ran out of wires/budget.

A foot of even 2/0 is going to make a difference in the resistance to that set of batteries. That set (on the shorter wires) will be doing most of the work. The interconnect wires should be as short as possible (no sense adding resistance, even tiny amounts). The 6 AWG will again cause unbalance problems eventually. We are talking very small amounts of resistance here, but the effect will accumulate over time. The most important thing is to keep the wires equal size/length so that the current flow in and out and through each battery is as close to equal as possible. I'd say your biggest wiring problem is the use of 6 AWG, followed by the one set with the leads being 1 foot shorter.

We all run out of budget. Otherwise I'd have 8 more panels on my roof and wouldn't be running the generator right now!