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#21
posted to rec.boats.cruising
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Golf Cart batteries / What I have learned
Jim wrote:
chuck wrote: Jim wrote: A day of learning: Two 6 volt, 220 amp batteries joined to make one 12 volt battery has 220 amps. Even though the guy at the battery store told me otherwise. My old 8Ds had a rating of 215 amps. 220/215, not much gain there. The cost of the 6 volt batteries is about 1/2 the cost of an 8D. A little more or a little less. $65 + $65 = $130. 8D, $140. Not much gain there. What this means is that there is little gained, initially, by going with the golf cart batteries. Since I have to buy battery boxes, it will cost me more. The golf cart batteries SHOULD be good for many more deep discharges than the 8D. The golf cart batteries are easier to move around, and have a smaller foot print. The battery boxes have more options for dimensions. I'm buying the golf cart batteries from a battery store. A few dollars higher than Costco. Five dollars each battery. I get the cables free from the battery store, so it's actually cheaper than Costco. I'm upgrading my charger to a Xantrex "True Charge" 40 amp, 3 stage charger. The "Equalizer" function is important to maintain the batteries. The old battery boiler charger is going in the trash. Just curious. How many years did you get from your old 8Ds and your old charger? How many more years do you expect to get from the golf carts and a new charger? Chuck Chuck; The old batteries were purchased exactly three years ago. Hard to believe that it has been three years . . . One cell is bad in one battery because the electrolyte boiled off and left the cell dry. While the other battery checks out ok, I'm not going to take it out so I can replace the battery behind it, then put it back. If I had replaced my old charger with a new one three years ago I may not have that dead cell. Of course, if I had watched the water level closer I may not be replacing it either. I do check the water level, but obviously not as well as I should have. How long do I expect the new setup to last? I have heard from a knowledgeable fellow that his have been in constant use for 7 years, and are still going strong. And he's been all over the South Pacific in the last 7 years. He's the guy who's recommendations I'm going to follow. Thanks for the info, Jim. I'd say you're getting good advice. Good luck! Chuck |
#22
posted to rec.boats.cruising
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Golf Cart batteries / What I have learned
Larry wrote:
Jim wrote in news:ANErg.4757$ye3.3213 @newsread1.news.pas.earthlink.net: The old battery boiler charger is going in the trash. Darn....Where do you live? I might try to get it! The 40A heavy duty charger in my stepvan that charges the house batteries from my Honda 3KW inverter-genset is the original OEM charger from my friend's Amel Sharki French ketch. It's one of the finest battery chargers I ever had, but you must regulate it manually through its 3 steps...low, medium and bigtime... (c; That old charger is a great battery charger IF you take the time to TIME its charging. It's just a rotten float charger for a boat..... The one under my desk rarely drops off past 20A, charging the 1930's vintage Edison Nickel-Iron-Potassium Hydroxide telephone cells under the house. That's the "house house batteries" here in hurricane country. POWER is REALLY our friend when the powerlines all lay in the street! The old charger is a "Professional Mariner" Newpro 20 (20 amp, three battery bank, hard wired charger). I believe the used boat parts places are full of them. They are old technology. Where are you located? You can have it if you wish. Probably would cost $10 or so to ship it UPS. You'll have to wait until I pull it out in a couple of weeks. I ordered my new charger on line last night. I'm not doing anything until the new charger arrives. |
#23
posted to rec.boats.cruising
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Golf Cart batteries / What I have learned
Jim wrote in news:zpHrg.1717$vO.610
@newsread4.news.pas.earthlink.net: He said two 6v 220 amp batteries will give 12v, 440 amps. Nope....nice dream, though. Two 6V 220 AH in series gives you 12V at 220AH, not 440 AH. It's still only 220AH, just the voltage doubled. The plates didn't get any bigger in the cells when you connected them in series. You can get 440AH at 6V by parallelling them....doubling the plate area.... |
#24
posted to rec.boats.cruising
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Golf Cart batteries / What I have learned
Jim wrote in news:qSQrg.4991$ye3.308
@newsread1.news.pas.earthlink.net: Where are you located? You can have it if you wish. Probably would cost $10 or so to ship it UPS. You'll have to wait until I pull it out in a couple of weeks. I ordered my new charger on line last night. I'm not doing anything until the new charger arrives. I was just trying to get you to save it for other purposes. I can't help it. I'm a packrat. There's somewhere around 8 chargers, even a couple that do 36 and 48VDC, around here.......er, ah.....somewhere.... I'm for saving the old charger for the dead car battery or the lawn tractor. But, if you must toss it, give it to someone on the dock. Set it out on the dock with a sign that simply says "FREE CHARGER that works". I bet it won't last a Saturday morning. Saves you haulin' it home. A great place is right under the marina bulletin board or the entrance to the Men's head....(c; Don't tell 'em whos it is or they'll be buggin' you to hook it up.... |
#25
posted to rec.boats.cruising
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Golf Cart batteries / What I have learned
Sorry Larry, you have some misinformation here. First of all, a pair
of Trojan T105's will happily accept 40-50 Amps for an extended period. I have 4 of them, and on a daily basis (when cruising) charge them with a 110 Amp alternator. The charge rate starts at about 104 Amps, and slowly goes down. After about an hour it might be down to 65-70 Amps, which is where I'll usually stop. My 100 Amp charger also hold the charge rate fairly high. Secondly, although I don't often discharge at 50 Amps for an extended period, most of my battery use is powering a DC fridge which draws 28 to 36 Amps. There is no evidence that this significantly reduces the capacity of my bank. I normally discharge to about 50% (down 200-210 Amp-hours) and at that point the bank is still holding about 12 Volts under load. This affect is described empirically by Peukert's Equation. For each battery design there is an exponent that allows you to predict a battery's performance as you vary the load. Using 1.24 as a typical "good" exponent means that 4 times the load drains the battery 5.6 times faster, implying an increase drain of a bit over a third. Looking at the specs from Trojan: http://www.trojan-battery.com/Produc...spx?Name=T-105 and Penn: http://www.eastpenn-deka.com/products/pdfs/0248.pdf it looks like they do about that. You would have to have a very high discharge rate - close to 200 Amps - to reduce to capacity by half. If you were actually interested in a battery for a high output application, such as an electric car, you might look for one with an exponent down around 1.1. Its possible that my regime of high discharge and fast charging has reduced the life of my batteries. But my first set lasted 7 years and and may have gone a few more if illness had not interrupted their proper care one winter. However, since a few phone calls turned up a golf cart dealer that could supply them at $70 each, the cost was only $40 per year. I have noticed that my new batteries perform better than the old, but at 7 years the old set was probably only down 10-15%. Larry wrote: Jim wrote in ink.net: I'm upgrading my charger to a Xantrex "True Charge" 40 amp, 3 stage charger. The "Equalizer" function is important to maintain the batteries. The batteries only need 20A, so that leaves you with 20A of load current while the charger is on. The battery store guy should know better. 220 ampere-hours has nothing to do with 220 amps. Ampere-Hour is a measure of the stored energy in the battery. The "rating" only holds true for ONE load, the load that drains it in 20 hours (that's about standard in the battery biz). 11 amps will drain it in 20 hours, so that would be the "standard load" for this battery. The slower you discharge it, the more ampere-hours of energy it will produce, way beyond its rating. The FASTER you discharge it, more than 11 amps, the LESS its ampere-hour capacity is at that load. This is caused by chemistry and physics. The chemistry is the speed at which the acid can eat away at the soft lead plate's surface area. Quickly discharging it with a heavy load, the acid by the plate is quickly consumed into lead sulphate ions in suspension, blocking more acid from attacking the plate surface. So, it's not some incredible limit. Starting batteries overcome this problem with an incredible number of plates producing an incredible surface area that can produce an incredible instantaneous current.....but for a price. To keep the physical battery size, the plates have to be very thin. Their amp-hour rating is actually very low, as anyone who has been cranking a dead motor for a few minutes when the lights go out can attest. Deep discharge batteries use thick plates with lots of lead to eat and much more acid to eat them....at a slower rate, 20 hours standard. At 50A, and I'm only guessing as I don't have a chart in front of me but you can find them on the net, the AH rating of the 220 AH battery is probably about half, maybe a little more. Well, you get the picture. It's not a bottomless pit of power, actually kind of small for its weight. Nice charger, but you'll only see 40A charging them for a few minutes before the charge quickly tapers off to a safe charging level below 20A. If you never discharge them below specific gravity of 1.125, they'll last a long time. |
#26
posted to rec.boats.cruising
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Golf Cart batteries / What I have learned
One other thing, golf cart batteries IIRC are designed to be discharged
a bit more deeply than are regular deep cycle batteries. Running a golf cart around a course all day is pretty taxing work for a battery. You'll probably get far more usable power out of the golf cart batteries than you did out of the 8D. And if you have a cell fail, as you did in the 8D, you won't have to spend as much to replace it. I do generally recommend that the batteries in a bank be the same age and make, but if you kill a cell, swapping in a newer battery of the same make is often doable. |
#27
posted to rec.boats.cruising
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Golf Cart batteries
On Fri, 07 Jul 2006 21:50:35 -0400, Larry wrote:
Does it say 20 Amps or 20 hour rate?? 20 hours would be 11 amps, right? Yes, I've probably got the numbers for my 4 batt bank in the back of my mind. |
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