| Author | Message | ||
| bruce knee (Bruceknee)
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Because this in my first coach, I'm not sure of my needs or how it will be used. I have a 24v. charging sys. I am going to use an sw4024, and my thoughts are 12 100 AH, 12v. Deka gel batteries. I have a rack that will hold 6 batteries on each level. The easiest way to plumb the batteries is parallel each level and series them at the end. Is the better way to series them into 24v. pairs and parallel the 3 pairs? Then tie them together at the end? Somewhere I think that I read pos cable from one end of the string and neg. from the other end. Will this size bank be an adequate size? I know that is a hard question to answer, not knowing my needs. I have supplied as much info. as I have, not knowing what my needs are yet. I will be using a house type frig, typical lighting through out, and basement airs. Also there is a 15k gen. in there somewhere. Is ther a chart of what uses how much? Thanks, Bruce | ||
| mel Rating: N/A |
It'd be fewer interconnect cables if you arrange it as 6 pairs of 2; also avoids the high amperage single point tie between the low and high halves. Too many batteries, though. Ideally, you want only a single string, so think about getting 12 nice massive Rolls / Surrette cells instead. | ||
| Richard Bowyer (Drivingmisslazy)
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As I recall, maybe you got these for free, so that is ideal! Richard | ||
| Jerry Liebler (Jerry_liebler)
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Bruce, In order to make certain that all the batteries share the load and charge equally, you should first, connect them in pairs, making 6 24 volt batteries, then tie the pairs together. In doing this your goal is that the length of wire that curent travels through is the same for each pair. One way of doing this would be to have all 6 pairs join at a large pair of terminals and use the same length wire from each pair to the terminals. Another would be to use equal length wires to terminals joining the 3 pairs, on each level and jumpers between the levels, then taking the load connection from one of the terminals on each level(for example + on the top and - on the bottom). Regards Jerry 4107 1120 | ||
| Sean Welsh (Sean)
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Bruce, My good friend Jerry (and Mel) has some good advice, but I think there is another factor you may need to consider. While they are quite correct that an ideal charging/discharging pattern is achieved through parrallel connection of serial strings (in other words, pair the batteries into 24-volt units and then tie those together in parallel), that assumes that you are using a straight 24-volt system. By which I mean that all your charging sources and all your loads are 24 volts. It is very common on bus conversions to have some number of 12-volt loads as well. While there are a number of ways to handle the 12-volt loads, some of which would not impact Jerry's advice, one possible (and common) way to drive 12-volt loads from a 24-volt system is to connect them to the center tap of the batteries, and use a battery equalizer (a special, dedicated type of 24-volt-to-12-volt converter) to "repay" the lower half from the upper half over time. IF you chose to design your 12-volt system this way, you are then better off making two parallel 12-volt banks and connecting those in series to make a 24-volt system. This lets the 12-volt loads draw equally from the entire lower half of the bank, and the equalizer to work on the entire bank as well. As I said, there are other ways to deal with 12-volt loads (for example, the same equalizer device can be used as a straight 24-to-12 converter to drive them, though this limits the total 12-volt load to the rated capacity of the equalizer) that avoid this issue -- you just need to know which way you are going to go before you lay out your battery bank and its cabling. Everything that Jerry said about wire lengths still applies, and you will want to ensure that you tap + and - from opposite ends of *each* 12-volt bank. (It doesn't matter which end of the inter-bank jumper you use for your 12-volt tap, but both the equalizer and the loads should be connected at the same point. And, yes, the inter-bank tie needs to be the same ampacity as the 24-volt positive and negative main cables.) -Sean http://OurOdyssey.US | ||
| Gary Stadler (Boogiethecat)
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An interesting way to handle 12 and 24 volt systems running with common bateries and without using equalizers is to put two 12 volt battery banks in series... one bank's (-) gets grounded and the normal bus's alternator (12 volt) hooks to that bank's (+) .. so far so good, a normal 12 volt system... Now you take bank 2 and hook it's (-) to the (+) of bank one, and the (+) of bank 2 becomes your 24 volt supply. Again normal... Now the somewhat unorthodox part... hook a second alternator up that is TOTALLY insulated from the bus frame (this is usually done using nylon bushings and washers in the alternator mounts) A 1-wire alternator is preferred for simplicity. Hook the frame, aka (-) of alternator #2 to the center tap of the battery banks and it's (+) to (+24) Now as you use current from bank 1, alternator 1 takes care of that bank. Thuswise alternator #2 takes care of bank #2. You can also wire two separate charger/converters up with the same scheme to your system, and now you have a 12/24 volt system that always has happy batteries no matter what the 12 or 24 volt load. I've done this in 2-3 hybrid vehicles and it works just fine.... hope my explanation is clearer than mud....  | ||
| Donald Lee Schwanke (Dontx)
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I got almost thru the first paragraph - then my brain turned to mud! Anybody follow it further than that? | ||
| Jerry Liebler (Jerry_liebler)
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Gary's clever method breaks down if you park for a little too long and run mostly 12 volt stuff while parked. It also will cycle the grounded 12 volt batteries more deeply and thereby cause them to fail earlier than the uppers. The best way is use an equalizer which will make the energy stored in all the batteries availabe to the 12 volt loads and keep the charge and discharge cycles the same for all the batteries. Regards Jerry 4107 1120 | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
Actually Jerry, if you size the batteries correctly my system will not "break down". The trick is keeping the batteries all charged properly, and having enough battery capacity for your anticipated loads between charges, and my method will do just fine. It's not conjecture at this point, I've done it, and more than once. Even if the two banks become unevenly discharged, as long as you don't let one of them discharge too deep (meaning you've sized them improperly) you won't have anything but a positive experience. I've proven this out with two systems now, one is a 36 volt motor drive with taps at 12 volts for massive lighting and stereo stuff and 24 volts for some pumps and compressors, and three alternators- one for each 12 volt battery section. The other system is quite similar. They both work perfectly and trouble free. I'm not saying this is a better approach to a system using equalizers, instead I'm just presenting a different option that does work, and it works well & trouble free. G | ||
| FAST FRED Rating: N/A |
Any and all of the "problems" with the system described can be banished for $150 with a good battery monitor , with an alarm feature. The problems would come from overdischarging , with a monitor , this need NOT be any problem at all. FAST FRED | ||
| motorcoach1 Rating: N/A |
heres an idea to clean up all that battery wire. back years ago we had an 83 ft fish boat with lots of batterys. I desigend a system like i saw at the telephone company switching buildings. the taps were 1/2 inch brass bars that the batterys were connected to so i did the same , these bars were bolted to the wall with insulators, I put mine in plastic EMT and secured them inside with plastic insulators and foamed the ends on. The reason for this was i didn't want someone dropping tools or falling on the hot bar. I drilled holes at right angles to put the batty lead up to the bar and one in the side to connect the 5/6 allen head SS bolt, after that was done the cap pluged the hole. this was done on the 24 volt service and the 12 volt service. with the 4 banks of batterys we had 6 per bank the + side was routed to the service pannels and the bars were taped in the center and were charged this way. It really cleand up a lot of cable. food for thought as F Fred says do it your way. | ||
| FAST FRED Rating: N/A |
"1/2 inch brass bars that the batterys were connected " I would guess if you looked closer those were COPPER bus bars. Copper has far better conductivity, than brass or most anything else .Silver or Gold excluded FAST FRED | ||
| motorcoach1 Rating: N/A |
may have been fred i had brass avalible at the time | ||
| JR
Rating: N/A |
I've read all the above information and consider myself fortunate that my 12 volt interior light works?! But it does. Jerry, are you an engineer too? I know that Sean is, and Richard must be. Keep up the great information in any event! This information (and the brake thread) couldn't be extracted from an engineering program at UNCC...(our local knowledge center)..you guys are a wealth of information! JR | ||
| Gary Stadler (Boogiethecat)
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Ah Fast Fred, caught you!! (a rare treat ) Gold has relatively crappy conductivity, worse than silver or copper, very close to aluminum. The only reason it's used so much is because it doesn't corrode... but it makes a worse conductor than copper... Here's how it goes (roughly): Silver Copper Gold Aluminum etc Ref: http://www.eddy-current.com/condres.htm | ||
| R.C.Bishop
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Gary, not for sure, but I think you missed the drift (ahem).... RCB | ||
| Bryce Gaston (Busted_knuckle)
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Better than missing the BOAT! LOL | ||
| Gary Stadler (Boogiethecat)
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Slippery when wet, all wet... I know.... Truthfully though, I was shocked over my history as an electronic engineer, at how many other engineers thought that gold was the best conductor. Very few realized that it was worse than copper!! It always made me laugh in the 70s when I'd see a guy specify that a circuit board be completely gold plated... I always asked why and the answer was always "to make it lower resistance"... which was totally wrong, costly, and plain dumb. Oh well so it goes! Ahoy Fred..... geesh, we all learn on this great board!!!! | ||
| FAST FRED Rating: N/A |
Silver Copper Gold Are ALL still far better conductors than SS or plain iron, which I see used at times to bolt the ground cable to the coach chasis. All the visitors to the great NASA surplus store in Orlando "Skycraft surpluss"can purchase copper wire , with a silver coating at really cheap pricing.(Compared to what Uncle paid) Good for the folks that want "the BEST" , as its made up in bundles with loads of conductors , some large. The best copper wire comes from Anchor , its tinned (so corrosion resistant) and very fine multi strand for flexability, and about 10% over sized in each grade , to run cooler and have less V loss.Great terminal ends too. The Gold belongs on the end of your HI FI and TV cables , where its ability to not turn green and degrade the signal is usefull. FAST FRED | ||
| Doug Dickinson (Dougd470)
Rating: N/A |
In my planning stage for batteries but here is something to think about: I am going with 4 large 6V "golf cart" batteries in series to run my SW4024 inverter. This gives me enough power to carry over when I shut down the big engine driven alternator on the coach or the gen set. Actuall, it will run 2 Ac units for 20 minutes easy. In this regard, it is more like a UPS. I can and will still use it for various intermittant loads while boondocking. My 12V loads are handled by a separate 12V battery (actually 2 more golf carts in series) so that I have plenty of 12V power to run stuff like the fridge and the heat blower. Charging is from a 120V convertor. I may add a separate 12V alternator on the engine some day IF I think I need it. For now, it can charge from the inverter on the road via the 12V convertor. A little less efficient, but better in the long run since an Inverter will cause low voltage off one half of the string (a 12V tap) when pulling a biig load. I want and need a full 12.8 volts most of the time. One more reason for separate strings - if you run a "mega" string of like 6 strings of 2 batteries each, you get the theoretical benefit, but will encounter problems when batteries age since they age at different rates. A shorted cell could drag the string down also. Of course, if the batteries are free - the price is right... Doug St Louis MC9 |