| Author |
Message |
jmaxwell (66.81.42.8)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 31, 2003 - 5:26 pm: | |
I'm contemplating my house bank and would appreciate some insight into the often mentioned avoidance of parallel strings. Whichever way I go, 6 or 12volt, I am going to end up with a series/parallel array to achieve the 24v bank. What is the problem with parallel strings and does it matter when a series/parallel array is necessary? Also, does anyone other than Surrette make AGM's that equal the reserve capacities of the better flooded cell deep cycles. All I have seen have inferior reserve AH ratings to the best flooded cells by Trojan and Johnson Control. |
DonTX/KS (66.82.9.40)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 31, 2003 - 6:24 pm: | |
Well, not often mentioned, but I vote for the least amount of batteries possible. I started with the big Trojans, ruined a set of them, then to some 12v ones.
If I had it to do over again, I think a large 24v battery would be my choice (in a 24v system of course). When the batteries crap out one ate a time you are faced with a mix of new and old, or all new ones. Food for thought. |
Tom Caffrey (Pvcces) (65.74.64.127)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 31, 2003 - 8:16 pm: | |
One of the reasons for avoiding parallel batteries was the possibility that one dead cell could bring down the whole bank.
That hazard exists mostly for starting batteries, because the separators are so much better in deep cycle batteries.
We have found that we can run a mix of hybrid and deep cycle batteries without difficulty if we separate them whenever the system sets idle for any time.
For overnight use, the hybrids have a slightly higher voltage and will discharge before the deep cycle batteries if given a chance. To prevent that, say in cold weather, we shut off the disconnect switch that separates the banks.
For us, the biggest single thing that has helped was installing the Link 2000 monitor. It gives us an easy to use gauge of each bank in percent of full charge.
As conditions change, we do not get surprised by undercharging or overcharging of either bank. I don't know how we could manage as well as we do without the Link.
I hope this helps.
Tom Caffrey PD4106-2576
Suncatcher |
FAST FRED (65.154.176.150)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, January 01, 2004 - 5:31 am: | |
You may find the system works fine but could be helped (longer life) by changine the position of the batts within the strings every 6 months or so.
A back issue of Home Power has discussions/ drawings on series / parallel setups for longest service life.
AS the system may frequently only be genset charged , (not solar or Power post charged )the set will only get back to 80% or 85% on most recharges , in the short time most folks will listen to the noise , or pay the fuel/maint bill.
That last 10 to 15% takes way too long!!
SO size the system to cycle between the 50% and 85% for your electrical needs.
This will require either a larger system , or more frequent recharges.
You will need at least a once a month full (100%) recharge AND an equalizing cycle to get good service life from the set.
AN E-meter or smart inverter with "Link" or similar is REQUIRED to operate any big bank like this. You must know percentage of charge at all times.
FAST FRED |
jmaxwell (66.81.208.183)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, January 01, 2004 - 3:07 pm: | |
Thnks for the answers. I now see 'the problem' w/the parallel strings, but it is still something I can't avoid, given my need for higher capacity at 24v. So, I will try to address that with cabling connections that can be changed periodically, since I always seem to be servicing batteries anyway. I also am planning separate connection points for the various charging systems (bus alternator, inverter, solar).
The 'system' will look somewhat like this: 2 8D flooded cells on the engine, probably 8 Trojan SCS 225 deep cycles on the house, connected via a manual/automatic continuous duty solenoid of 450amp capacity for engine re-charging/house re-charging. I like the Lifeline AGM batteries but I can't do this arrangement and keep the 2 fairly new 8Ds on the engine.
From there, I have a 4 panel 500w solar array, a C-35 solar charger w/remote panel, a PS 2524 inverter w/SWRC remote panel, and a Vanner60 equalizer for my 12v take-off. Also, a 7kw diesel genset wired 110v, which I will use primarily when running the conv/micro or boosting the batts for night use when boondocking, which is seldom for more than a few days at a time and
occasional use for a/c. The solar charging point is at the Vanner, cabled from there directly back to the house bank.
2 conditions given to me in exchange for "her blessings" to do another conversion were: 1. A larger electric fridge (fortunately she liked the 11.1 cu/ft GE) and 2. A widescreen monitor/tv for her 12-16 hours a day of viewing pleasure while parked. Fine, but, that 30 LCD consumes 220watt/hrs of juice along with the 30-35 whatever gizmo that is feeding it a picture. I suppose I could lock her in the bdrm, where she could watch the same thing on the 18" lcd that only eats 55watts, but that probably ain't going to happen.
Fortunately, most of the time I'm plugged into the local utility (and always when "parked at home"), so the Trace takes care of it. My concern is for should I decide to do more boondocking for longer periods, am I going to be set-up to do it without running the genset to excess? I don't mind it for 1-2 hrs. every other day or so and the intermittent use for cooking, but after dark and all day long seems to trip my trigger. So, beyond this, any suggestions for improvement? |
Craig S (68.156.254.32)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, January 01, 2004 - 7:05 pm: | |
In regards to the solar panels, a plan that handles the refer(16-24 AH) plus TV(24-30AH in your case)plus incidentals(5 AH) asks from a system 52 AH daily at 120VAC. For a 24VDC system with a SW4024, for example, the current draw would be about 260 AH at 24VDC. To charge from the sun at an estimated 5 hours of useable energy per day, you need 52 amps of solar cells. A matching charge controller would be needed. This equates to about 1200 watts of solar cells. On a finite roof area, the per panel wattage would be bout 8 150 watt panels. The battery bank should be about twice the daily need or about 520 AH for one day of use with sun. If the sun shines every day this will work. Usually a couple or three days of autonomy(battery backup without sun)is diserable. The numbers really work against a bus converaion due to the limited panel space. Don't stray too far from the pole. There are bus conversions using solar panels quite satisfactorily. The daily AH useage must be kept down though. Your mileage may vary.
Craig S. |
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