getting started off the grid

System

i hesitate for fear of sounding REALLY dumb but... First, i live in western Pa not noted for its bright sunny sky but do live in a field closest tree is about 600 yards in any direction and it does get breezy. i have been off the grid for about four years starting with a VERY elementary system i.e. a 600w xantrex running off the old ford ranger. it gave me lights, a small color tv, and my son's mandatory PS2. up graded a year later to two 6vdc 225ah "golf cart" batteries and a garage style charger run by a generator. then added a 1500w vector inverter. this system actually works great but i do run the gen set too much. time to up grade again, correct some mistakes, and have a realistic system with some umph! First problem was i had the system on the unheated back porch were the batteries got cold as well as the inverters which i gather neither like very much. the solution was to either heat the back porch or move everything inside, but i wasn't thrilled with the mess of flooded acid batteries, gassing etc. This led me to purchasing 6 12v 75ah AGM batteries and the ruination of my bank account. the plan (always a plan) is to use this battery bank to run the 1500w vector inverter and a 1000w xantrex (have) charging this via an airx 400 wind gen and 5 15w solar panels, and a TC 40 charger. Heat, cooking, and hot water is propane, at least for now, not bad in the summer, but the winters are a killer. this has led to several questions i can not seem to find an answer. 1. grounding--- directions always say ground the engine i aint got one handy to put in the kitchen, do i drive a grounding rod into the earth and ground the batteries and system to it? 2. the TC 40 has three charging outputs. Can i connect all three to the (same) battery bank (that doesn't seem right) or can a wire an interrupt switch and separate the bank into two banks of three batteries while charging (a lead to each bank) and switch back to all six when using the inverters? or even three banks of two and two switches? Would this decrease charging time and gasoline use needs? of course i decided to do this when the price or copper wire rivals gold krugerrands. By the way, recently purchased a LED bulb the replace the 60w incandescent not much light but only 3w and i don't step on the cat at night anymore.

crewzer

Re: getting started off the grid

1. grounding--- directions always say ground the engine i aint got one handy to put in the kitchen, do i drive a grounding rod into the earth and ground the batteries and system to it? 2. the TC 40 has three charging outputs. Can i connect all three to the (same) battery bank (that doesn't seem right) or can a wire an interrupt switch and separate the bank into two banks of three batteries while charging (a lead to each bank) and switch back to all six when using the inverters? or even three banks of two and two switches? Would this decrease charging time and gasoline use needs?

Bibion,

I’ll defer to others on Q #1. You might try researching grounding articles by John Wiles. Here’s a link to an example: http://www.nmsu.edu/~tdi/pdf-resources/cc74.pdf

As a former owner of a TC 20+, I know a bit about the TC chargers. There are indeed three (+) output connections, but they’re all just diode-isolated outputs from the same internal charging circuit. So, you can take all 40 A from one output, or you can take a total of 40 A from any combination of the three outputs. Your TC 40 is actually a good match for your 12 V x 450 Ah battery bank, so I don’t see the potential for any benefit in separating the bank.

If you haven't already done so, one thing that will help your battery bank would be to connect the charger to the bank in a "diagonal" manner. For example, charger (+) might be connected to (+) on battery #1, and charger (-) to (-) on battery #6. In other words, don't connect the charger's (+) and (-) outputs (or the inverter's inputs either, for that matter) to the same battery. See the lower left 12 V battery wiring diagram in the following link for an example: http://www.solarseller.com/battery_bank_wiring_diagram.htm

“Load shifting” is one way to decrease charge time and reduce gasoline consumption. The idea is to minimize loads on the batteries when the charger is in “bulk” charge mode so that as much charge current as possible is sent to the batteries. This shortens the bulk charge cycle. Then, apply loads to the batteries when the charger is in constant-current “absorb” mode. This won’t further decrease charge time, but extra current available from the charger can be used to power the shifted loads, and the overall generator efficiency should improve. Absorb current to the batteries will continue to drop as the stage progresses, so you can incrementally add loads as long as you don’t try to pull more than 40 A out of the charger.

HTH,
Jim / crewzer

niel

Re: getting started off the grid

bibion,
i am a bit concerned of you possibly undercharging those batteries. you will need more power to properly charge those expensive agms be it a neighbor with grid power, a generator, or more solar/wind power. you mentioned an engine, but you did not say if this is from a generator or not that is to be grounded. i am not as familiar with that controller as crewzer is, but with the batteries exposed to temperature extremes, you do need a battery temp sensor. i too am in western pa near pittsburgh in a town called swissvale and i'm wondering if you are near me. if you are leary of posting specifics to all on the forum i understand, but you can also send personal messages through the forum. you can enter it by going on your user info at the top of the page and clicking where it says messages. it is also easy to click on my name and it brings up my profile where you could send me a message via email(disabled on mine) or pm by going to where it says current status and click onto the box regardless if i'm shown to be online or not.
amended here i see you mentioned having a generator that you have to run too much. the only solution is more pvs to lighten the need to run the genny.

crewzer

Re: getting started off the grid

The TC 20 and TC 40 are fairly sophisticated 120 VAC -> 12 VDC multi-stage chargers. They include user-selectable charge algorithms for flooded-cell, gel and AGM batteries, and there’s a manual EQ mode that only works when the charge is set for flooded-cell batteries. The units also feature temperature compensation: manual via a three-way selector (hot, warm or cold batteries) or automatic via an optional RTS. The manual temp comp selector is overridden when the RTS is plugged in. These units were originally designed for marine use, so their design includes an isolation transformer. Very nice units indeed.

More info: http://www.xantrex.com/web/id/462/docserve.asp

HTH,
Jim / crewzer