Remote area off grid battery charging station.

**Wy_White_Wolf** · 02-27-2017, 10:30 AM

With MPPT controllers this would not work. They would all fight each other pulling the array voltage down trying to maximize power to themselves and not to other controllers.

PWM it could possibly work but I see the least charged battery as pulling the majority if not all the power from the array. So each CC would have to be large enough to handle all the power of the array. That would be more costly than smaller CC on separate arrays. Also charge controllers need to sense battery voltage first your switches would have to be between the array and CC. I also see problems should someone disconnect the battery without turning the switch off first.

Connecting and disconnecting batteries all the time just leads to too much of a chance for a spark around other charging batteries. I would never be comfortable with a system set up like that.

WWW

**LETitROLL** · 02-27-2017, 10:56 AM

Originally posted by Drew_NL

We have a sporting clay range that uses 12 volt batteries for the clay target throwers. During the winter they are used once a week then they will be left on the controller for the rest of the week. They are a variety of types, amp hours etc. but should sit in the 75 to 100 amp hour range deep cycle. Not sure if there are any AGM but probably will be in the future. During the summer they may be used a couple of times a week but of course the days will be longer with more charging time.

We do not need to make them into one battery bank and there will be no load on them while sitting and charging.

A cheap 25 watt panel keeps a battery topped up on the busiest machine with no problems.

Rather than putting multiple batteries on one controller and having all the issues that go along with that, is there any reason not to put multiple controllers on a larger panel or set of panels with one battery on each controller. The plan would be to connect say 4 on/off switches in parallel to the panel (or multiple panels in series/parallel ?), and run one controller off each switch. This would allow the controllers to be switched off when not in use, then a battery could be connected and the controller switched on.

Any thoughts on the best configuration of charging multiple 12v batteries in different states of discharge, with different specs for the batteries.

Unless i am missing something, it looks like a couple of different normal options would work fine for you, no sense trying to do anything fancy if your busiest machine stays charged fine with a 25 watt panel. One large properly sized panel to 2 6v deep cycle golf cart type batteries (calc exact loads to be sure), would probably be fine, then just have all the loads hooked to that simple battery pack with whatever switches on the machines if you want to control them separate.Otherwise just go independent 25 watt panels each to its own battery, PWM controllers are not that expensive and it doesnt sound like you would need much for batteries that way either, and just have 2 or 4 stand alone mini systems.

**Drew_NL** · 02-27-2017, 05:41 PM

We have to charge multiple batteries. Unplugging and plugging in a regular charger is common enough. We will have to put signs up and limit the people at the charging station, but the simple answer is we need to charge 6 to 12 batteries at a site with no electricity. The batteries are then carried around to the remote launchers, used for the day and then returned to the shed where they are put back to be charged. As far as sparks, that is a good thought, I missed it in my first reply. They will be sitting by an open garage door when connected and disconnected, they will also be low to the floor in decently vented shed. Evryone with a key will be taught about why the switches must be turned off before adding or removing batteries. For future use though I'll recommend non-gassing AGM as a way to clean that area up a bit, probably look at a wind driven vent as well.

PWM is planned. I don't mind the least charged battery pulling the biggest load since they will have a week to charge in most cases and we probably only drop them down to 80% from 100% each time they are used, the load should balance itself over a day or two.

Originally posted by Wy_White_Wolf

With MPPT controllers this would not work. They would all fight each other pulling the array voltage down trying to maximize power to themselves and not to other controllers.

PWM it could possibly work but I see the least charged battery as pulling the majority if not all the power from the array. So each CC would have to be large enough to handle all the power of the array. That would be more costly than smaller CC on separate arrays. Also charge controllers need to sense battery voltage first your switches would have to be between the array and CC. I also see problems should someone disconnect the battery without turning the switch off first.

Connecting and disconnecting batteries all the time just leads to too much of a chance for a spark around other charging batteries. I would never be comfortable with a system set up like that.

WWW

**Switchback** · 02-27-2017, 05:45 PM

We did something like this at a friends place. He has 2 throwers. The throwers don't see a lot of use so a 120 watt panel and a standard deep cycle battery (70-90ah I can't remember) worked fine for us.

We we had 2 switches between the battery and throwers. Turn on which ever thrower we use, switch them off when we were done. Much easier and safer than having multiple batteries and CC to switch on and off.

Id check how much energy the throwers use, once you have that you can figure out what size battery/panels you need. A big thing to consider with the 1 panel and battery bank system is the voltage drop you will get running dc voltage long distances. Setup the system as close to the throwers as you can

**Drew_NL** · 02-27-2017, 05:52 PM

Yes, you are missing something, There are 6-12 batteries (12 volt) that will be left on charge in the shed. Each week they will be unhooked and carried to the remote launchers where they are used for the day. The sporting clay launchers that are used are spread out over multiple acres and their locations change multiple times in a day. They have to be 12 volt and the locations will vary and have to be unhooked and spread around.

It simply costs allot less to have two 100 watt panels than eight 25 watt panels. It's also much more convenient only having to deal with two panels on the roof rather than eight. Although if the cost was similar 25 watt panels would be considered.

Originally posted by LETitROLL

Unless i am missing something, it looks like a couple of different normal options would work fine for you, no sense trying to do anything fancy if your busiest machine stays charged fine with a 25 watt panel. One large properly sized panel to 2 6v deep cycle golf cart type batteries (calc exact loads to be sure), would probably be fine, then just have all the loads hooked to that simple battery pack with whatever switches on the machines if you want to control them separate.Otherwise just go independent 25 watt panels each to its own battery, PWM controllers are not that expensive and it doesnt sound like you would need much for batteries that way either, and just have 2 or 4 stand alone mini systems.

**littleharbor** · 02-27-2017, 06:08 PM

How about a 48 volt charging setup. You will charge 4 series wired 12 volt batteries at once and since you are moving the batteries every time you use them any way It wouldn't matter what voltage you charge them at. The one issue I see is the batteries are disimilarly discharged. I'm not sure if there is a workaround for this. If the batteries are fairly evenly discharged each shooting session they may be close enough.

**Drew_NL** · 02-27-2017, 06:14 PM

This may be an option down the road as we replace the batteries. We should be able to buy 4 at a time and see they get very similar usage each time out. Right now I'm guessing the existing batteries are not close at all in terms of discharge or cycles.

Originally posted by littleharbor

How about a 48 volt charging setup. You will charge 4 series wired 12 volt batteries at once and since you are moving the batteries every time you use them any way It wouldn't matter what voltage you charge them at. The one issue I see is the batteries are disimilarly discharged. I'm not sure if there is a workaround for this. If the batteries are fairly evenly discharged each shooting session they may be close enough.

**littleharbor** · 02-27-2017, 06:16 PM

That's pretty much what I'm alluding to here. You are moving the batteries from the charging area to the launchers correct?

**Drew_NL** · 02-27-2017, 06:22 PM

We are moving them to the launchers but the batteries are not really going to be anything alike. They were bought before solar charging was considered.
The biggest problem is that some will be new, some old, different amp hours, different state of charge, some agm possibly most not. So I'm looking at the cheapest way to basically keep them away from each other, series or parallel.

Originally posted by littleharbor

That's pretty much what I'm alluding to here. You are moving the batteries from the charging area to the launchers correct?

**Drew_NL** · 02-27-2017, 06:55 PM

This is for a shooting club over multiple acres, Close is not an option.

Originally posted by Switchback

We did something like this at a friends place. He has 2 throwers. The throwers don't see a lot of use so a 120 watt panel and a standard deep cycle battery (70-90ah I can't remember) worked fine for us.

We we had 2 switches between the battery and throwers. Turn on which ever thrower we use, switch them off when we were done. Much easier and safer than having multiple batteries and CC to switch on and off.

Id check how much energy the throwers use, once you have that you can figure out what size battery/panels you need. A big thing to consider with the 1 panel and battery bank system is the voltage drop you will get running dc voltage long distances. Setup the system as close to the throwers as you can

**Switchback** · 02-27-2017, 09:46 PM

Makes a bit more sense. I'm a carpenter, and no expert by any stretch but I see one big flaw with the "charging station"

Since I'm guessing that nobody will be there to monitor the batteries during the week or switch out a fully charged battery for a dead one. That means you will need to charge multiple batteries at once like Littleharbor referred to. Since you have different ages/sizes/SOC of batteries, charging with a single CC in parallel (or series fir that matter) is a bad idea.

On the average day/weekend do you use all 12 batteries, or do you only really use 6-8 with a few backups? If you rigged up a switch setup, would someone be there to switch out a full battery for an empty one, or is it a club that people randomly stop in to blast off a few boxes of shells?

**Drew_NL** · 02-27-2017, 10:00 PM

The plan is to have as many charge controllers as batteries. One per battery. Each controller will go into float mode as the battery it is charged to is fully charged. So all would get a trickle charge first and then that would increase as as each cc went to float mode. At 12 volts these two panels can put out 12 amps but realistically probably half that around here so I'm thinking the best number to charge would be between 6 and 8. Maybe a couple of more if they are not heavily used, but 6 at a time would probably work for now, we can test to see what the real world results are like before trying to add more.

Originally posted by Switchback

Makes a bit more sense. I'm a carpenter, and no expert by any stretch but I see one big flaw with the "charging station"

Since I'm guessing that nobody will be there to monitor the batteries during the week or switch out a fully charged battery for a dead one. That means you will need to charge multiple batteries at once like Littleharbor referred to. Since you have different ages/sizes/SOC of batteries, charging with a single CC in parallel (or series fir that matter) is a bad idea.

On the average day/weekend do you use all 12 batteries, or do you only really use 6-8 with a few backups? If you rigged up a switch setup, would someone be there to switch out a full battery for an empty one, or is it a club that people randomly stop in to blast off a few boxes of shells?

**Mike90250** · 02-28-2017, 03:38 AM

You have a sticky problem. Short charging (deficit charging) for a week, means that at least some battery capacity is lost weekly, while the battery is below 75% charged
Apparently, it's been working for a while.

For connecting - disconnecting, I recommend Anderson Connectors, they are rugged (on the jumper cables and bumpers of tow trucks and police vehicles) and fairly idiot proof. But it's going to be a big expense to put them on each controller and battery and inverter station

**Drew_NL** · 02-28-2017, 07:17 AM

Not worried about short charging, they seldom see regular charging and will regularly drop far below any level they will see once we have a charging station on site. So in that area they will live much longer lives.

Got a link to the Anderson connectors? the ones I Googled don't seem too expensive.

Originally posted by Mike90250

You have a sticky problem. Short charging (deficit charging) for a week, means that at least some battery capacity is lost weekly, while the battery is below 75% charged
Apparently, it's been working for a while.

For connecting - disconnecting, I recommend Anderson Connectors, they are rugged (on the jumper cables and bumpers of tow trucks and police vehicles) and fairly idiot proof. But it's going to be a big expense to put them on each controller and battery and inverter station

Remote area off grid battery charging station.

Remote area off grid battery charging station.

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