advice for maintaining batteries off grid..

[jjwelly]

so much good info here, thanks! Many good options.

[littleharbor]

Clean looking building. The metal roof and wall mounted solar panels are screaming "Snow Country"

[hammick]

I use a 100w Renology panel on my south facing wall. Mostly for float charging small AGM batteries during the winter.

http://www.ebay.com/itm/BATTERY-TEND...item4ae65bb733

All batteries are fully charged when I arrive at my place.

[Sunking]

ok thanks you all, really, I very much appreciate all the help. I think this puts me back to thinking it doesn't make sense to use solar. Not very good saying that on a solar forum, I know, but I don't see how spending ~$150 for a solar charge/maintainer PER BATTERY is cost effective. .

Nah you will hear it here first. In fact you wil hear using solar for batteries is the last thing you want to do and to be used if there is no other option. Solar is the most expensive and least effective source there is.

[PNjunction]

I think this puts me back to thinking it doesn't make sense to use solar. Not very good saying that on a solar forum, I know, but I don't see how spending ~$150 for a solar charge/maintainer PER BATTERY is cost effective.

Actually, on this forum you'll find we often don't recommend solar for everything when it is extremely cost-ineffective, or just to much to maintain properly. You are on the right track, and most of us are honest when a sanity ratio has been exceeded.

At least for me. I may try using one of those 5-6 watt $40-50 setups on one of them to see if it helps me in the long run, but doesn't sound like those work well.

They are mainly designed to compensate for parasitic loads from a vehicle, but as you now know, if those maintainers find a battery in a 50% charged state, it will tend to leave it there and not actually charge. Sulfation still occurs. If you DO use one with a FULLY charged battery, (say you take your dc-dc charger out, finish a charge, and plop one of these solar maintainers on, they can easily overcharge that battery without a controller as seen in the earlier video....

So, I need to decide to either remove the batteries and bring home to ac power for storage, which is a PITA. Or just let them sit during the normal season, and remove and bring home during the off season.

I think the last option makes the most sense for you. Grab the Optimate 6 and during the off season, just rotate it around to all the batteries say once a week or so. At least it is better than doing nothing that you are doing now. It might be enough to justify the cost of the charger if only one battery lasts a year longer.

[jjwelly]

ok thanks you all, really, I very much appreciate all the help. I think this puts me back to thinking it doesn't make sense to use solar. Not very good saying that on a solar forum, I know, but I don't see how spending ~$150 for a solar charge/maintainer PER BATTERY is cost effective. At least for me. I may try using one of those 5-6 watt $40-50 setups on one of them to see if it helps me in the long run, but doesn't sound like those work well. So, I need to decide to either remove the batteries and bring home to ac power for storage, which is a PITA. Or just let them sit during the normal season, and remove and bring home during the off season.

[SunEagle]

they are all different types. Seems to me that it would be hard to parallel them while still remaining in vehicles. Would I just make some sort of extension cables with alligator clips branched off in order for me to hook them all up in while remaining in vehicles? Then I would be able to charge them all with 1 solar panel and 1 charge controller?

Only way to charge them all is to do it ONE AT A TIME. Running parallel charging wires to two different batteries at the same time will kill one or both and definitely if you connect all four at the same time.

[Sunking]

they are all different types. Seems to me that it would be hard to parallel them while still remaining in vehicles. Would I just make some sort of extension cables with alligator clips branched off in order for me to hook them all up in while remaining in vehicles? Then I would be able to charge them all with 1 solar panel and 1 charge controller?

You could but would be extremely dangerous.

[jjwelly]

they are all different types. Seems to me that it would be hard to parallel them while still remaining in vehicles. Would I just make some sort of extension cables with alligator clips branched off in order for me to hook them all up in while remaining in vehicles? Then I would be able to charge them all with 1 solar panel and 1 charge controller?

[Sunking]

Have not read through all the replies, and have no intention to do so.

Are all your batteries same type. If they are you can parallel them and keep them charged.

How many?
What Size?
What Type?

If it is a mix of AGM, FLA, starting and deep cycle you have some incompatibility. However you can find a happy medium. Float range between the types is 13.2 to 13.6 volts. You would need to shoot for 13.4. Not perfect but better than dead and doing nothing.

[jjwelly]

Well, i'm not very knowledgeable on solar panels, charge controllers, etc, but when you say i can use a 40 W panel and charge controller, is that setup good for only 1 battery? I have 4 batteries, and if the cost of this 40 watt panel is where I think it is, and if I would have to have one per/battery, sure doesn't make sense to me. Help me understand the equipment needs and costs associated with setting something like this up.

[littleharbor]

"Seems like there's not a good option solar for these items"
Not sure what you mean by this? You could use a small 40 watt panel for maintenance charging or go up to a 120 or larger panel for dry camping. I have done many pop up installs with great success.

[jjwelly]

The popup currently is stored at my house outside. I do know that there's at least a smoke alarm or some sort of alarm that does pull power when the battery is connected. There's a fuse that I just yank when not in use so there's no draw on the battery. Since this is stored with juice available, I'm going to put an optimate 2 on it. I have since bought an optimate 6 as well as 3 optimate 2's as suggested by PNjunction. However I do foresee the popup possibly joining my other equipment offsite where power is not available. (bobcat, 4 wheeler, and lawn tractor). Seems like there's not a good option solar for these items.

[littleharbor]

I noticed you said your popup battery is the one that needs to be revived/replaced. When not in use is your popup indoors or out? There are parasitic systems in RVs like co2 sensors and smoke alarms that are battery killers if you allow the RV to sit unused for any length of time. If the popup is outdoors and in the sun you can mount a solar panel and charge controller in the roof which will keep your battery topped off and happy between camping trips. There is usually a channel in the canvas that carries the wiring for the overhead lights. You can fish the wire from the solar panel through this and on to your charge controller location. I have done this many times on friends popups. If you mount enough solar on the roof you are set for dry camping as well.

[PNjunction]

Sounds good - just know that Battery Tenders brand float near 13.2v. That will void the warranty on an Odyssey agm being too low in voltage - and they are sticklers about that.

We know that it takes at least 8-12 minimum at 13.6v to actually finish the job, no matter how fast you do absorb, so the best bet is to let your Optimate 6 charge, do it's 12 hour test automatically, and then at least another 12-24 hours of float after the led goes SOLID green, since it has a 50% duty cycle in float. THEN place your BT's on the battery you wish to maintain.

If you place the BT's on too soon, they may not get fully charged, and just maintained in a 99.5% state, which is what Odyssey's beef seems to be about being walked down over time. Plenty of BT vs Odyssey float voltage material out there so I won't bring out the drama here.