Looking For A 36v Solar Battery Maintainer

[Rickochet]

I leave my cart parked for weeks in an area where there is no electricity. I leave them on full charge when I park it and I leave nothing on and switch the run/tow to tow. The amount the pack self discharges seems to be getting larger as the batteries age (2012 batts). I am planning to add a 80" roof this winter and would like to incorporate a solar panel. What I am looking for is a solar trickle charger that would give me enough boost to offset the self discharge of the pack. I see units that can do a full recharge of discharged batt packs but they are twice the price of a new set of batts. I have looked into this before and there was one company that had something that might work but their site is gone. My knowledge of electronics is limited. I find a bunch of 12v solar maintainers but nothing with 36 v output. Could I use a 12v panel/maintainer and step up the output voltage from 12v to 36v or might this fool the overcharge protection built in to the 12v unit?

Any input would be appreciated.

i saw this a few weeks ago

http://www.ebay.com/itm/100-WATTS-FL...-/262066763445

[Swan]

nice but pricey . if you watch the video he put up 5 on that rv

[Rickochet]

Originally Posted by crash test dummy

i saw this a few weeks ago
http://www.ebay.com/itm/100-WATTS-FL...-/262066763445

Nice looking unit but it still looks like a 12v charger for a gas golf cart and not a charger for an electric cart. Looks like the guy putting 5 on his RV is for a bank of 12v batts for an inverter.

[radioman]

You might try hooking the output of three 12 volt solar trickle chargers in series to get 36 volts.

[Rickochet]

Originally Posted by radioman

You might try hooking the output of three 12 volt solar trickle chargers in series to get 36 volts.

I had mentioned that but I would like someone with some electronics knowledge to comment on this. I think I would want some overcharge protection if needed and don't know how hooking three together might effect that. That would be wonderful if it worked because their are some pretty inexpensive units out there.

[Sergio]

Since You are running a 36v system, You don't need to worry about connecting the chargers in series.

Get 3 x 12v solar chargers and wire each to a set of 2 batteries.

It will be better to charge the batteries in banks anyway.

Pay close attention to the technical details of the solar chargers, typically the terminology "trickle charger" is pretty bad as it implies a constant current source that will gas out your batteries.

You need a charger/maintainer that will keep the voltage below gassing levels.

As far as size, a typical 6v-225AH battery will loose 1% capacity a day or 2.25AH.

Converting it to watts hour @ 12v to make calculations easier, it comes out to 27watts/hour.

So it will take a 12w panel running for about 2 sunny hours to compensate the self-discharge.

A 6w panel will take about 4 hours... You get the idea, and allow some margin of error for non-sunny days.

[Rickochet]

Thanks Sergio. That gives me a place to start. I guess a goal might be to be able to have the batt pack at least 80% after sitting 4 weeks.

Rick

[radioman]

Connecting the three charger outputs in series might be better to assure each battery gets the same amount of charging current and you would need to run only two wires from the three chargers location to battery bank.

[Rickochet]

Originally Posted by radioman

Connecting the three charger outputs in series might be better to assure each battery gets the same amount of charging current and you would need to run only two wires from the three chargers location to battery bank.

My concern with that would be the over charging protection built into the chargers. I am guessing that something in each panel senses a max charging voltage, say 13v. If I hook three together will the 36v from the pack tell the over charge sensors to shut off the charging? Please understand that I know very little about electronics.