Solar Renogy?

Stu Jackson · Jul 2, 2017

rpludwig said:
is one enuff to keep a C22 battery charged?

Open ended question...without any more info we can't answer. If you want to keep your battery charged during the week you're away from the boat, sure. How big a battery? How do you use your boat? Your question is like how long is a piece of string... See, the more info you provide the better folks can help without asking more questions.

dzl · Jul 2, 2017

Well.... I've got two smaller batteries that equal around 95AH I think, and I have a 5 watt solar charger that keeps them topped off. If I run a fan all night it would need additional charging to bring it back up, but just with depth finder and running lights the solar will catch up the next day... I'm not real smart in this area so I can't give knowledgeable advice, but it seems like a 30 watt would do the job.

Gene Neill · Jul 2, 2017

First ... I am an electrical DUNCE. Do not take anything I say seriously.

But in my very humble and very ignorant opinion ... if you haven't already bought that dual-purpose battery, I would do a little more research. You can do a lot better with a deep cycle battery. In order to get accurate apples/apples comparisons, look for capacity measured in amp hours (Ah) at a 20 hour rate, and pass on any battery not rated that way. My understanding is that the top shelf (without going into golf cart batteries, floor scrubber batteries, etc) consists of Crown, Trojan, and US Battery. I am somewhere on the second tier with a Duracell Ultra, made by Deka. I like it and am happy with it for now. I will look for one of those other three next time.

On to panels ...

We started with a 15 watt Harbor Freight panel, which was kind of a joke. We upgraded to a 30 watt Renogy panel, which was a big improvement, but still didn't keep up with our needs. The second 30-watt panel did the trick, with a little help from the outboard.

Bear in mind though, we are power hogs. We have a GPS with 7" display, an autotiller, we carry two cell phones and a tablet, a bluetooth speaker, plus interior lighting, masthead light, and occasionally navigation lighting. All the lighting is LED of course, but it still counts. And I was not going to be happy until we had enough panels to keep up with all of this draw for an indefinite period of time.

Again, I know nothing. Double check anything I say before you put any faith in it.

dzl · Jul 2, 2017

One thing of interest I found out the other day while looking at masthead lights... I wanted to go led because of power consumption of course, but after looking at the specs the led I was looking at was double the wattage draw than the simple festoon incandescent. Good LEDs are low power, but cheaper ones may be made with many resistors and of course they just pull power. It doesn't matter that the actual lighting units are low draw if you're running loads of resistance to get the voltage right .... I'm still fully incandescent and I've ran my lights up to four hours with zero voltage drop on my batteries. It's not worth the cost for me yet, but if I do more overnight trips I'll make the plunge and buy good LEDs.

greg_m · Jul 3, 2017

Hi Guys

Never take the AmpHour reading from a battery manufacturer as gospel. They will have been tested in a lab under very strict conditions = nothing like reality on a boat! Hi density (read expensive) batteries may give you about 80% for the stated rating while dual purpose may give you less than 60% of the stated rating.

Domestic (house batteries) should rather be of the deep cycle type as they can withstand long deep discharges much better than the dual purpose or starter batteries. Again deep cycle batteries can withstand many deep discharge/charge cycle way more than dual purpose or starter batteries.

Like a chain - it's only as strong as the weakest link! The whole electrical system: wires, connections, connectors, plugs etc etc all play a part in losses along the way. No point in lovely big expensive battery then you attach a cheap charging source and charging controller!

P=VI ... in DC circuits you could calculate your electrical demand by knowing the Amps drawn from the circuits.

Don't know them from a bar of soap but check out a youtube channel "Gone with the Wynns"... they have a very good video on this subject covering batteries as well as solar panels and the have extensive experience with living "off grid" as it were!

Gene Neill · Jul 3, 2017

rpludwig said:
daysailing only, an occasional 1 niter, and have dock power

Ron

With a good (never mind top shelf) battery, you should be just fine with one 30 watt panel under those conditions. Heck, maybe even with no panel at all.

Our biggest battery draw seems to come from charging the tablet. Charging cell phones takes a good bit of power too. Our Bluetooth speaker needs no charging for the first couple days, so in your case it would count for nothing. I don't know what those Caframo fans draw though, we have no fans.

dzl · Jul 3, 2017

That's what I found also, that charging phones etc draws a lot of power. I bought a 20,000mah battery for that purpose and it does a great job. It'll charge an iPhone something like 5 or 6 times and doesn't pull down the house battery. Also I can charge it in the cockpit.

Jacktar · Jul 4, 2017

Just a couple of comments:
1 I just switched out my marine starting group 24 battery because it would drop charges and not bounce back even with running the motor for a few hours. With the duracell ultra group 27 deep cycle it stays charged dockside and recovers quicker to charging underway .
2 I converted all the running and cabin lights to LED except the steaming light incandescent which because I am in a slip I have not switched out as I am too lazy and busy sailing to lower the mast for the changeout.
Except for the VHF with remote command mike and built in GPS for DSC and the depthfinder on while sailing the battery holds up well. When I anchor I plug in my little 15 watt harbor freight solar panel mostly for a little trickle charging. No real outages and it runs my phone charger fine but I plug it in while motoring not while sitting around at anchor. In fact anything I have that needs a charge other wise I plug in while motoring.

greg_m · Jul 5, 2017

Jacktar said:
Just a couple of comments:
1 I just switched out my marine starting group 24 battery because it would drop charges and not bounce back even with running the motor for a few hours. With the duracell ultra group 27 deep cycle it stays charged dockside and recovers quicker to charging underway .
2 I converted all the running and cabin lights to LED except the steaming light incandescent which because I am in a slip I have not switched out as I am too lazy and busy sailing to lower the mast for the changeout.
Except for the VHF with remote command mike and built in GPS for DSC and the depthfinder on while sailing the battery holds up well. When I anchor I plug in my little 15 watt harbor freight solar panel mostly for a little trickle charging. No real outages and it runs my phone charger fine but I plug it in while motoring not while sitting around at anchor. In fact anything I have that needs a charge other wise I plug in while motoring.

Good information - thanks.

Batteries made for starting engines application have a different construction to those made for "domestic" use application.
When going cross country through the African bush in a very capable Jeep Grand Cherokee 2.7 CRD, you definitely learn very quickly that not all batteries are the same and you definitely learn about a dual battery installation and charging systems.

One never wants to run a FLA starter battery below 50% charge because the chemical sulphates that deposit on the electrodes become hard and do not reconstitute back to lead and sulphuric acids during the charging process completely = battery dies a slow death!