Any members who are knowledgable about solar?

[Table Rockin]

I know this is of no real help, but there must be a tried and true solar method. The corps on TRL requires all new docks to be powered via solar and you see the panels (which really are fairly small) on 12-20 slip community docks all the time. That's a lot of boat lifts to power.

[sailor55330]

I know this is of no real help, but there must be a tried and true solar method. The corps on TRL requires all new docks to be powered via solar and you see the panels (which really are fairly small) on 12-20 slip community docks all the time. That's a lot of boat lifts to power.

You would think the choices would be multiple, but in reality, there aren't as many "off the shelf" systems as you would think, at least not from a Google standpoint. I'm sure you can put your own together if you're knowedgable. I'd be happy if I could get a straight answer on using an inverter and AC vs converting to a DC motor but ask 5 people and you will get an even split.

[Table Rockin]

anything of interest here?

https://www.boatliftanddock.com/categor ... rging-kits

[kbloom72]

I run my boat lift and dock lights (LED) off of 2 12v batteries with a 20w-24v charging kit. It works without any issues. I use the lift at least 8-10 times a week in the summer.

Thank you--that is a similar system to what I am considering, but wasn't sure whether to go with a 20w or 40w panel. Sounds like 20w works well, so 40w it is (using BBP"s engine analysis here---Captain Overkill has arrived)

Are you using deep cycle batteries?

20w works great for me. I used this one on my Father in Law's setup which is similar to mine.

[sailor55330]

anything of interest here?

https://www.boatliftanddock.com/categor ... rging-kits

That's the system I've been looking at. Here's their direct website:

https://www.lakelifter.com/

Seems to be a pretty well thought out system overall.

[Krob1114]

40W feels small, but you're only drawing high current for short periods of time so it may be enough. For reference, a typical current-gen full-size residential panel (a single panel is maybe 40"x67") in the 350W range.

Math is fairly straightforward - 40W for an hour is 40 Watt-hours replenishment. Watts are Volts times current (Amps) for instantaneous calculation, or Watt-hours or Amp-hours for capacity and draw. So, 40 Watt-hours divided by 12 Volts (e.g., to recharge a 12V battery) is 40/12 or 3.3 Amp-hours of battery replenishment per hour. If everything is 12V, you can simply choose between adding up Amps or Watts to determine capacity, charging rate, and draw.

Thank you JHN-

So, now my ignorance is showing because I really understand nothing you posted---watts vs volts vs amps vs current loses me.

if I stay with 110 and an inverter, then it's a 12amp motor that will run for about 5-6 minutes a cycle. Would that be about 1.2amps of power?

If I go with a DC motor, it's rated at 1800w, which would be about 150w to run for a 5 minute cycle?

What does going to a 24v system do vs 12 volt. It sounds like a 40w panel would provide a charge rate of about 1.6 amp-hours (40/24)?

In other words, a 40w panel should replenish a single use of the lift in about 2 hours?

So frustrating because I can see exactly how to wire it in my head and how to install it, but I am lost on the capacity/calculations.

I really appreciate the help.

I majored in engineering in college. Basic starter course in Civil Engineering was Statics (Objects at rest basically); Dynamics (objects in motion) for Mechanical Engineering; and Circuits Analysis for Electrical Engineering. I just didn't get it on Electrical engineering so that was last class I took.
Fraternity + Drinking = No Degree though.

I would think starting boat would not drain a 12 volt battery, so it should charge faster. If so, I wouldn't be able to start boat so many times a day.

[Big Block Power]

My brother just runs leads from his boat battery and uses that. Then you can use another battery for your lights. Like others have said I don't think you need much.

[sailor55330]

Thanks Everyone-

I didn't think it would take too much and it sounds like the consensus here is to convert to a DC lift motor and run straight from the batteries vs using the existing AC motor with an inverter? Seems like the inverter loses a lot of power, but you can't run any 110 tools from straight DC.

Am I missing anything?

[jhnmdahl]

Thank you JHN-

So, now my ignorance is showing because I really understand nothing you posted---watts vs volts vs amps vs current loses me.
if I stay with 110 and an inverter, then it's a 12amp motor that will run for about 5-6 minutes a cycle. Would that be about 1.2amps of power?
If I go with a DC motor, it's rated at 1800w, which would be about 150w to run for a 5 minute cycle?
What does going to a 24v system do vs 12 volt. It sounds like a 40w panel would provide a charge rate of about 1.6 amp-hours (40/24)?
In other words, a 40w panel should replenish a single use of the lift in about 2 hours?
So frustrating because I can see exactly how to wire it in my head and how to install it, but I am lost on the capacity/calculations.

I really appreciate the help.

1800 Watts times 1/12 of an hour (five minutes) is indeed 150 Watt-hours of draw on the batteries. A 40 Watt solar cell would therefore need about four hours to replenish the used power (40 Watt hours times four is 160 Watt hours, or just over the 150 Watt hours you've used).

It's perhaps easier to stick with watts, as using amps start to get harder once you convert to different voltages, involve AC, etc. The 12 amp motor on the inverter, for example, will draw 12 amps whenever its running, but I don't know at what voltage. Double the voltage and you can cut the current in half to get the same power in watts. If everything past the inverter was 12V, though, a 12 amp (and 12v) motor running for six minutes would draw 1.2 Amp-hours from a 12v battery, and need to be replenished with 1.2 Amp hours at 12v. Now if your solar cells are 40v, you're looking at something more like .4 Amp hours coming off the solar cell or array, but in either example you're right about 150 Watt hours (watts of power=volts times current in amps).

[sailor55330]

Thanks John!

[bruceb58]

If your lift draws 12A at 120VAC, that's 1440W. if you run it once a day for 15 minutes that's 360WH. Add another 60WH for your 3 lights, that's 420WH. With an inverter that's 85% efficient, that is around 500WH

If where you are has 4 equivalent sun hours a day, you would need a 125W panel to recharge the battery.

A standard 12V 100AH battery is around 1200WH so one 100AH battery would be plenty since you don't want to discharge it under 50%.

You can modify my example if it takes less power/time than I was estimating.

Another option is bringing down one of those portable power stations down to the dock and charging it up at your house. it is basically a lithium battery with an inverter in a case.

Here is an example:
https://www.jackery.com/products/explor ... NgQAvD_BwE

[sailor55330]

Thank you Bruce-

The portable power option is an interesting concept until you have to carry it 100 yards down a hill/dirt path and then back up @ 22lbs.

I'm really leaning towards converting the blower motor to a 24v DC motor with a 200ah battery bank (I think Deep Cycle would be the way to go) That with a 40w panel should give me plenty of run time for the lift and lights on any given day during the weekends. While not the biggest, I think 40w would let me put some juice back in on a busy day and definitely recover on slower days..

Everything I've read about running AC lift motors through an inverter points to an unhappy motor. It will work, but with slower output and more strain.

So, to recap, here's what I'm thinking:

24v blower motor
battery charge controller
2 deep cycle batteries @ 100ah each (leaning towards Renology as they seem to be the favorite with the off grid crowd)
40w panel
2-3 LED lights for nightime

This should give me more than enough power to do whatever I want. It's still way cheaper than installing 110AC---Assuming the batteries last 4-5 years then it would take over 20 years for the cost of batteries to outweigh the cost of 110 installation, which usually goes bad in that time anyway since they use direct bury wire.

Am I crazy?

[bruceb58]

Thank you Bruce-

The portable power option is an interesting concept until you have to carry it 100 yards down a hill/dirt path and then back up @ 22lbs.

I'm really leaning towards converting the blower motor to a 24v DC motor with a 200ah battery bank (I think Deep Cycle would be the way to go) That with a 40w panel should give me plenty of run time for the lift and lights on any given day during the weekends. While not the biggest, I think 40w would let me put some juice back in on a busy day and definitely recover on slower days..

Everything I've read about running AC lift motors through an inverter points to an unhappy motor. It will work, but with slower output and more strain.

So, to recap, here's what I'm thinking:

24v blower motor
battery charge controller
2 deep cycle batteries @ 100ah each (leaning towards Renology as they seem to be the favorite with the off grid crowd)
40w panel
2-3 LED lights for nightime

This should give me more than enough power to do whatever I want. It's still way cheaper than installing 110AC---Assuming the batteries last 4-5 years then it would take over 20 years for the cost of batteries to outweigh the cost of 110 installation, which usually goes bad in that time anyway since they use direct bury wire.

Am I crazy?

If you use a pure sine wave inverter, there is no issue. RVs are running 120VAC fridges and air conditioning all day long on them.

Renogy are really not that popular with the off grid people. They have pretty poor customer service. Not really a problem if you are going with a lead acid battery but don't buy one of their lithiums if you are thinking about them. There are better options.

[madalinet]

I've got some experience with solar and it sounds like you've got a good plan. Going solar is a great way to save money in the long run and it's great for the environment too. I checked out that link you posted and it looks like a great resource for DIY off-grid solar systems.
For your situation, it seems like a 40w solar panel with a 2 battery setup from https://www.dragonsbreathsolar.co.uk/pr ... stem-kits/ should work for your needs. Since you're in Georgia, you'll definitely get a good amount of sun exposure. As for the type of battery, I'd recommend going with lithium ion. They're more expensive upfront, but they last longer and can handle deeper discharges compared to AGM batteries.

[Whippled263]

I run two boat lifts all summer. 2000 pound boat and 6000 pound boat. Both have two 12 volt battery's/ 24v volt system charged by a solar panel. Go to lakelite.com and pick your system. I have NEVER run out of battery power from cycling up and down. Even on the 4th of July. Easy as it comes.