Solar, inverter, battery upgrade. DIY vs professional install and spec

[Redhawk106]

Hi all,

 

On the subject of solar, inverter and batteries, is this something can can safely be done by someone who has no experience in this area?

I can do woodworking, and have done basic 5v electric arduino things years and years ago (forgotten it all by now).

 

I'm trying to decide whether to attempt it myself or get someone in to do it. We live on a 55 by 10ft canalboat, permanently moored in London Marina, but we want to go cruising this summer for a week or 2.

 

Basically our setup currently is as follows:

- 2 x 110Ah AGM Lead Acid batteries for the main boat, and 1x 110Ah LA for the starter. There are 3 switches so any of the 3 batteries can be switched to engine/home/both.

- The alternator on the 1987 Vetus engine says 30A. There is also a split charger.

- We have shore power currently.

 

Items that need 230V power:

- 230V fridge

- Laptops and monitors for working from home 8 hrs a day, although these could be powered by 12V if I can source the right adapters.

- Wet & Dry vac, will likely only be needed if there is a severe leak etc.

 

Others that are powered by 230V but dont have to be used during cruising:

- 2KW portable oil radiator.

- Ninja Air fryer/pressure cooker

 

Theres probably other things, but basically the fridge and laptop/monitors are the 'essential' ones.

I was thinking will probably need a 3000W inverter, and maybe 1 or 2 more LA batteries. And then at a minimum hoping this could be charged by the engine, but the 30A alternator seems small, heard lots of people talk about 90A on their boats.

 

And then if budget can go to it, Im thinking solar (Panels, MPPT etc also needed then), and wondering if I could do it myself, or do I need to have a pro do it. We now have a baby on board, so I want to be even more careful about doing things wrong.

 

So with the above background, in case it helps, I'll summarise the questions:

1. Whats the minimum we need to do to be able to go away and cruise for a week.

2. Can our engine/alternator alone charge things for a small 1 week cruise.

3. If solar is needed, can we DIY or better to get someone.

4. Any other things needed I have forgotten about?

 

Let me know if I have missed any important info in order to answer the question.

Thanks in advance!

Edited May 6 by Redhawk106

[Tony Brooks]

I think that you need to do a power/energy audit on paper so you can see how much electricity you need (you don't give current draws or times). Then the charging calculations to see if they fit your usage pattern. These are all specific to your boat and yourself.

 

With an MPPT controller, the chances are that the panels will be wired in series or possibly series parallel. Both means that you will have to deal with high voltages (60V+) and that is getting on to electric shock territory, so if you have maybe changed a socket or run a spur at home I think DIY s perfectly possible. If you wire the panels in parallel, so a maximum voltage of between 20 and 30 volts, then there is little danger of shocks.

 

Personally, I doubt a 30 amp alternator will answer during cloudy  spells because it will only average about 15 amps over the  first three or four hours and then drop to lower and lower averages. Is this a very small or an old engine, I can't imagine Vetus fitting a 30 amp alternator by 1989 except as an engine alternator on a twin alternator engine.

 

I got along perfectly will with a 60 amp alternator and about watts of solar BUT I was careful about using high-powered things, providing adequate charging times and no large inverter. I had a 12V fridge and a bank of 3 x 110 Ah domestic batteries. I ran my laptop from a 12v car adaptor, not an inverter. At full power, that inverter will be drawing 300 amps plus a little from the batteries, even when not inverting it will still draw a small amount of power, how much depends upon the quality of the inverter and if the fridge or anything else "mains" you use can wake it up from sleep mode.

 

We don't know what sort of split charge device you have, so a photo will help identify it. One particular type is almost certainly going to adversely impact the charging, while others will allow the solar to charge both battery banks.

 

[Tracy D'arth]

Having an isolator switch for each battery is unusual. I cannot understand how you can have a split charge system with 3 batteries and 3 isolators.

15A alternator is woefully small.

At present you have no inverter?

[Tony Brooks]

5 minutes ago, Tracy D'arth said:

Having an isolator switch for each battery is unusual. I cannot understand how you can have a split charge system with 3 batteries and 3 isolators.

15A alternator is woefully small.

At present you have no inverter?

 

He said 30 amp alternator, I said 15 amps average over 3 to 4 hours because that is roughly what it will work out as with lead acid batteries, and as he talks of adding extra ones I don't think he is contemplating Lithium.

 

I wonder if he has a 1, 2, Both, off type switch that has been badly explained to him. If not the system is far more complicated than it needs to be.

 

 

Edited May 6 by Tony Brooks

[Redhawk106]

Hey both, thanks for replying.

 

I'll get some photos in and that should help. Can't do that right now though. I thought about Lithium but my electrician said she was not convinced on the safety side of doing Lead Acid + Lithium Hybrid approach. I've seen posts of many who have done so successfully, but with a baby, and also the cost, I'd rather stick to tried and tested LA after that advice.

 

Tony is correct, its 30A, not 15A. Although I have not had a good look at the other side of the engine due to how its housed inside the boat, who knows, maybe it is a twin alternator?

 

Definately no inverter at the moment, thats one of the things im looking at.

 

Tony, yes you're right, I should probably do a power audit and share that, but last time I did it, it came out at something insane like over 10 Kw I think. So thats with everything we want to run thats currently run on shore power.

So thats why I thought I just need to get the biggest yet affordable setup that allows for a decent amount of items, but not all of them. And then be carefully picking and choosing what to turn on, rather than sizing a system for my actual needs.

 

But I'll do some photos and a new powe audit this week, and get back to you.

 

In the meantime, what about the more general question of DIY vs getting someone to do it. What are the pros and cons on that?

Edited May 6 by Redhawk106

[Tony Brooks]

First of all, I think you misunderstood the power audit. You do not put in everything you want to run off the batteries. You put in what items and how long you will run them in a 24 hour period, or even just the time the engine is turned off for from evening to morning.  Over a period things you don't use every night should even themselves out as long as you put a representative number in. Anyway, whatever you come up with is only a rough guide, so you plan on a semi-decent basis and not just guess work. If we assume a typical (not 30 amp) then using things like the air frier whilst moving will, in a great part, be covered by the alternator, so nor supplied by the batteries.

 

I through I had given you some pointers as to DIY or paying someone, but suspect the talk of series, series parallel, and parallel connection of the solar panels may have gone over your head. If you are happy with parallel connection and can drill & tap unless you intend to glue the panels down then if you can work with 5V DC circuits you should be equally at home with 12V DC, but you need to take care over the cable sizes in longer runs. If you want to connect them is parallel or series parallel and are worried about what up to 100V DC may do to you then pay someone, but get all the information re switches and/or fuse locations first.

 

It would be a very unusual boat that has twin alternators plus a split charge system, although some people use split charge system components to parallel up twin alternators in the hope of getting a faster charge.

 

Unless the boat already has battery monitoring equipment installed, then you should budget for that as well, otherwise you will have very little idea about "be carefully picking and choosing what to turn on". There are gotchas with many battery monitors, but we can explain that to you when you get the basics sorted. It is all to easy to destroy LA batteries within weeks unless you are on top of the charging.