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**StuM** · 03-09-2017, 14:43

Quote:

Originally Posted by Last Call

This panel configuration put my peak voltage around 18v and the amps around 12. I'm not sure but I think in the stepping up of the voltage from 12 to more than 48 by this charger will be reducing my amps to do so. I couldn't find documentation to back that up (yet). I could be wrong in this thought process. Changing the motor to 48 volt electric as a after thought introduced more issues to deal with.
...
Thoughts?

My first thought is that your original question and this statement suggest that you need to put a lot more study into basic electricity before messing around with 48V banks on a small boat.

You also said:
So in summary I have the following hardware:
...
two- 30 watt 12 volt panels @ 1.65 amps ( My plan was to make it four)
one - 100 watt 12 volt panel @5.23 amps
Total 12 volts 220 watt @ 8.53 amps Parallel

Those numbers don't add up. If you have 2 x 30W panels, the total is 160W, not 220W. And throwing panel specification amps into your calculation just confuses things. It's best to just stick with Watts until the final stage of your calculation.

The bottom line is that you have apparently have 160W Watts of panels, regardless of voltage.
Going into a 12V battery bank at a nominal charge voltage of say 14.4V, you will be looking at a peak charging current of around 11 Amps. Going into a 48V bank at say 57V charging, you will get about 3 Amps.

Apart from that:
How many Amp hours (at 48V) in your current and proposed AGM battery banks?

What sized generator are you talking about here "I will have a generator if push come to shove for the shore charger."

senormechanico · 03-09-2017, 15:18

Stu,
Your math is pretty much correct, but NOBODY ever gets the rated power out of solar panels.
160 watts rated is a lot more like 100-120 in the real world.
There's bird doo, dust, wiring resistance, smog, clouds and sun angle to name a few.

**StuM** · 03-09-2017, 16:07

Quote:

Originally Posted by senormechanico

Stu,
Your math is pretty much correct, but NOBODY ever gets the rated power out of solar panels.
160 watts rated is a lot more like 100-120 in the real world.
There's bird doo, dust, wiring resistance, smog, clouds and sun angle to name a few.

Never say nobody!

Some people actually exceed rating sometimes for short periods of time under optimal conditions.

It's easiest and safest to use rated outputs for planning purposes to determine maximum likely current/voltage.

Then when determining likely daily Amp hours recovered, you take in to account your listed factors (along with location, time of year, panel orientation, potential shading etc, etc) by applying an appropriate "hours full sun equivalent" multiplier to the rated wattage - which could be anywhere from 3-6 depending on circumstances.

senormechanico · 03-09-2017, 17:41

Stu,
I should have picked my words more carefully.
I have seen short duration peaks on both my boat and my home's systems as you describe, but they are so short as to be insiginificant for our descussion's purposes.
To see anything over the specifications requires a cold day with clouds and wind, and all of a sudden the sun comes blasting out of the clouds.
The cold panels in full sun (hopefully at solar noon) will heat up within a minute, and there goes the over spec condition.

Last Call · 04-09-2017, 10:28

First let me apologize for this long winded post. I may not be clear in my explanation. Writing clearly is not at the top of my skill set, with that said here goes.

I have four 12 Agm optima batteries in series at 66 ah each
I have a a 48 volt brushless three phase dc motor for a kicker 50 amp continuous
I provided some images for clarity
I have two 30 watt panels and I have room to make it four panels if needed at 1.63 amps
I have 1 100 watt panel @ approximately 5.5 amps

I have at present one 48v to 12v dc converter @ 30 amps but I plan on making that two in parallel for 60 amps. Unless there are issues to prevent it.
The reason for the second converter is , the on board items such as , Bilge pumps, wash down pump and anchor winch are heavy loads. (hopefully bilge pumps not needed) After adding everything up in situations where running lights ,deck lights and bilge pumps are all active, 30 amps from a single dc to dc converter is just barely getting by. Example : 14 amp for bilge no 1, + 5 amp bilge 2 + 6 amp marine radio, + 4 amps deck and running lights. Worse case scenario. 29 amps fuse blows at thirty
Note: I could not go directly to the 48 volt battery with the bilge pumps bypassing the inverter without tapping the bank at one battery which i didn't want to do.

My house loads are negligible a Engle fridge/ freezer runs at a 2.5 to 3 amps in most situations I doubled that to 5 amps

Three Led cabin lights, a couple cell phone / tablet charges a twelve volt TV and a 12 volt hot spot router.

Other than that running lights, fore, aft deck utility lights and one hatch ventilation fan and a couple other small circulation fans on the bulkheads

My pumps are:
One 14 amp 3700 gph bilge pump
One 3 amp 1100 gph bilge pump
One 14 amp washdown
One 2.7 amp fresh water

All seldom used.

I have a 110v 600 watt microwave that will be seldom used that I want to put on a 48 volt 2000 watt inverter. Turned on only when needed and I will use the microwave when docked on shore power

I have a gimbald gas bottle type coffee warmer and for cooking origo alcohol stove

I mention only mentioned this because no electricity involved.

Some photos: I am into this project up to my eyeballs and it will be done one way or another.

https://www.dropbox.com/sh/65h7zf5a6...9_ogY3ESa?dl=0

I made the enclosure and every thing on it is twelve volt except for the microwave and that situation has changed to 110 on a inverter due to cost of 12 volt microwaves and the benefit of having a inverter for different Items even if rarely used.

So you see all my house needs that amount to anything are , emergency pumps , fresh water pump, anchor winch and a inverter running a microwave a few minutes a day (maybe)

I dont see the need for another bank other than the issue of charging with solar panels that you mentioned. The problem I see is my mismatched panels it would be better if all were identical watts and output in amps. Then my charger would need to be one that charges uphill or my panels in series up to more than 48 within the max allowed by a 48 volt charger charger . I hear series panels are not recommended. I'm not sure I understand the issue with if a main diode, fuses and bypass diodes for each panel are being used.

I think I have a handle on the wiring aspect I have every circuit drawn out every wire numbered and and I am using double walled adheasive clear shrink connectors with solder in them on every wire connection. My wire numbers will also be covered with shrink wrap.

Now if I have two 48v to 12v thirty amp converters in parallel feeding my house panel and the 50 amp kicker on its own dedicated fused main. Why is adding a 12 volt bank needed. I thought if I were going to add another bank it would be another 48 volt bank for more amp hours. I know the charger is the issue and to your point that charging a twelve volt bank with twelve volt panels was your main suggestion. In my mind with the addition 12 volt bank I would be going for days maybe a week or two with the 48 volt bank not being maintained (not charged per say) just not sitting there with nothing being added just losses from not being used. Its my understanding you have a percentage of loss per day if not on a float charge. I would be leaving that bank like that while charging another bank at twelve volts that will be only used for minimal loads . If they are as you said small loads why another separate 12 volt bank? I'm not arguing the point I just need to understand what your saying. You are correct I do not understand totally solar panels and different configurations .

That is why I am here.

john61ct · 04-09-2017, 13:08

I would say just forget the solar, since as stated its contribution is practically nothing compared to your overall needs.

But you already have it right?

You need multiple solar controllers because you have different panels and also different angles.

SCs that output charge current suitable for 48V are very rare and expensive.

If 200 or so AH is enough storage, a pair of Duracell 6V GCs will cost you $180 and last for years.

This will allow you to use Victron 75/15 per matched set of panels (by model and orientation) at under $100 each.

And maybe save you buying another 48-12 converter?

Plus some redundancy for critical comms and nav gear if your propulsion bank goes down to know where the reefs are to sail around them, maybe even call for rescue.

Just an idea though, if you prefer to keep all storage at 48V, see how much extra that costs.