Small Solar Proposal

Talk about anything and everything here within reason.
BlueBell   10 W

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Re: Small Solar Proposal

Post by BlueBell » Feb 27 2018 11:32am

dogman dan wrote:
Feb 27 2018 8:44am
Somehow, I got the idea this was a remote controlled boat. With a person aboard, if possible go with the safest chemistry you can, lifepo4.

If you do need to go a smaller and lighter chemistry, just get the battery modules from a very high quality source. $$$

It could be possible to get true 12v by doing a 4s pack, then voltage convert to steady 13v. ( like a 12v lead battery full)
The battery can be smaller in AH, not larger in size or weight. Just same size in watt hours.

Example. 10 ah of 4.2v is 42 watt hours. 5 ah of 8.4v is also 42 watt hours. Both could be the same number of 18650 cells.
Thanks Dan.

Just to clarify, it is not a remote control boat.
The auto-pilot is like having a really good-tempered, second crew-member on board who doesn't eat (accept electrons, gobble-gobble), sleep, bitch, whine, and very, very rarely makes mistakes and allows me to fly the kite, eat, etc.

At 3.7 v max from lipo cells, that makes 14.8 peak voltage 4s.
!2.6v would be the objective but "voltage converting?
I'm a mariner, not an electronics tech.
How would this be done, reliably, safely, economically by a competent novice?
Some kind of "limiter" I would imagine.

No matter, I think the fire risk is simply too high with the 18650's compared to the lifepo4 chemistry.
And way less work to build and install.
Even if I can contain a fire, I'm still out of the race without power.

On that note, is it okay to embed the lifepo4 in insulating foam?
The case will be a snug fit with no ventilation, i.e. sealed.
I could run copper tubing ($$$) salt water cooling off a venturi vent in the hull only inches away at zero risk.
But I'd rather not.
I suspect 15 amp max charging is a reasonable charging rate for a 75 ah lifepo4.
I guess it would be prudent to put a temp sensor on it so I know.
I can always retrofit cooling if need be.

Thoughts?

Thanks
Last edited by BlueBell on Feb 27 2018 12:49pm, edited 1 time in total.

BlueBell   10 W

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Re: Small Solar Proposal

Post by BlueBell » Feb 27 2018 12:21pm

And could I get some recommendations on terminal fuse options in my case?
As well as a controller/charger for my circumstance.
I'm planning to use circuit breaker style marine switches, Blueseas is a product I'm familiar with but open to suggestion.
I do know tinned wire is a must.
Thanks

billvon   1 MW

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Re: Small Solar Proposal

Post by billvon » Feb 27 2018 12:58pm

BlueBell wrote:
Feb 27 2018 12:21pm
I'm planning to use circuit breaker style marine switches, Blueseas is a product I'm familiar with but open to suggestion. I do know tinned wire is a must.
Tinned wire (purchased that way) is more corrosion resistant, but sealing the terminals is more important than type of conductor finish.

Under no circumstances should you "tin" stranded copper wire with solder before crimping it.
--bill von

BlueBell   10 W

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Re: Small Solar Proposal

Post by BlueBell » Feb 27 2018 6:57pm

billvon wrote:
Feb 27 2018 12:58pm
BlueBell wrote:
Feb 27 2018 12:21pm
I'm planning to use circuit breaker style marine switches, Blueseas is a product I'm familiar with but open to suggestion. I do know tinned wire is a must.
Tinned wire (purchased that way) is more corrosion resistant, but sealing the terminals is more important than type of conductor finish.

Under no circumstances should you "tin" stranded copper wire with solder before crimping it.
But I'm not using standard copper wire.. I'm using tinned wire... see above.

To which terminals are you referring, the battery in it's sealed compartment?

billvon   1 MW

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Re: Small Solar Proposal

Post by billvon » Feb 27 2018 7:33pm

BlueBell wrote:
Feb 27 2018 6:57pm
To which terminals are you referring, the battery in it's sealed compartment?
All terminals in a marine environment.
But I'm not using standard copper wire.. I'm using tinned wire... see above.
OK. The problem arises when people "tin" the wire they are going to use with solder; that is very problematic with crimped or swaged connectors.
--bill von

John in CR   100 GW

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Re: Small Solar Proposal

Post by John in CR » Feb 28 2018 12:48am

Like you said, the autopilot is getting rid of an extra person whining, complaining, and whatever else, so think of the space and weight savings of any lithium chemistry as giving you that advantage. All chemistries come in an 18650 version, so the thing you really want to exclude is any that can go into thermal runaway, which to me includes not only RC lipo, but all of the highest energy density batteries. Remember those Teslas that turned into raging infernos, while we never hear about Nissan Leafs, Chevy Volts, or others doing the same despite having far more cars on the road.

Cylindrical cells by their very shape take up 22% more space, which is wasted space. Your current demands of the pack are quite low, so you really don't have to worry about heat dissipation. Instead I would be focused on 2 things...
!. Making absolutely sure the pack is strapped down so it can't bang around in any way. Not only can that play hell on wiring and cause a short, but physical damage can lead to internal shorts within the individual cells or between cells resulting in rapid heat build-up and more serious problems. BTW, forget fire retardant systems, once lithium starts to go, there's nothing stopping it until the energy has been dissipated. I'd build it as 2 parallel packs physically separated by some kind of barrier for that reason...ie so you still have a battery to use the radio and call for help.
2. Making absolutely sure that salt water can't get into the pack- The way to go is to pot the entire 2 packs in something watertight, say a silicone gel and then wrap that in fiberglass/epoxy. You will still have wires going to the pack, your pos and neg leads and balance taps (or voltage reading taps at the cell level. For the wiring use solid core, since water can travel inside of insulation between strands.

To me the chemistry that makes the most sense is Lifepo4, because its voltage range works perfectly as a substitute for a 12V lead battery. I've used one I made as my car battery for going on 4 years. You're only talking about a bit more than a 1kwh battery in total, so the difference in size and weight of a few kilos at the most for piece of mind at sea knowing that only an external short igniting a flammable material is the only way to have a battery caused fire. The cells themselves aren't going to self ignite. Sure there are other just as safe lithium batteries that are more energy dense (less weight for same energy capacity), but you still haven't told us about the absolute voltage range required by your equipment.

I personally view BMS's as potential sources for failure, multitudes of potential sources in even a 4 cell BMS. I'm my own battery management system. All you need it a tiny cheap voltmeter and switch for each of the 4 parallel groups of cells...8 if you go dual parallel batteries. It's not like you won't have some free time to check your pack(s) status occasionally. eg I check the one on my car for balance about 3 times a year. If you have some kind of watt meter measuring what goes in and comes out of your battery,, you'll really only need to worry about monitoring anything if you run into a stretch with no sun, or worse, your solar panels get damaged and you're not charging at all.

Punx0r   10 GW

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Re: Small Solar Proposal

Post by Punx0r » Feb 28 2018 4:08am

Bluebell,

I appreciate you're getting a lot of comments on batteries and that's because a lot of the interest/knowledge on this forum is related to batteries. I know you're looking for some feedback on your selection of PV panels and a charge controller but stick with it, there are a few guys here you have home solar setups or mobile ones they use to charge their bike. Unfortunately it's not something I have much experience with.

I one way, settling on a battery will cement the required spec for the charge controller.

I've seen some nice glue-lined heat-shrink crimp terminals that were rated for marine use. Can't recall the brand right now, but they were said to be around $1 each, so pricey but there are products out there that are up to the job.

Punx0r   10 GW

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Re: Small Solar Proposal

Post by Punx0r » Feb 28 2018 4:12am

Forgot to say, a 5A constant, 13A peak draw on a ~75Ah battery is very gentle and the heat generated, even for low discharge-rated LiFePO4 cells should be minimal/negligible and should be OK in your proposed padded & sealed battery box. I figure you'll be running a discharge test of the system before hand so you can slip a temperature probe in the box and also account for the max ambient temp. you'll likely see on your race. The data sheet for the batteries will have a maximum rated operating temperature.

This boat and race sound quite something!

John in CR   100 GW

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Re: Small Solar Proposal

Post by John in CR » Feb 28 2018 8:41am

Punx0r wrote:
Feb 28 2018 4:12am
This boat and race sound quite something!
+1 Please be sure to share photos and video of your rig in action. Will it have foils?

What about storms? I can't even imagine flying a big powerful kite during a storm/

BlueBell   10 W

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Re: Small Solar Proposal

Post by BlueBell » Feb 28 2018 11:17am

Thank you all for your replies and comments, I appreciate your efforts.
Out of respect, I will address each of your comments but some of my original questions seem to be falling on deaf ears.

John, space is not so much the issue as is shape and weight as it relates to loading and impact.
I've already decided on lifepo4 so let's move on.
The battery wont bang around, that is a marine given, hence my concern about heat dissipation in foam.
The battery will be packed into the monocoque polystyrene foam construction of the boat with a fiber-epoxy lining.
Heat will not escape.
But at my charge rate and draw rate, it would seem there won't be an issue with lifepo4 and heat...
There is no BMS on the single 75ah 12v lifepo4. (I have back-up communications systems in place.)
Solid core wire and a very well sealed battery compartment will eliminate any water from getting to the battery provided the boat stays in one piece.
With five kite sizes on board (they are ridiculously light weight) I won't be having a huge kite up in high winds.
I appreciate your concern but what I really need help with is the electrical system.
Charger/controller selection, fusing, anything I'm not aware of in that department as it's not my forte.

PunxOr, thank you.

So, what controller/charger would be a good match and with what 75ah 12v lifepo4.
Any terminal fuses you'd recommend?
Any electrical issues you feel I may be overlooking here?
Who on the forum might be more likely to be able to help me?
I could PM them.
I'm running out of time and need to order my components.
Please help.

billvon   1 MW

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Re: Small Solar Proposal

Post by billvon » Feb 28 2018 11:53am

BlueBell wrote:
Feb 28 2018 11:17am
So, what controller/charger would be a good match and with what 75ah 12v lifepo4.
Any terminal fuses you'd recommend?
The Outback Kid is a great 30 amp MPPT controller and has a marine version as well. It will handle up to about 600W of solar. It can be set for LiFePO4, has an auxiliary output which is handy for standalone applications and is very rugged.
--bill von

BlueBell   10 W

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Re: Small Solar Proposal

Post by BlueBell » Feb 28 2018 12:46pm

[/quote]
The Outback Kid is a great 30 amp MPPT controller and has a marine version as well. It will handle up to about 600W of solar. It can be set for LiFePO4, has an auxiliary output which is handy for standalone applications and is very rugged.
[/quote]

billvon, thank you.
However, I Googled your key words and got everything but Outback Kid 30 amp MPPT controller.
There's Outback, and there's Kid but not 30 amps and lots of expensive features that I don't need.
Are you sure you have the name right?

Nice that some come with a battery temp sensor, that will increase safety hugely.
I'm only doing one bank, so no multi-bank charging needed.

Cheers

billvon   1 MW

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Re: Small Solar Proposal

Post by billvon » Feb 28 2018 1:42pm

BlueBell wrote:
Feb 28 2018 12:46pm
However, I Googled your key words and got everything but Outback Kid 30 amp MPPT controller.
There's Outback, and there's Kid but not 30 amps and lots of expensive features that I don't need.
Try this:

https://www.wholesalesolar.com/3930000/ ... controller
--bill von

BlueBell   10 W

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Re: Small Solar Proposal

Post by BlueBell » Feb 28 2018 3:14pm

billvon wrote:
Feb 28 2018 1:42pm
BlueBell wrote:
Feb 28 2018 12:46pm
However, I Googled your key words and got everything but Outback Kid 30 amp MPPT controller.
There's Outback, and there's Kid but not 30 amps and lots of expensive features that I don't need.
Try this:

https://www.wholesalesolar.com/3930000/ ... controller
Yup, that works.
Wow!
I just read through the instruction manual, OMG, is there anything it won't do?
What an education!
Years ago I wired and set-up remote, solar-powered seismic stations.
It was all plug and play, mostly.
I didn't need to know much but a little seeped in so I have a rudimentary knowledge and understanding.

Isn't 77 degrees F kind of low for the controller to start limiting charging?
I didn't see that it was adjustable.
I don't want to lose out on any "electron-loading" if 77F is too low.
In my sealed, packed foam battery situation, 77 may be a bit conservative...?
Thoughts?

And thank you.
(And I didn't bitch about the cost compared to the $25 chinese special...)
I'm also building (long term) a houseboat that I can transfer all this stuff too between races so the cost is a little more justifiable.

billvon   1 MW

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Re: Small Solar Proposal

Post by billvon » Feb 28 2018 3:37pm

BlueBell wrote:
Feb 28 2018 3:14pm
Isn't 77 degrees F kind of low for the controller to start limiting charging?
I didn't see that it was adjustable.
I don't want to lose out on any "electron-loading" if 77F is too low.
In my sealed, packed foam battery situation, 77 may be a bit conservative...?
Thoughts?
You won't be using the temperature sensor. That's for lead acid batteries. If you really want a temperature sensor, you can use the sensor on your battery and connect it to any display that can use a 10K thermistor as a sense element (i.e. do not use it with the Kid.)

You can use something like this:
https://www.adafruit.com/product/576?gc ... tYEALw_wcB
--bill von

BlueBell   10 W

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Re: Small Solar Proposal

Post by BlueBell » Feb 28 2018 4:38pm

billvon wrote:
Feb 28 2018 3:37pm
BlueBell wrote:
Feb 28 2018 3:14pm
Isn't 77 degrees F kind of low for the controller to start limiting charging?
I didn't see that it was adjustable.
I don't want to lose out on any "electron-loading" if 77F is too low.
In my sealed, packed foam battery situation, 77 may be a bit conservative...?
Thoughts?
You won't be using the temperature sensor. That's for lead acid batteries. If you really want a temperature sensor, you can use the sensor on your battery and connect it to any display that can use a 10K thermistor as a sense element (i.e. do not use it with the Kid.)

You can use something like this:
https://www.adafruit.com/product/576?gc ... tYEALw_wcB
Good to know, thank you.
I have to admit, I reviewed most of the instruction manual, vs "read" it.

BlueBell   10 W

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Re: Small Solar Proposal

Post by BlueBell » Feb 28 2018 4:47pm

I read the manual and it says it is adjustable for other than lead/acid.
So wouldn't I be a fool to not have it kick in by 90F as a safety precaution?
The more auto-magic safety features I have the better.
A high battery temp alarm may be prudent.

billvon   1 MW

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Re: Small Solar Proposal

Post by billvon » Feb 28 2018 4:58pm

BlueBell wrote:
Feb 28 2018 4:47pm
I read the manual and it says it is adjustable for other than lead/acid.
So wouldn't I be a fool to not have it kick in by 90F as a safety precaution?
The function they refer to is usually referred to as temperature compensation, and it decreases maximum charge voltages at high temperatures due to limitations of lead acid batteries. LiFePO4 does not have that limitation.

If you want to do a temperature alarm, then by all means do that. But don't use temperature compensation to do so.
--bill von

BlueBell   10 W

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Re: Small Solar Proposal

Post by BlueBell » Feb 28 2018 7:11pm

billvon wrote:
Feb 28 2018 4:58pm
BlueBell wrote:
Feb 28 2018 4:47pm
I read the manual and it says it is adjustable for other than lead/acid.
So wouldn't I be a fool to not have it kick in by 90F as a safety precaution?
The function they refer to is usually referred to as temperature compensation, and it decreases maximum charge voltages at high temperatures due to limitations of lead acid batteries. LiFePO4 does not have that limitation.

If you want to do a temperature alarm, then by all means do that. But don't use temperature compensation to do so.
Thank you. It is just that, voltage reduction at temperature. Okay, I won't use it I promise.

Is it prudent to have an over temp alarm or will this battery never get hot under these circumstances?
Would you put one in? If so, what temp threshold?

billvon   1 MW

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Re: Small Solar Proposal

Post by billvon » Feb 28 2018 9:47pm

BlueBell wrote:
Feb 28 2018 7:11pm
Is it prudent to have an over temp alarm or will this battery never get hot under these circumstances?
Would you put one in? If so, what temp threshold?
Overheating typically isn't a problem at your charge/discharge rates - the batteries will not generate much heat. Only way I could see them overheating is sun exposure or something.
--bill von

BlueBell   10 W

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Re: Small Solar Proposal

Post by BlueBell » Feb 28 2018 11:35pm

billvon wrote:
Feb 28 2018 9:47pm
BlueBell wrote:
Feb 28 2018 7:11pm
Is it prudent to have an over temp alarm or will this battery never get hot under these circumstances?
Would you put one in? If so, what temp threshold?
Overheating typically isn't a problem at your charge/discharge rates - the batteries will not generate much heat. Only way I could see them overheating is sun exposure or something.
Ya, so there is a problem here.
Everything in this set up is so unconventional.
The battery is embedded in insulating foam.
Sealed in it. Virtually zero heat will escape.

Punx0r   10 GW

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Re: Small Solar Proposal

Post by Punx0r » Mar 01 2018 3:55am

I have run RC lipo packs in sealed, foam-lined metal boxes before with no problems. However, there were gaps in the foam (it was for mechanical support/vibration resistance) which would allow some heat to escape. The main issue was the sun as the boxes were black. Silver boxes would be fairly effective protection from the sun.

A single block 12V LiFePO4 battery seems like a good idea and there's no reason to use a BMS.

I'd recommend a resettable circuit breaker rather than fuses as that way there's no running out of spare fuses ;)

I believe the connectors I was looking at are made by "Ancor". I see a lot of boating supply businesses stocking them with a google search.

BlueBell   10 W

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Re: Small Solar Proposal

Post by BlueBell » Mar 01 2018 12:54pm

Punx0r wrote:
Mar 01 2018 3:55am
I have run RC lipo packs in sealed, foam-lined metal boxes before with no problems. However, there were gaps in the foam (it was for mechanical support/vibration resistance) which would allow some heat to escape. The main issue was the sun as the boxes were black. Silver boxes would be fairly effective protection from the sun.

A single block 12V LiFePO4 battery seems like a good idea and there's no reason to use a BMS.

I'd recommend a resettable circuit breaker rather than fuses as that way there's no running out of spare fuses ;)

I believe the connectors I was looking at are made by "Ancor". I see a lot of boating supply businesses stocking them with a google search.
Okay, fair enough, thanks.
I will heed your advice.

I'm going to put a sensor/display in just to know what's going on in there.
What would a less than favourable temperature scenario look like and how would I mitigate it?
Climbing temp that passes 90F?, alarm trips, I start shutting off panels I guess...?
Doubt it's going to get warm discharging at 3 - 5 amps, more likely on charging at 16.5 amp max mid day (mid June).
But even then I understand it's not likely, especially if I get a high charge rate battery?
I do need to formulate an emergency plan however, before the emergency, if it never happens, fantastic, but I need to be prepared.
"Don't be scared, be prepared."
I can always retrofit a sea water copper cooling coil after sea-trials if need be.

The terminal fuses I was referring to were mounted right onto the battery terminal and were a one shot deal.
High amperage but a huge safety feature should even the terminals get shorted.
More along the lines you were mentioning, perhaps a 30 amp breaker that would also be my main power shut-off?
No reason why I couldn't mount that right into my breaker/switch panel with a red plastic safety cover over it?

Any name to avoid or favour in solar panels these days?
Siemens and BP used to be the way to go.
Anything descent out of China now... all of them I guess!

Expanding on your battery box, mine will be 2" from the epoxy-fiber, narrow, flat bottom of the boat (like expensive ballast!).
What to use to fill that 2" gap to reduce hull shock?
How shock sensitive are these batteries compared to lead-acid, which I'm used to?
Speeds will be on the higher side (I'm hoping) and there is lots of very large jetsam and flotsam, especially 2-3 foot diameter, 50 foot logs awash, that are invisible, day and night. Sea-containers awash, submarines, whales -both dead and alive, rocks!
The strike zone is further forward but the shock will be transferred directly.
Rubber? I can't place it on the polystyrene foam as it will crush and create space for it to bounce.
I could drill 3/8" holes in it for some cooling effect from the 50F sea water on the other side of the 3/16" hull.
It would also make the rubber slab more forgiving and shock absorbent.
A little outside your realm, but thought I'd ask.

Thank you.

BlueBell   10 W

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Re: Small Solar Proposal

Post by BlueBell » Mar 02 2018 7:05pm

Happy Friday!

Just realized, this doesn't add up.
4 amps draw times 24 hours = about 100 ah.
15 amps charging times six hours per day = 90 ah...
And that's if the sun's out...
Oh, good grief Charlie Brown.

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Re: Small Solar Proposal

Post by Hillhater » Mar 02 2018 7:51pm

:idea:
This forum owes its existence to Justin of ebikes.ca

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