I have found that with these cheaper DVOM that if the battery is low , it will read high.
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I use cheap meters to check battery voltage. The only thing you get by
checking the voltage is an idea how much of a charge you have. If you look at
the charts on voltage vs. charge you will see the battery must rest for many
hours to use the chart reliably.
That being said, an option to check the accuracy of your meter is to use a
high quality spdt switch. One connection connected to the battery bank. The
other connection to a regulated power supply. you can use the power supply to
verify the meter before you trust the battery reading.
Another option would be to use op amps in conjunction with your power supply
output to light an LED as a warning when the half way mark was hit on your
journey. Or you could set the op amp to signal a fully charged bank. Of course
only high quality small tolerance components will help with such a set-up (the
problem with low end meters).
As we all know only a complete monitoring of the power in, power out, will
give you any useful information.
Kevin Pemberton
On Monday, December 22, 2014 09:22:27 AM you wrote:
> I have used the inexpensive digital panel meters for years and not found
> them to be significantly inaccurate or unreliable, as verified by using a.
>
> A quality digital meter is the best investment you can make. A basic Fluke
> can be had for around $150 and will last a long time. The two Flukes I
> have, going on 30 years, are still as good as when I bought them!
>
> John
>
> Flatwater Electronics
> www.flatwaterfarm.com
> "Neurosurgery for computer looms."
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Martin,
The power from both the batteries and the Genset go through one distribution box. If the genset is running power is fed to both the motors and the batteries. As the power is charging the batteries I see an amp gauge decrease the output from the genset and know when it gets to 3 to 5 amps I have around a 90% full battery pack and can shut the genset off. I also have a relay system called LOGO that will trip the generator off if I exceed the output rating of around 100A. Mind you I haven't explored all the capabilities of this relay, I know I can use it for many other things but that's another story, however it's a simple push of a button to reset the generator and decrease the load to get it to continue to run. If I set the genset to output 160V I can't hurt the batteries (144V pack).
Typically I 'll start out under batteries alone. IF there is enough wind to get me sailing to around 6 to 8 knots the REGEN through the props is enough to charge the batteries, over say 8 hours, that when I come back in the batteries are close to when I left less the run time getting in.
Honestly I've never disconnected the batteries to see if the Genset would run the motors by themselves but see no reason that it couldn't as long as I didn't throw the throttles into full open exceeding the gensets amp output tripping the breaker.
My LA pack of AGM's is getting old at 9 years and I'm losing run time so have started to think hard about switching to Lithium's in another year or more (hopefully). I'll be asking questions about the use of contacts to control the charging of the pack, something I haven't been able to find clear answers for. All I need is the cash to do it! 8o)
Steve in Solomons MD
Lagoon 410 S2 E
Steve,
You need your batteries to start both of your motors...right? then your genset can do the job...
Martin
Kveðja – Regards
Stefán B. Jónsson
Sími: +354-4781309 GSM: +354 8946541, skype: stefan.martolvan.is
Trúnaður /Disclosure
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Martin,
The power from both the batteries and the Genset go through one distribution box. If the genset is running power is fed to both the motors and the batteries. As the power is charging the batteries I see an amp gauge decrease the output from the genset and know when it gets to 3 to 5 amps I have around a 90% full battery pack and can shut the genset off. I also have a relay system called LOGO that will trip the generator off if I exceed the output rating of around 100A. Mind you I haven’t explored all the capabilities of this relay, I know I can use it for many other things but that’s another story, however it’s a simple push of a button to reset the generator and decrease the load to get it to continue to run. If I set the genset to output 160V I can’t hurt the batteries (144V pack).
Typically I ‘ll start out under batteries alone. IF there is enough wind to get me sailing to around 6 to 8 knots the REGEN through the props is enough to charge the batteries, over say 8 hours, that when I come back in the batteries are close to when I left less the run time getting in.
Honestly I’ve never disconnected the batteries to see if the Genset would run the motors by themselves but see no reason that it couldn’t as long as I didn’t throw the throttles into full open exceeding the gensets amp output tripping the breaker.
My LA pack of AGM’s is getting old at 9 years and I’m losing run time so have started to think hard about switching to Lithium’s in another year or more (hopefully). I’ll be asking questions about the use of contacts to control the charging of the pack, something I haven’t been able to find clear answers for. All I need is the cash to do it! 8o)
Steve in Solomons MD
Lagoon 410 S2 E
Steve,
You need your batteries to start both of your motors...right? then your genset can do the job...
Martin
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Just don't run them up over 8kw each and it will work.
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Hi Martin,
I've attached an article on the first of 3 410 S2 E electrics produced with the Solomons system. The original diesels where rated at around 27HP each side.
http://www.multihull-maven.com/Electric_Lagoons
Waypoint has several articles out there so do a search if you want to see some other comments. Even at 8 knots I still have some throttle left so in rough weather I can push harder. The output of the genset limits me to around 80A.
Happy Holidays,
Steve in Solomons MD
410 S2 E
From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com]
Sent: Thursday, December 25, 2014 10:19 AM
To: electricboats@yahoogroups.com
Subject: RE: [Electric Boats] running the motor on genset
Steve,
What size diesel engine(or engines) your two 12hp electric motors replace?
you say that you do hull speed with your genset but what about in rough weather?
Martin
To: electricboats@yahoogroups.com
From: electricboats@yahoogroups.com
Date: Tue, 16 Dec 2014 07:08:55 -0500
Subject: RE: [Electric Boats] running the motor on genset
Martin,
I have a 41 foot Cat with the Solomons Tech system, Twin ST74 motors putting out 12HP(24HP) on each side. I also have a 16 KW Genset that meets the needs to get to hull speed, around 8 knots. With a variable speed output on the genset I charge the batteries then any excess power is sent to the motors. Now here's the kicker. I run at 144V DC which means I only need around 80A to run at hull speed so the 16KW genset meets the needs of the motors. By setting the genset output to anywhere from 144V to 164V DC I can safely charge the batteries then run the motors with the genset since the amperage is reduced to the batteries. I can run all day on genset only if I had to.
So to answer your question yes you can but Genset size would depend on your voltage output (amps) of the genset and the motor requirements. This sounds like you're looking at a mono boat in the 40 ft range?
Steve in Solomons MD
Lagoon 410 S2E
did someone run his motor only on generator power without any batteries? was this discussed before? would it need a too big generator ? I was thinking of a 15 hp motor driven by a 25kw generator?
any opinions?
Thanks, Martin
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Hi Martin,
I've attached an article on the first of 3 410 S2 E electrics produced with the Solomons system. The original diesels where rated at around 27HP each side.
http://www.multihull-maven.com/Electric_Lagoons
Waypoint has several articles out there so do a search if you want to see some other comments. Even at 8 knots I still have some throttle left so in rough weather I can push harder. The output of the genset limits me to around 80A.
Happy Holidays,
Steve in Solomons MD
410 S2 E
From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com]
Sent: Thursday, December 25, 2014 10:19 AM
To: electricboats@yahoogroups.com
Subject: RE: [Electric Boats] running the motor on genset
Steve,
What size diesel engine(or engines) your two 12hp electric motors replace?
you say that you do hull speed with your genset but what about in rough weather?
Martin
To: electricboats@yahoogroups.com
From: electricboats@yahoogroups.com
Date: Tue, 16 Dec 2014 07:08:55 -0500
Subject: RE: [Electric Boats] running the motor on genset
Martin,
I have a 41 foot Cat with the Solomons Tech system, Twin ST74 motors putting out 12HP(24HP) on each side. I also have a 16 KW Genset that meets the needs to get to hull speed, around 8 knots. With a variable speed output on the genset I charge the batteries then any excess power is sent to the motors. Now here's the kicker. I run at 144V DC which means I only need around 80A to run at hull speed so the 16KW genset meets the needs of the motors. By setting the genset output to anywhere from 144V to 164V DC I can safely charge the batteries then run the motors with the genset since the amperage is reduced to the batteries. I can run all day on genset only if I had to.
So to answer your question yes you can but Genset size would depend on your voltage output (amps) of the genset and the motor requirements. This sounds like you're looking at a mono boat in the 40 ft range?
Steve in Solomons MD
Lagoon 410 S2E
did someone run his motor only on generator power without any batteries? was this discussed before? would it need a too big generator ? I was thinking of a 15 hp motor driven by a 25kw generator?
any opinions?
Thanks, Martin
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I am analytical and look at numbers.
As such, the project is expensive but doable.
25 kWhr usable load needs a minimum 30 kWhr battery (similar size as a tesla), and with some margin 40 kWhr.
At 500 $ / kWhr, ==> 20.000$.
At, say, 100 Wh/kg, => 400 kg battery mass.
Thus, its technically feasible, since the motors will be small and light.
The extra battery mass is likely still doable.
I would suggest planning around 100.000$ for systems cost.
Note requirement for proper schematics, survey, a licensed marine engineers write-off on safety etc. as its a commercial vessel.
Perhaps double insulated cables.
In a fjord (Norway) the engineers costs and licensing will be reasonable.
All prices are in line for any other custom commercial, insured, build, in my opinion and in my experience.
Any custom build will have the same safety and licensing costs, anyway.
The last thing you look at, or should think about, is motors, controllers etc.
The first thing you look at is systems cost, legal, engineering practicalities, and any suitable "white-box" technology will slot right in.
All good engineering solutions are pretty much comparable, and any one will work.
The legal aspects are about 2/3 the total cost and work, and should be the overriding focus, in the initial business plan.
In the us, or here in spain, the legal aspects might easily cost more than the 100k budget I mentioned.
In scandinavia, not necessarily.
I can advise further, if there is interest.On 24/12/2014 20:57, 'Myles Twete' matwete@comcast.net [electricboats] wrote:Any feedback for this gentleman?
From: electricboats-owner@yahoogroups.com [mailto:electricboats-owner@yahoogroups.com] On Behalf Of Stefán Brandur Jónsson stefan@martolvan.is [electricboats]
Sent: Tuesday, December 23, 2014 9:11 AM
To: electricboats Moderator
Subject: Re: FILE - Welcome
Hi All
I'm Stefan from Iceland, I'm an electronics field engineer by profession and bit of an boat and energy efficiency enthusiast.
My latest project is an feasibility / business plan for an catamaran tourist boat for using in my fjord that is for the most part very shallow, I think that an electric Jet drive would be the best fit where I need to overcome currents up to 8 knots in graceful manner. are there any ones that have some good advice on motor, battery and controller choices. My goal is to go electric only on approx hour trip on approx 25 KW load (max power 2 x 28 KW).
Look forward to comments.
,_._,___-- -hanermo (cnc designs)
Kveðja – Regards
Stefán B. Jónsson
Sími: +354-4781309 GSM: +354 8946541, skype: stefan.martolvan.is
Trúnaður /Disclosure
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I am analytical and look at numbers.
As such, the project is expensive but doable.
25 kWhr usable load needs a minimum 30 kWhr battery (similar size as a tesla), and with some margin 40 kWhr.
At 500 $ / kWhr, ==> 20.000$.
At, say, 100 Wh/kg, => 400 kg battery mass.
Thus, its technically feasible, since the motors will be small and light.
The extra battery mass is likely still doable.
I would suggest planning around 100.000$ for systems cost.
Note requirement for proper schematics, survey, a licensed marine engineers write-off on safety etc. as its a commercial vessel.
Perhaps double insulated cables.
In a fjord (Norway) the engineers costs and licensing will be reasonable.
All prices are in line for any other custom commercial, insured, build, in my opinion and in my experience.
Any custom build will have the same safety and licensing costs, anyway.
The last thing you look at, or should think about, is motors, controllers etc.
The first thing you look at is systems cost, legal, engineering practicalities, and any suitable "white-box" technology will slot right in.
All good engineering solutions are pretty much comparable, and any one will work.
The legal aspects are about 2/3 the total cost and work, and should be the overriding focus, in the initial business plan.
In the us, or here in spain, the legal aspects might easily cost more than the 100k budget I mentioned.
In scandinavia, not necessarily.
I can advise further, if there is interest.
On 24/12/2014 20:57, 'Myles Twete' matwete@comcast.net [electricboats] wrote:
Any feedback for this gentleman?
From: electricboats-owner@yahoogroups.com [mailto:electricboats-owner@yahoogroups.com] On Behalf Of Stefán Brandur Jónsson stefan@martolvan.is [electricboats]
Sent: Tuesday, December 23, 2014 9:11 AM
To: electricboats Moderator
Subject: Re: FILE - Welcome
Hi All
I'm Stefan from Iceland, I'm an electronics field engineer by profession and bit of an boat and energy efficiency enthusiast.
My latest project is an feasibility / business plan for an catamaran tourist boat for using in my fjord that is for the most part very shallow, I think that an electric Jet drive would be the best fit where I need to overcome currents up to 8 knots in graceful manner. are there any ones that have some good advice on motor, battery and controller choices. My goal is to go electric only on approx hour trip on approx 25 KW load (max power 2 x 28 KW).
Look forward to comments.
,_._,___
-- -hanermo (cnc designs)
Kveðja – Regards
Stefán B. Jónsson
Sími: +354-4781309 GSM: +354 8946541, skype: stefan.martolvan.is
Trúnaður /Disclosure
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Hi Martin,
I’ve attached an article on the first of 3 410 S2 E electrics produced with the Solomons system. The original diesels where rated at around 27HP each side.
http://www.multihull-maven.com/Electric_Lagoons
Waypoint has several articles out there so do a search if you want to see some other comments. Even at 8 knots I still have some throttle left so in rough weather I can push harder. The output of the genset limits me to around 80A.
Happy Holidays,
Steve in Solomons MD
410 S2 E
From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com]
Sent: Thursday, December 25, 2014 10:19 AM
To: electricboats@yahoogroups.com
Subject: RE: [Electric Boats] running the motor on genset
Steve,
What size diesel engine(or engines) your two 12hp electric motors replace?
you say that you do hull speed with your genset but what about in rough weather?
Martin
To: electricboats@yahoogroups.com
From: electricboats@yahoogroups.com
Date: Tue, 16 Dec 2014 07:08:55 -0500
Subject: RE: [Electric Boats] running the motor on genset
Martin,
I have a 41 foot Cat with the Solomons Tech system, Twin ST74 motors putting out 12HP(24HP) on each side. I also have a 16 KW Genset that meets the needs to get to hull speed, around 8 knots. With a variable speed output on the genset I charge the batteries then any excess power is sent to the motors. Now here’s the kicker. I run at 144V DC which means I only need around 80A to run at hull speed so the 16KW genset meets the needs of the motors. By setting the genset output to anywhere from 144V to 164V DC I can safely charge the batteries then run the motors with the genset since the amperage is reduced to the batteries. I can run all day on genset only if I had to.
So to answer your question yes you can but Genset size would depend on your voltage output (amps) of the genset and the motor requirements. This sounds like you’re looking at a mono boat in the 40 ft range?
Steve in Solomons MD
Lagoon 410 S2E
did someone run his motor only on generator power without any batteries? was this discussed before? would it need a too big generator ? I was thinking of a 15 hp motor driven by a 25kw generator?
any opinions?
Thanks, Martin
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