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A genuinely silent generator


harrybsmith

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Evening all, I've had a bit of a brainwave...

 

One of these popped up as recommended for me:

https://www.amazon.co.uk/Portable-Generator-220V-240V-Flashlights-Emergency/dp/B07H3X4MLL/ref=sr_1_1?ie=UTF8&qid=1541017601&sr=8-1&keywords=lithium+generator

 

It's a sizeable (but portable) lithium battery pack, a bit like the ones many people have to recharge phones only a good deal higher capacity (claimed 150Wh) and with the all important 12v output. I'm able to charge it up at work no bother, am I right in thinking that if I connected a boost converter set to 14.4v to the 12v output (along with a volt meter and ammeter) I could do a tail current charge on my batteries? If my batteries were below 80% ish discharged i'd give the engine a run first to do the heavy lifting, but rather than sitting with the engine running annoying all my neighbours it would be ideal to top 'em up with this.

 

(should add, 220ah battery bank, low electrical usage, on mooring without electricity hookup)

 

 

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Genius!!

 

Long ago I imagined a similar plan using two banks of LA batts but it would never have worked. Lithium changes the game for peeps with access to a 240Vac grid connection.

Best bit is you can do the tail current charge after 8pm.... 

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1 minute ago, WotEver said:

Bear in mind it’ll give you less than 10Ah at 14.4V. So your 220Ah bank would need to already be at 95% charged for it to top them up to full. 

 

 

Had already clocked that, but it's that last 5% (or 10% with two of them in parallel...) that's the most elusive as I know you know. 

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14 minutes ago, harrybsmith said:

Had already clocked that, but it's that last 5% (or 10% with two of them in parallel...) that's the most elusive as I know you know. 

Clever Stuff Harry ,I can do the same by Isolating 3 out of a 6 Battery Bank and charging the" Idle" 3 from Inverter and Charger using power from "Service"3. next Day swap them over and all is good. I do this once a week when the Boat is away from its Home Mooring.

 

Edited by cereal tiller
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7 hours ago, cereal tiller said:

Clever Stuff Harry ,I can do the same by Isolating 3 out of a 6 Battery Bank and charging the" Idle" 3 from Inverter and Charger using power from "Service"3. next Day swap them over and all is good. I do this once a week when the Boat is away from its Home Mooring.

 

Wot. Howsat work den? :)

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Been thinking of something like this...

 

The power pack we've been dithering about (link below) is a lot more expensive.... the OP's link is very tempting. 

 

The battery/ies takes about 8 hours via a 240 connection for fully charging, which as we motor a couple of hours a day, and using solars on the odd days the winter sun comes out, the pack could be kept topped up. We also visit marinas for a few days every month in the winter, so another top up there. 

 

https://www.amazon.co.uk/Portable-54000Mah-Emergency-Household-Cigarette/dp/B07HJSDS91/ref=sr_1_1?ie=UTF8&qid=1541061130&sr=8-1&keywords=large+power+pack%2C+12v%2C+240

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24 minutes ago, Jennifer McM said:

Been thinking of something like this...

 

The power pack we've been dithering about (link below) is a lot more expensive.... the OP's link is very tempting. 

 

The battery/ies takes about 8 hours via a 240 connection for fully charging, which as we motor a couple of hours a day, and using solars on the odd days the winter sun comes out, the pack could be kept topped up. We also visit marinas for a few days every month in the winter, so another top up there. 

 

https://www.amazon.co.uk/Portable-54000Mah-Emergency-Household-Cigarette/dp/B07HJSDS91/ref=sr_1_1?ie=UTF8&qid=1541061130&sr=8-1&keywords=large+power+pack%2C+12v%2C+240

This one also has the advantage of a pure sine wave compared with the OP’s suggestion which has a modified sine wave.

Interesting thead ?

Edited by gbclive
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4 hours ago, rusty69 said:

Wot. Howsat work den? :)

 

I'll translate Cereal Tiller's post into plain English for you...

 

Get yourself two separate banks of domestic batteries. Arrange isolation switches so either bank can be isolated or brought into service (i.e. connected to your 12v domestic boat electrics), leaving the other battery bank disconnected and resting (or 'idling', to use CT's terminology). 

 

Get yourself an inverter and connect it to your 12v domestic boat electrics. Get yourself a decent mains three stage battery charger and connect it to the inverter. Now operate your isolator switches so as the connect one battery bank to your boat electrics while the other battery bank is disconnected (i.e. at idle). Start your engine and give the battery bank in service a good bulk charge using your alternator, up to say 80%. Stop the engine and switch over banks, start the engine again and bulk charge the other bank also to 80%. Neither charge will take that long as you are only going up to 80%. 

 

By now it is however 8pm and both banks are only charged to 80%. Connect the output of your battery charger to the 'idle' bank of batteries, and fully charge it up to 100% overnight. Eight hours of silent charging should do it. This will deplete your domestic 'in service' bank to maybe 55% so next day, in the daytime, run your engine for a couple of hours to bring them back up to 80%. Stop your engine. Use this bank as normal for a couple of days, charging back up to 80% as necessary using the engine but when it is time to give it the weekly charge up to fully 100%, first use the engine to bulk charge to 80% then use the previously 100% charged 'idle' set and the inverter and charger to charge the 'in service' battery bank to 100%.

 

Now switch over battery banks using your isolator switches and use the other bank for a few days, while the first battery bank sits waiting at 100% SoC ready to be used again. 

 

Repeat ad infinitum.

 

The point of this is to avoid ever having to run the engine for eight hours at a stretch waiting for the tail current to get down to 1%.

 

Edited by Mike the Boilerman
To improve clarity
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3 hours ago, Halsey said:

Can we have an idiots (I'm the idiot in this case) guide to what this does?? And where it plugs in and is that a permanent plug in?

KISS

A KISS guide:

 

The "Lithium Generator" as in my link (and in the links of others) has three outputs; USB (5v, for phone charging etc), 230V AC ( limited to 150w so not especially useful) and crucially 12v. The device is effectively a big battery with various protection circuitry on it that enables it to be charged up safely from mains and to output the three voltages.

 

Into the 12v output of the "lithium generator" you would plug in a boost converter. This is a little gizmo that takes 12v and transforms it into 14.4v for battery charging. I would then propose to plug this into an Anderson plug (a type of high current waterproof plug often used to connect winches) which would be connected to the same terminal as my alternator, so to a battery monitor it looks like the engine is running.  

 

It wouldn't be permanent, I plan to disconnect the "lithium generator" when flat and take it into work to charge. It's not very big so will easily sit in a rucksack.  In my charging routine it'll basically do the job that solar would in summer. 

 

Hope that helps!

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So being dim(ish) where electrics are concerned, you have to charge these units up from 240v and then you can withdraw the stored power when you're off grid. Would/could you charge this via an inverter with t'injun running ie. cruising?

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2 hours ago, Mike the Boilerman said:

 

I'll translate Cereal Tiller's post into plain English for you...

 

Get yourself two separate banks of domestic batteries. Arrange isolation switches so either bank can be isolated or brought into service (i.e. connected to your 12v domestic boat electrics), leaving the other battery bank disconnected and resting (or 'idling', to use CT's terminology). 

 

Get yourself an inverter and connect it to your 12v domestic boat electrics. Get yourself a decent mains three stage battery charger and connect it to the inverter. Now operate your isolator switches so as the connect one battery bank to your boat electrics while the other battery bank is disconnected (i.e. at idle). Start your engine and give the battery bank in service a good bulk charge using your alternator, up to say 80%. Stop the engine and switch over banks, start the engine again and bulk charge the other bank also to 80%. Neither charge will take that long as you are only going up to 80%. 

 

By now it is however 8pm and both banks are only charged to 80%. Connect the output of your battery charger to the 'idle' bank of batteries, and fully charge it up to 100% overnight. Eight hours of silent charging should do it. This will deplete your domestic 'in service' bank to maybe 55% so next day, in the daytime, run your engine for a couple of hours to bring them back up to 80%. Stop your engine. Use this bank as normal for a couple of days, charging back up to 80% as necessary using the engine but when it is time to give it the weekly charge up to fully 100%, first use the engine to bulk charge to 80% then use the previously 100% charged 'idle' set and the inverter and charger to charge the 'in service' battery bank to 100%.

 

Now switch over battery banks using your isolator switches and use the other bank for a few days, while the first battery bank sits waiting at 100% SoC ready to be used again. 

 

Repeat ad infinitum.

 

The point of this is to avoid ever having to run the engine for eight hours at a stretch waiting for the tail current to get down to 1%.

 

But surely if you have two battery banks then as long as you get a modern very efficient inverter and battery charger you would never need to run the engine at all ?

 

.................Dave

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56 minutes ago, Nightwatch said:

So being dim(ish) where electrics are concerned, you have to charge these units up from 240v and then you can withdraw the stored power when you're off grid. Would/could you charge this via an inverter with t'injun running ie. cruising?

You can charge from 240v, I believe you can also charge from 12v (dunno though) and you can definitely charge direct from a solar panel with no charge controller required. I probably wouldn't usually charge off my inverter when cruising but no reason why you couldn't. 

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