Battery Bank Sizing and Type

[Alan de Enfield]

8 minutes ago, plb210 said:

Running a benchmark for worst case scenario first. 

Also testing each item individually so can make a spreadsheet.

 

Pump is 70w 24hrs

TV is 280w 4hrs

Fridge when compressor on 70w 24hrs

I know its not the most exciting job - when estimating your fridge you do need to note the run time.

I sat in our dining room (opposite the kitchen) for a couple of hours reading, and noted the on-off-duration time of the fridge running - that was obviously 'ideal' conditions because the door was not opened during the test-time. For my Waeco it was approximately 18 minutes per hour which I then took to be 1/3rd of an hour so, the fridge was assumed to run 8 hours per day.

 

During typing Robbo has pre-empted me on the TV - is it steam powered ?

 

Edit to Add :

 

My Waeco Fridge manual states 'Average consumption 40w'

Where are you obtaining your fridge info from ?

Edited April 29, 2017 by Alan de Enfield

[plb210]

Yeah we are going to get a true 12v tv for when out on the cut. Save running the BEAST.

 

Think mite tell mum n dad to get a shunt for 12v and a 240v current meter to leave fitted in the control board.

[Robbo]

The plugin ac monitor's can also tell you how many kWh's are used, this is more important than the watts use.   Plug the device in for an applicance and over 24 hrs read the kWh total.   This will get a more accurate reading for a fridge/freezer, etc.

[Arthur Brown]

Buy the smallest set of batteries that will do your job, or the largest set that you can afford to lose. 

Most battery problems resolve to -I haven't charged them and now there is nothing there to take out , leading to the engine not starting and the batteries being left empty til they are past recovery.

The best battery life reported on here is ten years, the worst is ten weeks. the difference is how you treat your batteries. As you have an inverter I'd suggest a complete roof cover of solar 500 to 1000w would be a good start, then accept that for three months solar will produce effectively nothing, so you will need a generator period or a cruise time -or both. 

[rusty69]

2 minutes ago, Arthur Brown said:

The best battery life reported on here is ten years, the worst is ten weeks. the difference is how you treat your batteries

As well as their quality. 

[WotEver]

As it's not been said concisely, I'll chip in with this...

1. Calculate your daily usage. 

2. Determine how you will generate this plus 20% each day, particularly in winter, allowing for inefficiencies and long absorption times. If you are unable to make this balance with 1. then you must reduce 1. until you can.  

3. Once 1. & 2. balance, and not before, select a battery bank size of 2.5 to 3 times 1.  

Dont think of batteries as 'power generators', think of them as 'power storage containers with losses'  

Tony

[Robbo]

54 minutes ago, Mike the Boilerman said:

As an aside, an ordinary mains central heating pump rated at 70w only draws 70w when set to max speed. They usually have three user-selectable speeds. In my experience the lowest speed (typically about 25w) will run six smallish radiators perfectly happily.

These newfangled 'high efficiency' central heating pumps which self-modulate can be a PITA though. I've heard they don't like being run/refuse to run from certain makes/models of inverter.

You could also run the pump from a pipestat? that only runs when the back boiler is up to temperature.

[plb210]

3 hours ago, Robbo said:

You could also run the pump from a pipestat? that only runs when the back boiler is up to temperature.

Yeah been thinking that also looking at a good 12v pump 

[jddevel]

So how many  would consider Lithium ion deep cycle batteries if you had a couple of grand to spend?? 

12v 40 AH Lithium ion deep cycle battery RB40

Equivalent to 70 ah when compared to wet lead acid, agm and gel type. Can be charged with conventional chargers Great for Extreme heavy duty use such as live aboard Boat, leisure,Motorhome and Caravan use. Solar and renewable systems

[WotEver]

52 minutes ago, jddevel said:

Can be charged with conventional chargers

I'd want to see documentary proof of this along with an explanation of 'how'. 

[jddevel]

I seem to have deleted rather than commented about the remarks written by Mboss in August 16 about a company called RoadPro he`d  been in touch with who seemed to have solved the problem.

[WotEver]

My recollection of that thread was that he never received a satisfactory answer. But maybe I'm mis-remembering it?

[Robbo]

35 minutes ago, jddevel said:

So how many  would consider Lithium ion deep cycle batteries if you had a couple of grand to spend?? 

12v 40 AH Lithium ion deep cycle battery RB40

Equivalent to 70 ah when compared to wet lead acid, agm and gel type. Can be charged with conventional chargers Great for Extreme heavy duty use such as live aboard Boat, leisure,Motorhome and Caravan use. Solar and renewable systems

Me personally am looking at lithium batteries.  Don't think the overall cost is cheaper than traction, but the lithium has good advantages in other areas especially if charging via genny.  Look at Relion batteries as these have a BMS built in so are a direct drop in (you charge like they were AGM's).  

[plb210]

What's people's thoughts then flooded or agm

 

[MtB]

On 29/04/2017 at 20:59, plb210 said:

What's people's thoughts then flooded or agm

 

Both will work.

What are YOUR thoughts?

[peterboat]

Late to this but I have 1500 ah of full traction batteries one bank 12 years old the other 6, I have looked after them with 900 watts of solar and a whispergen that does 72 ah at 12 volts. The whispergen in winter runs for 3 hours a day making up for the missing solar plus it does the central heating. If you have a big battery bank you have to have a good charging regime like mine to stop damage, the MPPT controller does equilisation when required and a watering system keeps the batteries topped up. When living off grid you have to look at your energy usage, and keep it to the minimum for winter time lack of sun!

I am currently getting ready to convert a broads cruiser to electric drive and I am going through everything to minimise energy usage which means things like gravity instead of pumped rads, electricity is easy to use but hard to make so consider whats important and what isnt