Jump to content

Recommend me a battery setup


Rory_d

Featured Posts

3 minutes ago, TheBiscuits said:

16W sounds low for an eversplutter.  Where did you get that figure?

 

yw forum I think, its a start up and 4 hours running and a shut down, just background.

According to Eberspacher, the D4 uses a max of 40W when running at full power - that's about 3.5A - and only 13W (just over 1A) at medium setting. I think some Eberspacher owners must have inaccurate ammeters!

Link to comment
Share on other sites

42 minutes ago, TheBiscuits said:

What does it draw on startup?  Some can draw 10 or 12 amps during their startup phase.

 

( I won't say for how long to avoid confusion!)

"Blimey, my D5 heater according to my Nasa BM1 uses 20amp for about a minute at start up and close down and 6-7amp when running! I never realised the D4 used so much less current, mind you we do run ours on full power all the time. After 1 hour it automatically switches off!

"The power requirements for my D4 Plus, are quoted (in watts) as:
Start. 100
Max Power. 55
High Power. 30
Medium. 16
Low. 7
 

so  depends on the model

Its easier to  multiply by 10 or 20, i chose [20 wi fi]

I think its back to the drawing board on  some of those figures, but I really wanted some guide on batteries/solar

Edited by LadyG
Link to comment
Share on other sites

3 hours ago, TheBiscuits said:

What does it draw on startup?  Some can draw 10 or 12 amps during their startup phase.

 

( I won't say for how long to avoid confusion!)

 

Yes its about 10a for not that long. Three or four minutes I'd guess, but I haven't timed it. 

 

Link to comment
Share on other sites

As I see it.

It seems to me that selecting and sizing a  battery bank depends on your unique electrical demands over each week of the year, You must factor in worst case periods of high or prolonged demand without adequate recharging ability such as laid up on a "no engines running" mooring and needing the oil fired central heating to stay warm. Effectively abusive discharge.

What are the sources of charging available, Engine, Solar, Shore power, and separate generator. The availability of these sources is dependant on your choice of a cruising, living, and laying up regime and your boats own equipment. 

Maintaining lead acid batteries to minimise their degradation is complicated by their charging curve that needs long periods on charge to squeeze the last of the charge in up to float voltage and that any deep discharge degrades them. 

Unless you can regularily acheive getting the batteries back to float state, and you never leave them in a depleted state you must suffer shortened battery life. Effectively abusive charging.

If you can avoid abusive discharging and can always acheive effective recharging, then you should expect years out of a large quality battery bank. Other forum members can probably enlighten us on achievable life.

But if abusing your batteries either on discharge or charging is inevitable to your intended operations or equipment limitations, then you can limit the damage potential by running a smaller battery bank of lower grade batteries and resign yourself to replacing them every one or two years. I suspect hire boat operators use this method as they have little controll over both the usage and charging regimes. The worst thing though is to have an expensive battery bank and then abuse it. It just takes just a little longer to goose a large bank of expensive batteries then a minimal bank of cheapies.

 

 

 

 

 

 

 

Link to comment
Share on other sites

Just now, Mike the Boilerman said:

 

Yes its about 10a for not that long. Three or four minutes I'd guess, but I haven't timed it. 

 

That's another good reason not to short-cycle them then, but does make me wonder how they get average power figures.

 

Run it for ten minutes and you'll get a 4 minute 10A startup cycle, 6 minutes running at 4A and maybe a 2 minute shutdown cycle at 8A if it does that.

 

That's a lot of amp minutes.

 

 

 

Link to comment
Share on other sites

How many batteries? This question does not have an easy answer even with power audits etc.  But to summarise all the good points from above, and adding a couple of points of my own, this may help the op if they are still reading.

 

1 - At normal ‘dark weather’ usage how long do I reasonably want to power the boat between charges without going below 50% soc.  

1.1. Bearing in mind that the longer between charges the greater the damage.  I wanted 2.5 days (2days & 3 nights) though it was not my intention to do this often.

1.2. When battery manufacturers state their batteries have say 350 cycles they mean discharge to 50% soc at a current of 5A per 100Ah battery in the bank, and upon reaching 50% soc immediately recharge to 100% and at the end of 350 cycles the battery will have lost 50% of it’s capacity.  So if you routinely use 50Ah per battery it will not be long before you are discharging to a lot more than 50% of available capacity, so don’t expect 350 cycles.

1.3. The manufacture’s discharge spec takes 10hours to discharge to 50% soc before recharging, higher currents or longer periods before recharging will reduce the battery life.  So actually achieving the number of discharge cycles to 50% in the real world is basically impossible.

 

2 - Max power demand for more than a minute.

2.1. Batteries are ‘happy’ for brief high power demands (consider engine starting) however for longer periods, high currents are harmful, so running a 2kW inverter for 10 mins (say a microwave and small hair drier running at the same time) will not run happily from a couple of 110Ah batteries, you will damage the plates.  To share the load the bank needs to be bigger.  -  I would add that this should not be normal behaviour, but if you have a big inverter it may (will) happen especially if you lend out your boat.

 

3 -  The bigger the bank the better the SOC at the end of each day and the better the ability to supply large powers without damage, so with care the longer the bank will last.  BUT and it’s a big BUT the bigger the bank the more it costs to replace.

 

So the final choice of ‘how many batteries’ will also include deciding how much you can afford and how often for replacement batteries and then adjusting your power consumption and recharging patterns to suit.

  • Greenie 1
Link to comment
Share on other sites

May I add that seeing how well, or not, many boat builders adhere to the BMEA code about batteries being easy to access the weight of a battery may determine the size you choose simply on the grounds of having to manhandle it into position. Basically the fewer parallel connected batteries you have to provide a given number of Amp hours the better but not if the individual batteries are so heavy/large you struggle to get then into their allotted space. Hence I would suggest the popularity of 1110Ah batteries.

  • Happy 1
Link to comment
Share on other sites

10 hours ago, TheBiscuits said:

That's another good reason not to short-cycle them then, but does make me wonder how they get average power figures.

 

Run it for ten minutes and you'll get a 4 minute 10A startup cycle, 6 minutes running at 4A and maybe a 2 minute shutdown cycle at 8A if it does that.

 

That's a lot of amp minutes.

But isn’t the general advice to run them for about an hour?  The average will be a lot lower if so. 

Link to comment
Share on other sites

1 minute ago, Tony Brooks said:

May I add that seeing how well, or not, many boat builders adhere to the BMEA code about batteries being easy to access the weight of a battery may determine the size you choose simply on the grounds of having to manhandle it into position. Basically the fewer parallel connected batteries you have to provide a given number of Amp hours the better but not if the individual batteries are so heavy/large you struggle to get then into their allotted space. Hence I would suggest the popularity of 1110Ah batteries.

Wish I was strong enough to pick up one of those ?

  • Haha 2
Link to comment
Share on other sites

Thanks for all of the advice .

 

i have got a big generator so will run that daily to power washing machine as I don’t want to kill the inverter or batteries.

 

as for the batteries and power it’s hard to do an audit without some stuff being purchased as yet.

 

the power inverter I have bought is a sterling combi s inverter charger 2500w 

 

i have ordered 2 220amp batteries to get me started so I can have the lights etc working whilst the rest of the refit is done and so it can go back in the water.

 

when it is in the water I will do a full power audit and if needed will order more batteries   And adjust to suit our needs

Link to comment
Share on other sites

9 hours ago, Rory_d said:

Thanks for all of the advice .

 

i have got a big generator so will run that daily to power washing machine as I don’t want to kill the inverter or batteries.

 

as for the batteries and power it’s hard to do an audit without some stuff being purchased as yet.

 

the power inverter I have bought is a sterling combi s inverter charger 2500w 

 

i have ordered 2 220amp batteries to get me started so I can have the lights etc working whilst the rest of the refit is done and so it can go back in the water.

 

when it is in the water I will do a full power audit and if needed will order more batteries   And adjust to suit our needs

Don't forget to carry out guestimates about charging. More batteries are ruined by undercharging than being under capacity for the job. You really do need to get battery monitoring and learn how to use it if you want to optimise battery life. Make sure you understand how lead acid batteries demand a very long, low current charge to get close to fully charged. We are talking many, many hours.

Link to comment
Share on other sites

9 hours ago, Rory_d said:

i have ordered 2 220amp batteries to get me started

They are what I use.

I have 6 of them and they are not easy (at 58kgs each) to wriggle them into tight boat spaces.

If you have ordered but not yet despatched - Ensure you have ordered the ones which have removable caps so you can top-up the water levels or they won't last very long.

Link to comment
Share on other sites

11 minutes ago, Tony Brooks said:

Don't forget to carry out guestimates about charging. More batteries are ruined by undercharging than being under capacity for the job. You really do need to get battery monitoring and learn how to use it if you want to optimise battery life. Make sure you understand how lead acid batteries demand a very long, low current charge to get close to fully charged. We are talking many, many hours.

 

Or more helpfully, 12 hours to charge from 50% to 100% according to Battery University. 

Link to comment
Share on other sites

23 hours ago, Tony Brooks said:

May I add that seeing how well, or not, many boat builders adhere to the BMEA code about batteries being easy to access the weight of a battery may determine the size you choose simply on the grounds of having to manhandle it into position. Basically the fewer parallel connected batteries you have to provide a given number of Amp hours the better but not if the individual batteries are so heavy/large you struggle to get then into their allotted space. Hence I would suggest the popularity of 1110Ah batteries.

Completely agree. The vast majority of boats/boaters I have known use 110 bog standard batteries due to weight as you say being able to manhandle the damn things, price,  and importantly because of their obvious popularity immediately available from eighteen billion sources including on the shelf at most boatyards if needed in a hurry. If the boat moves a lot or a good charging regime otherwise is maintained they do an admirable job. I have to add that I will never again have a boat without a travel power which are fantastic bits of kit. To me it is more important on my wants list when I buy a boat than ensuring it doesnt have a pram hood or cratch cover although of course those items can be binned.

Link to comment
Share on other sites

23 minutes ago, blackrose said:

Just back to this thread.... Are we still ganging up and slagging off this guy for asking a battery question without doing a power audit? :icecream:

Rather that than slagging off people  who don't even have a boat?

 tbf [I think they were pretty kind :) ] to me ..................

I think he's pretty brave to do a fit out by the learn as you go method. He'll know a lot more in a year or three. 

He's bought 2 x 220 batteries.

Edited by LadyG
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.