Jump to content

24v system, new batteries.


Mark 0810

Featured Posts

7 minutes ago, Mark 0810 said:

Because I always forget to switch off the plug. Having now written this I hope I will remember to do so! But that wouldn't account for such a drop would it?

And however much I leave the engine running battery monitor never goes above 98%.

May depend on your monitor. In general because of the inefficiencies between energy in and energyout, a simple measure of amp hours will never return to 100%. What some systems do is to assume that after a given period at a specified voltage means fully charged and will reset the reading accordingly. 

Link to comment
Share on other sites

3 hours ago, ditchcrawler said:

Are you sure he ones you have are beyond their useful life

I have a 24 volt system and have 4 Trojan T105 batteries in series, they ate 6 volt batteries

 

Yes I've heard that Trojan batteries have cannibalistic tendencies. ?

  • Haha 1
Link to comment
Share on other sites

1 hour ago, Mark 0810 said:

Because I always forget to switch off the plug. Having now written this I hope I will remember to do so! But that wouldn't account for such a drop would it?

And however much I leave the engine running battery monitor never goes above 98%.

What monitor, most of the percentage ones are just a guess 

Link to comment
Share on other sites

1 hour ago, Mark 0810 said:

I think so, just by the fact the monitor never shows 100% and will drop to below 80% even if I'm out for the day and only 24v fridge & freezer are on and TV on standby?

A fridge and freezer if that is 2 units will probably use 60 Ah in a day at 24 volts, if the TV is on standby what about the inverter? edit to add and the sat decoder, self seeking dish etc.

Edited by ditchcrawler
Link to comment
Share on other sites

15 minutes ago, ditchcrawler said:

A fridge and freezer if that is 2 units will probably use 60 Ah in a day at 24 volts, if the TV is on standby what about the inverter? edit to add and the sat decoder, self seeking dish etc.

To the op (in the nicest possible way) -  ahhh you have much to learn grasshopper

Link to comment
Share on other sites

Boater Sam I have no neighbours for a long way at the moment!

 

Battery monitor is mastervolt BTM III

 

No sat equipment, just TV (& mobile router which I can't see would take much)

 

Chewbacka, yes I'm sure I have lots & lots to learn!

 

 

Link to comment
Share on other sites

6 minutes ago, Mark 0810 said:

Boater Sam I have no neighbours for a long way at the moment!

 

Battery monitor is mastervolt BTM III

 

No sat equipment, just TV (& mobile router which I can't see would take much)

 

Chewbacka, yes I'm sure I have lots & lots to learn!

 

 

Inverter?

I would just read the volts and amps on that monitor.  When charging look for a voltage of 14.4 volts give or take .2 and a charge current of below 4 amps that would be a good indication your batteries are full.

Link to comment
Share on other sites

6 hours ago, Mark 0810 said:

I had solar panels fitted last week...  ... they said they don't see many 24v systems. I was surprised as I just assumed it's a 12v system, I've only had the boat a month.

 

I was budgeting on new batteries anyway...   ...they're 4 batteries, 2 pairs linked in series then both linked in parallel.

 

I'm a cont cruiser so need all the battery storage I can get! Any advice would be appreciated!

 

Thanks. ?

Same as the setup on our boat, it's is less common but by no means unique. The was a bit of a spike in the late 80s due to the availablity of coach equipment I believe, and a mini resurgence recently for very 'high spec' boats with large inverters and microwaves etc as the higher voltage means lower current for the same amount of power. 

 

Anyway and as said, four batteries wired to give 24v store the same amount of power as if they were wired as 12v because also the Amp hours (Ah) is half the Watt hours (Wh) is the same and that's the actual amount of energy, same as the kWh (kiloWatt hour) you get billed for on your electric bill. 

 

In terms of charging; the last bit of charging lead acids if very slow, so while running the engine can give a good boost from say 50-i0% the last 10-20% the alternator will have backed right off to slow rate of charge which is very inefficient in terms of diesal into charge unless your already due to be moving. This is where solar comes in.

So best to run the engine during periods of high load if you have any, or for an hour in the morning after an evenings use to dump a reasonable amount in before the solar takes over some engines/alternators also need to be just above tickover to get good charging.  Unless you are moving most days cc-ing and or have enough solar they can keep up alone which is obviously best. 

 

You may have an Ampmeter somewhere that shows how much the alternator is putting in to the batteries (engine batteries and or leisure batteries) which will help learn what works best. And you will also learn the limitations and short falls of whatever battery status meter you have. 

 

In terms of new batteries; there are many schools of thought from 'buy the cheapest you can and replace regularly' through to 'buy the best you can and they will last forever' and it does slightly depend on the application. If you can't keep them charged any battery will fail prematurely, so your routine matters. 

Personally we opt for buying reasonably inexpensive big standard 110Ah ish wet cell lead acids, whichever of the known brands is available at a reasonable price, which seems to use ok for our application.

 

In terms of usage; depending on what else you have a fridge is one of the hardest things to run because although the draw at any one time is low (40-50 Watts) it's on all day at maybe 50% duty cycle so your on like 500Wh a day. Big headline loads like a microwave, kettle, hair dryer, washing machines can also take their toll but can be greatly reduced if you for instance run a wash while moving along. Plus a 3000W kettle running for 1min is 50Wh so less than a fridge for the day. 

 

Because we just use the boat weekends and holidays we tend to move the boat most of the day, and the turn the fridge off overnight, and don't have a TV onboard. So the batteries really only have to run the lights and water pump. We tend to get ten years out of a set of batteries but they capacity is I'm sure we'll down by the end. 

 

 

Daniel

Link to comment
Share on other sites

Wow, thanks for another comprehensive answer! I will have to get into a routine as you say, and turning the TV off at the socket etc. I will re-read and inwardly digest the whole lot of everyone's advice tomorrow, and hopefully won't have to get or delay getting new ones!

Link to comment
Share on other sites

2 minutes ago, Mark 0810 said:

Wow, thanks for another comprehensive answer! I will have to get into a routine as you say, and turning the TV off at the socket etc. I will re-read and inwardly digest the whole lot of everyone's advice tomorrow, and hopefully won't have to get or delay getting new ones!

 

Never mind inwardly digesting all the answers so far, the only post you actually NEED to read is WotEver's "Battery Charging Primer", here:

 

 

Now go and read it, and come back with the massive list of questions it will provoke.

 

 

 

Link to comment
Share on other sites

1 hour ago, Mark 0810 said:

Boater Sam I have no neighbours for a long way at the moment!

 

Battery monitor is mastervolt BTM III

 

No sat equipment, just TV (& mobile router which I can't see would take much)

 

Chewbacka, yes I'm sure I have lots & lots to learn!

 

 

 

Link to comment
Share on other sites

If I read your initial post correctly - "fridge and freezer" - voltage not specified?

These will consume a lot of power in a day, thut noit to be dismissed as 'only'

I assume that the tv and router are 240v units? in themselves they are not power hungry, BUT if powered through an inverter, that fact will add quite considerably to the power draw.

The fact that you have xxx watts of solar doesn't mean that it will actually produce xxx watts all the time....

That's why current wisdom suggests that you do a power audit...

Link to comment
Share on other sites

10 minutes ago, OldGoat said:

If I read your initial post correctly - "fridge and freezer" - voltage not specified?

These will consume a lot of power in a day, thut noit to be dismissed as 'only'

 

I thought that too. 

 

Both fridges and freezers use a large amount of leccy and both together will be a hefty drain on the batteries, dwarfing all other leccy needs. 

 

 

Link to comment
Share on other sites

Sorry I thought I'd said fridge & freezer both 24 volts. Yes TV and WiFi router are 240v. My inverter is 3000watt. I will now be switching TV off at the socket after use (2 or 3 hours in the evening) but prefer for WiFi to be on all day & evening. Router transformer plug says output 12v at 2amps. Could I cut transformer off and put cigar lighter plug on it as I've got a spare 12v socket close to where my router is to go? The only other thing that has to be on overnight is my breathing machine for my sleep apnoea. It's basically an air pump that keeps air pressure up in my lungs/throat. That power brick outputs 12v at 5amps. Again could I cut off transformer and run off bedroom 12v cigar socket?

 

Thanks!

Link to comment
Share on other sites

11 minutes ago, Mark 0810 said:

The only other thing that has to be on overnight is my breathing machine for my sleep apnoea.

That sounds rather more important than "the only other thing..."! - Shouldn't your power audit start with "whatever happens the supply to ... must not fail without warning overnight ..." and take it from there? 

Link to comment
Share on other sites

1 hour ago, Mark 0810 said:

No, it sounds more important than it is, if machine switches off, I wake up by automatic reaction. Worst is I have a bad night's sleep & as a result I drop off a lot the next day! Lol!

The concern with the inverter - and it depends on which one as they are not all the same - is that even if not much is connected eg WiFi, tv in standby, the inverter itself will often take 20w which at 24v would be 0.8A which is about 20Ah per day.  Which is maybe more than you realise.

 

Added - as to chopping off the 12v supply and running from a 12v outlet the answer is maybe.  A boat 12v supply will be anything between 12v and 14.4v when recharging and will also be electrically noisy.  If a bit of kit is designed for car use then it will probably be fine, but some bits of kit are designed for a ‘good quality’ and stable 12v and may even be damaged by a direct connection to a boat supply.  

Edited by Chewbacka
Link to comment
Share on other sites

 I see a can of worms is now opening wide.....

Methinks the only real solution is to:-

Increase the alternator capacity

Fit an alternator controller (if not already)

Increase the battery capacity (what was it anyway?)

 

Short term gains may be to set the inverter to low power mode, although I've found that some makes won't then start a fridge motor.

 

In domestic terms you're not power hungry - in boating terms you are because - even with lots of battery capacity - charging them up is a pain if you're static (and don't use the engine to propel the boat if you're old enough the non boaty buzz word is "Ibasiac"

Link to comment
Share on other sites

1 hour ago, Mark 0810 said:

This is my inverter, just had a thought, if I turn off all trip switches on the fuseboard other than the fridge & freezer when I leave the boat or am cruising would that be better for the batteries?

IMG_20190812_144043.jpg

When I leave the boat I turn off my inverter [my fridge freezer is 24 volts] and the other issue is are you sure your cigar sockets are 12 volts? they might be 24 volts,

I have the same inverter its a good quality unit

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.