Is 805 AMPs enough to run 240 v fridge & 240 v freezer

[luggsy]

as title I have 7 x 115 amp calcium battery's and I am struggling to keep the smart gauge above the 50% soc , battery's are only 4 months old , both fridge and freezer are A+ rated , fridge is 113 kWh/annum freezer is 166 kWh/annum , we have 400w of solar and are c/c thanks in advance and a happy Christmas and prosperous new year to all

[RLWP]

What alternator(s) do you have and how long do you run them for?

 

Richard

[magnetman]

That seems like a pretty big battery bank but its more about how much charge you are putting into it with the engine/generator. Its winter. solar doesn't do a lot in winter unless you have a tennis court sized array.

[nicknorman]

As mentioned, you have to put back in what you take out, regardless of the battery bank size. What SoC do you charge the batteries to? If they are going from 100% to under 50% in a day, there is a problem with the batteries, but until you give us more information, we won't be able to give you any help.

 

Freezers are pretty "thirsty" - maybe you should consider turning it off over the winter when the solar doesn't do much?

[Groundhog]

If my maths is correct and assuming a 12volt system you need 64 amp hours + the losses from the inverter a day to run your fridge and freezer. Your battery bank from fully charged could run these for 6 and a bit days before reaching 50% soc. Obviously you need to account for other uses, lights, pumps etc which will eat into that.

[luggsy]

Engine is a Barrus shire alternator for domestic is 140A I think , I have not got a problem getting them up to 100% according to the smart gauge as I have a 2.2kw generator or run the engine , I can go to bed with them up to 100% but when I get up they are under 50% surely the fridge/freezer can't be using over 400 amps , inverter is a victron 3kw 120amp charger , the smart gauge is starting to rule my life as I am constantly looking at it

[Robbo]

It's not the size of your battery bank that's important, it's how you charge them that's key. If you battery's are 805ah capacity then you'll need to put around 480ah back in if at 50% soc That's going to take a long time (around 10-12hrs) with a "standard" engine alternator.

Engine is a Barrus shire alternator for domestic is 140A I think , I have not got a problem getting them up to 100% according to the smart gauge as I have a 2.2kw generator or run the engine , I can go to bed with them up to 100% but when I get up they are under 50% surely the fridge/freezer can't be using over 400 amps , inverter is a victron 3kw 120amp charger , the smart gauge is starting to rule my life as I am constantly looking at it

Take a voltage reading around 2 hours after fully charging them and leaving them with no load on. That will tell you uf its the smart gauge misreading.

Edited December 22, 2014 by Robbo

[luggsy]

I always charge them back to 100% according to the smart gauge , it takes about 4/5 hours with the genny

[cereal tiller]

That seems like a pretty big battery bank but its more about how much charge you are putting into it with the engine/generator. Its winter. solar doesn't do a lot in winter unless you have a tennis court sized array.

I heard about a Chap that had a Solar set-up of the size you suggest.

He took it off the boat,just got fed up with feet pounding on the boat's Roof and people shouting 'Deuce',,14 Love' and other similar phrases

CT

[RLWP]

Are the fridge and freezer 12V or 240V?

 

Richard

[Murflynn]

The OP is clear that he charges the batteries back to 100%, regardless of whether it is by generator or by engine alternator.

But it would be helpful if he can say which form of charging he uses and for how long, instead of relying on the smartgauge which may be misleading for some reason.

 

PS: battery capacity is measured in AMP.HOURS (Amps x Hours), not Amps.

 

 

Edit: crossed post with the OP.

Edited December 22, 2014 by Murflynn

[Robbo]

In addition is the Victron setup correctly for your battery charge/float, etc voltages? Does it go into float mode or do you switch off when the smartguage reaches 100%?

[b0atman]

reach 100% then do absorb charge time about 2 hours then onto float before stopping generator should help.

[Robbo]

I always charge them back to 100% according to the smart gauge , it takes about 4/5 hours with the genny

That doesn't sound long enough for 400ah with a 90amp charger (Victrons are setup by default at 75% max charge).

[Paul C]

In theory a Smartgauge should do the job but in practice, something that measures current (Amps) is very useful in these types of situation. For example a clamp ammeter. You might have another load as well as the fridge & freezer, which explains why the batteries are being discharged so much. Or, it might reveal there is no other load - pointing to a degraded set of batteries.

[nb Innisfree]

Sounds like batts are stuffed, if capacity has dropped below 50% then Smartgauge will be inaccurate.

[luggsy]

We turned the fridge of one night and to be honest there was not much difference , so tonight we will be turning the freezer off when the battery's are 100%

[dor]

That doesn't sound long enough for 400ah with a 90amp charger (Victrons are setup by default at 75% max charge).

 

My thoughts too. In some respects, large battery banks are not necessarily an advantage as they take that much longer to get that long charging tail back into the batteries. What is the current when you think they are fully charged? Should be less than 6 amps regardless of the size of the charger, assuming around 14.6 - 14.8 voltage.

 

It does sound though as if it is too late for your current battery set, probably because they were not getting that long slow final charge.

[luggsy]

Boat was on shoreline from the 19th oct until the 20th nov bar 1 week , so we have only been cruising for 5 weeks in total , we had 6 battery's to start with but we where struggling to keep it above 50% so we had another fitted on the 27th of nov and it has gone worse since , at the moment the genny is on and smart gauge is showing 85% & 14.65/70 v

[b0atman]

Probably gone worse because with 6 you where not charging enough now you have got a 7th to share the same charge why not try 4 batts to see if it improves.

[bottle]

The battery bank should be more than enough but apart from all the above suggestions you may have one or more batteries that are 'kaput' and it is that, that is dragging the batteries down.

 

Has the Victron been set up (with the aid of a laptop) to the correct battery type and charging setup?

 

 

Just a note:

I have 330 amp.hrs battery bank @ 24v and it is well past its best.

Smartgauge shows around 95 to 100% at 20:00 hrs, 2 hours of TV, fridge and freezer running (both 240v), LED lighting.

It will show approximately 75% at 22:00 hrs and be down to about 50 or 55% by 08:00 Hrs the next morning.

[nicknorman]

The Smartgauge will be reasonably close when it says 100%, but as mentioned measuring the tail current is a better way to know when the batteries are fully charged. Anyway, if you have 800AH of batteries starting at ~100% but you can't keep the fridge and freezer going overnight without dipping below 50%, there are two possibilities:

 

1/ There is something else taking a considerable amount of electricity that you don't know about/have forgotten.

 

2/ The batteries are way down on capacity.

 

Sorry but despite their age, 2/ is the most likely scenario. Personally I am disenchanted with calcium leisure batteries, they just don't seem to like being cycled. I now have Trojans which, so far (touch wood) are far better.

 

You will probably be able to recover a fair bit of capacity if you equalise the batteries but you need to be careful if they are sealed, not to overdo it. Do you have means of turning the charge voltage up to say 15.5v after fully charging the batteries? You really need a means of monitoring the current whilst you are doing that. A DC clamp-meter at the least.

 

It's worth mentioning that calcium batteries do seem to like quite a high charge voltage, 14.8v seems about right (temperature compensated). If you are regularly charging them at 14.4v, I suspect that is not really enough.

 

If you have a means of measuring current, you will also be able to compare the discharge rate with the rate of decrease of the Smartgauge and thus get a pretty good idea about your batteries' actual capacity.

Edited December 22, 2014 by nicknorman

[bottle]

Just to add 100% SOC (State OF Charge) does not mean you have the original capacity, it means that the batteries are at 100% SOC of their present capacity.

[luggsy]

As you can gather I know fxxk all about the electric side of things the boat is a new build ,I was advised to have 6 battery's with the set up we where having ie all 240 V and 400 w of solar , don't know about the victron being set up with a lap top I would of thought so as the man who did it seems to be very good at his job , I would like to disconnect 3 of the battery's but as it is only 4 months old I don't want to touch any of it as it may invalidate my guarantee and warrants

[RLWP]

How much of 'all' your stuff is 240V? Fridge/freezer/cooking/kettle/washer/dryer/TV/Laptop/lights/pumps...

 

Richard