Suitability of these batteries on our boat??

[HONEYMOMMY]

The following link is to the batteries son and hubby are looking at for our boat.

http://www.tayna.co.uk/J185H-Trojan-Battery-Superior-Deep-Cycling-P7329.html

They want two of them...

The logic behind it is..

There are three teenagers on the boat that want to watch TV, charge phones and laptops.
The usual appliances will be fridge, heater fan, water pump, toilet, shower. The fridge being the largest drain on power.

Our current batteries are total of 240 Ah and we run them down in approx 4 hours when the kids are aboard.

So would the trojan batteries be suitable as a total of 430 Ah.

My concern is the size.. They can fit but there doesn't seem to be a battery box high enough, meaning the box it will fit in will have about a 10cm gap between the top of the box and the lid.. Is this safe??

The cost.... Yup a lot, but if it sorts out the problem at least it's done....

I haven't got a clue about batteries except from another forum member explaining to add up the amps we use to work out what we need. hubby and son think this is the way to go....

OK... give it your best...

 

[VicS]

The two Trojans will give you a capacity of 450Ah

If your existing 240Ah battery bank is not a true deep discharge battery you should not normally run it below 50% giving a useful capacity of only 120Ah.

It should be possible to run the Trojans to a lower state of charge, 20%, so not only will you benefit from a larger capacity battery but you will be able to use a larger %age of their nominal capacity.

80% of 450 is 360. So the useful capacity of your Trojans will be 360Ah. 3 times what you have available at present.

 

[HONEYMOMMY]

The two Trojans will give you a capacity of 450Ah

If your existing 240Ah battery bank is not a true deep discharge battery you should not normally run it below 50% giving a useful capacity of only 120Ah.

It should be possible to run the Trojans to a lower state of charge, 20%, so not only will you benefit from a larger capacity battery but you will be able to use a larger %age of their nominal capacity.

80% of 450 is 360. So the useful capacity of your Trojans will be 360Ah. 3 times what you have available at present.

Thanks for that. I have to say I thought they were a bit over the top to be honest, which is why I posted the question. With your reply I think it may be a good option to ensure the kids are entertained on a rainy day without running the power right down.

So.... Safety.....

Battery box.......

We have the right size in width and length but the height is 10cm too short and we cannot find a taller one anywhere... Is it safe to have the lid on with a gap between it and the top of the box? Obviously it will be strapped and fixed for safety..

 

[hlb]

I presume the box will be fibre glass, so wont present a problem.

Have you thought of a little Honda genny, for when shore power is not available?

We used to cruise all winter, with the little Honda genny.

If folk were around, we'd have it in the cockpit, if not, it would be about 20 yards down the pontoon.

The little honda would get us out of all sorts of trouble, if things went down.

Plus, it would keep the heating going and the TV and other stuff.

Mind we had gas, so it did not need to cook stuff.

 

[HONEYMOMMY]

I presume the box will be fibre glass, so wont present a problem.

Have you thought of a little Honda genny, for when shore power is not available?

We used to cruise all winter, with the little Honda genny.

If folk were around, we'd have it in the cockpit, if not, it would be about 20 yards down the pontoon.

The little honda would get us out of all sorts of trouble, if things went down.

Plus, it would keep the heating going and the TV and other stuff.

Mind we had gas, so it did not need to cook stuff.

Thanks for your input..

We have a honda generator, but don't want to annoy other boaters having it on all the time, therefore bigger batteries seems like an good plan.

The box is fibreglass yes...

So unless someone else comes along and advises otherwise, I guess the batteries will be OK...

I still feel apprehensive for some reason... Perhaps the thought of spending the money.

 

[hlb]

Be very carefull you dont extend the problem, by wanting hair dryers and all sorts of other stuff. Inverters will just add to the problem, less you can keep it down to one that plugs in to the cig lighter.

"My house", is not a big help. Mooring in winter, in the West Country, was never a problem with the genny. The neighbours had one far bigger.

 

[BGW]

No one seems to have mentioned charging....
It's one thing to increase the battery bank by 2 to 3 times the original capacity but you still need to have sufficient charging capacity to recharge them before you start the next 'rainy day' of discharge.
You will need to ensure that you have the capacity to fully recharge the batteries after each heavy usage.

 

[Richard10002]

If folk were around, we'd have it in the cockpit, if not, it would be about 20 yards down the pontoon.

The little honda would get us out of all sorts of trouble, if things went down.

Hi Haydn,

How did you go on if it was raining? Does the Honda work OK in the rain?

 

[PaulGooch]

I agree with Brian, charging needs thinking about. It's no good fitting upteen amp hours of capacity if the batteries can't be charged quick enough. Deep cycle batteries have different charging requirements to normal batteries, so more money will most likely need to be spent there.

No mention has been made of the boat, the engines or the charging equipment on the boat. Where is it berthed ? Why can't shore power be used ?

Flattening 240ah of batteries in four hours seems extreme to me and needs looking into. Are the current batteries just not holding charge ? Of the things you mention that you run, the fridge is indeed the biggest consumer, but you should be able to run that all day without flattening a single 110ah battery. You do mention TV, some TV's can use a lot of power.

IMO, a pair of deep cycle batteries is not the answer. Spending over £600 for two batteries and just throwing more AH at the problem isn't the way to go. At the very least, a simpler and cheaper solution would be to fit more normal leisure batteries. If you doubled you AH by fitting four 110AH batteries you'd be OK for 8 hours. But, i'm not sure that event that is the complete solution.

You need to provide more information. Then you need to look at better managing your use. You need to check your current batteries and charging systems. Finally, look at how you can best supply the power you need and charge the batteries.

 

[sarabande]

HM, I think you and the family should get to grips with batteries as a source of energy and as part of your boat-ownership skills.

There's a very good and readable website called

http://batteryuniversity.com/


where all the how and why of batteries is explained. It would be good for the children as part of their Technology education, too.

And you and husband, as the payment sources, will have a better understanding of why you need to balance use and re-charge away from the marina.


You will have to work out the cost-benefits of installing a huge battery bank (and relying on shore power to charge it up when you are back in the marina) and having an independent source of power for a smaller and cheaper bank (suitcase genny) which will enable you to extend your cruising range (as no doubt you will want to do , as you gain experience.

Haydn's solution is best, based on masses of experience: genny (I suggest a 2KW Honda) inputting 240v to e.g. hairdryer, etc, when needed, or into the battery charger at other times.

 

[HONEYMOMMY]

We are near Windsor.
Engines... Twin Volvo AD31's hubby doesn't think charging will be a problem and the idea is to have enough power so we don't have to use the generator unless daughter and I use a hair dryer etc.

 

[PaulGooch]

We are near Windsor.
Engines... Twin Volvo AD41's hubby doesn't think charging will be a problem and the idea is to have enough power so we don't have to use the generator unless daughter and I use a hair dryer etc.

How do you normally charge your batteries ?

Flattening 240ah batteries in 4 hours is just not right. You either have dodgy batteries or you need to look at your usage. It's all well and good adding more power reserves, but better management needs to be looked at too.

What will you use to charge deep cycle batteries ?

 

[Relax.A]

Your batteries are just like a reservoir only any good as long as it gets topped up.
So do check charging will be sufficient.
I sold my honda as although an excellent generator the places I like to more I never
Felt it was fair on other boats to leave it running for any length of time. I think they
are great for short stints like a quick microwave or hair dry but to use to recharge bats I found a couple of hours use anti social. Which means we are going down the built-in silent
type which I appreciate is not for everyone . If you are using your boat for a night or two and then back to the marina to let the shore power take on the bulk of domestic recharge then simply bigger batteries will work but don't expect to go away for a week and all to be ok without lots of cruising or some special alternator set up.
As for the Trojan batteries I happen to know they are excellent and after testing many
types Kris cruisers use them on all their electric day boats.

 

[bradtarga34]

One of the downsides of cruisng on the Thames, the plethora of honda generators... Glad to see you are looking at upping the battery capacity to keep generator use to a minimum and appreciate the fact that you too realise part of the lure of boating on the Thames is the peace and quiet it offers. I was suprised how many boats moored up over Easter had generators running for hours on end in tickover, so obviously not actually doing anything but making noise. I would also look at changing light bulbs to LED's, as the halogen's really draw a lot of power.

 

[HONEYMOMMY]

One of the downsides of cruisng on the Thames, the plethora of honda generators... Glad to see you are looking at upping the battery capacity to keep generator use to a minimum and appreciate the fact that you too realise part of the lure of boating on the Thames is the peace and quiet it offers. I was suprised how many boats moored up over Easter had generators running for hours on end in tickover, so obviously not actually doing anything but making noise. I would also look at changing light bulbs to LED's, as the halogen's really draw a lot of power.

We have already change the cabin lights to LED, which will make a big difference.

I am going to have to check on the charging issues that may be a problem with the bigger batteries, but if that's. Of an issue I thnk it will be the way to go.

It will be expensive but if cared for well they should last a good while. I was dubious due to wanting peace and quiet on the boat myself, but we have to cater for the fact that with 4 teenagers they will want their stuff to some extent. Better to give in a little for the times they are there than have them decide they don't want to come. The generator we have bought is for occasional use or for the times when we have no neighbours to annoy. I totally agree with the noise on the Thames from generators taking away from the peaceful time we seek.
We plan to take a couple of weeks away and this seems like a good option.

 

[VicS]

One of the downsides of cruisng on the Thames, the plethora of honda generators... Glad to see you are looking at upping the battery capacity to keep generator use to a minimum and appreciate the fact that you too realise part of the lure of boating on the Thames is the peace and quiet it offers. I was suprised how many boats moored up over Easter had generators running for hours on end in tickover, so obviously not actually doing anything but making noise. I would also look at changing light bulbs to LED's, as the halogen's really draw a lot of power.

Larger capacity batteries extend the time interval between charging but the running time of the generator will be longer
unless you also upgrade the battery charger to a higher output model.

 

[HONEYMOMMY]

Larger capacity batteries extend the time interval between charging but the running time of the generator will be longer
unless you also upgrade the battery charger to a higher output model.

So...

Volvo AD31 will charge the batteries as we run them while under way. Not sure how long they will need though to fully recharge. Thats my question.

When we are on shore power the battery charger will gradually charge the batteries. Bearing in mind we would usually leave the boat for a few days on shore power this won't be an issue I believe.

 

[HONEYMOMMY]

So...

Volvo AD31 (my mistake on engine size before) twin engines... will charge the batteries as we run them while under way. Not sure how long they will need though to fully recharge. Thats my question.

When we are on shore power the battery charger will gradually charge the batteries. Bearing in mind we would usually leave the boat for a few days on shore power this won't be an issue I believe.

Quoting myself now... LOL....

Son has just found the answer. The AD31 engines will replace 50 amp per hour per engine.

So with 430 Ah total battery power it would take approx 4.3 hours to recharge from flat. Bearing in mind they wouldn't be run enough to go flat this shouldn't be a problem.

So now I have that bit of info does it mean the batteries are appropriate?

May be sounding a bit thick here, but just want to make sure it is possible before spending out..

 

[BGW]

Quoting myself now... LOL....

Son has just found the answer. The AD31 engines will replace 50 amp per hour per engine.

So with 430 Ah total battery power it would take approx 4.3 hours to recharge from flat. Bearing in mind they wouldn't be run enough to go flat this shouldn't be a problem.

So now I have that bit of info does it mean the batteries are appropriate?

May be sounding a bit thick here, but just want to make sure it is possible before spending out..

That is a theoretical maximum - and you are unlikely to achieve it - and unless you have some clever electronics fitted it will drop off quite rapidly.
You may also find that only one engine charges the domestic batteries.
You still need to do a bit of investigation I think.

 

[PaulGooch]

Quoting myself now... LOL....

Son has just found the answer. The AD31 engines will replace 50 amp per hour per engine.

So with 430 Ah total battery power it would take approx 4.3 hours to recharge from flat. Bearing in mind they wouldn't be run enough to go flat this shouldn't be a problem.

So now I have that bit of info does it mean the batteries are appropriate?

May be sounding a bit thick here, but just want to make sure it is possible before spending out..

Those figures will be wrong. How wrong may depend on how the charging system is set up. You might find that one engine charges the engine batteries and the other charges the domestic bank. You'll also be unlikely to see the max output from the alternator, even if the battery is close to flat.

You say that your current batteries are flat in 4 hours, but let's say they have only used 120Ah. So during a 12 hour period, you'd use 360Ah. If you only have one engine charging the batteries, at something like 30a it'll take 12 hours of engine run time to charge them back up.

You "might" halve that if both engines charge the batteries. You really do need to look at how the current system works first, then you will almost certainly need to improve it. Fitting an advanced charging system will be as important as getting new batteries.

You seem to have missed a very important question as well, are you sure your existing batteries are good ? Are they fully charged at the start of the day ?Your usage seems extremely excessive for the items you mentioned. I can sit at anchor all day with the fridge on, chart plotter, VHF, FM radio, fish finder, electric water pump, electric toilet, phone on charge, laptop on charge and not put too much of a dent in a single 110Ah leisure battery.