Battery Bank Size

[Just Bob]

I'm building a new trawler with a 24v 5000w inverter being installed and am getting differing opinions on the size of the house bank to power it. The boat is a 54' with normal cruising needs. Any advice from more expierienced cruisers would be helpful.

Thank you!

 

[Killick]

It would be helpful to know what kind of daily AC loads you anticipate for your inverter between charging cycles.* 'Normal cruising needs' vary a great deal amongst cruisers.*

That inverter will require a pretty large house bank if the regular AC loads approach it's max capacity and you don't want to be running the gennie all the time.* What kind of charging system are you considering?

 

[Daddyo]

It's a function of your overall power management/generation systems. Your bank size relates more to how long on the hook without the genny running, and or how often are you under power and charging versus elec load. We can go three days with our two fridges and conservative not primitive elec use between firing up a noisemaker. I like our 920AH setup as a minimum.

 

[Jay N]

Just Bob wrote:
I'm building a new trawler with a 24v 5000w inverter being installed and am getting differing opinions on the size of the house bank to power it. The boat is a 54' with normal cruising needs. Any advice from more expierienced cruisers would be helpful. Thank you!

*About 12 years ago when I purchased/installed a 3000 watt inverter, I flat out missed considering the amperage draw in idle/low output*mode.* It turned out to be 5 amps (12VDC) to charge my laptop and light an AC reading light.

Subsequently installed a separate 400 watt inverter with separate wiring to all low amp needs, it costs a tenth of an amp to idle.

While I haven't analyzed present inverters to see if this issue has been improved, it used to be the the larger the inverter, the higher the idle/low output amperage comsumed.* It may be that your inverter needs might be better served with a couple of smaller units.

*

 

[FF]

How are you doing refrigeration? Cooking?

With a really fine (read expensive ) reefer system the batt set can be minor.

It takes tons of lead if a house fridge is simply stuck aboard.

With a need for a large capacity the Sunfrost line is perfect , IF you have the room.

 

[Just Bob]

Thank you all for your thoughtful replys. I too had not given any thought to idle amp usage. I'll have to see what that is.


It terms of usage, your assumptions and description of usage is correct, I'd like to get a few days without the genset.


We do unfortunately have a full size household fridge, didn't have a choice here, per mate not manufacturer! The other usage is general, cooktop is propane but oven is electric, clothes washing, probably not drying, don't watch TV. Haven't investigated water making yet and have never had one, assuming they're AC??


We have two generators, one 16 and one 8. and I planned to install some number of solar panels on the hard top. I'm not sure how many I can get up there or the output of those yet.


The boat ia an Ocean Alexader 54 Trawler, the invertor is a Victron 24/5000.


Thank you all, this has been quite a learning process!

-- Edited by Just Bob on Thursday 14th of April 2011 01:49:25 PM