So36i battery box for engine start

[oasis36i]

I have finally added an extra battery to my So36i (3 cabin) and almost doubled the capacity. Others have posted extensively on this - this is my take.

I am a long weekend user and always start with fully charged batteries from shore power. As delivered, I had 2 70ah for house and 1 70ah for engine. I wanted about double the house capacity.

My solution was to move the engine start away from the battery box to give space for 2 X 135ah for a house bank. But where to put the engine start?

After some head scratching, I spotted a space aft and outboard of the existing battery bank. This is an irregular shape and not very deep. I would need an odd shaped battery.

So I now have 2 X optima 6v red top 55ah batteries in series side by side laying at an angle in a new plywood and epoxy battery box. These batteries claim to be rugged and useable at any angle except upside down.

I made a mock up of the battery box in foam while at the boat and constructed it at home.

The engine start is now further from the engine so I specified very thick cable to keep resistance low.

What about the settings on the cristec charger? I settled on treating everything as flooded (float at 13.4v) to be kind to the house bank. The optimas claim to accept a very wide range.

I installed a NASA bm1 at the same time so I can see the volts, amps and total amp hours on the house bank and the voltage on the engine start.

I will post any updates here. Photo of my funky battery box below.

Ian

[tedp]

That's interesting, very neat too. So these batteries can be used lying flat on their side? What about sailing on your ear - won't they leak into the box?

[oasis36i]

The optima website claims these are "completely sealed" and "won't spill, leak or corrode" and "can be mounted in any position - sideways or even upside down".

If the claims are true, I should not have any problem! I will keep a close eye.

[Trevor]

Very innovative Ian,

I didn't think they could be used at that angle but it seems that may be an old fashioned restriction. Great use of precious space. I would be keen to know if it all works out ok in the longer term.

Regards,

Trevor

[oasis36i]

A brief update. After sailing 3 hours heeled well to starboard, there seems to be no problem. At this angle, the batteries would be about 10 degrees below horizontal. I will keep a close eye over the next few months and post here.

[so36idavid]

Ian,

What brand/model batteries did you go with for the house bank? The best I could fit were 2 Trojan AGMs at 100Ah each.

Thanks
David

[allegria]

Hi David,

I have a 2010 SO36i, 2 cabins.

I managed to fit 2 x 120Ah AGM Absorbed Power batteries in the original space. I have also added 1 120Ah + 1 80Ah in the lazarette, under the floor.
Total 360Ah for the house battery + 80Ah for the starting one.

Very happy with the setup.

Cheers,
Allegria

[so36idavid]

Thanks Allegria. 360 Ah is great. I did some work on the fridge to reduce demand and I'm adding some solar to increase supply but I'd love to have the extra capacity.

[oasis36i]

David

I went for standard sealed lead acid from Advanced battery supplies. They claim to be deep cycle. My thinking is that, given the relative low price, I may need to replace these relatively frequently, but that is fine as they are easily accessed and simply wired.

Next job is to tackle the fridge. As you and others have posted, this seems to consume in excess of 60Ah per 24 hours and should be nearer 30Ah with some better venting if heat and more accurate thermostat.

Ian

advancedbatterysupplies.co.uk/product/advanced-xd35-dual-purpose-leisure-battery/

[teodoro]

Hi,

I'm also going to replace batteries on my 2010 36i before leaving for a longer vacation in August. I have the Tudor batteries provided by Jeanneau which are really getting old and are not the best solution for the house bank according to what I understand.

I do have a problem with the size of battery compartment however: in my 3 cabin setup I have the batteries in the starboard cabin but the box is really tight, particularly when it comes to height: I measured 820x190x245mm, but I took the measures without taking out the batteries.

With this limited height, I believe it's very difficult to fit deep cycle batteries that tend to be taller. Has anyone tried taking out the wooden box and enlarge the space? The alternative I see is using the space below the port cabin that appears to be taller - where already 1 additional house battery has been added.

Comments and suggestions are welcome!

[Quiddle]

Jul 6, 2016 10:47:13 GMT teodoro said:

With this limited height, I believe it's very difficult to fit deep cycle batteries that tend to be taller. Has anyone tried taking out the wooden box and enlarge the space? The alternative I see is using the space below the port cabin that appears to be taller - where already 1 additional house battery has been added.

Comments and suggestions are welcome!

Blueeyes posted an excellent guide on this here:

jeanneau.proboards.com/thread/4429/raising-cabin-allow-taller-batteries

[vasko]

instead all this complication just change the starter battery with :


www.ev-power.eu/LiFeYPO4-batteries-12V-1-1/Lithium-Battery-LiFePO4-12V-20Ah.html

it is equal to about 100ah starter battery and do not need a box, is small and light and will outlast the boat itself...  and is drop-off replacement ....  I already use it for about two seasons and all is perfect 

[oasis36i]

Just an update. We have sailed on our starboard ear a few times now, so the engine start batteries would be about 20 degree below horizontal, with no problem at all. The engine starts just as briskly as with the original battery.

So I am chalking this up as a success. It only took a bit of plywood and epoxy and some longer thick cables to double the house capacity.

The fridge is still consuming 60Ah per 24 hours and will definitely be he next project.

[oasis36i]

Just an update years on. The angled engine start battery of 2x6v optima red top is still going strong as are the 2x135 house batteries in the original space.

[rene460]

Hi Oasis, thanks for posting that update.

The motion of a sailboat is pretty hard to adequately simulate, and it is easy to wonder how any modification stands up over time.  It is always good to hear how things workout in the long term.

rene460

[dagern]

Hi,


In port cabin it is exactly the same space for batteries, but I had to build a plywood base for batteries to sit on. I moved the start battery to the port cabin, and used up all the space in the battery compartment in the starboard cabin for LiFePo4 batteries.

But this is just another way to do it

[no3l]

Hi

I did the same, I moved the engine battery to the space in the port aft cabin and fitted a third domestic battery in the starboard cabin. I used a heavier guage wire for the new engine battery as it is bit further away.

All that was needed was a base and restraing strap for the new engine battery.

Regards
Noel

[oasis36i]

I am amazed to see that 7 years have gone by since this modification. Anyway, batteries are still going strong, engine starts briskly and no leaks. The claim optima makes about their batteries seems to hold true.