Battery Size

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DIGGER-NZ
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Battery Size

Post by DIGGER-NZ » Jun 12th, '17, 19:09

I'm considering a battery purchase and trying to size what I need. Currently I have 4x 7.2AH SLA batteries running in series. Basically I got them for free from some UPS we were pulling out of a customers site. The UPS wasn't very old (so I thought).

Anyway the batteries are pretty buggered, they drop to 10v pretty quickly and just sit at that although they hold enough charge to run the tiller pilot for a good 4 hours (I've never run out of battery) but I need something a bit more reliable.

Basically I figure I neee to be able to run:

-TillerPilot for 4 hours (?)
-Nav Lights for a few hours (LED, around 0.01a each from memory)
-Anchor Light for 8 hours (LED, areound 0.01a)
-Some cabin lights, they will be LED and possibly some strip lights, I haven't set this up yet.
-Charging cell phone

I'll be looking for just overnight trips at this stage and will look to add solar and a controller at some stage when I start to need it. I may also have access to one of those little generators in the near future.


So I'm thinking perhaps an 18ah SLA as these can be had quite cheaply or perhaps a 26ah Deep Cycle SLA which is a bit more but might be worth the extra capacity.

Thoughts?
Bonito Aquarius 22 'Unnamed' (T2438), 10Hp Honda

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zebedee
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Re: Battery Size

Post by zebedee » Jun 12th, '17, 20:13

DIGGER-NZ wrote:I'm considering a battery purchase and trying to size what I need. Currently I have 4x 7.2AH SLA batteries running in series.
I hope not, that would make for 48V and 7.2AH. In parallel would give you 12V and 28.8 AH.
DIGGER-NZ wrote:Basically I got them for free from some UPS we were pulling out of a customers site. The UPS wasn't very old (so I thought).

Anyway the batteries are pretty buggered
The advantage of free batteries - nothing lost other than convenience.
DIGGER-NZ wrote:Basically I figure I neee to be able to run:
-TillerPilot for 4 hours (?)
-Nav Lights for a few hours (LED, around 0.01a each from memory)
-Anchor Light for 8 hours (LED, areound 0.01a)
-Some cabin lights, they will be LED and possibly some strip lights, I haven't set this up yet.
-Charging cell phone

I'll be looking for just overnight trips at this stage and will look to add solar and a controller at some stage when I start to need it. I may also have access to one of those little generators in the near future.
Unless you're using quite a bit more electricity, a bigger battery rather than adding solar makes most sense for extending your time on the water. But a modest solar panel, say 20W-40W, with a cheap conventional regulator will be sufficient to recharge a small battery over a couple of weeks if you don't want to have to run mains power to the boat or remove the battery when at home.
DIGGER-NZ wrote:So I'm thinking perhaps an 18ah SLA as these can be had quite cheaply or perhaps a 26ah Deep Cycle SLA which is a bit more but might be worth the extra capacity.

Thoughts?
I think 18Ah might be a bit marginal; the next common physical size is ~25-28Ah and not all that much more. I wouldn't bother going any bigger than 40Ah for your needs.
A man's boat is his Castle. The Gippsland Lakes are my moat. Castle 650 #10, Roller Coaster.

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DIGGER-NZ
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Re: Battery Size

Post by DIGGER-NZ » Jun 12th, '17, 21:49

Haha, yes good spotting...they are running in Parallel :)

I haven't seen any 40ah, I'll have a look round and see if I can find one. The next step is 80 which is overkill!
Bonito Aquarius 22 'Unnamed' (T2438), 10Hp Honda

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Toad of Toad Hall
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Re: Battery Size

Post by Toad of Toad Hall » Oct 31st, '17, 23:03

Copy of Ganz_Solar_Calculator.xls
(33 KiB) Downloaded 52 times
Find attached above, a modified Ganz excel solar chart which tells me how big the battery and solar panels are required to be, to run the gadgets that I want to fill the boat with, for extended cruising when the sun shines for 6 hours a day.

Interesting to see how the figures change when the sunlight is less or greater than 6 hours.

Ive worked out that I could have gotten by with a 120w solar panel instead of the 150 watt solar panel I bought from supercheap for $195.
It came with a mounting bracket kit, so it might end up on the caravan instead.
Im starting to think that a folding removable 120w panel might be a more practical solution.

The best 105ah battery deal I could find was the Allrounder Super Charge on Quicksales.com.au with free delivery for $189 each.
Im liking the idea of using a battery drill with adaptor as a winch handle, so the battery charger for that needs to be added as well.

Ive copied Zeb's pivoting mounting bracket and frame idea because the stern of the Masrm is very similar to the Castle, and shaped up the bearing blocks out of black nylon, but Im a bit concerned about the windage of the 1450mm x 730mm panel, and how you would get it down to store it below, when you are anchored bow and stern in shallow water (with the keel partly up) and the wind changes to abeam. It is certainly going to make the boat weathercock on a beam reach when singlehanding and the wind gets under it. The pair of 31kg batteries under the quarterberths will be a help there.

I guess the trick is to keep the solar panel mounting frame as low as possible (perhaps keep it at the height of the pushpit frame top or hard against the parked bimini, and make one end of the crossbar removable from the pushpit like a gate, to get past, but high enough to still be able to lift the rudderblade and reach the motor.)

If anyone has a recommended wiring loom, for a twin battery configuration using a normal regulator, Id appreciate it.
Regards, T.
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Copy of Ganz_Solar_Calculator.xls
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zebedee
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Re: Battery Size

Post by zebedee » Oct 31st, '17, 23:40

According to the figures for various places around Australia found at this website, daily insolation in kWh/m²/day (which is effectively a fancy way of saying "horizontal surfaces get sunlight equivalent to this many hours of direct sunlight a day") pretty much everywhere is about 6 (hours...) per day. What the tropics gain in having the sun overhead, they lose in shorter days than say Tasmania.

Autumn and Spring see about half that, and winter can be grim...

My panel hasn't been off the boat in five years; I certainly wouldn't want to be manhandling and storing a 130W panel on the water! It is stabilised by the mast when towing.

I've been using second hand AGM batteries, typically out of standby power systems, where they get turned over to a schedule for reliability; I generally get 4 or 5 years out of them and I doubt I'd get much more out of new batteries. As such, capacity tends to be driven by availability and physical size; at the moment I have just one 70Ah in the boat, but 300correction 250Ah (4x 125Ah 6V batteries, $200 the lot) in the back of the ute. Until late March/April, the 130W panel is sufficient to keep me going indefinitely so 70ah is plenty. The car has a 200W panel; I don't even have to think about my batteries when camping. I leave the car fridge in the ute year round, except when it is in the boat.

When I have two batteries in the boat I just connect them in parallel. With the solar mounted permanently, they'll stay charged even when one has had the gong, so it's important to separate them and use just one occasionally to detect when they give up.
A man's boat is his Castle. The Gippsland Lakes are my moat. Castle 650 #10, Roller Coaster.

lockie
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Re: Battery Size

Post by lockie » Nov 1st, '17, 14:34

zebedee wrote: I've been using second hand AGM batteries, typically out of standby power systems, where they get turned over to a schedule for reliability;
No wish to highjack the thread, just a quick question for Graham: I'm a huge fan of these batteries, but I haven't seen any on Gumtree or eBay for quite a while. Have you seen them?

Cheers, Graeme

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zebedee
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Re: Battery Size

Post by zebedee » Nov 1st, '17, 15:04

I've bought half a dozen 6V 150 correction 125Ah batteries from a guy in Lower Plenty. they're each about the same size and weight as a 12V75Ah battery, which is about my upper limit for manhandling into the boat.

I first found him through ebay, but next time I wanted to buy batteries from him it took me ages to find his contact details. So I put his number in my phone, under "batteries": 0418 547997.

And it turns out I posted about them here too!

Melbourne (Plenty) 125AH batteries $110
A man's boat is his Castle. The Gippsland Lakes are my moat. Castle 650 #10, Roller Coaster.

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Toad of Toad Hall
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Re: Battery Size

Post by Toad of Toad Hall » Nov 1st, '17, 18:20

ive heard that the other good source of second hand batteries is an electric wheelchair service technician. They cant afford to have a battery failure and its an item which private health pays for , so they swap them out annually.

lockie
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Re: Battery Size

Post by lockie » Nov 2nd, '17, 10:19

Thanks chaps

lockie
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Re: Battery Size

Post by lockie » Nov 3rd, '17, 18:13

Here's a link to 80Ah batteries in Doveton:

https://www.gumtree.com.au/s-ad/doveton ... 1162420428

One of these served me excellently as house battery for about 5 or 6 years, until I stupidly sucked squillions of amps out of it with the anchor winch in a fatigue-induced senior moment, and killed the poor thing.

I will be buying another.

Cheers, Graeme

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