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Batteries and being off grid


rowland al

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On ‎2017‎-‎12‎-‎15 at 12:17, rowland al said:

I understand that starter batteries like to work between 70-100% capacity unlike deep cycle domestic batteries which are happier down to 50%. So I guess it's important to make sure they don't drop below this

As I say, it's all a bit of an experiment at the moment and it's early days. Even if this single 12v battery cops out after 2 years. It cheaper to buy another one than 4 new domestics (which is where I started from!). 

Batteries do not like to work but that aside a starter battery is more close to 90-98% and a domestic 50-80% if you like to get a full lifetime out of them.

Where you started from was not ideal for you so a comparison with that makes no sense. I'd guess that your battery will last for 6 months compare that with one 100Ah domestic.

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On 12/15/2017 at 17:19, KenK said:

Ignoring the argument regarding the correct method of expressing energy usage. Some real world information.

This year we changed the way we use our boat, for twelve years it has been used for holidays and weekends, for that purpose six 110 Amp Hr Numax leisure batteries have been satisfactory, the first set lasting nearly eight years, we replaced them with the same type.

This year we used the boat as liveaboards cruising from  Newbury to Leeds covering all the waterways we could on the way. It became very obvious early on in the journey that the now four year old batteries were not performing as we needed. We have a Smartgauge and a Smartbank fitted, so we know we were charging correctly but we were dropping to around 60% after a nights use. We have all LED lights but the fridge and TV both run from a PSW inverter. The fridge was the problem even though it was new A+ unit it could easily cause the inverter to trip not long after we had moored up because the compressor starting current was greater than the batteries could supply to the inverter.

I replaced the six Numax batteries with five 170 Amp Hr traction batteries, these are flooded tubular plate beasts, they weigh twice as much as the Numax at 40 kilos each. The difference is amazing a nights use sees a drop of less than 5 % on the Smartgauge and the fridge has been tamed.

We have had this discussion many times but so called leisure batteries are for the most part simply larger starter batteries and therefore not ideal as domestic batteries, easy to tell, if there is a CCA figure quoted in the description it is a starter battery. Traction batteries are more expensive but they work and provided they are looked after will last longer.

I have no idea how the OP uses his boat but my experience suggests that for liveaboard use a simple starter battery will have a short life as they are simply not designed to be used as domestic batteries.

 

Ken

Can I add to your real world off grid experience with my vastly longer liveaboard experience. I always use " Leisure " batteries and get two sometimes three years out of  them. I had a set of proper traction batteries on one boat but removed them for leisure due to ease of maintainance ( non ) I too am usualy off grid and have inverter on 24/7 fridge etc etc. I know my way works but am interested in any possible improvement. Two questions realy please one being how much were the set of traction batteries and do they need any maintainance? 

Cheers

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  • 4 months later...

Just an update. The single starter battery is still going strong after 5 months. 

I’m planning to remove it about every 3 months to give it a full trickle charge at a friends house. This is very easy being a single lightweight car battery with handles! 

Hopefully in a few years with advances in battery technology, this problem will get easier to deal with  (but maybe more expensive). 

 

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44 minutes ago, rowland al said:

Just an update. The single starter battery is still going strong after 5 months. 

I’m planning to remove it about every 3 months to give it a full trickle charge at a friends house. This is very easy being a single lightweight car battery with handles! 

Hopefully in a few years with advances in battery technology, this problem will get easier to deal with  (but maybe more expensive). 

 

That is exactly what I would expect for a starting battery, many single starting batteries last getting on for 10 years and without any form of external charging.

If you are saying that you are using a single car starter battery for domestic use for anything more than just a little lighting and a water pump then you are doing well and probably have organised very frequent full recharging and very low depths of discharge so a half decent dual purpose or deep discharge battery should last longer.

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48 minutes ago, Tony Brooks said:

That is exactly what I would expect for a starting battery, many single starting batteries last getting on for 10 years and without any form of external charging.

If you are saying that you are using a single car starter battery for domestic use for anything more than just a little lighting and a water pump then you are doing well and probably have organised very frequent full recharging and very low depths of discharge so a half decent dual purpose or deep discharge battery should last longer.

I’m also using it for TV, radio and charging up devices. It will usually drop to about 50% capacity each night. 

I run the engine for at least 3 hours each day as we need hot water. Also about half of the engine running hours are cruising time. 

I have no idea how anyone has succeeded to run fridges (ours is gas) and washing machines when being completely off line for years at a time. We wash by hand when we are on the boat and cheat at my missus house whenever we go back there! ?

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My starter is charged only when the engine is running. It was on the boat when we bought it in 2011, and was at least 3 years old at the time. Hasn’t missed a beat, starts the engine fine every time, and is always about 12.7V when I check it. Presumably it uses very few Ah when starting and is soon full with the engine running.

just shows that if you discharge by only 1% or so then charge to 100% every time, you get more cycles than you can imagine, even out of a cheap starter Battery. (I don’t know how much it cost, but it’s a generic with a chandlers sticker, so nothing special).

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2 hours ago, Mike the Boilerman said:

 

As would the engine alterntor, surely?

Depends upon how much load, if any and how long between engine starts.  A car with lots of electronics and a decent alarm will probably be below 50% soc after parking for a month.  I would expect a boat to last much longer as there should only be a couple of percent per month from self discharge, though if you were to leave it backing up a radio and maybe some kind of alarm, then..........

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