New batteries needed, AGM or FLA?

[Alan de Enfield]

40 minutes ago, Mikexx said:

Yes, but he also talked of his boat in Cardiff, have a look a a graph titled "Cardiff annual energy for flat panel (blue) tilted but fixed (red) and fully tracking (black)".

I have no idea where you got your figures of 100W vs 3.5W, but the figures in Cardiff show an energy difference of 8:1, and with less daylight implies at noon the solar output at midday might be closer to 4:1

Yes - I referred to the Cardiff graph.

In Jan he got 3Kwh in the month, compared to 26Kwh in June  - ie about 12% output in Jan compared to that of June (in Cardiff)

It is of little use saying he got a 'useful output' at midday, it is the total daily output that is either useful, or not.

My experience of having solar for a few years on the boat is that it is virtually 'worthless' for (probably) 3-4 months of the year, and a little help on 2 other Months (October & February)

 

This was my instantaneous output 18th Feb - I was so impressed I took a picture (from a 170w 'low-light' panel)

 

Edited February 21, 2018 by Alan de Enfield

[rusty69]

3 minutes ago, Mike the Boilerman said:

 

My 560W of solar will typically charge at 0.1A for about three hours in the middle of the day around Dec/Jan (into a 24v battery bank). Do you regard that as 'useful'?

Yep,anything less and they have been knicked

[MtB]

Just now, Mikexx said:

 

That might be down to your controller.

 

And it might not, given I'm on my third duifferent make/model of controller now and the mid winter behaviour remains the same!

Just now, rusty69 said:

Yep,anything less and they have been knicked

 

Knickers to that...

[mrsmelly]

1 hour ago, Mikexx said:

This topic is of interest to me.

2 years of battery life with light use sounds worryingly short. To the OP: at what point do you change your batteries?

No one has mentioned equalisation charging, which given the stationary nature of batteries on a boat might extend battery life, if not from desuplferisation, from reducing stratification of electrolyte.

I had thought that solar could still provide a useful output during the winter months?

Personally I would go for cheap batteries, its easy to damage batteries from unintended discharges, which will damage expensive batteries just as well as cheap. Battery technology is pretty mature, and I am yet to be convinced of the various buzzwords associated with 'new' technologies provide any meaningful extension to battery life.

BICBW

Why do you think 2 years is worryingly short?  If he is a liveaboard off grid like I am most of the time and assuming he has a couple of weeks ish away from the boat on holiday each year then the batteries are still being cycled around 700 times even if he isn't taking them below fifty per cent that's damned good for my money. If he were a hobby boater and the boat spent most of its life in a marina on hook up then yes two years would not be good but he says he lives aboard. Living aboard and Hobby boating are as different as chalk and cheese.

[WotEver]

6 hours ago, Mikexx said:

2 years of battery life with light use sounds worryingly short.

Does it?  Sounds about normal to me for a liveaboard. 

Oh, missed Mrs Melly’s response. At least we agree

 

Edited February 21, 2018 by WotEver
Added a bit.

[smileypete]

Might be worthwhile to get a cheap ebay '5 digit multimeter' and workout the approx depth of discharge from the batts 'resting voltage':

https://www.ebay.co.uk/itm/DEOK-0-36-5-Digit-DC-0-33-000V-Digital-Voltmeter-Blue-LED-Display-Panel-3-Wires/222794662267

(about half the price from china via the slow boat)

700 cycles to 50% would be bloody marvellous from 'el cheapo' leisures, but 700 cycles to 10% maybe not so much, could even be better off getting a single batt instead of two.

Non sealed leisures are thin on the ground these days (Banner do them?) maybe non sealed truck batts eg Numax or Varta in 664 size would be worth a go. With such a low alt charge voltage I doubt water loss will be a problem in winter.

(There are some out there who mistakenly assert that truck batts have thinner plates then leisure batts; the latter often have the same or higher CCA which suggests otherwise. )

Edited February 23, 2018 by smileypete

[Alan de Enfield]

41 minutes ago, smileypete said:

Numax or Varta in 664 size would be worth a go.

I have 6x 625's at 220Ah each. Weigh in at 32.5kgs each.

Work well for me

[Ssscrudddy]

Charging via alternator every few days... Batteries don't like being left discharged (ask MTB), so I would do it every day.

However 2 years is 730 cycles for a battery that's likely to be a 500 cycles. Seems pretty good to me.

Are they 500 cycles? My current batteries I recently found out from the manufacturer are only 85 cycles!

& As someone with 660W solar they are pretty much useless in the 4 months over winter. With that said I've seen enough solar on a perfect sunny winter's day to run my fridge for 8 hours. Also seen them do nothing in the summer, May last year 1 day was bloody freezing & dark, solar only doing about 1A, lights were on all day & I lit the fire.