Solar panels......

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mikeonb4c
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Re: Solar panels......

Post by mikeonb4c » Mon Jul 10, 2017 10:43 am

g8dhe wrote:I would stick with a minimum of a 100 Watt panel (mainly for the fridge requirement) and an MPPT controller (handles lower light levels better), as I would guess that you will want to keep the battery topped up when not in use which could be for much longer periods than a van and during winter the light levels can be a lot less than it first seems.
One thing I've always wondered is how much the constant small charge/discharge might shorten the life of a lead acid leisure battery compared to less frequent deeper discharge / charge from the alternator. Also - if cost were no object, which sadly it is - how much better a lithium battery might perform as a leisure battery both in terms of longevity and being able to use much more of its capacity without voltage drop (and consequent low voltage cutout as on my waeco compressor coolbox). Any thoughts Geoff?
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Re: Solar panels......

Post by g8dhe » Mon Jul 10, 2017 12:00 pm

Well if your not actually running a compressor fridge then you could drop the power requirement below a 100 Watt to 50-80 without problem provided you use an MPPT controller.
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Re: Solar panels......

Post by g8dhe » Mon Jul 10, 2017 12:17 pm

I would agree that using Lithuim Ion is probably going to be the way it goes in the future, but at present the cost is a lot higher simply because of the demand rate from users is that much lower. Rather like the way that 42Volts was going to be the new standard for cars, which never really took off, so much stuff would have to be redesigned and then we would all be locked into the propriety systems that manufacturers would insist on.

They are available now as "12volt" 100AmpHr units see https://www.alibaba.com/showroom/12v-10 ... ttery.html
but then you need to cost in a charger as well, the old lead acid charger style won't cut it with Lithuim Ion or LiPo4 unless it has the relevant electronics included - but be warned these are normally only protection circuits that disconnect the charger if it spots charge rate or temperature going awry!!
Again its a case of features being used to sell devices without the warning that once the protection circuit operates it may have to be returned to reset it, a lot of the current protection circuits simply disconnect the terminals until the internal voltage rises sufficiently high to operate again, however there is then no way to put charge back into the battery to raise the voltage......

These units are a different matter http://www.claytonpower.com/products/li ... batteries/ but so is the price ;-)
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Re: Solar panels......

Post by Bob » Mon Jul 10, 2017 12:24 pm

g8dhe wrote:Well if your not actually running a compressor fridge then you could drop the power requirement below a 100 Watt to 50-80 without problem provided you use an MPPT controller.

Splendid, thanks Geoff. =D>
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Re: Solar panels......

Post by mikeonb4c » Mon Jul 10, 2017 9:02 pm

Thanks Geoff. Such a shame lithium is so out of reach on cost as itd be a much better performing solution. Do solar panels wear out lead acid batteries prematurely?
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Re: Solar panels......

Post by Bob » Mon Jul 10, 2017 9:14 pm

Having been looking around, following Geoff's advice, I recon battery life will be extended.

The top notch controlers will top keep the battery full without overcharging, this has to be better than discharging a good way then topping up when you drive or have a charger.

Geoff will hopefully add to this.
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Re: Solar panels......

Post by g8dhe » Mon Jul 10, 2017 10:22 pm

No the method of charging lead acid batteries is exactly the same from whatever source. What is different can be the way the batteries are used, if you have a constant load 24 hours like trackers and cameras etc then if left running 24/365 then there are a lot more charge cycles per year, ok each cycle won't be a full charge/discharge but if its only say 20% then every 5 days you have the equivalent of a full cycle so 365/5=73 charges just on background load alone let alone fridge, lights, radios computers & phones during times away your going to be up to the 200ish charge cycles that most lead acid's are designed for ...
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Re: Solar panels......

Post by mikeonb4c » Mon Jul 10, 2017 11:12 pm

g8dhe wrote:No the method of charging lead acid batteries is exactly the same from whatever source. What is different can be the way the batteries are used, if you have a constant load 24 hours like trackers and cameras etc then if left running 24/365 then there are a lot more charge cycles per year, ok each cycle won't be a full charge/discharge but if its only say 20% then every 5 days you have the equivalent of a full cycle so 365/5=73 charges just on background load alone let alone fridge, lights, radios computers & phones during times away your going to be up to the 200ish charge cycles that most lead acid's are designed for ...
That's interesting Geoff. It seems to suggest people need to give a little thought as to how to manage device useage and charging regimes with a view to preserving LB life. In simple terms, except where (for example) a fridge needs to be kept running, it would be better to switch it off and take the leisure battery offline from usage and charging circuits such as solar panels.
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Re: Solar panels......

Post by g8dhe » Tue Jul 11, 2017 9:29 am

Yes indeed Mike, it caught me out in that my standing load had grown slowly but without impact on the day to day usage of the LB, it was only after spotting that my LB up time was shrinking rapidly at the end of its first year of use after a previous replacement. Since then I now keep the van plugged into the EHU at home so that rather than the LB taking the strain the standing load is taken by the mains charger.

I suspect that if/when I ever get a new van then I would re-think the whole of the wiring scheme to ensure that the battery is used in a more efficient manner given the three possible sources of power and the nature of each supply. Possibly even switching the LB completely out of use when a reliable/consistent power source is available and the battery is fully charged.
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Re: Solar panels......

Post by mikeonb4c » Tue Jul 11, 2017 10:10 am

g8dhe wrote:Yes indeed Mike, it caught me out in that my standing load had grown slowly but without impact on the day to day usage of the LB, it was only after spotting that my LB up time was shrinking rapidly at the end of its first year of use after a previous replacement. Since then I now keep the van plugged into the EHU at home so that rather than the LB taking the strain the standing load is taken by the mains charger.

I suspect that if/when I ever get a new van then I would re-think the whole of the wiring scheme to ensure that the battery is used in a more efficient manner given the three possible sources of power and the nature of each supply. Possibly even switching the LB completely out of use when a reliable/consistent power source is available and the battery is fully charged.
Very interesting indeed Geoff and thanks++ for taking time to post. If someone as savvy as you can get caught out it sends a clear message to those less savvy that there are holes you can call down. What it amounts to I think is that a leisure battery might best be seen as the source of last resort i.e. charge it and only bring it online for drawdown when other sources unavailable or inadequate. Looked at laterally, and taking fridge as an example, we might hope that a 100w solar panel can run it during a sunny day and could invest any surplus in freezing/cooling some other reservoir. That reservoir could then be used for maintaining a cold fridge throughout the night in preference to calling in leisure battery power. Or the solar panel surplus could be used to charge cheap lithium battery powered LED lights for use after dark etc. Rather than have these use the LB. It could even get to a point where the LB is only there for use as the electrical equivalent of a spare tyre!
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Re: Solar panels......

Post by Bob » Tue Jul 11, 2017 11:28 am

Yes, thanks Geoff. =D>
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