solar charging regulators

Thunderchild · Mar 21, 2009

so its the charging that going to be an issue ? I can charge them seperately one panel per battery.

Basically your saying that by putting them in series I will be forcing one cell to pass more current than it would want because another one wants it so ?? so I take it its not a case of the cell that wants more power will have to make do with what the ones passing less will want.

Do I correctly assume that discharging them in series will not be an issue provising I don't try to take huge currents out and make one work harder than it can ? I could use voltage sensing cicuitry to cut the supply when anyone of the two batteries is getting discharged.

Thunderchild · Mar 21, 2009

if I put the panels in series and the batteries in series but also had a centre "tap" from the battery junction to the panel junction then they would be each individually charged but i would still be able to get 24 volts back for the inverter

nickelflippr · Mar 21, 2009

One word of caution also on the type of battery you bought. Standard auto battery's are just meant to start the car, and that is about it, as the alternator takes over pretty much from there. A deep cycle battery used in marine and Rv applications are constructed with thicker plates? to withstand high depth of discharge. Golf cart battery's are excellent examples of deep cycle-ability and are the gold standard for cost/AH.

Can see the advantages of putting your solar panels in series, but not so much the batteries. With 40W of solar, there isn't enough power to justify a two battery setup. If one had upwards of 100W of solar, then maybe.

The battery life will depend on the energy budget allowed, and how quickly you can recharge between power cycles. One typically limits the discharge cycles to half the rated amp-hour rating of the battery for best longevity. If you consistently blow your energy budget, then an increase in solar and/or battery capacity as required.

Could use the older battery as a practice battery, until you get the charging operation that you are looking for.

Thunderchild · Mar 21, 2009

hm well maybe I'll just return the new battery and use my old one and then invest next in some real batteries (4 X Trojan 6V 220 A) rather than getting more panels next, won't feel the pinch so much if I get my tax rebate (another long story)

nickelflippr · Mar 21, 2009

Took a fella about 5 days of intense southern Baja, Mx sun, to recharge just two 6V Trojan batteries, with a 75W panel. No controller, just direct connect, and no other loads.

The reason behind the 24V volt battery bank again?

Thunderchild · Mar 21, 2009

nickelflippr said:
Took a fella about 5 days of intense southern Baja, Mx sun, to recharge just two 6V Trojan batteries, with a 75W panel. No controller, just direct connect, and no other loads.

The reason behind the 24V volt battery bank again?

erm I won't stop at 40 W of solar panel, I intend to gradually increase the panels but don't want to be buying batteries all the time, larger batteries will be more durable I assume ? last longer cost less per W (assuming I want all that power). If I get 12 volts worth I won't really be able to add to it later will I ? I was led to beleive that 24 V inverters are more robust than 12 V ones and I'm pretty sure overal efficiency of a 24 V set up is going to be better than 12 volts.

nickelflippr · Mar 21, 2009

Thunderchild said:
erm I won't stop at 40 W of solar panel, I intend to gradually increase the panels but don't want to be buying batteries all the time, larger batteries will be more durable I assume ? last longer cost less per W (assuming I want all that power). If I get 12 volts worth I won't really be able to add to it later will I ? I was led to beleive that 24 V inverters are more robust than 12 V ones and I'm pretty sure overal efficiency of a 24 V set up is going to be better than 12 volts.

O.K. got it.

Inverter? Jeez, if someone would just answer 'one' of those urgent,... need 1000W inverter, pls include schematic, pcb files, and source code, postings!....haha Any candidates for a combo inverter/charger?

Thunderchild · Mar 21, 2009

General idea with 2 different car batteries is as attached.

Sceadwian · Mar 21, 2009

Thunder if you charge them separately you have to discharge them separately. So you'd basically have two separate 12 volt systems.

Thunderchild · Mar 21, 2009

well then I'll return the battery and get some bigger ones later, only thing is if i get 12 volts of batteries will I be able to put another 12 volts worth in series later ? me thinks not, that why I was going to try for the 24 V straight off

bbhs · Mar 29, 2009

I find the best cost effective batteries are the ones removed from telephone exchanges - they can be 2.5v, 6v and 12 volt that I have seen and are gel batteries designed to stand for long periods as well.
I used some 120ah ones which were over 6 years old and they were still fully functional - they do come up on ebay pretty often.
If your budget extends to it a good charge controller is recommended and would handle future expansion as your array increases.

Thunderchild · Mar 29, 2009

well I'll use a 5 A SMPS for now as a charger just to make the most of the power I'll be getting, I'll worry about a full blown controller later.

wombweller · Mar 29, 2009

Hi

Been in the shed as the topic of Gel batteries came up, I have a 12v 35AH gel battery that I would like to safely solar charge.I want to run from this an host of LED. garden lights.

The idea is to use recycled Jam jars to make the garden lights and if I say that there might be approx 10 lights each having say 4 LED's in them.

Should I purchase an off the shelf solar trickle charger or construct something?

Regards Mark

Thunderchild · Mar 29, 2009

for leds a ver small panel will do so if you have a decent sized battery it would withstand the constand current ? some one else is probably more qualified than me to answer that one though

Thunderchild · Mar 29, 2009

for leds a very small panel will do so if you have a decent sized battery it would withstand the constand current ? some one else is probably more qualified than me to answer that one though

wombweller · Mar 29, 2009

Thunderchild said:
for leds a very small panel will do so if you have a decent sized battery it would withstand the constand current ? some one else is probably more qualified than me to answer that one though

Cheers the main question is on a suitable solar charger unit for this battery.

Regards Mark

Nigel Goodwin · Mar 29, 2009

wombweller said:
Cheers the main question is on a suitable solar charger unit for this battery.

Regards Mark

It depends entirely on what you're using, you first need to monitor how much power the panel can supply (by measuring over a range of conditions) - for most panels you probably need no regulator at all.

ericgibbs · Mar 29, 2009

wombweller said:
Cheers the main question is on a suitable solar charger unit for this battery.

Regards Mark

hi Mark,
Not much Sunshine in Wombwell.

You can trickle charge the SLA at about 13.8V.

The size of the solar panel will depend upon the power required by the LED's
eg: current and the time the LED's are lit.
[I would have a simple dark detector and an OFF timer to conserve battery power]

The charge efficiency of a SLA can be 70%, so say for every unit of current you discharged
from the battery you would need to recharge at 1.3 times.

If you used a SMPS/controller the efficiency of the controller, say 85% would also have to be allowed for as loss.

Get the local sunshine hours and intensity for your area and work out how much power you would get from
say a 1mtr square solar panel.
[the solar panel manufacturers data will give the power outputs]

wombweller · Mar 29, 2009

ericgibbs said:
hi Mark,
Not much Sunshine in Wombwell.

You can trickle charge the SLA at about 13.8V.

The size of the solar panel will depend upon the power required by the LED's
eg: current and the time the LED's are lit.
[I would have a simple dark detector and an OFF timer to conserve battery power]

The charge efficiency of a SLA can be 70%, so say for every unit of current you discharged
from the battery you would need to recharge at 1.3 times.

If you used a SMPS/controller the efficiency of the controller, say 85% would also have to be allowed for as loss.

Get the local sunshine hours and intensity for your area and work out how much power you would get from
say a 1mtr square solar panel.
[the solar panel manufacturers data will give the power outputs]

Hi Eric

Solar panels or chargers seem to be sold in quite varying price ranges.I had a look in Maplins for something that I thought might be suitable-**broken link removed**

I could maybe add a couple together.This is £40 ish for the one.

At Farnell not much available other than a £385 panel.

Think I need to educate myself first on solar cells and paneling.

Not been vey lucky also at finding the sunshine hours and intensity in my area.
Keep on digging.

Regards Mark

ericgibbs · Mar 29, 2009

hi Mark,
The Maplins data says that if the SLA battery is over 12AHr, [yours is 35Ahr] no controller is required.

Also the panel is already fitted with a reverse blocking diode.

Regards

EDIT: a starting point.

**broken link removed**

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