Spliting solar charge

the diodes will lower the floating voltage to the batteries by about 0.5V depending upon the diode type. but it's a cheap way of getting near 100% charge.
twin outputs is best, but costs more.
my rutland regulator levels out at 14.4, most folk would be happy with a floating charge of 13.9 on their batteries . . . .
 
Assume it's a engine battery and service battery ?

What is your standard charge system now for the engine to service battery ?

If you cannot use your standard system, then for the current you have then a split charge relay from Maplin will do the job for a few £'s.

The solar panel is on the service battery, when the voltage gets up it will link in the engine battery, drop out when the sun goes in.

If you have a bi-direction split charge relay, you can use that one.

Brian
 
I had an earlier version of one of these which worked fine until its mechanical relay failed after about 8 years. The current versions are solid state, so I doubt that this problem would occur again.

I replaced it with one of these , now been in service for about four years and seems excellent. displays voltages of both batteries and the current generated by the panel(s)
 
This Kemo device regulates and splits (via a no-loss MOSFET device), and it costs buttons (20 euro with P&P). Bought one but haven't fitted it yet, so don't know how it works in practice. It has been recommended on here before though - also available from Maplins, I think.
 
For a 27 W (peak) solar panel, any form of control system will significantly reduce the available charge as most of the time in the UK you will only get less than half of that 27 watts - i.e. around 1 amp, or less!! In view of the fact that the panel will NEVER fully charge your main battery in this climate because of internal self-discharge, I would forget splitting the charge. Connect the panel to the more important battery (engine battery) and make sure that you have a switch than can parallel the batteries in an emergency if you do not already have one. That way you maximise the charge capability. If you have other means of charge such as alternator or wind, then fine - split those. but leave the solar panel on the one battery.
 
I would be careful advising connecting a 27 watt panel directly to a battery. Although it is often cloudy in UK, there are periods when the sun shines for days on end, even in winter. There would quite often be times when gassing of a relatively small battery would occur. 10 watts is the maximum that is normally advised for direct connection.

My 38 Watt panel, through the controllers described above, keeps three 105 Ah batteries (two domestic, one starter) fully charged throughout winter and was capable of keeping them reasonably well up during normal sailing in northern Europe before we ran a fridge full time.
 
I use this Lead Acid Battery Split Charge Module from Maplin £8.99

n73au.jpg
 
Can you substantiate the comment "maplin controller is a load of ***** "
Mine has been in constant use for 5 years now and is giving trouble free service.
Remember, this is intended to service a 27w solar panel, not an engine alternator. Granted that the splitter is rated at 20W, but I would be surprised if the solar panel could produce it's 27W around the Bristol Channel!
Note: If concerned that it is under rated, two could be used in parallel.
 
I agree with Diversgold you should not need a regulator with only 27W in UK.
That is a bit over 1 amp at best for a few hours per day tapering off due to sun angle etc.
However you should charge all batteries and to do this you fit diode spiltters.
This is one diode for each battery 2amp 400v silicon diode costs a few pence from electronic supplies. If you can find the blocking diode built into the panel you can fit another diode next to it. ie anodes together to solar +ve cathodes to each battery +ve. ie uses the blocking diode as one isolation diode.

The thing is a solar panel produces about 20v no load (unregulated) The voltage drops to that of the battery under load. So loss of additional .7 volt from diodes is no real loss. But if you use diodes for isolation after a regulator the precise 14v as regulated when reduced to 13.7 will reduce charge dramatically.

So to Cardiffcruiser just add 2 diodes and use solar panel no regulator for max charge from the solar. If in summer you are using too much water in batteries then you need a regulator but I can't imagine that happening with 95AH batteries. good luck olewill
 
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