solar charge controller i thought i understood this . . .

simonfraser

simonfraser

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on my previous boat, solar panels, and controller, the highest voltage for the liquid acid battery charge was 13.8

on this one, gell battery, it tops out at 15.8

i thought the controller was faulty so bought a new one, but it levels out at the same voltage, i.e. 15.8 ???

i am sure i have the positive connections correct for the controller, i might have the earths confused, but even if i have, they are both the same, so it doesn't matter ?

what's going on ? /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif
 
most liquid acid have highest charge at 14.4 volts, with a float at abt 13.8 I knew gel could accept a higher voltage (thus a faster charge) but didnt realise it was as high as that.
 
15.8v is too high. What type of controller? Measure the battery negative to the controller negative? Once a gel starts venting gas there is no recovery.
 
The controllers are either a bypass type which simply connects in effect across the battery or a series and bypass type which limits the solar panel current as well as providing some bypass.
To test your controller especially the bypass type. Remove the controller and connect the solar panel directly to the battery and measure the charging voltage.(if it is 15.8) Connect the regulator and if the battery is still 15.8 then you have a dud controller.
Most agree that 15.8 is too high for a charging from a big sollar array. NB don't be confused a solar array will give around 20 volkts without a battery connected this falls when you connect the battery. good luck olewill
 
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most liquid acid have highest charge at 14.4 volts, with a float at abt 13.8 I knew gel could accept a higher voltage (thus a faster charge) but didnt realise it was as high as that.

[/ QUOTE ]

I thought GELS had to be lower voltage than wet cells, due to gassing issues, but they accept more charge at the same voltage as wets. All my smart regulated stuff is max 14.6 for wets and max 14.4 for GELS.
 
What type of charge controller have you got?

I have this one, from Compass:

0111480_r2_FS05im.jpg
albeit it looks different

On mine you connect the +ve and the -ve from the solar panels into one side, and then a +ve and -ve from the battery into the other side, with a fuse installed close to the battery. This regulator will take up to 4a from the panels and has its own built-in fuse.

I can often get >20v open circuit from the solar panels and about an amp off each (2 x 13w panels). When I connect these to the regulator, it limits the charging voltage to about 13.3-13.5 volts. When the battery is approx 13-13.2 volts the indicator shows it as being fully charged, and stops the charging.... found this out by watching it and measuring it... goes green, a while later after using some power, goes to red and starts charging until its green again.

I find the panels and this setup works very well for my use and has not given me any problems since installed. It keeps my 85ah battery topped up, even after heavy use it charges again within a few hours.
 
Simon I think you missed apoint here. "Solar panel is 19 volts but through regulator is 15.8."
The solar panel will be 19 + volts with no battery connected. What I was advocating was to connect the solar panel to the battery for a time then check the voltage as compared to the voltage of the battery with controller (regulator) connected. If the battery is fully charged there shouylld be significant difference.
The solar panel voltage will always be pulled down to that of the battery. The question is how far up will the solar pull (charge) the battery. The regulator should limit this battery voltage to a suitable max charge voltage. ie 14 volts.
Without a regulator a solar panel will try to charge over a long period to 19 volts. It won't acheive that but will boil the battery trying. Unless it is a small current panel in which case no harm is done and battery just won't rise above 14 volts or so.

One last warning. When digital voltmeters get a flat battery they read higher than true. So check the DVM battery. olewill
 
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