solar and battery charger conflict

Submitted: Monday, Apr 20, 2009 at 21:12
ThreadID: 68055 Views:2087 Replies:2 FollowUps:6
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Hey can any body help. We have a bus (nissan civillian ) ftted out by ourselves several years ago . We have 2x80 watt solar panels a pl 20 plasmatronic contrller 4x 6volt deep cycles at 12 volts giving us 440 amp hrs. We have just introduced a cteck 7000 battery charger to the system fo r when the sun isnt happening . The problem I seem to have isthe pl 20 is giving me a strange soc reading when the cteck charger has said the batteries are full and has gone into a state of maintenance eg soc 65% ceteck is on float .

any thoughts regards dave
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Reply By: Lex M (Brisbane) - Monday, Apr 20, 2009 at 21:29

Monday, Apr 20, 2009 at 21:29
Need a lot more information. How is it wired, shunt used etc.
AnswerID: 360611

Follow Up By:- Monday, Apr 20, 2009 at 21:38

Monday, Apr 20, 2009 at 21:38
Thanks for your reply. No shunt fitted to the system. The solar panels and the pL20 plasmatronic regulator are wired up as the manufacturer instructions. Does that help you help me? Dave
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Follow Up By: Lex M (Brisbane) - Monday, Apr 20, 2009 at 22:00

Monday, Apr 20, 2009 at 22:00
Without a shunt the pl20 will not be able to measure the input from the charger and calculate the SOC correctly.
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Follow Up By:- Monday, Apr 20, 2009 at 23:26

Monday, Apr 20, 2009 at 23:26
Cheers Lex will give that a try and see where we end up . thanks Dave
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Follow Up By: Peter_n_Margaret - Tuesday, Apr 21, 2009 at 08:34

Tuesday, Apr 21, 2009 at 08:34
As Lex says, you need to charge via a shunt and a Plasmatronics PLS2 that tells the PL20 what is going through the shunt, then the PL20 will know wt goes in and out. The same shut can be used for loads as the PLS2 is 2 way.

Cheers,
Peter
OKA196 Motorhome
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Reply By: Member - Barnray (NSW) - Monday, Apr 20, 2009 at 23:12

Monday, Apr 20, 2009 at 23:12
http://www.energymatters.com.au/plasmatronics-20a-multivoltage-reg
ulator-charge-controller-p-98.html
Have a look at this site and the pdf's at the bottom of the page. Any 2 chargers are going to sense the voltage of the other and reduce the amount of charge because the charge level of each is higher than the actual battery level and they are sensing each other. B
AnswerID: 360632

Follow Up By: Maîneÿ . . . (WA) - Tuesday, Apr 21, 2009 at 09:59

Tuesday, Apr 21, 2009 at 09:59
""Any 2 chargers are going to sense the voltage of the other and reduce the amount of charge because the charge level of each is higher than the actual battery level and they are sensing each other""

Yes, the same applies to the Alternator & Solar when driving too

Mainey . . .
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Follow Up By: Lex M (Brisbane) - Tuesday, Apr 21, 2009 at 12:53

Tuesday, Apr 21, 2009 at 12:53
Interesting statement.
Both chargers are sensing battery voltage and trying to do what they want. Neither knows or cares why the voltage is what it is.

An alternator is a voltage controlled charger so unless the solar is capable of pulling the battery voltage higher than the alternator voltage it makes little difference to the alternator.
If the solar charger is a smart charger than it is probably trying to get the battery voltage higher than the alternator output voltage and can only do that if it can supply enough current to supply all the engine running requirements and have some enough left over to charge the battery. This would mean the output of the alternator would reduce to (almost) nothing. If either source can raise the battery voltage sufficiently to affect the other then the battery(s) must be charged sufficiently so it doesn't really matter.

From measurement:-
If the battery is well charged, my solar charger increases its current output with the engine running as the battery voltage it sees is lower than when the engine is stopped.
If the battery is down, the solar output does not change as was (and still is) trying to charge the battery higher than the alternator voltage.

Disconnecting the solar changes the alternator current output by approx what the solar was outputting at the time.

The measured input to the aux battery with the battery well charged and good sunlight and engine running is nearly 4 amps from solar and about the same or slightly less from alternator.

(120ah AGM, 80 watt mono panel mounted flat, and powertech controller.)
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FollowupID: 628470

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