Wooie Posted July 16, 2012 Share Posted July 16, 2012 Hi folks, I`m adding a second leisure battery and i`ve a question about the inverter that`s already fitted. The two batteries will be next to each other and i will connect them in parallel. The vehicle will be connected to the batteries as follows : The positive to the positive of the first battery and the negative to the negative of the second battery. All cables will be of equal length and suitable guage. This as far as i know after research is better than connecting both the positive and negative to the first battery. http://www.smartgauge.co.uk/batt_con.html What i need to know is where do i connect the inverter ? Do i connect it the same as now i.e. both terminals to the first battery or do i split them i.e. the positive to the first battery and the negative to the second battery ? I`m sure someone will know. Regards Graham. Link to comment Share on other sites More sharing options...
hallii Posted July 16, 2012 Share Posted July 16, 2012 I think your over complicating things, you only have two batteries and the cable length connecting them will be short. If you use a heavy starter type cable to connect them the resistance will be very small. Since you have done them how you have then you can connect the inverter to + on one battery and -ive on the other or the other way round, it doesn't matter really. Also, if you did draw a bit more current from battery "A" then the voltage would drop, then battery "B" would recharge "A" as soon as they came off load until the voltages were equal. All this asumes you will not be drawing mega amps, if so some careful calculations would need to be done and the connections hard soldered and tested. H Link to comment Share on other sites More sharing options...
onecal Posted July 16, 2012 Share Posted July 16, 2012 Hi,Yes you can connect as you say , but to have better battery balance,if you connect on one Pos' +from your inverter on one battery Pos+,,,,, and the Neg' _ of the inverter to the other neg' _ battery, make sure you keep the inverter as close as possible to your Batteries and also the Fuse,Regards,Brendan Link to comment Share on other sites More sharing options...
Wooie Posted July 16, 2012 Author Share Posted July 16, 2012 onecal - 2012-07-16 3:42 PM Hi,Yes you can connect as you say , but to have better battery balance,if you connect on one Pos' +from your inverter on one battery Pos+,,,,, and the Neg' _ of the inverter to the other neg' _ battery, make sure you keep the inverter as close as possible to your Batteries and also the Fuse,Regards,Brendan Hi onecal. that was my way of thinking, both batteries and the inverter are right next to each other. so it isn`t a problem to connect them either way. As i read it on the link it is better to connect to diagonally opposite corners and i thought it would be better to do the same with the inverter but just wanted to make sure. Regards Graham. Link to comment Share on other sites More sharing options...
onecal Posted July 16, 2012 Share Posted July 16, 2012 Hi Graham,Glad to be able to help, just ensure also the Inverter has good ventilation so as not to over heat.Regards,Brendan Link to comment Share on other sites More sharing options...
Wooie Posted July 27, 2012 Author Share Posted July 27, 2012 Another quick question for the " Techies " All fitted and everything went OK , i use these to connect the batteries together :- 1 battery is new ( today ) and the other is 2 months old, both are the same make and size. http://www.ebay.co.uk/itm/221070813909?ru=http%3A%2F%2Fwww.ebay.co.uk%2Fsch%2Fi.html%3F_sacat%3D0%26_nkw%3D221070813909%26_rdc%3D1 As soon as i connect the second battery the voltage from the panel drops from 20.9 down to 13.8 volts and the voltage from the regulator drops from 14.4 down to 13.8 volts whilst the amps goes up from 1.6 to 3.2 amps. This is in full sun at lunchtime with the sun almost directly above. These figures are on the regulator and double checked with a multi-meter. Each time i disconnect i cover the panel so the voltage is almost nil and i reconnect everything in the right order. If i go back to 1 battery the voltage and amps revert to the first figure in each set . I have changed the " Rated Value " on the regulator settings from 100 to 200 amps as per the instructions, i have tried changing it back to 100 amps but it still does the same. Everything on the regulator is good with a nice smiley face and it says normal and the temperature is normal with green lights. What have i done wrong ???? Regards Graham. Link to comment Share on other sites More sharing options...
Wooie Posted July 27, 2012 Author Share Posted July 27, 2012 Just had a thought, will the original cable from the battery to the distribution board be up to the job of now having 2 batteries ( twice the amps ) connected to it ? It is only 70cms long with the built in fuse but i don`t know what gauge it is. Regards. Link to comment Share on other sites More sharing options...
sshortcircuit Posted July 27, 2012 Share Posted July 27, 2012 You have only doubled your battery capacity and not your use, current drawn. The existing cables do not need to be changed Link to comment Share on other sites More sharing options...
sshortcircuit Posted July 27, 2012 Share Posted July 27, 2012 Wooie - 2012-07-27 7:35 PM Another quick question for the " Techies " All fitted and everything went OK , i use these to connect the batteries together :- 1 battery is new ( today ) and the other is 2 months old, both are the same make and size. http://www.ebay.co.uk/itm/221070813909?ru=http%3A%2F%2Fwww.ebay.co.uk%2Fsch%2Fi.html%3F_sacat%3D0%26_nkw%3D221070813909%26_rdc%3D1 As soon as i connect the second battery the voltage from the panel drops from 20.9 down to 13.8 volts and the voltage from the regulator drops from 14.4 down to 13.8 volts whilst the amps goes up from 1.6 to 3.2 amps. This is in full sun at lunchtime with the sun almost directly above. These figures are on the regulator and double checked with a multi-meter. Each time i disconnect i cover the panel so the voltage is almost nil and i reconnect everything in the right order. If i go back to 1 battery the voltage and amps revert to the first figure in each set . I have changed the " Rated Value " on the regulator settings from 100 to 200 amps as per the instructions, i have tried changing it back to 100 amps but it still does the same. Everything on the regulator is good with a nice smiley face and it says normal and the temperature is normal with green lights. What have i done wrong ???? Regards Graham. It suggests that your new battery is flat and needs a good charge. Can you disconnect your existing battery and connect your new battery only. Link to comment Share on other sites More sharing options...
hallii Posted July 28, 2012 Share Posted July 28, 2012 2 batteries will take twice the current (limited by your regulator). A slight voltage drop at the regulator is normal as the load (current) incteases. The voltage of 20.9v from the panel is an "off load" voltage, as you put a load on the regulator with the second battery the voltage will drop to the "on load" voltage. The electronics will monitor the battery (for it will be seen as one bigger battery) voltage and the current will reduce as the battery voltage rises. 14.4v is what they tend to show when the battery is fully charged in bright sunlight. It will drop to something like 13.5 - 13.8v when the solar panel is not producing voltage. In short all appears to be normal :-) H Link to comment Share on other sites More sharing options...
Wooie Posted July 28, 2012 Author Share Posted July 28, 2012 hallii - 2012-07-28 10:32 AM 2 batteries will take twice the current (limited by your regulator). A slight voltage drop at the regulator is normal as the load (current) incteases. The voltage of 20.9v from the panel is an "off load" voltage, as you put a load on the regulator with the second battery the voltage will drop to the "on load" voltage. The electronics will monitor the battery (for it will be seen as one bigger battery) voltage and the current will reduce as the battery voltage rises. 14.4v is what they tend to show when the battery is fully charged in bright sunlight. It will drop to something like 13.5 - 13.8v when the solar panel is not producing voltage. In short all appears to be normal :-) H I`ve got it set up so i can read the voltage ( with a multi-meter ) on both sides of the regulator. Does the voltage on the panel side of the regulator drop as well ? i would have thought that this stayed the same and it was the voltage from the regulator to the battery that changes as it goes through Boost......Float etc. ? Regards Graham. Link to comment Share on other sites More sharing options...
hallii Posted July 28, 2012 Share Posted July 28, 2012 Well, if the panel had an infinite charge current the voltage would not fall. But since it has a finite output the voltage will drop as the load increases. The panel output is unregulated until it gets to the regulator so the voltage will rise and fall depending on the sun or lack of it and the load (current drawn). The regulator will put as many amps into the battery as are available (actually Volts/current or watts) until the voltage rises to a given value and then the current will be reduced until it's just a trickle charge. It's tricky electrickity, quatum mechanics etc. I failed that part of the course so we won't go into it :-D H Link to comment Share on other sites More sharing options...
Clive Posted July 29, 2012 Share Posted July 29, 2012 Look here http://motts.org/second%20leisiure%20battery.htm Link to comment Share on other sites More sharing options...
Wooie Posted July 29, 2012 Author Share Posted July 29, 2012 I`ve sorted out what the problem was, A DUFF BATTERY !!!!! The new battery i bought was a duff one, went back to the dealer and said there was a problem with the new battery. they first said " it can be duff because it`s new " I asked them to test it, they wasn`t very happy but i insisted. They took it into the workshop and after an hour ( good job there`s plenty to look at) the service manager came marching in dumped the battery at my feet and said it was perfect and nothing wrong with it. I told him that it was not working properly on my van to which he just said that it was my van at fault and it wasn`t his problem and walked off. Call me " sensitive " if you want but i`m not being spoke to like that by no-one !!!!!!!! The dealer offers a 28 Day no quibble refund which i asked for and got . I went round the corner to the next dealer and bought one there, same brand, same size but £5 more expensive. Took it home put it on the van connected exactly the same as i did before ( same as your diagram Clive ) and everything is fine . It`s the last time i shall step foot on that dealers premises in time honoured fashion they can " Go To Hell " Regards Graham. Link to comment Share on other sites More sharing options...
Clive Posted August 4, 2012 Share Posted August 4, 2012 Job sorted then. Take care C. Link to comment Share on other sites More sharing options...
Hilux Posted August 6, 2012 Share Posted August 6, 2012 So far there has been no mention of fuses. There should be a fuse of about 40 to 60 amps very near the +ve terminal on both batteries. Without such a fuse, in the event of the +ve wire shorting it could cause a fire. Also you must remember that if you take a battery out of circuit the wires from the removed battery are still live. You don't want them waving about without a fuse to protect a short circuit. H Link to comment Share on other sites More sharing options...
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