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Post by lollygagger on Jan 21, 2018 8:52:03 GMT
In my camper I have 2 batteries. I do short journeys and the starter gradually flattens. Everything else including the radio is on the LB which is attached to a solar panel. During the winter I don't use the LB much though I like to keep it topped up, but I think my van would be better served if I could switch the solar onto the Starter battery from time to time. Is this doable or will the controller loose it's settings? I know when connecting you must attach battery before solar so I don't hold much hope for the idea, but if it were a goer, what switch would the team recommend to cope? Ta.  |
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Post by Graham on Jan 21, 2018 9:21:44 GMT
The best possible answer with just two batteries I would suggest would be a Cyrix 120A battery combiner. It senses both batteries and joins them when the charging condition are right. It also has the facility to join the batteries for starting at the press of a button. www.batterymegastore.co.uk/victron-cyr010120011.html |
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Post by JohnV on Jan 21, 2018 9:22:06 GMT
I am a long way from an expert on solar matters but if it is just an occasional thing, then why not just put in a switch which parallels the two batteries when you want to charge up the starter battery ...... as long as you remember to turn it back off ...... possibly a small fuse in series with the switch might be an idea.
As far as the controller is concerned it just sees a sudden discharge of the battery.
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Post by Telemachus on Jan 21, 2018 9:22:27 GMT
It’s generally a bad idea to disconnect the solar controller from the batteries when the panels are getting sun even momentarily. With some types of controller, it can blow it. Why not just have a switch that parallels the leisure and starter batteries - the current from the solar will tend to go to the lower state of charge battery?
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Post by JohnV on Jan 21, 2018 9:25:45 GMT
The best possible answer with just two batteries I would suggest would be a Cyrix 120A battery combiner. that's new kit to me ....... the only ones I remember were a damn sight more expensive than that and only practical for commercial operation. |
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Post by lollygagger on Jan 21, 2018 9:49:28 GMT
It’s generally a bad idea to disconnect the solar controller from the batteries when the panels are getting sun even momentarily. With some types of controller, it can blow it. Why not just have a switch that parallels the leisure and starter batteries - the current from the solar will tend to go to the lower state of charge battery? If I had two switches, could I switch in the second battery before switching off the first? I prefer to have control over what's happening and don't want to discharge the LB in order to charge the starter one. |
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Post by Telemachus on Jan 21, 2018 9:55:30 GMT
It’s generally a bad idea to disconnect the solar controller from the batteries when the panels are getting sun even momentarily. With some types of controller, it can blow it. Why not just have a switch that parallels the leisure and starter batteries - the current from the solar will tend to go to the lower state of charge battery? If I had two switches, could I switch in the second battery before switching off the first? I prefer to have control over what's happening and don't want to discharge the LB in order to charge the starter one. You could, but it introduces a lot of scope for human error! |
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Post by lollygagger on Jan 21, 2018 11:24:26 GMT
If I had two switches, could I switch in the second battery before switching off the first? I prefer to have control over what's happening and don't want to discharge the LB in order to charge the starter one. You could, but it introduces a lot of scope for human error! Perhaps, if there is such a thing, I would be safer with a "one/the other/both" switch so the controller would always have power? I would prefer a manual switch as I don't really want to connect the batteries together, I just want to decide (that's me, not a computerised switch) which battery to connect to the solar but without having to switch cables around. |
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Post by Telemachus on Jan 21, 2018 11:30:19 GMT
You could, but it introduces a lot of scope for human error! Perhaps, if there is such a thing, I would be safer with a "one/the other/both" switch so the controller would always have power? I would prefer a manual switch as I don't really want to connect the batteries together, I just want to decide (that's me, not a computerised switch) which battery to connect to the solar but without having to switch cables around. Yes that would probably be OK since those switches are normally make before break (you should check that for the specific switch you are thinking of). It’s something I’d still be a little uncomfortable with because such a switch might be fine when it’s new, but a bit prone to an intermittent disconnect as it’s rotated, due to accumulated dirt and/or corrosion, when it’s old. However with a good quality switch it will probably be OK. And don’t rotate it to the “Off” position when there is light on the panels! |
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Post by Deleted on Jan 21, 2018 11:37:35 GMT
The 1, both, 2 off switches are good if you buy a good quality one. Ours is of indeterminate age and has been to bits once for a scrub of the contacts. As soon as you rotate the knob it engages in the contacts of the next position. They are spring loaded so there are no contacts to bend and loose the connection. Blue sea are fine. www.sailsmarine.com/ItemDetail.aspx?c=33567&l=g&cc=GB |
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Post by Graham on Jan 21, 2018 12:25:58 GMT
If I had two switches, could I switch in the second battery before switching off the first? I prefer to have control over what's happening and don't want to discharge the LB in order to charge the starter one. You could, but it introduces a lot of scope for human error! The Cyrix will break the connection that reduces the voltage on either battery to 12.8V so there is no danger of it discharging either battery. It only joins then when the voltage of one battery is over 13V |
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Post by Graham on Jan 21, 2018 12:28:28 GMT
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Post by Graham on Jan 21, 2018 12:31:12 GMT
It’s generally a bad idea to disconnect the solar controller from the batteries when the panels are getting sun even momentarily. With some types of controller, it can blow it. Why not just have a switch that parallels the leisure and starter batteries - the current from the solar will tend to go to the lower state of charge battery? If you want to switch the solar off for any reason, have a switch in the positive cable from the solar panels to the controller. Turning disconnecting the panels makes the controller think the sun has gone and does not damage the controller. |
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Post by Graham on Jan 21, 2018 12:39:06 GMT
Oh and regarding manual switches that join the batteries, I would never have them on my boat. The number of time I have helped people who have flattened their batteries because they forgot the switch was on both. I have used the Cyrixs for many years and recommended them and have yet to know of a failure. They will do the job safely and properly.
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Post by Deleted on Jan 21, 2018 13:56:15 GMT
Oh and regarding manual switches that join the batteries, I would never have them on my boat. The number of time I have helped people who have flattened their batteries because they forgot the switch was on both. I have used the Cyrixs for many years and recommended them and have yet to know of a failure. They will do the job safely and properly. It's amazing how many people can't use a battery selector switch correctly. Here's how to do it properly. 1 - start battery. Use this for the initial start of the engine. Leave it selected for 30 minutes to replace the miniscule amount of energy that was used to start the engine 2 - domestic battery. Switch to this position after the start battery has been topped back up. LEAVE IT IN THIS POSITION. With a decent battery bank there should be enough juice to start the engine using the domestic batteries the following day. If there isn't simply select position 1 and repeat the above. THE ONLY TIME 'BOTH' SHOULD BE SELECTED IS IF THE START BATTERY IS A BIT DOWN AND WON'T WANG THE STARTER OVER QUIET QUICK ENOUGH. IT SHOULD BE REGARDED AS AN EASY METHOD OF JUMP STARTING ONLY. TURN TO POSITION 1 ONCE STARTED AND FULLY CHARGE START BATTERY BEFORE SWITCHING TO POSITION 2 AS NORMAL. Off - pretty self explanatory, but don't turn it to off with the engine running. How anyone can find the above difficult is beyond me. Number of flat batteries in 9 years = 0 |
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