Salar panels to two batteries

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KAM

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I had a search but can't find the information I am looking for. I have two batteries with a standard split charge diode arrangement. During the summer the solar panels fed the domestic batteries only. I now want to charge both domestic and starter batteries during the winter. The MPPT controller only has a single battery connection plus a load connection. I tried connecting it to the same point as the alternator but it does not work very well as the controller needs 12v to operate so on low light days the display is blank due to the diodes. I need to connect the output directly to the two batteries presumably I can do that by just putting an extra diode in each line but I still need power to the controller. Could someone point me in the right direction for a diagram and possibly suggest suitable diodes.
 
I just put in a temporary winter link between the two batteries so the panel charges both. Just remember to remove it in the spring. No additional diodes required.
 
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When you say " I have two batteries with a standard split charge diode arrangement " I assume you mean a VSR?

If this is so, how does it not charge both banks?

If not a VSR perhaps you should change your present " split charge diode arrangement " for a VSR and it would solve your problems?
 
xeitosaphil said:
When you say " I have two batteries with a standard split charge diode arrangement " I assume you mean a VSR?

If this is so, how does it not charge both banks?

If not a VSR perhaps you should change your present " split charge diode arrangement " for a VSR and it would solve your problems?
Click to expand...

KAM said:
No its diodes which I am quite happy with.
Click to expand...

I would assume ( correctly it seems) that "split charge diode arrangement" means just that a split charge diode arrangement . That is what is causing the problem

A VSR in place of the diode splitter would solve the problem and, if the alternator is not battery sensed, it would improve the charging from the alternator by eliminating the volts drop across the diodes.

If the alternator is battery sensed the battery which is sensed should be the priority battery with a VSR.

A dual sensing VSR would enable the other battery to be the priority battery for the solar charging if required.
So the starter battery could be priority for the alternator while the services battery is the priority battery for the solar system.
 
I don't want to change the diodes they work well with the Adverc charge controller. All I want to do is connect the solar panels to both batteries in the winter. It must be a fairly common set up.
 
KAM said:
I don't want to change the diodes they work well with the Adverc charge controller. All I want to do is connect the solar panels to both batteries in the winter. It must be a fairly common set up.
Click to expand...


Apologies I missed the mention of the Adverc !

But Xeitosaphil's suggestion to use a VSR is still a valid one AFAIK

How about separate solar panels for the two batteries?
 
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I have two battery banks with an Adverc charge controller, along with a VSR and a 100w Solar panel. It all works perfectly, and with no Voltage drop across the Diodes, the Solar panel and Adverc charges both banks automatically through the VSR , winter and summer no problems.

Great set up. :)
 
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KAM said:
I had a search but can't find the information I am looking for. I have two batteries with a standard split charge diode arrangement. During the summer the solar panels fed the domestic batteries only. I now want to charge both domestic and starter batteries during the winter. The MPPT controller only has a single battery connection plus a load connection. I tried connecting it to the same point as the alternator but it does not work very well as the controller needs 12v to operate so on low light days the display is blank due to the diodes. I need to connect the output directly to the two batteries presumably I can do that by just putting an extra diode in each line but I still need power to the controller. Could someone point me in the right direction for a diagram and possibly suggest suitable diodes.
Click to expand...

Do you have some sort of emergency parallel switch which allows you to connect the two batteries together? If so, why not use that? Until last winter I had a solar panel wired to one battery, so I simply left the 1-2-Both I had on "Both" for the winter. Worked fine.
 
JumbleDuck said:
Do you have some sort of emergency parallel switch which allows you to connect the two batteries together? If so, why not use that? Until last winter I had a solar panel wired to one battery, so I simply left the 1-2-Both I had on "Both" for the winter. Worked fine.
Click to expand...

Only problem with that idea is if one battery is not as good as the other, one could l pull the other down, also the diode voltage loss will be coming out of both sets of batteries and he could possibly end up with two banks discharged / flat?

At least with a VSR there are pre-set connection and disconnection limits to avoid the possibility.
 
JumbleDuck said:
Do you have some sort of emergency parallel switch which allows you to connect the two batteries together? If so, why not use that? Until last winter I had a solar panel wired to one battery, so I simply left the 1-2-Both I had on "Both" for the winter. Worked fine.
Click to expand...

The most sensible way of wiring an emergency paralleling switch is so that is parallels the two circuits ( starter and service) on the downhill side of the isolators.

That way you can leave a dud battery isolated and run both systems from one good battery. You can of course still benefit from the combined might of both batteries if necessary by closing both isolators and the emergency switch.

The downside is that you cannot charge both batteries from a single source without closing the isolators.

If the emergency paralleling switch is on the uphill (battery side) of the isolators switch you can charge both from a single source without closing the isolators but you cannot leave a dud battery isolated and operate both systems from a single battery.

Pro and cons! Personal choice.

I suppose two paralleling switches is the answer. One between the batteries and one between the switched circuits .... but that is starting to get too complex. VSR a better answer with a paralleling switch between the circuits ... I think.
 
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I've connetcted two cheap controllers to one 80w panel, each connected to one battery.It's been working beautifuly.for the last few months.The fact that there's quite a lot of sunlight here in the winter helps.
 
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Yes you have to accept that in winter there will not be much charge anyway. Hopefully enough to keep the batteries happy. I wonder however if the battery voltage would rise under solar in winter to operate the VSR.
OP could add separate diodes to each battery from the charge controller however the diodes may stop the controller working as suggested because it can not sense 12v battery connected. The diodes will mean that their volt drop .7v for silicon diodes will maen the charge controller will sense full charge .7v before full charge but this may not be a concern in winter. In any case VSR or diodes a bad battery will suck all the charge to the detriment of the good one. The only way to avert that I think is 2 solar panels.
I would as suggested parallel the batteries witha temporary jumper or use the emergency paralleling to charge both batteries as one. good luck olewill
 
xeitosaphil said:
Only problem with that idea is if one battery is not as good as the other, one could l pull the other down, also the diode voltage loss will be coming out of both sets of batteries and he could possibly end up with two banks discharged / flat?
Click to expand...

I am sorry, but I really don't understand the diode bit. Yes, if you leave two batteries connected and one's dud then it will drain the other, but that's easily avoided by not having a dud battery!

At least with a VSR there are pre-set connection and disconnection limits to avoid the possibility.
Click to expand...

VSRs bring their own issues with low-current supplies. Imagine your panel feeds (1) and the VSR connects it to (2). (2) gets flat, somehow. (1) is OK, so as soon as the sun shines, the voltage rises and the VSR closes. (2) then pulls the voltage down and the VSR opens. And closes, And opens. And closes. Chatterchatterchatterchatterchatter and not much charging.

VicS said:
The most sensible way of wiring an emergency paralleling switch is so that is parallels the two circuits ( starter and service) on the downhill side of the isolators. ...

That way you can leave a dud battery isolated and run both systems from one good battery.
Click to expand...

I now have independent house and engine circuits, with a BlueSea dual breaker. Turn it once and both circuits are live. Turn it a bit more and they are joined. If for some reason I ever wish to connect both circuits to just one battery, I have breakers on the batteries and can pop one of them to disconnect. VSR for alternator charging (switched so it only works when the engine is running), dual battery regulator from the solar panels. The idea is to have a system which works all by itself, and it seems to be fine - I turn the switch on at the start of a trip, off at the end and forget about it meantime.
 
yoda said:
Why not just fit a controller like this:

http://www.ebay.co.uk/itm/10A-Duo-B...61485368185?pt=UK_Gadgets&hash=item3ce1be1379

I have one and it does just what you want. Some also prioritise which battery is charged.

Yoda
Click to expand...

It appears to be a dual on/off controller not MPPT or even PWM.

The OP has an MPPT regulator and I doubt if wishes to down grade to a simple on/off controller.

Replacing the existing single output MPPT regulator with a dual output one would be a solution to the problem however.
 
KAM said:
I don't want to change the diodes they work well with the Adverc charge controller. All I want to do is connect the solar panels to both batteries in the winter. It must be a fairly common set up.
Click to expand...

Simple - I just connect the domestics (4 x 110) to the engine battery with jump leads. You do need a decent charge controller to make sure that you dont overcharge. I have done this now for 5 winters - boat in Greece where I cannot check up on it. I have 2 85 watt panels, one is vertical and the other horizontal to reduce the amount of overall charge.

Seems to work........
 
Thanks for all the good advice. Its a bit academic as the sun has not appeared for several days now. I think ill just go the jump leads in parallel route for now as I am very happy with the existing charge set up.
 
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