Direct connection of solar panel to input of split charger?

[Dull Spark]

To those who gave me guidance on the Xalt and Xsplit alternator and split charging system, many thanks. I am now considering incorporating a solar panel, say 80W, feeding 1x110Ah and 2x110Ah battery banks.

The Xsplit charge splitter manual notes that where there is a multi-source charging capability (in addition to the normal alternator), these other sources can be paralleled to the alternator. This seems fairly clear, and I assume that the alternator doesn't have to be generating when the other sources are supplying.

My query is whether the solar panel would be back feeding the stationary alternator. Would it matter if it did? Is there any way the 20V no-load from the panel could be applied or cause damage?

My inclination is to connect the solar panel directly to the batteries with crocodile clips and avoid having to think too hard, but the opportunity seems worth considering!

 

[lpdsn]

80W is enough to cause damage if you left it. Controllers are pretty cheap. You could fit a basic one and feed the output direct to the domestics. If your existing installation is good there shouldn't be any need to charge the engine battery unless leaving the boat for quite a while.

 

[PaulRainbow]

80W is enough to cause damage if you left it. Controllers are pretty cheap. You could fit a basic one and feed the output direct to the domestics. If your existing installation is good there shouldn't be any need to charge the engine battery unless leaving the boat for quite a while.

I agree. Connecting 80w solar panels without a controller is a no-no.

 

[William_H]

As said 80w is too much for the batteries in that if you get a really sunny day it could well overcharge your batteries and boil them. You need a simple cheap controller to avert this. 2 controllers one to each battery from the one solar would be my choice. Or a controller for 2 batteries. Not such a good idea to run solar through a charge splitter. Diodes will drop voltage so limit max charge while a VSR will use power to operate it. good luck olewill

 

[earlybird]

Not such a good idea to run solar through a charge splitter. Diodes will drop voltage so limit max charge while a VSR will use power to operate it. good luck olewill

Solar charging is not my scene, but the X-split, which the OP has, has only a few mV. drop, with complete separation and so shouldn't cause a problem in this respect.

 

[VicS]

To those who gave me guidance on the Xalt and Xsplit alternator and split charging system, many thanks. I am now considering incorporating a solar panel, say 80W, feeding 1x110Ah and 2x110Ah battery banks.

The Xsplit charge splitter manual notes that where there is a multi-source charging capability (in addition to the normal alternator), these other sources can be paralleled to the alternator. This seems fairly clear, and I assume that the alternator doesn't have to be generating when the other sources are supplying.

My query is whether the solar panel would be back feeding the stationary alternator. Would it matter if it did? Is there any way the 20V no-load from the panel could be applied or cause damage?

My inclination is to connect the solar panel directly to the batteries with crocodile clips and avoid having to think too hard, but the opportunity seems worth considering!

No the solar panel will not back feed the alternator

As said in other posts a controller for a solar that size is essential.

Your choice whether to opt for an MPPT controller, which in maximise the output from the solar panel, a PWM controller or a simple on/off controller.

A PWM controller will modulate the charge rate as the batteries become charged to give something similar to the absorption and float stages of a multi stage mains powered charger.

An on/off controller has little to commend it apart from being cheap. It will cut out as soon as the volts reach 14.4 and not reconnect again until they have fallen to 13.4.

If you do not wish to use the X split ( or a VSR) to charge both banks then you could use a dual output PWM controller but as Earlybird says the volts drop across the X split is very low but as lpdsn says it should not normally be necessary to change the engine start battery.

I would not use crocodile clips for the battery connections!

The connections to the battery positives should be fused