Charles Posted June 14, 2017 Share Posted June 14, 2017 Allan would a solar installation usually be isolated when you're driving as the alternator takes over? Or when on hook up? As the mains charger would be on?. I was thinking solar might help when driving because the battery only gets 13.2v and I know it doesn't charge the battery fully because when I plug in hook up after a long drive the battery charges at 6amps. The charger is just a 13.8v power supply. Thanks Link to comment Share on other sites More sharing options...
aandncaravan Posted June 14, 2017 Share Posted June 14, 2017 Some chargers work out their charge program based upon the 'battery voltage', or more correctly the voltage at the battery. May I explain what I mean by Voltage at the battery as opposed to the batteries voltage as there is a huge difference? The voltage of the battery might only 12.2v, but if you start the engine the control display voltmeter will leap up to 14.4v the moment the Alternator starts charging the battery. No matter how hard you try, you won't be able to see the batteries true 'state of charge' 12.2v. This also applies to any electronics trying to read the battery voltage, they will only ever 'see' the 'voltage at the battery terminals'. If it is being charged, that will be the charger voltage, be it Alternator, Mains, Solar or Efoy. So if you had an ECU controlled Alternator, then at engine start up it might sample the voltage at the battery before deciding if it was going into full power 14.4v charge mode or a gentler 13.8v 'trickle' charge. If the Sun is high in the sky and the Solar regulator is already charging the battery at 14.4v the Alternator ECU would only be able to sense the 14.4v from the Solar charger so might decide the battery is already adequately charged and switch to a lower voltage. The battery would still draw a decent current but it would be less effective at a lower voltage, so take longer. Some 'intelligent' mains chargers do the same with the same result, as do Solar battery chargers. So how you manage your charging would be unique to your setup. I would imagine, from your description of the Mains Charger as being fixed 13.8v, that it is unlikely to be intelligent nor very heavy duty, so Solar would most likely provide a decent additional boost to the Mains charger. Unlikely the Alternator in your Motorhome is ECU controlled, so that won't need consideration. If I was you I would leave the Solar battery charger connected all the time you want to charge the batteries. Link to comment Share on other sites More sharing options...
Charles Posted June 15, 2017 Share Posted June 15, 2017 Thanks, I was leaning that way but wondered how the Votronic duo would react to having another charger (alternator) on. I suppose it can only charge more or not at all and as long as it doesn't damage the solar charger all is well. B-) Link to comment Share on other sites More sharing options...
Charles Posted June 23, 2017 Share Posted June 23, 2017 Charles - 2017-05-24 6:59 PM I grudgingly ordered the temperature probe with it. When it comes I'll measure the resistance and temperature and see if it's a standard 100k ohm one or whatever. If it's a standard thermistor you can get them for pence on eBay. Edit: don't hold your breath though, I'm in Spain for about 4 weeks yet B-) Right I'm back, the temperature sensor is a PTC 2k ohm thermistor. (Not 2.2k ntc which are more common) probably get one on eBay for 50p. Link to comment Share on other sites More sharing options...
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