Hi All, Could I please ask for some advice ! I have had an idea about using a Jackery power bank to plug my troll EHU supply into. My thinking is that we could go off grid or to sites with no EHU and then keep the leisure battery topped up from the Jackery. My concern (and advice from others) is that if the leisure battery was at say 50% and I plugged in my EHU cable there might be a Big Bang or similar event (small fire under the bed) as there is no control over the amount of juice going from the Jackery to the leisure battery - or even some reverse juice going back to the Jackery. But I was curious to understand, what stops such an event from happening when the EHU cable is plugged into a normal 13amp wall outlet ? Many thanks in advance, Robbie

the CSV409A charge controller controls the current flow from the mains to the battery

charge controllers work by sensing the voltage of the battery they are trying to charge: they dont just apply a fixed voltage.

Thats the same for solar charge controllers: they look at the voltage of the battery and adjust their voltages accordingly

if you apply a solar panel direct to a battery the battery will initially hold the voltage of the solar panel down but if left to its own devices as the battery charges up its voltage rises thereby ebanling the solar panel voltage to rise too.

A battery normal takes a charging voltage of between 13.8 and 14.2 V. A solar panel can up its voltage to more than 20V - this will nobble a battery

by the way, if you connect a mains voltage of 240Vac to your EHU with a leisure battery at 50% then the charge controller controls the voltage and therefore current supplied to the battery to charge it up in a controlled manner.

Connecting a battery in a discharged state to one that is fully charged (which is what you were thinking of doing by connecting the Jackery 12V output to the battery in the van as I understand it) , means the current/power flow from the fully charged battery to the discharged battery is not controlled

You could of course connect the 240Vac output of the Jackery to the 240Vac EHU input but this would be a very inefficient transfer of power:)

Electrically this is ok since the 240Vac inverter is controlling the output of the Jackery and the EHU charge controller is controlling the DC input to the battery

Yes !!!! Thanks JC, thats what I was after, but probably did not explain it that well in my post. My idea is/was to plug my 240v EHU cable from the Eriba into the 240v outlet on the Jackery (not into the 12v on the Jackery). So the Jackery is then topping up the leisure battery with the juice it used on lights and water pump from the night before. I guess if we are economical with the lights and pump it should not be too much to replenish each day. Also because the Jackery has “pass through” charging it will charge leisure battery in the van and then top itself up when done. This way I only need 1 solar panel and get rid of the need/cost off the solar controller (and the agro for fitting it). The end result (I hope) is a way to keep the leisure battery topped up and have a portable power source to have/use outside the Eriba at night (LED light strip, phone/ipad charging etc). Thanks again.

Advice from Jackery on the Amazon site about their product:

Q: Can the Explorer 240 be charged while using?
A: Yes, Explorer 240 supports pass-through charging. But we don't suggest, it will cause damage to battery life.

To be honest, I'd be very surprised if this configuration would be of any practical use due to the lack of constant sun, low power solar panel and energy losses in your inverter/charging devices