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bossrox avatar image
bossrox asked

How to or not properly connect a charger?

I'm curious if there's a critical protocol for connecting or disconnecting a charge controller. It's my assumption it's ok to tie in live panels so long as a battery is connected & to disconnect any live panels before removing the batteries. Would that be right? And is it a bad move to connect live panels with no battery connected? Or suppose a battery breaker trips & disconnects the battery from the charger with live panel power, would that fry a charger? I'd like to think Victron has these scenario's covered for protection against such things but I had 2 chargers fail within a couple of days of each other & not sure if 1 of those was the cause.

charger
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Mike Dorsett answered ·

Hi bossrox, you have the fundamentals correct. Battery should always be connected first, and yes, if the battery circuit gets disconnected with the panels well energised it could fry the charger. Note - I'm not saying it will - I'm not into destructive testing on my own budget, so I haven't tried it with a Victron MPPT, but the scenario did fry another charger I once had.

The way to get round this IF you fit an additional breaker in the Battery circuit of the MPPT is to get a 2 or 3 phase circuit breaker - so the phases all disconnect at the same time. The battery goes through one phase, and the PV through the other (two) phase(s). If the PV voltage is high like 150 to 250V open circuit, then you WILL need to wire two phases of a breaker in series to open the PV circuit. Remeber that the dc rating of a breaker is less than half of its AC rating - though you can get special DC rated circuit breakers too.

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