Blue smart charger slows down USB ports

DIY
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1

I’ve installed a 30a Blue smart charger to my campervan which has a single output to 2 batteries connected in parallel. The positive connects directly to the positive terminal on the first battery, whilst I connected the negative to a negative bus bar to save wiring but also because I was unsure if the negative could be battery side of the smart shunt. The charger all works well and is powered from shore power.

However, one issue is that all of my fast charging USB ports now charge phones/ipads at a trickle rate when the blue smart charger is running. As soon as I turn it off, the USB ports charge very quickly. I’ve only had this issue with the batteries both at 100%, haven’t had the opportunity to try it when the batteries are of lower charge.

Does anyone have any suggestions on how to fix this?

Thanks.

2

Your charger negative should connect to the system side of the shunt not the battery negative so you probably have it correct.

When your charger is running the battery voltage will be around 14.4V rather than 12.8V for a normal lead acid. Are your USB chargers rated for higher input voltage during battery charging, if they are only rated for 12V input then they may not like 14.4V input. Check your USB charger specification.