Using deep cycle batt/batts to charge Shimano battery

[Cyclopath1000]

I dry camp on the ca coast in a camper on my truck. Last year I brought two of my old rv batts with me fully charged ( bought 2 new ones last year), a cheap inverter from walmart ( $65 around) , my oem Shimano e8000 charger and two Shimano batts. So after a long ride the set up works and will fully recharge the Shimano battery but this setup basically hits the system pretty hard with charging voltages as measured by the inverter ( which the Shimano charger is plugged into ) dropping into the 11.8 v range. My fear is that if I keep this up I will fry the Shimano charger. Are experts in agreement? I'm looking into upgrading the sat panel on top of my rig to a 300 watt with a mppt controller for around $600. I'm not ready to go there or to some kind of lithium ion rv battery though it's a thought . In reality I'm usually going for 4ndays of riding and therefore I'm using the spare rv battery once per trip.

 

[nosenada]

Sounds like you may need thicker wires from your rv battery to the inverter. Thicker wires = less voltage drop (and less amps going through the wires).

The 11.8v at the inverter may or may not be an issue, it really depends on how many volts the AC the inverter is putting out. I recommend you measure the AC voltage and as long as it is in range for the Shimano charger 100-240v you should be fine.

 

[jimbob]

As above. Very unlikely to damage the charger, but not the best setup for the inverter. Shouldn't damage it, but would be improved by increasing cable size by the sounds of it. You should be able to get more energy from the lead batteries too then.

 

[flash]

Your charger is safe. But really what do you expect from old batteries and a cheap inverter?

Gordon

 

[Cyclopath1000]

@flash and all...I agree that I shouldn't expect too much from this janked setup of old batts. While on the cheap my fear was to ruin the Shimano charger. The old rv batts and the inverter are minor worries compared to needing a new e bike charger. So I will measure the output of the inverter when charging the batts. If it sinks towards 100 v output then I need a more expensive solution. Having two batts takes the pressure off other solutions. The place where I camp has 120 to the bathrooms and the camp host but I don't like walking away from the charger and battery. Nor do I relish begging the host to let me use an outdoor socket. Plus if I'm really bored I can run a tv and blue ray off them.

 

[Slapbassmunky]

The Shimano charger will be fine. The inverter will (probably, check) have a low input voltage cut and will power down when the input voltage drops too low. As the input voltage drops it will pull more current in order to keep the output voltage steady. A 4A Shimano charger will put 160W maximum into the battery, including inverter losses I'd bank for 200W.

So about 18A input. As has been said check the volt drop on your input cables, but you're probably hitting the leisure batteries hard. They don't like going below 50% charge and the capacity will be considerably lower than what's written on the label. If you have access to the specs look up the C5 rate.

You haven't said what your leisure battery setup is.