Charging without a Charge controller

westbranch · June 2011

I have a need to connect, short term, a PV or 2 to my camper battery. We are demolishing our old cabin and using the camper for sleeping in, a bit of cooking and showers etc... both my CC's are still in use and I don't want to buy another one for this temporary setup.

Is there a rule of thumb to use for this hookup?

~ 660 amp battery, 25 W and 70 watt panels available. not direct sun as in the shade.

thanks
Eric

mike95490 · June 2011

Re: Charging without a Charge controller

panels in the shade will never charge a battery

You have more chance, without a charge controller, of the panels discharging the batteries at night (backfeed)

660A of battery, 100W of panel, even in full sun, you won't keep up with self discharge.

Cariboocoot · June 2011

Re: Charging without a Charge controller

Eric;

The only thing you can do is put a Voltmeter on it and watch. Together those two panels might produce 5 Amps? Not much for a 660 Amp hour battery (assuming the extra 'm' was superfluous), but even a small charge on a not-so-drained battery can push the Voltage too high. That's really all a PWM does; you'll have to stand in for connect/disconnect. But you don't have to do it dozens of times per second, okay?

Seven · June 2011

Re: Charging without a Charge controller

I have to ask a simple question. Is that battery a 660 amp hour battery or 660 cranking amps? At 660 Ah, that is a massive battery for a camper. Is it is 660cca, running a panel directly to it should keep it charged depending on the amp produced by the panel. I have a couple 100w panels hooked directly to a couple of marine batteries and the most I have ever seen them produce was 17a, and it was short duration.

***edit***
Be sure to run a diode if the panels stay hooked up an night.

westbranch · June 2011

Re: Charging without a Charge controller

sorry, that is 660CCA as Leper pointed out. Probably in the ~100 A range of most car type batteries.

Ya, caught in the PV panel trap of hi Voltage/low amperage output.

It is a 'marine battery' used for the camper and the fishing trolling motor.

Just ordered a cheapo 10a PWM CC off Ebay. Now I can put the panels in the full sun without too much worry.

thanks for the quick comments.

Eric

mike95490 · June 2011

Re: Charging without a Charge controller

Since that battery is a "hybrid" and contains the worst of both starting and deep cycle, avoid discharging below 70%, or you may not get started some morning !

westbranch · June 2011

Re: Charging without a Charge controller

Mike I think you are confusing a camper with a "Winnebagel".

:roll:;)

The camper slides on and off the pickup and has its own on board, independent battery, hence the 'marine type' as it is a bit better for long slow use... the main drawback is there isn't enough room for a couple of real deep cycle 6 volt batteries.
We only get about 2 days before needing to charge up. Water pump gets left on all day, Fridge and water heater are pilot-less units, the furnace fan is the big one and then lights and radio... oh and there is a magic fan that is temperature activated and the seldom used bathroom fan

Charging without a Charge controller

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