ANOTHER battery charging question

glad you have asked the question as i have had a crack at looking it up but just so much info out there i got a headach and gave up .....
So come on all you wise ones ..
Cheers
Joe

I have heard about some chargers which get "confused" with multiple charge sources, but mine and most seem quite OK to accept solar plus alternator direct at the same time. In fact I get both charge potentials added together although the alternator charge rate drops off as the battery voltage comes up.

Cheers,
Peter
OKA196 Motorhome

Some will work in parallel whilst others will get confused.
I have three 40 amp dumb chargers that work well together and will produce 120 amps when connected in parallel.
On my caravan I have a 15 amp smart charger connected in parallel with a 20 amp smart solar panel regulator. One is a 3 stage and the other a 5 stage with different algorithms – no damage done but one tends to take over as they sense each other’s voltage and get confused about the batteries state of charge.

Pop,

Here's the method I use.
I have a Ctek D250S dual charger in the camper.
It has two input ports.
1. Alternator input
2. Solar input

If you are using a fixed solar panel on the roof of the camper and plugged into the solar inport port and also have the alterator input circuit connected, the D250S will determine the best source and use the one it considers best. In other words you can have both alternator and solar inputs to the dc-dc charger at the same time while driving, or with engine running.

A 240v charger is connected directly to the terminals of the battery bank and doesn't go through the dc-dc charger. When using the 240v charger simply disconnect the feeds to the other two circuits by removing the connection plugs.

I don't actually use the solar panels when driving. They are a bi-fold arrangement and I employ them when stationary at camp. However, should I leave the alternator circuit connected and happen to start the engine, again the D250S will determine the best source and use that.

OK thanks for your help guys. It sounds like most of you do not have a problem with leaving 2 charging sources connected at the same time. I will try that over the coming months and see how I go.

Cheers
Pop

Hi Pop,
The Ctek dc-dc charger is a great device.
You need to know that a car alternator will not charge an AGM battery to 100%.
An AGM battery really needs around 14.5v during their charging cycles to get to their full charge.
Most modern "smart" car alternators will only put out 13 -13.6 v so by the time it get through the Anderson plug then to the batteries you are probably only charging to 70-80%capacity - the end result will be a permanently damaged battery.
The Ctek type chargers will put out 14.5v (when required) regardless of of the input voltage ie it will take the alternators' 13.6v and boost it to 14.5v for the initial charge then drop back to 13.8v for maintenance.
Likewise with your solar panels - it will take the 17+v input and output between 13.8 to 14.5v depending on what the battery requires. Ive seen my solar voltage output drop to 4v at dusk but the voltage coming out of the Ctek is still 13+v albeit with bugger all amps but it is still putting in something.
Money well spent IMHO.
Bruce.