Charging battery while travelling

[crockitt]

Hi I have a 20 amp charger on order and want to power it with our 600watt inverter. The system at present is a redarc smartstart near the battery then to van.Will it work if I just install the charger in the van and connect to battery and inverter without any other alterations? Dave

[T1 Terry]

The only issues might be the inverter starting up under full battery charger load. some inverters have no problems with this, some chargers have a soft start function, where they check the battery condition first and then slowly ramp up the charge, this allows the inveter to fully power up before the charger load is applied
The system we fitted up into Erich & Lesley's (Swisslulu) Cruiser ended up needing a CTek charger as it has a soft start, but basically, everything is left turned on, when the start battery voltage gets high enough to close the redarc VSR, the inverter and battery charger starts, when the engine stops, as soon as the start battery voltage drops, the VSR opens and the inverter and charger shuts down.

[John M]

Hi I have a 20 amp charger on order and want to power it with our 600watt inverter. The system at present is a redarc smartstart near the battery then to van.Will it work if I just install the charger in the van and connect to battery and inverter without any other alterations? Dave

Hi Dave,
I have (and recommend) a Redarc (BCDC1220) Dc to Dc Battery charger this is connected from the ignition and charges the 12v house batteries from the 24v motor alternator, it is switched through the ignition has a 24v 100A relay which switches the feed from the solar to the regulator off, there is an incompatibility problem between the two charging systems where the charger and the solar appear to read the charge from each other instead of the battery voltage. (I have been told that this is a common fault with MPPT regulators)
Redarc have a BCDC40 charger which also works as a solar controller, but I understand they also need a relay to select the power source, either Solar or DC.
I reckon the main benefits of the redarc system is that the charger will work from 10v to 32v input which means that it is less susceptible to voltage drop as well as having the added advantage of being able to charge a 12v system from 24v input.

[T1 Terry]

the inverter/charger will work the same from very low voltages, the VSR you already have will protect the start battery so it's voltage drop across the cable length that becomes the issue. As you are only looking at powering a 600w inverter the 6B&S cable should be fine. If you have a PWM solar regulator it will work fine with the battery charger, and both the inverter and battery charger have a dual use

T1 Terry

[BruceS]

I've watched this thread with interest.
I'm considering not charging my house batteries at all from the alternator even though both are the same voltage.
I have 'ample' solar to keep the house ones up.
At present I drive down the road & with the Redarc unit working I see about 27V in both sets of batteries.
I park & switch off the engine & I immediately see 29.5V in both sets. (from Solar)
I start up the engine & when driving it goes back to 27V again.
If I manually disconnect the Redarc I then see 29.5V in the house batteries.
Obviously the solar controller, being 3 stage, can do a 'better' job than the alternator (or regulator).
Probably a manual cutoff relay would be the answer? First 20km use the redarc & then isolate it.
Solar reg is NOT MPPT.

[T1 Terry]

So, do you turn the solar off when the alternator is charging? I had a similar problem with the Kombi and direct alternator charging, the PL20 solar regulator was set to charge to a much higher boost voltage than the VW alternators regulator. After a very short drive, the solar would take over all the charging duties, the alternator would not contribute anything because the battery voltage was higher than the voltage set in the alternator's regulator. It was truely solar powered, but as soon as the sun went down and the head lights were turned on, the house battery was dragged down to around 70% SOC before the alternator resumed duties. This was all with AGM batteries of course, the Li batteries charge at a lower voltage so there wouldn't be so much of a voltage mismatch, but I will be using the inverter/charger method to charge the Li house batteries when I put it back on the road.

[BruceS]

T1 at present I haven't isolated anything but watching the voltage gauges doing the continual soft foot shuffle can't be doing the alternator regulator any good.
I'm thinking I'll just isolate the house batteries & let the solar do it's job on them. Mine are not portables so ......
I've been reliably informed I can install a switch (relay?) in the black wire on the redarc to stop it connecting to the house or disconnecting it if it has already connected.

[T1 Terry]

A simple switch in the black wire will do the trick, then you can turn the link on if you have had a few crap solar days and you need a bit of alternator charging. Seems strange the solar doesn't simply take over the charging role and bring both batteries up to 29.5v

[oldtrack123]

T1 at present I haven't isolated anything but watching the voltage gauges doing the continual soft foot shuffle can't be doing the alternator regulator any good.
I'm thinking I'll just isolate the house batteries & let the solar do it's job on them. Mine are not portables so ......
I've been reliably informed I can install a switch (relay?) in the black wire on the redarc to stop it connecting to the house or disconnecting it if it has already connected.

Hi Bruce
It is very unlikely to do any harm to the Alternator OR the altrenator reg
It is just EACH doing their own thing
It is quite a common event once the House battery voltage exceeds the vehicle battery voltage , just that MOST would not be aware unless they had dual voltmeters or a centre reading Amp meter connected in a location showing the current from the solar going into the vehicle 12v system
{would show as a discharge , & probably cause quite a worry , even though nothing was wrong]

It even helps the vehicle battery to be near fully charged !!
But a lot depends on the available solar input
It does mean the final stage [SOC]of the house batteries is tied to the tug battery SOC


PeterQ

[crockitt]

Thanks for the helpful advice I do not at this stage have any solar panels so I will carry on with the charger setup when the goods arrive Dave