Redarc 40 amp DC to DC Charger issue

Teleman wrote:
I don't leave the ignition on with the engine not running. Like I said it was just an experiment.

I understand you have no plans to leave the ignition on with the engine not running.

I was only suggesting that a simple voltage check could have easily determined whether you had a defective BI or underlying problem in your vehicle. A BI is a very, very simple device. If it doesn't work, it's either a defective BI or a very simple wiring problem.

otrfun wrote:

Teleman wrote:
Using the battery isolator didn't work. It didn't shut down so we connected the ignition wire and now it turns off with the ignition. Don't worry, even if there wasn't a warning beep when the ignition is on until starting the motor it's not something I'd forget.

Did you happen to check voltage at the battery isolator with the engine not running? If the BI didn't shutdown the dc to dc charger that suggests your BI was defective or it was receiving >13.3v when the alternator was off-line. A fully charged automotive, lead-cell battery can only produce a max voltage of 12.7v-12.8v when the alternator is off-line (even with the ignition on). In any event, if you're ok having your dc to dc charger active with the ignition on and the engine not running, that's certainly your call. Good luck with everything.

I don't leave the ignition on with the engine not running. Like I said it was just an experiment.

Teleman wrote:
Using the battery isolator didn't work. It didn't shut down so we connected the ignition wire and now it turns off with the ignition. Don't worry, even if there wasn't a warning beep when the ignition is on until starting the motor it's not something I'd forget.

Did you happen to check voltage at the battery isolator with the engine not running? If the BI didn't shutdown the dc to dc charger that suggests your BI was defective or it was receiving >13.3v when the alternator was off-line. A fully charged automotive, lead-cell battery can only produce a max voltage of 12.7v-12.8v when the alternator is off-line (even with the ignition on). Not enough voltage to keep the contacts on a BI closed. In any event, if you're ok having your dc to dc charger active with the ignition on and the engine not running, that's certainly your call. Good luck with everything.

If it’s working no reason to change it I just wanted to relay my experience.

S Davis wrote:

Teleman wrote:

S Davis wrote:
I would disconnect your blue trigger wire and see if it will work sensing the alternator voltage, less chance of drawing down your starting battery.

Again that was the original configuration and it didn't work. The charger stayed active.
I'm constantly monitoring my battery shunt and I have power pack to jump start the battery, generator, erc. It's fine.

Ok no problem, I would check again. On mine it takes 30 sec to 60sec to turn off after the ignition is shut off. It freaked me out at first because I thought it was not turning off. I I think takes a little bit for it to sense the voltage drop.

It's in the shop now but I'll do some more experimenting when I get it home.

Teleman wrote:

S Davis wrote:
I would disconnect your blue trigger wire and see if it will work sensing the alternator voltage, less chance of drawing down your starting battery.

Again that was the original configuration and it didn't work. The charger stayed active.
I'm constantly monitoring my battery shunt and I have power pack to jump start the battery, generator, erc. It's fine.

Ok no problem, I would check again. On mine it takes 30 sec to 60sec to turn off after the ignition is shut off. It freaked me out at first because I thought it was not turning off. I I think takes a little bit for it to sense the voltage drop.

S Davis wrote:
I would disconnect your blue trigger wire and see if it will work sensing the alternator voltage, less chance of drawing down your starting battery.

Again that was the original configuration and it didn't work. The charger stayed active.
I'm constantly monitoring my battery shunt and I have power pack to jump start the battery, generator, erc. It's fine.

I would disconnect your blue trigger wire and see if it will work sensing the alternator voltage, less chance of drawing down your starting battery.

otrfun wrote:

Teleman wrote:
I only turned the ignition on to measure the current briefly out of curiosity before I started the motor. The charger activates with a signal from the ignition. The output current is about 43A at higher rpms and 48 at idle like I said.

I prefer using a battery isolator because it requires >13.3v to activate the dc to dc charger. Zero chance of inadvertently discharging the starter/TV battery—ignition on or off.

I was hoping it was your input current fluctuating. Very unusual for charge current to fluctuate like that based on alternator rpm/output. The whole purpose of a dc to dc charger is to stabilize the charge process.

Using the battery isolator didn't work. It didn't shut down so we connected the ignition wire and now it turns off with the ignition. Don't worry, even if there wasn't a warning beep when the ignition is on until starting the motor it's not something I'd forget.

I have manual control of the isolation relays.