DC-DC Charger...Does It Ever Need to Be Disconnected When Stopped?

[Wallowa]

My question refers to the possibility that current could flow through my Victron DC/DC charger from the BB battery in the Hawk into the Tundra battery...or, when Tundra is on Battery Tender in shop that current could go from Tundra into the BB in Hawk...

When parked on trips or in shop, I have been opening the breaker and isolating the BB, but do not know if that is necessary..

When and if I need to run my Warn winch off the Tundra battery, I will need to have the motor running for power from the alternator and then would open breaker to prevent the alternator from too much load..

Thanks for any insights...

Phil

 

[Jon R]

The Victron Orion chargers do not allow current to flow back to the truck source. No need to shut it off for that reason. Although if you are doing truck maintenance where having power could cause damage or injury, I’d disconnect it anyway for double protection.

(Paragraph deleted due to error pointed out by Vic below)

Makes sense to shut off the Orion if you are worried about overloading your alternator while using a winch. It can be shut off via bluetooth and the phone app.

 

[Wallowa]

Thanks Jon...forgot about the Bluetooth....but is very simple to open the breaker mounted under the hood on the firewall...appreciated the info....no really easy way to disconnect the BB; so breaker is the point of disconnect..

Phil

 

[Vic Harder]

When your Tundra is on the battery tender I would shut off the Orion charger or disconnect the camper battery to avoid overcharging the camper battery with the tender.

Jon R - I don't think there is any need to turn off the Orion or disconnect the Camper battery when the truck starting battery is on a tender. Yes, the Orion may sense enough voltage to turn on and charge the Camper battery, if it needs it. The Orion would function the same way as if the truck was running, and it is smart enough for that, so why second guess it when using the tender?

 

[kmcintyre]

I will say that I had to play with the settings on my Victron DCtoDC unit so that the camper battery would charge because the engine shutdown detection was/is set to 14v (?) and due to voltage drop from my alternator to the Victron is was less than that so it wouldn't allow current to flow so no battery charging. I lowered that value and it now is fine .

 

[Wallowa]

I will say that I had to play with the settings on my Victron DCtoDC unit so that the camper battery would charge because the engine shutdown detection was/is set to 14v (?) and due to voltage drop from my alternator to the Victron is was less than that so it wouldn't allow current to flow so no battery charging. I lowered that value and it now is fine .

Good stuff from all of you and appreciated...KM: Is the voltage drop you have due to wire sizing between alternator/Victron/battery? Mine is wired with 4 gauge....

 

[Jon R]

Jon R - I don't think there is any need to turn off the Orion or disconnect the Camper battery when the truck starting battery is on a tender. Yes, the Orion may sense enough voltage to turn on and charge the Camper battery, if it needs it. The Orion would function the same way as if the truck was running, and it is smart enough for that, so why second guess it when using the tender?

Agreed Vic. Thanks for correcting my mistake.

 

[kmcintyre]

Good stuff from all of you and appreciated...KM: Is the voltage drop you have due to wire sizing between alternator/Victron/battery? Mine is wired with 4 gauge....

Could be; I think I 6 guage but it's probably a run of about 15'. I see 14v at the battery, and sometimes see 14v at the charger but it's fluctuates between 12.4 and 13.5 most of the time so I see the victron cycling on and off. With bluetooth though, I can just turn off the engine shutdown detection, let the batteries charge and turn it back on to protect the truck battery (I've been adjusting the detection voltage so I don't have to do that but worried that if I set it to low, I could run the truck battery down).... now, we don't use much battery power (LED lights, maybe the furnace, so we really don't have to charge much).

 

[Wallowa]

Could be; I think I 6 guage but it's probably a run of about 15'. I see 14v at the battery, and sometimes see 14v at the charger but it's fluctuates between 12.4 and 13.5 most of the time so I see the victron cycling on and off. With bluetooth though, I can just turn off the engine shutdown detection, let the batteries charge and turn it back on to protect the truck battery (I've been adjusting the detection voltage so I don't have to do that but worried that if I set it to low, I could run the truck battery down).... now, we don't use much battery power (LED lights, maybe the furnace, so we really don't have to charge much).

My Bluetooth and complete Victron / Battleborn Li battery set-up was installed in June and I have used the Hawk on two trips since then....but observed, recorded and dinked with DC/DC, solar and 110v charging systems ...first off the Li set-up is outstanding...the DC/DC charger is a game changer when no solar or 110V input is very high or non-existent...on start-up of Tundra the output of the DC/DC is about 30+ amps and decreases as SOC on BB increases...going from Bulk to Float...when Tundra is shut down, the DC/DC output stops...not sure why you would ever disable the DC/DC shutdown when vehicle motor/alternator stops as you sometimes do...

In the final run-up I believe that Vic's explanation of the DC/DC cycle makes sense and I will stop disconnecting the breaker when Tundra motor is off....with or without Battery Tender...will only use the breaker if I ever have to use my Warn winch..

Phil

 

[Jon R]

Your 4 gage wire and shorter wire run is apparently keeping your voltage at the charger high enough that your charger isn’t cycling, and probably also doesn’t need to do the “”is the engine still running” test every 2 minutes.

 

[Wallowa]

Your 4 gage wire and shorter wire run is apparently keeping your voltage at the charger high enough that your charger isn’t cycling, and probably also doesn’t need to do the “”is the engine still running” test every 2 minutes.

Thanks...never even knew that the "test' occurred if motor was still running ..assumed this only happened when the motor was shut off....makes sense and appreciate the insight...

Phil

 

[Vic Harder]

Another thought. If you are wanting the LiFePo4 battery to NOT be fully charged at all times (it has been recommended to not store these batteries fully charged) then you may want to disconnect the DCDC charger when your truck is on the trickle charger.

 

[Wallowa]

Vic...good thought...still in process of determining IF the DC/DC will pass current from the Battery Tender to the BB battery with Tundra motor off....your suggestion is a good one...any pointers on desired storage voltage for a BB? Now sitting at 13.25v.

Phil

 

[Jon R]

You should be able to tell from the Victron phone app what the charger is doing.

 

[Vic Harder]

.any pointers on desired storage voltage for a BB? Now sitting at 13.25v.

Phil

I would not use voltage. As I think rando and I have said before, 50-80% SOC is where you could store it for optimum life span... IF YOU CARE to have the battery last longer than you will on this earth.

 

[Jon R]

For my battery I use 14.2 volts as the maximum charging voltage, and sync the monitor to 100% when it stops charging at that level. Relative to that slightly conservative 100% value, 13.3 volts seems to be about 75-80% charge with the battery resting, so 13.25 is probably just fine for storage if you don’t have a monitor to be more precise.

 

[Wallowa]

For my battery I use 14.2 volts as the maximum charging voltage, and sync the monitor to 100% when it stops charging at that level. Relative to that slightly conservative 100% value, 13.3 volts seems to be about 75-80% charge with the battery resting, so 13.25 is probably just fine for storage if you don’t have a monitor to be more precise.

I agree, not withstanding the Victron 712 SOC....the voltage also reflects the SOC....I do have a monitor but as has been pointed out the exact SOC is very difficult to pin down; and, the SOC / voltage range is a very tight one....not many volts to dramatically change the SOC...so we guess and hope for the best...in my case 13.25v.

 

[Wallowa]

You should be able to tell from the Victron phone app what the charger is doing.

yes, I have been monitoring the DC/DC on Bluetooth and the voltage on the BB while on Battery Tender...so far no input showing or voltage increase in BB..

 

[Wallowa]

Went back to check Prowse's UTube on Voltage vs SOC on BB...what complicates judging the SOC for me is the non-linear and increasingly often abrupt drop in % as the voltage goes down...like from 13.3V to 13.2V it drops 20% [from full] and then 30% more at 13.1V....

My Victron 712 shows 13.24-13.25V steady state with no discharge and master switch off and yet it shows "100% SOC"...how is that possible?

I am missing something....

14.4V.....100%
13.6V.....100%
13.4V..... 99%
13.3V..... 90%
13.2V..... 70%
13.1V..... 40%
13.0V..... 30%
12.9V..... 20%
12.8V..... 17%
12.5V..... 14%