15 replies to this topic

[Wallowa]

Question:  

 

Can the current and then voltage from a Battery Tender connected to my Tundra starter battery [AGM] trigger an "output" from my Victron DC/DC charger into the BB battery in the Hawk with the Tundra motor is off.

 

Still trying to understand the function and timing of the DC/DC settings.

 

Thanks,

 

Phil

[Jon R]

The manual provides a good explanation of the settings for charging threshold and engine running detection. The charging voltage of the battery tender as the battery approaches fully charged may be high enough to hit the charging threshold voltage setting you need to use for your alternator. However, I suspect that as soon as the Orion turns on the battery tender will not be able to supply adequate current to keep the voltage up and the voltage will drop sufficiently to trip the engine shut down detection. The Orion then cuts off the current to measure the voltage to check if the engine is really shut down as opposed to there being excessive voltage drop due to wire resistance. When the current stops the voltage will go back up and the Orion will reaume charging if the voltage is above the charging (engine running) threshold voltage. This voltage checking cycle is repeated every two minutes. This is how rhe Orion is able to allow charging with high wire resistance from small wire size. I suspect if this cycling is allowed to continue the vehicle battery will eventually be depleted because the battery tender can’t supply the current drawn by the Orion.

The only way to avoid this cycling is if you can set the engine running threshold above the output voltage of the battery tender. However, to do so may require a high enough setting that a smart alternator voltage won’t trigger charging. It shouldn’t hurt anything just to try it and monitor what the Orion is doing via the app and bluetooth.

[Wallowa]

Jon R.

 

Thanks, that was my assumption also...my solution, although not elegant, is to simply open the breaker on the DC/DC to isolate the BB battery from the Battery Tender attached to my Tundra AGM battery while in my shop...AGM benefits from the Tender, the BB does not.

 

Thanks again for your insights..

 

Phil

[Old Crow]

I don't know the Orion but will just add that my DC-to-DC charger (a Ctek D250SA) does indeed charge my camper's (AGM) battery when I put my AC-to-DC charger on my Tundra's starter battery.

 

My Hawk shell doesn't have the Iota DLS-30 or a shorepower connection.  So I used to run an extension cord in through a tie-down door to top off or recondition the camper battery with a portable battery charger.

 

But one day I checked the camper battery shortly after starting to charge the truck's battery with a portable charger and saw a reading of 15 volts on that camper battery.  It took me a minute to realize what was happening.   The shorepower charger was charging the truck battery at 14.4 volts and the DC-to-DC charger was triggered by that voltage.  It was not only charging the camper battery, it was charging it at 15 volts because of its temperature-compensation feature (it was a cold day).

 

The other factor I'll mention is the capacity of the shorepower-charger.  Most portable charger manuals have a spec on how much capacity they are supposed to be able to charge or maintain (float).  I've charged my combined truck and (single) camper batteries with my 5-amp, 10-amp, and 25-amp portable chargers.  I believe I'm pushing the limits on the 5-amp one as the manual says it can charge up to 110 amp-hours and float up to 160 amp hours. 

[Wallowa]

Crow,

 

Indeed both your AGM batteries [Tundra and camper] would seem to benefit from a smart charger maintaining them....my 100ah Battleborn Li battery in the Hawk once near 100% is best left alone and with no loads when stored in my shop...while I do wish to float and maintain the Tundra AGM starter battery with my Battery Tender; hence opening the breaker linked to my Victron Orion Tr DC/DC charger....seems like subtle but significant differences in maintaining AGM vs LiFeP04 batteries.

 

Phil

[Jon R]

In addition to the concerns about floating a lithium battery when it doesn’t need it, again I’d be concerned that a 3 amp trickle charger like my particular battery tender combined with the Orion’s small-wire-compensation approach to engine running logic would lead to the vehicle battery being depleted. Given enough time the battery tender would catch it up, but you would have deeply cycled the AGM and may have a period where it can’t start the truck during that cycling.

This is my speculation based on my understanding of how the Orion works. I have not tested to see if this actually occurs.

[Wallowa]

Interesting..."small wire"...my Orion Tr DC/DC was installed with 4awg and an 80 amp marine breaker...my Battery Tender has three charging modes and cycles through to optimize the level of SOC; again I only use this on AGMs since I can not control the voltage or amps in the BT...neat thing about the Victron products is that they can be programed; but of course for me, knowing which are the best program values is a mystery in many cases...

Edited by Wallowa, 18 June 2021 - 03:50 PM.

[Jon R]

I used 6 awg marine cable to avoid the voltage drop causing the input voltage to the Orion falling below what the manual refers to as V enable. Your 4 awg will obviously do the same, so you should not see that test cycle interrupting charging every 2 minutes when your truck is running.

The problem is when your truck is not running the battery tender will likely trigger charging by registering above V enable when there is no current being drawn. However, when 30 plus amps are being drawn by the Orion, the input voltage will fall to the truck battery voltage minus the wire loss. This will cause the Orion to run it’s check to see if the truck is running by stopping charging and measuring input voltage, which will go back up to the tender charging voltage. The Orion logic will think the engine is running each time it does the 2 minute test so it will keep turning charging back on, pulling more current than the tender can give (3 amps?), and the rest of the current (30 amps) will come from the truck battery. The Orion is happy, but your truck battery is getting discharged.

Again, this is my understanding of how it works, but I haven’t tested it.

[Wallowa]

Jon,

 

Agreed, but again I avoided all this by simply opening the DC/DC 80amp breaker [on firewall of Tundra] and the DC/DC was then unpowered and the Battery Tender [only used when Tundra/Hawk parked inside my shop] no longer could push current to the DV/DC charger.  When I take the combo out for use I will just re-set the breaker and put the DC/DC charger back in the loop.  Cool seeing 30 amps pumped out when Tundra motor lights up the DC/DC...

[Jon R]

Phil,

It just occurred to me that I’m probably not focusing on the scenario you are concerned about. I was thinking of a situation where you have an at least somewhat depleted camper battery.

If you are storing your truck and camper with the camper battery fully charged, the truck battery depletion won’t occur because the Orion will only draw a small float current for the float time limit. If the concern you really have is that the battery tender will trigger on the Orion and lead to excessive charging of the camper battery, you can either dial down the charging voltage settings in the Orion or disconnect it as you were thinking.