Battery management + battery separator = ??

[DavidR]

Hello all,

I just moved our 4WC slide-in pop-up camper from the old Ranger to the new one. It has a battery that charges from the truck's electrical system through a battery separator. After double-checking my wiring, I hooked it up, but the battery separator did not connect, so the camper battery did not start charging.

After measuring all the voltages, I discovered that the Ranger's battery, even with the engine running, was sitting at only 12.4V It appears that to increase battery life, they now manage the battery charging and only charge it when it drops below a certain point. (in the past, the old truck always charged the battery, resulting in it always being at 13.8V.)

I appreciate longer battery life, but the problem is that the battery separator won't engage unless the truck battery is above a certain threshold. I'm sure the truck will eventually decide to charge its battery and then the separator will connect, but I'm concerned that it might not connect often enough to keep the camper battery charged, especially when using the fridge. I don't' like using the fridge on propane while driving.

Has anyone else encountered this? Are there newer types of battery separators that can deal with these newer host vehicle charging systems?

I'll be heading out tomorrow, so we'll see how well it all works..

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[t4thfavor]

I do notice that my Kenwood ham radio does not like the lower voltage of the Ranger, I plan to put a small battery behind the seat to combat this.

The battery disconnect isn't needed though as the truck manages the charging circuit all by it's self.

 

[dceggert]

Hello all,

I just moved our 4WC slide-in pop-up camper from the old Ranger to the new one. It has a battery that charges from the truck's electrical system through a battery separator. After double-checking my wiring, I hooked it up, but the battery separator did not connect, so the camper battery did not start charging.

After measuring all the voltages, I discovered that the Ranger's battery, even with the engine running, was sitting at only 12.4V It appears that to increase battery life, they now manage the battery charging and only charge it when it drops below a certain point. (in the past, the old truck always charged the battery, resulting in it always being at 13.8V.)

I appreciate longer battery life, but the problem is that the battery separator won't engage unless the truck battery is above a certain threshold. I'm sure the truck will eventually decide to charge its battery and then the separator will connect, but I'm concerned that it might not connect often enough to keep the camper battery charged, especially when using the fridge. I don't' like using the fridge on propane while driving.

Has anyone else encountered this? Are there newer types of battery separators that can deal with these newer host vehicle charging systems?

I'll be heading out tomorrow, so we'll see how well it all works..

Yes, this is a fuel saving method. Running the alternator all the time uses quite a bit of fuel. It is managed to some extent to charge on deceleration when the fuel is turned off.

You may need an old fashioned relay like a starter relay. When the ignition is on it would connect the two and disconnect when you key off. It would take a while to connect up though.

You may also find this function already in the trailer connection in the 7 pin connector. There is a trailer battery circuit that should only be active when the key is on. Routing this circuit to your auxiliary battery may take care of this without added hardware.

 

[dceggert]

I do notice that my Kenwood ham radio does not like the lower voltage of the Ranger, I plan to put a small battery behind the seat to combat this.

The battery disconnect isn't needed though as the truck manages the charging circuit all by it's self.

In the case of a camper, though, using 12v stuff in the camper overnight like a heater or fridge can drain the battery. If it isn't disconnected it would run both batteries out and then the truck will not start. l rewired my motorhome a couple years ago with 4 6v deep cycle batteries to run the coach separated from the under hood battery. I also added a 2nd 12v start battery just for the generator that is also isolated. I then hooked up a 2k inverter to the house bank and changed my fridge to a regular 120v house style. It isn't enough to run the roof air but it all works pretty slick.

 

[DavidR]

In the case of a camper, though, using 12v stuff in the camper overnight like a heater or fridge can drain the battery. If it isn't disconnected it would run both batteries out and then the truck will not start. l rewired my motorhome a couple years ago with 4 6v deep cycle batteries to run the coach separated from the under hood battery. I also added a 2nd 12v start battery just for the generator that is also isolated. I then hooked up a 2k inverter to the house bank and changed my fridge to a regular 120v house style. It isn't enough to run the roof air but it all works pretty slick.

Yeah, hard-wiring the two batteries together runs the risk of draining the truck battery too much.

I'll check out the possibility that there's a simple ignition-controlled relay already provided with the towing package. That would probably be the best solution if it's already there.

Our camper is pretty small and minimalist, and doesn't use much power overnight, the main load being the furnace fan, since I always switch the fridge to propane at night. The lighting is all LED, so doesn't consume much, and we don't have AC. I do have space for a second battery in the camper, so I might add that, giving me two deep-cycle 12V batteries in the camper. With that much capacity, I can probably safely hard-wire wire them to the truck battery and not worry about consuming so much charge overnight that the truck won't start. There would still be a small risk if I forget to switch the fridge from 120V to propane, but I have never forgotten to do that, so I'm probably okay.

For my trip tomorrow, since I don't have time to do anything, I'm going to just run it as it is and see if the truck ends up charging enough of the time that it's not a problem. If it doesn't, I'll just hard-wire them together and disconnect them at night for this trip and look into these other things later.

 

[DavidR]

I do notice that my Kenwood ham radio does not like the lower voltage of the Ranger, I plan to put a small battery behind the seat to combat this.

The battery disconnect isn't needed though as the truck manages the charging circuit all by it's self.

I also have a Kenwood HF rig, but I haven't used it for years. Unlike the camper appliances, though, the radio directly loads the truck battery. IIRC, the Kenwood will draw 20A peak during SSB operation, I'm surprised that doesn't cause enough of voltage drop to trigger the truck's battery manager into turning on the charger significantly more often, but yeah, you still won't get a solid 13.8V

 

[t4thfavor]

I also have a Kenwood HF rig, but I haven't used it for years. Unlike the camper appliances, though, the radio directly loads the truck battery. IIRC, the Kenwood will draw 20A peak during SSB operation, I'm surprised that doesn't cause enough of voltage drop to trigger the truck's battery manager into turning on the charger significantly more often, but yeah, you still won't get a solid 13.8V

Mine is a D710GA, and it also directly wires to the battery via 12AWG stranded copper. It still shuts off each time the Auto Start Stop is triggered. It's super annoying, and I've gotta do something about it.

In the case of a camper, though, using 12v stuff in the camper overnight like a heater or fridge can drain the battery. If it isn't disconnected it would run both batteries out and then the truck will not start. l rewired my motorhome a couple years ago with 4 6v deep cycle batteries to run the coach separated from the under hood battery. I also added a 2nd 12v start battery just for the generator that is also isolated. I then hooked up a 2k inverter to the house bank and changed my fridge to a regular 120v house style. It isn't enough to run the roof air but it all works pretty slick.

Check the connector, I do not believe there is voltage on the charging circuit after a few minutes of the truck being off. I haven't checked my own truck, but I did read that here on this forum somewhere, and it makes sense to me.

 

[Noseoil]

Just put a small solar panel on the roof & charge the camper anytime it's daylight outside. That's what we do in the teardrop (100 watt panel & 100 AH AGM battery) which works pretty well for us. No charging circuit from the tow vehicle & we always have power.

 

[DavidR]

Check the connector, I do not believe there is voltage on the charging circuit after a few minutes of the truck being off. I haven't checked my own truck, but I did read that here on this forum somewhere, and it makes sense to me.

That may be true if connecting through the trailer wiring, but that's not how it's currently hooked up. The default setup for these campers is a direct connection from the truck battery to the auxiliary battery through an automatic battery separator. It makes installation simple since it works on trucks without a tow package, and there's no need to connect to a voltage that is ignition-driven since the separator is automatic. The battery separator requires 13.3 volts on the truck battery in order to connect, which wasn't a problem on older trucks which charged the battery continuously.

I think the long-term solution is to use an ignition-controlled relay instead of the automatic battery separator like dceggert suggested. When I get back, I'll check if the tow package already includes that, if not, I'll have to wire one in.

On the other hand, maybe the charging system will come on often enough to keep the aux battery adequately charged, we'll see..

And yeah, I can see that auto start-stop would wreak havoc with a radio. You'll probably have to disable it. I've upgraded to LED headlights and it makes those momentarily shut off for a fraction of a second - a little annoying, but not as bad as it would be with a radio.

 

[VAMike]

And yeah, I can see that auto start-stop would wreak havoc with a radio. You'll probably have to disable it. I've upgraded to LED headlights and it makes those momentarily shut off for a fraction of a second - a little annoying, but not as bad as it would be with a radio.

Probably needs to be wired differently. The truck radio doesn't turn off...

 

[t4thfavor]

Probably needs to be wired differently. The truck radio doesn't turn off...

Direct to the battery using #12 stranded copper. Battery volts are probably just dropping a bit too far for the Radio. It's not every single time, but about 95+%. Battery and huge diode behind the seat are my future fix. Now I just disable the feature when I'm talking.

 

[VAMike]

Direct to the battery using #12 stranded copper. Battery volts are probably just dropping a bit too far for the Radio. It's not every single time, but about 95+%. Battery and huge diode behind the seat are my future fix. Now I just disable the feature when I'm talking.

I would guess the truck systems are behind a voltage regulator.

 

[DavidR]

I would guess the truck systems are behind a voltage regulator.

That's probably true, and the regulator is designed to be able to buffer the power across the expected voltage and time gap. The ham radio doesn't expect that. Nor do the after-market LED headlights

You could build a power conditioner to do something similar for the ham radio, but the problem will be transmit current draw. The D710GA draws up to 13A on transmit. To buffer the voltage with that much current draw for 0.5 second or so would require impractically large capacitors. Probably the best bet is to buffer the power with a small 12V battery as @t4thfavor mentioned. You could design a fairly simple low drop-out charger to keep the buffer battery charged to within 100mV or so of the truck battery. A simple power VMOS current source should work.

 

[DavidR]

An update on the battery separator issue. I thought that driving with the headlights on might create enough load that the Ranger would have to charge the battery fairly often, and hence trigger the battery separator, so I drove out to my destination with the lights on, both high and low beams since I have LED headlights. It worked, sort of - the camper battery was fully charged when I arrived. You can probably guess the sort-of part. I forgot to turn the lights on for the drive back today, and the camper's battery dropped below the threshold of the 120V inverter that powers the refrigerator. Without the lights on, the Ranger won't charge its battery enough to keep the camper battery charged through the battery separator. Fortunately, it was on the way back home, so it didn't matter that I arrived with the aux battery almost dead.

I don't really want to be dependent on never forgetting to turn the headlights on during the day, so I'll be trying to figure out how to rig up a relay that triggers off the ignition instead.

 

[RoadBoss]

An update on the battery separator issue. I thought that driving with the headlights on might create enough load that the Ranger would have to charge the battery fairly often, and hence trigger the battery separator, so I drove out to my destination with the lights on, both high and low beams since I have LED headlights. It worked, sort of - the camper battery was fully charged when I arrived. You can probably guess the sort-of part. I forgot to turn the lights on for the drive back today, and the camper's battery dropped below the threshold of the 120V inverter that powers the refrigerator. Without the lights on, the Ranger won't charge its battery enough to keep the camper battery charged through the battery separator. Fortunately, it was on the way back home, so it didn't matter that I arrived with the aux battery almost dead.

I don't really want to be dependent on never forgetting to turn the headlights on during the day, so I'll be trying to figure out how to rig up a relay that triggers off the ignition instead.

I was talking about this to the owner of Equipt outfitters the other day at off-grid expo in denver, he was suggesting a DC to DC charger for vehicles with variable alternators like the ranger. I still don't quite understand how they work, and they're a bit more expensive than typical battery isolators, but supposedly it should do the trick.

edit: Also, you don't want to have the aux battery connected straight, or just off a relay that's otherwise straight to the ranger's main battery. a battery isolator's job is to prioritize the main battery getting charged first and then supply current to the aux as available. if they're both just wired together, and not identical batteries they can get all sorts of screwed up, I'm sure the variable alternator will make that scenario even worse.

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