FWC Electrical basics and upgrading to lithium!

[lmwilco1]

I note that the voltages are NOT adjustable on that unit. They use 14.6 for charging, for example. Better and future proof would be a unit with adjustable voltages

If you buy a current manufactured unit it does drop to 13.6V. I am not sure when the change was made but I bought a second one 4-5 months ago from etrailer and it is working fine and drops to 13.6V once the battery is fully charged. Now I have a 14.6V power supply sitting on the shelf....

 

[Vic Harder]

If you buy a current manufactured unit it does drop to 13.6V. I am not sure when the change was made but I bought a second one 4-5 months ago from etrailer and it is working fine and drops to 13.6V once the battery is fully charged. Now I have a 14.6V power supply sitting on the shelf....

Thanks for that info. This implies that the float voltage is 13.6, which is also higher than some recommend. I use 13.4V for my float voltage.

 

[BerkeleyCarlos]

If you buy a current manufactured unit it does drop to 13.6V. I am not sure when the change was made but I bought a second one 4-5 months ago from etrailer and it is working fine and drops to 13.6V once the battery is fully charged. Now I have a 14.6V power supply sitting on the shelf....

Which model did you buy? How was the fitment in place of the Iota ?

 

[maurzog]

Has anyone here considered the use of something like a Victron Multiplus, I like that you can use the same plugs for the inverter and shore power seamlessly. My camper is currently wired with one plug for shore and one running the inverter.

https://www.victronenergy.com/inverters-chargers/multiplus-12v-24v-48v-800va-3kva

 

[pawleyk]

The multiplus is a great bit of equipment, but for a vast majority of FWC installs is larger, more expensive, and more complex than really necessary. It's crowning feature is it's hybrid ability, but most FWC customers are A: Not running large AC loads consistently and B: Not plugged into a shore line while actually camping

We've been using the Progressive Dynamics PD1600 with good results. It's compact, robust, and powerful, with a built in transfer switch. It's not a charger, but we typically just use the factory IOTA for Battleborn installs, as the DCDC and MPPT handle cell balancing/topping off just fine.

https://www.progressivedyn.com/1600-pure-sine-wave-inverters/

Has anyone here considered the use of something like a Victron Multiplus, I like that you can use the same plugs for the inverter and shore power seamlessly. My camper is currently wired with one plug for shore and one running the inverter.

https://www.victronenergy.com/inverters-chargers/multiplus-12v-24v-48v-800va-3kva

 

[pawleyk]

Hey Carlos, I called SOK tech yesterday and they were of the opinion that our IOTA was not compatible for many varied reasons including improper cell balancing. As I do more research seems if I remove the IOTA I will lose the AC to DC connection to the rest of the electrical system while on shore power as the IOTA serves as a DC load device. Not a very big deal except for those occasions I want to pre-cool the Isotherm Fridge before a trip and don't want or can't use the battery (say a very cloudy day or the camper is stored in the garage before loading. Though I suppose I could just plug the Fridge into an extension cord directly on that rare occasion. This brings up another question, (I am entering the rabbit hole) my Isotherm 85L has a 120v plug to an outlet in the cabinet next to the unit. Does this mean it will charge via 120v if the IOTA is removed? Also Can the Isotherm 85L do the 120v vs 12V switching automatically?
I rarely us novice and electricity in the same sentence.

We consistently use the IOTA as a tertiary charger for Battleborns. I'm sure the SOK are very similar. They are right, it wouldn't balance the cells correctly, but most FWC installs are using a DCDC and MPPT as the primary chargers, and they'll balance the cells just fine. I really wouldn't worry about the IOTA at all unless it's going to be your primary source of charge.

FWIW, FWC uses the Redarc Manager 30 to handle shore, dcdc, and solar. It has it's benefits, but we vastly prefer the victron equipment.

 

[pawleyk]

Hey Carlos, I called SOK tech yesterday and they were of the opinion that our IOTA was not compatible for many varied reasons including improper cell balancing. As I do more research seems if I remove the IOTA I will lose the AC to DC connection to the rest of the electrical system while on shore power as the IOTA serves as a DC load device. Not a very big deal except for those occasions I want to pre-cool the Isotherm Fridge before a trip and don't want or can't use the battery (say a very cloudy day or the camper is stored in the garage before loading. Though I suppose I could just plug the Fridge into an extension cord directly on that rare occasion. This brings up another question, (I am entering the rabbit hole) my Isotherm 85L has a 120v plug to an outlet in the cabinet next to the unit. Does this mean it will charge via 120v if the IOTA is removed? Also Can the Isotherm 85L do the 120v vs 12V switching automatically?
I rarely us novice and electricity in the same sentence.

Also, the fridge will run from 120v, even with the converter removed. It has it's own, internal 120-12v converter. It doesn't "charge" just runs, but I've never really understood the benefit of a compressor fridge that runs off of shore. If you're plugged in, you're charging at a much higher rate than the fridge uses power, so the whole 120-12v double conversion thing never made sense to me. Just a weird aside.

 

[BerkeleyCarlos]

My Hawk is only mounted to the truck part time. It is plugged into shore power for 3-5 weeks at a time. I am thinking of moving the DC2DC in between the IOTA and the battery. I think that would properly charge from both truck connection and shore power that way?

 

[pawleyk]

My Hawk is only mounted to the truck part time. It is plugged into shore power for 3-5 weeks at a time. I am thinking of moving the DC2DC in between the IOTA and the battery. I think that would properly charge from both truck connection and shore power that way?

I really don't think it'll be an issue. As stated above, it'll eventually just drop to 12.8 and stay there. You probably won't get 100% (unless solar is in the equation too, and then I'm not sure why it's plugged in at all unless it's under cover).

Also, most lithium batteries have very little self drain so there's not much reason to leave them on a charger at all.

Generally, running a charger through another charger isn't advised, but I can't come up with any reason to tell you not to do it, other than your time would be better spent camping and money better spent on beer and gas.

KP

 

[BerkeleyCarlos]

I do have 210w of solar to my Victron MPPT. It gets a decent amount of sun. I should unplug from shore power and see how many
Watt Hours it is pulling in during the day.

I am still running the stock 90ah AGM, but going with LifePo4 soon(ish). I think I need to move the DC2DC closer to the battery , getting different charge status from the MPPT and DC2DC while running both. MPPT , which is 6” from the battery , 8g wire . DC2DC is 10-12’ of stock 10g wire to the battery.

The MPPT tells me I am in “Float” , the DC2DC will show bulk,absorb and then float after driving for 45 mins.

 

[BerkeleyCarlos]

I wouldn’t be adding any new equipment, so beer money is safe.

 

[pawleyk]

Sounds good. Report back and let us know how it works!

 

[pawleyk]

I do have 210w of solar to my Victron MPPT. It gets a decent amount of sun. I should unplug from shore power and see how many
Watt Hours it is pulling in during the day.

I am still running the stock 90ah AGM, but going with LifePo4 soon(ish). I think I need to move the DC2DC closer to the battery , getting different charge status from the MPPT and DC2DC while running both. MPPT , which is 6” from the battery , 8g wire . DC2DC is 10-12’ of stock 10g wire to the battery.

The MPPT tells me I am in “Float” , the DC2DC will show bulk,absorb and then float after driving for 45 mins.

The biggest issue is the stock 10awg. Just install the correct sized wire for 30amps at that distance. And make sure they're programmed the same.

Otherwise, don't worry about it too much. As long as the battery is charged, your beer will be cold.

 

[Vic Harder]

The fattest wire that will fit in your DCDC chargers is 6 AWG. At 12', your voltage drop is less than 3% which is acceptable. Of course, moving your converter to be closer to the battery would be ideal.

 

[IDPaddler]

Hello
first, thanks to KP for the great thread! Rather than start a new thread I'll just ask here...

I installed a Renogy 12v 50A dcdc this weekend. I ran 4 gauge wire for the whole system. All the lights came on properly. I selected the correct battery (single 12v AGM, 90ah). Attached the small wire to "override" the Smart alternator. I am using a Victron smart shunt and only seeing ~9ah being pulled while driving when battery is at 92%. This doesn't sound right. Any thoughts? Does the battery need to be drained further in order to pull higher current?
Thanks

 

[pawleyk]

Hello
first, thanks to KP for the great thread! Rather than start a new thread I'll just ask here...

I installed a Renogy 12v 50A dcdc this weekend. I ran 4 gauge wire for the whole system. All the lights came on properly. I selected the correct battery (single 12v AGM, 90ah). Attached the small wire to "override" the Smart alternator. I am using a Victron smart shunt and only seeing ~9ah being pulled while driving when battery is at 92%. This doesn't sound right. Any thoughts? Does the battery need to be drained further in order to pull higher current?
Thanks

I the battery is truly at 92% that sounds like it totally could be right. Charging will taper off near full into an absorption state (higher voltage/lower amperage) to top the battery off completely when it's near full.

What kind of amperage do you see when the battery is at say, 50%?

 

[IDPaddler]

I the battery is truly at 92% that sounds like it totally could be right. Charging will taper off near full into an absorption state (higher voltage/lower amperage) to top the battery off completely when it's near full.

What kind of amperage do you see when the battery is at say, 50%?

That was my thought….charging tapered off at near full SOC.

I ran the heater last night and it only dropped to 92%. In reality I’m not sure I’ve ever even run it down to 50%. I’ll keep the heater going and turn on some lights to try to get it to run down further… Then recheck.

Thx!

 

[IDPaddler]

Update,

This morning the Renogy DCDC50A pulled up to 43ah with the battery down to 70% (solar disconnected, alternator only). So it seems to working just fine. As above, the charge rate must drop when is goes into absorption state if the battery is near full...like in the 90% SOC range.


It charged from 70% to 78% after driving for just 10 min or so. I'm totally stoked with this performance! IMO it's a fantastic upgrade.

 

[Jon R]

A dc-dc charger can only do so much within its design parameters. My guess is you are still either wire-limited or alternator-limited on your current if you are only getting 43 amps with your battery that low. But so what? If you are satisfied with that nearly full charger capacity current, call it good. Many of us are happy with the 30 amp output of other units. Bigger copper is expensive and difficult to run, and 43 amps will serve you well and keep your charger at a lower operating temperature.

 

[pawleyk]

Update,

This morning the Renogy DCDC50A pulled up to 43ah with the battery down to 70% (solar disconnected, alternator only). So it seems to working just fine. As above, the charge rate must drop when is goes into absorption state if the battery is near full...like in the 90% SOC range.


It charged from 70% to 78% after driving for just 10 min or so. I'm totally stoked with this performance! IMO it's a fantastic upgrade.

I'd say it sounds like it's working pretty good. I'm not familiar with the Renogy DCDC50, but 43amps out of a Renogy sounds pretty good to me. We typically see 25-32 from the 30amp Victron units.