How is this for a power system? Solar vs battery balance?

L

LosAngeles

Active member
How is this for a power system? Solar vs battery balance?

Hi all

Have owned a couple RVs, and now designing (with Hallmark) a 9.5’ Everest pop up truck camper.

How is this for the balance of 200 watts of solar and 200 amp hours of (probably Lithium) batteries?

I’m aware that the Lithium are very expensive, but they can be run down to 90% depleted without any damage….. plus they last many times longer than wet cells, so in the really long run, probably (hopefully) no more expensive. The Battleborn batteries (likely get these) have a built in battery management system that makes sure the battery can be used (or discharged) at temperatures as low as -4°F. However, the battery will not accept a charge below 25°F. The BMS also makes sure they dont over charge or under charge.

Planned system:

Propane for stove…. and Truma Combi. (hot water and air.)
(of course 12v needed to run the Truma Combi too)

7.2 CU side by side. 2 way compressor. Novacool RFS7501 fridge.

Maxx fan.

Interior LED lights.

Solar System: 2 X 100 Watt Soft Panels on roof.

Xantrex 817-2080 Freedom XC 2000, 2000 Watt Pure Sine Wave 12 Volt Inverter/Charger

Victron BMV 712 Battery Monitor w/ Bluetooth Lifepo4 Ready

2 (two) x Battleborn 100 amp hour (each) Lithium

Other occasional loads:
Small microwave. Blender. computer maybe.

We camp 4 seasons…. sometimes below freezing. Sometimes higher altitudes. Sometimes in cloudy Pacific NorthWest. So the ability to discharge the Lithuim 90% with smaller bulk and weight has advantages.

We mostly boondock. We prefer the quiet.
Occasionally we stay someplace for 2 nights, but often drive around a bit, to explore, each day (so the F350 would also help charge up the batteries)

Thanks for any and all thoughts.

J.
 
dreadlocks

dreadlocks

Well-known member
You dont need as much capacity with Lithium as you would with lead, looking at your load out I think you'd be perfectly happy with a single BattleBorn.. spend the money either on more solar panels or better yet a generator.. I'd only do a dual lithium setup if I wanted to make the jump to 24v so I could run a higher power and more efficient inverter.

The extra efficiency, deeper discharges and quicker charge times make it a totally different paradigm than lead systems.. I'm going in excess of 300W solar for a single BB, it could take up to 600W of charge current in ideal conditions.. then you only need enough power to get through the night and for the sun to break the trees/clouds for a few hours in the day to get it recharged.. worst case I run my genset for a few hours, but with lithium you went to like 3h charge time instead of 6h+ minimum on lead.
 
Last edited:
L

LosAngeles

Active member
dreadlocks said:
You dont need as much capacity with Lithium as you would with lead, looking at your load out I think you'd be perfectly happy with a single BattleBorn.. spend the money either on more solar panels or better yet a generator.. I'd only do a dual lithium setup if I wanted to make the jump to 24v so I could run a higher power and more efficient inverter.

The extra efficiency, deeper discharges and quicker charge times make it a totally different paradigm than lead systems.. I'm going in excess of 300W solar for a single BB, it could take up to 600W of charge current in ideal conditions.. then you only need enough power to get through the night and for the sun to break the trees/clouds for a few hours in the day to get it recharged.. worst case I run my genset for a few hours, but with lithium you went to like 3h charge time instead of 6h+ minimum on lead.
Click to expand...

Thanks... very helpful. Really dont want to carry a generator, for both space and noise reasons.... would rather go for a 30 min (?) drive and get a extra heavy duty alternator in the yet-to-be-ordered F350.... if that helps (?)

but yes - many kind folks are suggesting 200 watts solar is not near enough....
 
dreadlocks

dreadlocks

Well-known member
yeah with a truck camper you can use your engine instead, your'll want a DC to DC changing system for it and some heavy gauge wiring.. if you double up batteries your going to need to double up your charge amps or double the charge time.. raising the amps raises the costs significantly as your house charger, solar charger, alternator charging systems have to go up in price.. if you double the time you need to extend how far you drive or idle the engine every few days and that starts making a small genset more attractive.. my Honda on the end of a 100ft extension cord charges my BB up from 20% to 100% in ~3.5h on eco throttle and I can hardly hear it, had to install a status LED because inside the trailer so I could not tell if it was running or not.

Lead batteries spend most of charge time in absorb mode which is just a few amps, so you cant put a big solar setup behind em without adding more and more batteries.. the generic rule is 1W of solar for 1AH of Lead, but with Lithium you can go like 6W of solar for 1AH of capacity.. this is a boon for expo use because in a mobile rig conditions are rarely ideal and getting 6h+ of good, consistent sunlight that lead requires for a charge cycle is really, really unlikely and difficult.. With lithium if you can only get a few good hours of sunlight you can dump enough amps into the bank that you can make significant charge progress in that short time, regardless of the batteries original charge state.
 
luthj

luthj

Engineer In Residence
Note that the BB BMS will disconnect if for over/under voltage. However sustained charging at higher voltages will degrade the pack. Especially float charging. So follow and understand the BB specs. Personally I would avoid charging over 14.2V for maximum battery life.

Lots of products claim "lithium compatible" But read and compare the tech specs carefully.
 
dwh

dwh

Tail-End Charlie
The Trojan has 3x the continuous discharge amperage rating and 2x the peak discharge amperage rating as the Battle Born.

The (coming soon? one of these days?) on-board data logging and CANbus networking is extremely interesting.

"Proudly Developed in the USA" is egregious hype that really means, "NOT made in the USA".
 
L

LosAngeles

Active member
mrfoamy said:
Here is a related post:
https://www.expeditionportal.com/fo...p-options-everest-or-exc.201048/#post-2571129
Click to expand...

Yes indeed Mr Foamy, I did read your reply on the other thread, back when you posted it. Very sorry you had a bad experience with Hallmark.

For what it is worth - every single other opinion that I have found of Hallmark has been nothing but positive.... and I have found quite a few other opinions....

We have decided to go with Hallmark, for a wide variety of reasons. It is great to have numerous manufacturers to choose from. :)

But I dont mean to derail this thread. Now we are planning our solar and battery system.

thanks,

J.
 
Arclight

Arclight

SAR guy
Keep in mind that a 12V system is marginal for actually powering a 2KW inverter at full load. It might work with Lithium batteries if they are rated for 1-2C or greater discharge and you keep the cables short and large gauge. I can say that my twin L16s in series will definitely drop below the cutout voltage of the inverter if I'm trying to start a large load. Supercaps in parallel can also help here.
 
L

LosAngeles

Active member
Hi all again - 7 months later. :)

So we are finally about to place our order for our 9.5 foot long Hallmark pop up truck camper.

How is this for a (revised) power system?

* * in terms of amount of solar panel WATTS specifically. * *

I want to make sure i have enough solar panel power. The fridge will be the biggest draw, by far.

Plan below has 540 watts solar, but for an extra $400 or so I could have a 4th 180 watt panel added - so that would make it 720 watts solar total.

Planned system:

200 amp-hours of Battleborn Lithium batteries. (2 x 100 amp hour batteries)

Propane for stove…. and Truma Combi. (hot water and air.)
(of course 12v needed to run the Truma Combi too)

7.2 CU side by side. 2 way compressor. Novacool RFS7501 fridge.

Maxx fan.

Interior LED lights.

Solar System: 3 X 180 “Grape” solar panels on roof = 540 watts

(or maybe 4 panels? = 720 watts)

“(each panel) Produces on average 45 Amp-hours/540-Watt-hours per day, EACH” (so 135 amp-hours a day for 3, on average, when the sun is out i suppose)

Power Converter 60A Mini Lithium Ion Power Center Black PM4060LIK

Victron 100/30 SmartSolar charge controller MPPT Solar Charger w/ Bluetooth Lifepo4 Ready

Xantrex 817-2080 Freedom XC 2000, 2000 Watt Pure Sine Wave 12 Volt Inverter/Charger

Victron BMV 712 Battery Monitor w/ Bluetooth Lifepo4 Ready

2 (two) x Battleborn 100 amp hour (each) Lithium

Other occasional loads:
Small microwave. Blender. computer maybe.

4 season camping. Yes there will be some rain and short grey days…. sometimes below freezing. Sometimes higher altitudes. Sometimes in cloudy Pacific NorthWest.

So the ability to discharge the Lithuim 90% with smaller bulk and weight has advantages.

We mostly boondock. We prefer the quiet.

Occasionally we stay someplace for 2 nights, but often drive around a bit, to explore, each day (so the F-350 would also help charge up the batteries)

Thanks for any and all thoughts.
J.
 
Last edited:
L

LosAngeles

Active member
shade said:
You can add a pair of Victron BatteryProtect modules to automate charge & load disconnects.
Click to expand...

I have never heard of these things... wouldnt the built in Battery Management System in the BattleBorn batteries do the same thing?

(so be not needed) ?
 
shade

shade

Well-known member
LosAngeles said:
I have never heard of these things... wouldnt the built in Battery Management System in the BattleBorn batteries do the same thing?

(so be not needed) ?
Click to expand...
You can rely on the Battle Born BMS, but remember that you have no control over it, and it would be the only automated charge & load disconnects in the system. Since you're already using a BMV-712, it can be used to control BatteryProtects at user defined limits. I'd rather leave the internal battery BMS as last ditch protection than as part of the control system, but that's me.
 
Photobug

Photobug

Well-known member
shade said:
You can rely on the Battle Born BMS, but remember that you have no control over it, and it would be the only automated charge & load disconnects in the system. Since you're already using a BMV-712, it can be used to control BatteryProtects at user defined limits. I'd rather leave the internal battery BMS as last ditch protection than as part of the control system, but that's me.
Click to expand...

Based on Dreadlock's recent experience, maybe need to rethink this approach. Does this mean two methods of protection, or two modes of failure? If you are going to invest a well designed system to charge and control your lithium needs, why not chose a battery without a BMS to prevent a potential source of failure.
 
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