Super Solar Charge Times - Montana Owners Club

rames14 · 02-09-2021, 07:43 PM

I know that we will not always be able to charge our batteries to full with the 1200 watts of solar. Rain, clouds, etc could force us to use our generator(s). We have two Honda 2000’s, so I can run 15 or 30 amps. Is there a formula to calculate?

**AZ Traveler** · 02-09-2021, 08:21 PM

Ron,

Math in public will often get you in trouble but I will give it a try.

Running both of your gennys will buy you 30 amps times the number of hours you run them and then you need to add amp times hours from your solar depending on what you are getting real time and subtract the amps time hours that you are using.

A good battery monitor should tell you how many amp hours your battery bank is from fully charged.

rames14 · 02-09-2021, 09:13 PM

It will have the Victron monitor (current unit has the Bogart). We don’t get our unit until April but thought it would be less time than that. It just seems wrong. I would normally recharge my golf cart batteries in less time than that. My unit routinely used about 150-200 ah at night plus what we would use during the day. W could run 6-8 hours and be at 100% at night.

**AZ Traveler** · 02-09-2021, 09:23 PM

Ron,

As I said, math in public can make you look silly.

I forgot to include the voltage change. Your 30 amps at 120v is 300 amps at 12v but your converter or inverter/charger will be the limiting factor at 125 amps or whatever capacity yours has.

It will recharge pretty fast.

rames14 · 02-09-2021, 09:36 PM

Thanks, Zack. I’m trying to find the Magnum charge rate for lithium. It would be nice to be able to just take one generator.

Creeker · 02-09-2021, 09:48 PM

Its dependent on your battery bank and your charging devices output in amps. Amp hours that have been removed from battery bank?
Charging acceptance rate of your batteries?
Output of your charging device?

Some Lithiums can be charged at a C1 rate. Meaning a 100Ah battery can be charged at 100 amps. You will be limited by your charging devices output.

Say you removed 150Ah's from your battery pack with a C1 charging rate.
Your charging device output is 100 amps. 150/100=1.5 hrs in theory but probably a bit more in reality.

MAWilsonPE · 02-10-2021, 05:57 AM

Hi Ron,

Congratulations on your choice of the Super Solar Flex option! We got ours in October and so far it has performed nearly flawlessly. When plugged into shore power I have seen a charge rate of 100 amps (@ 12+ volts) so I would expect that you would see a similar rate with a generator. So that is a maximum of 5 hours to fully recharge dead batteries. Zack is right in that 15 amps at 120 volts is 150 amps at 12 volts so you should be able to run just one of those generators.

I do have a 30 amp generator that I have considered bringing with me in case of poor weather and low solar ability. However the whole idea of the Super Solar is to get away from generators. I am considering backup charging using my tow vehicle and the Precision Circuits BIM to connect the truck alternator to the system:

http://precisioncircuitsinc.com/wp-c...i-BIM-Rev1.pdf

This will not be as fast shore power or a generator but it is virtually free charging while going down the road. The real challenge is the size of wire that must be run between the truck battery and the camper battery. I figure I need almost 40 feet of connecting wire. They suggest an 80 amp breaker. This will require at least a 2/0, maybe 3/0 gauge, set of wires ($$$).

I would be curious to hear from anyone who has installed this BIM unit.

Best Regards, Mike

Daryles · 02-10-2021, 06:17 AM

@MAWilsonPE
I have been looking at the Renogy 60A DC to DC charger. There are a few things I have to figure out yet before I buy it.

MAWilsonPE · 02-10-2021, 06:26 AM

Hello Daryl,

I also considered a DC-DC charger but the BIM is less expensive, more compact and I think really makes more sense (and was recommended over a DC-DC charger by Future Sales who builds the Super Solar system). Another nice feature of the BIM is that if you drain your truck battery for some reason you can reverse the charge direction and charge your truck from the house batteries.

Best, Mike

rames14 · 02-10-2021, 06:43 AM

Mike, have you got a price on BIM? The reason for my question on the generator is we are planning a trip to Alaska in 2022. It would be nice to cut out an extra 50 lbs, but my generator setup today includes a 6 gallon tank between them. I only have about 200 ah of usable today (in theory 270 but voltage drops too). Out west we see over 300 days of sun, with almost unlimited boondocking. Looking forward to getting away from generators.

MAWilsonPE · 02-10-2021, 06:46 AM

Hi Ron,

$172.00 on Amazon:

https://www.amazon.com/dp/B07DY8S815...v_ov_lig_dp_it

Plus wiring and breakers....

Best, Mike

kowbra · 02-10-2021, 07:23 AM

Quote:

Originally Posted by MAWilsonPE

Hi Ron,

Congratulations on your choice of the Super Solar Flex option! We got ours in October and so far it has performed nearly flawlessly. When plugged into shore power I have seen a charge rate of 100 amps (@ 12+ volts) so I would expect that you would see a similar rate with a generator. So that is a maximum of 5 hours to fully recharge dead batteries. Zack is right in that 15 amps at 120 volts is 150 amps at 12 volts so you should be able to run just one of those generators.

I do have a 30 amp generator that I have considered bringing with me in case of poor weather and low solar ability. However the whole idea of the Super Solar is to get away from generators. I am considering backup charging using my tow vehicle and the Precision Circuits BIM to connect the truck alternator to the system:

http://precisioncircuitsinc.com/wp-c...i-BIM-Rev1.pdf

This will not be as fast shore power or a generator but it is virtually free charging while going down the road. The real challenge is the size of wire that must be run between the truck battery and the camper battery. I figure I need almost 40 feet of connecting wire. They suggest an 80 amp breaker. This will require at least a 2/0, maybe 3/0 gauge, set of wires ($$$).

I would be curious to hear from anyone who has installed this BIM unit.

Best Regards, Mike

Hi Mike,

I am considering the BIM vs a Renogy DC-DC charger.
I'm surprised the wiring needs to be that big; I was thinking that 1/0 gauge would work. But there doesn't seem to be much info on these installations.

I'm also curious -are you considering installing the BIM in the truck or RV? The usual for a DC-DC charger is to install in the RV as it will boost the voltage back up if there is line loss. But, I don't think the BIM does that, so I was considering installing it in the truck.
Since the BIM is also a switch, I was thinking of installing in truck, then use one of the trucks aux switches to turn on and off. This could allow for selective use such as powering other things off that Anderson connector (air compressor, etc). Also, then I think you could use the BIM momentary switch to run booster cables from the connector.
Cables such as these may work with the above...
https://www.amazon.com/Booster-Jumpe...2966983&sr=8-3

I may not be on the right path, but curious your thoughts on the above.

Thanks!
Brad

MAWilsonPE · 02-10-2021, 07:57 AM

Hi Brad,

Let me first say that I am not an electrical engineer so I have to rely on my research. I found the attached wire size chart for distance vs amps needed. I like this chart because it makes it clear that the total run for a 12 volt circuit includes both the + and - runs.

I plan to put the BIM near the house batteries in the camper.

Future Sales (the builder of the Super Solar system) recommends two 80 amp breakers in the BIM circuit, one on the truck, one in the camper. I measured about 25 feet of wiring needed just to get from my truck battery to the back of the truck bed. I plan to put an Anderson quick connect in the truck bed. From there I need another 15-20 feet of wire to get from the Anderson connector up to the hitch, into the camper and to the house batteries. So that is 40-45 feet total one way, or 80-90 feet round trip!

This chart is for a 3% loss in the circuit. More loss means more heat.

You should not need to boost the voltage as the alternator will put out in excess of 14 volts while charging which is enough to charge lithium batteries. Curiously, having lead-acid batteries in the truck and lithium in the camper is a plus as you can charge your truck in reverse without shore power. Charged lithium battery = 13.3 volts, discharged lead-acid battery < 11 volts.

I only have this type of chart to go by so I hope someone who has installed the BIM can chime in. Will you get nearly 80 amps? I doubt it. I am hoping to get 50-60 amps through the BIM. According to the chart this is 2/0 or 3/0.

I believe the reason they can rate a set of 30 foot, 1/0 jumper cables for 1500 amps is because it is only for a few seconds. I understand the BIM alternatively runs for 15 minutes and shuts off for 15 minutes to save your alternator from working too hard, but that is plenty of time to overheat your wiring.

If any one disagrees with my logic please chime in and save me some $$

Best, Mike

kowbra · 02-10-2021, 08:13 AM

Quote:

Originally Posted by MAWilsonPE

Hi Brad,

Let me first say that I am not an electrical engineer so I have to rely on my research. I found the attached wire size chart for distance vs amps needed. I like this chart because it makes it clear that the total run for a 12 volt circuit includes both the + and - runs.

I plan to put the BIM near the house batteries in the camper.

Future Sales (the builder of the Super Solar system) recommends two 80 amp breakers in the BIM circuit, one on the truck, one in the camper. I measured about 25 feet of wiring needed just to get from my truck battery to the back of the truck bed. I plan to put an Anderson quick connect in the truck bed. From there I need another 15-20 feet of wire to get from the Anderson connector up to the hitch, into the camper and to the house batteries. So that is 40-45 feet total one way, or 80-90 feet round trip!

This chart is for a 3% loss in the circuit. More loss means more heat.

You should not need to boost the voltage as the alternator will put out in excess of 14 volts while charging which is enough to charge lithium batteries. Curiously, having lead-acid batteries in the truck and lithium in the camper is a plus as you can charge your truck in reverse without shore power. Charged lithium battery = 13.3 volts, discharged lead-acid battery < 11 volts.

I only have this type of chart to go by so I hope someone who has installed the BIM can chime in. Will you get nearly 80 amps? I doubt it. I am hoping to get 50-60 amps through the BIM. According to the chart this is 2/0 or 3/0.

I believe the reason they can rate a set of 30 foot, 1/0 jumper cables for 1600 amps is because it is only for a few seconds. I understand the BIM alternatively runs for 15 minutes and shuts off for 15 minutes to save your alternator from working too hard, but that is plenty of time to overheat your wiring.

If any one disagrees with my logic please chime in and save me some $$

Best, Mike

Thanks Mike, great summary and thanks for the wire chart.

Once you get this all sorted out, I'd really like to know more details.
This new SSF is completely new to me, so I don't even know the most basic thing like how to connect the truck charging source into the battery bank. (whether BIM or DC-DC).

I'm still curious what advantage there is to have the BIM in the trailer vs the truck?

Brad

MAWilsonPE · 02-10-2021, 08:44 AM

Brad,

I don't think it matters where you put the BIM. I want to put it in the camper near the batteries so I don't have a (really big) hot wire extending outside the camper.

I also thought about building a set of jumper cables with an Anderson connector on one end so that I could plug it into my new connector in the truck bed. This will require the elimination of the recommended 80 amp breaker in the truck line though as you would definitely pop that in jumper cable mode.

I will likely install a big solenoid relay near the truck battery so I could turn that circuit on or off with an aux switch and not have a (really big) hot wire in my truck bed.

I just sent a message to Future Sales to see what wire gauge they recommend and how many amps I could realistically expect with the BIM.

Best, Mike

kowbra · 02-10-2021, 08:55 AM

Quote:

Originally Posted by MAWilsonPE

Brad,

I don't think it matters where you put the BIM. I want to put it in the camper near the batteries so I don't have a (really big) hot wire extending outside the camper.

I also thought about building a set of jumper cables with an Anderson connector on one end so that I could plug it into my new connector in the truck bed. This will require the elimination of the recommended 80 amp breaker in the truck line though as you would definitely pop that in jumper cable mode.

I will likely install a big solenoid relay near the truck battery so I could turn that circuit on or off with an aux switch and not have a (really big) hot wire in my truck bed.

I just sent a message to Future Sales to see what wire gauge they recommend and how many amps I could realistically expect with the BIM.

Best, Mike

Yes, good point about the hot wire; I was focused on switching if off in the truck, but it would also be hot coming from the RV...
Drop back with what you find out from Future Sales, and thanks!

Brad

Creeker · 02-10-2021, 10:42 AM

I'm not familiar with the BIM device but I would want to know the following;
Is it actually a charger or simply an isolator?
Does it buck or boost voltage coming from the alternator?
Can it limit the current coming from the alternator?
Can you select charging profiles for different recommended batteries/voltages?

The Renogy and other DC to DC chargers do all the above.

When your smart alternator in the truck senses the truck batteries are full it cuts voltage back to 13.xx. The DC to DC chargers boost this voltage (output side) back up to 14.xx+ Depending on how you set the up the charging profile. You can set up different charging profiles just like your solar controller or inverter/charger.

The DC to DC chargers will absolutely protect your trucks alternator by limiting the current being pulled by whatever size charger you buy. Lithium battery banks can pull 100's of amps from an alternator. I don't want an extra 100's of amps being pulled from my alternator for no amount of time.

I chose the Renogy 40A for the above reasons. This BIM device may very well do some or all the same. I would want to know before installing though.

kowbra · 02-10-2021, 11:32 AM

Quote:

Originally Posted by Creeker

I'm not familiar with the BIM device but I would want to know the following;
Is it actually a charger or simply an isolator?
Does it buck or boost voltage coming from the alternator?
Can it limit the current coming from the alternator?
Can you select charging profiles for different recommended batteries/voltages?

The Renogy and other DC to DC chargers do all the above.

When your smart alternator in the truck senses the truck batteries are full it cuts voltage back to 13.xx. The DC to DC chargers boost this voltage (output side) back up to 14.xx+ Depending on how you set the up the charging profile. You can set up different charging profiles just like your solar controller or inverter/charger.

The DC to DC chargers will absolutely protect your trucks alternator by limiting the current being pulled by whatever size charger you buy. Lithium battery banks can pull 100's of amps from an alternator. I don't want an extra 100's of amps being pulled from my alternator for no amount of time.

I chose the Renogy 40A for the above reasons. This BIM device may very well do some or all the same. I would want to know before installing though.

@Creeker - I agree with your questions as above. I asked Matt at Future Sales about some of them as he does recommend the BIM.

From that, I think I understand some of the answers. It does seem like the Precision BIM is simply an isolator that will neither boost nor limit voltage.

But, I didn't get from Matt on how it handles smart alternators or how it prevents a large lithium bank from drawing 100% of the alternator output.

For example, I have a single 220 amp alternator - will the BIM draw 220 amps for 15 minutes? Matt at FS did say a few weeks ago that he typically sees 70 amps draw, which may be fine for my setup.

I've emailed some of those questions to support at Precision. That was a few weeks ago and no one has answered them yet.

So, I like the idea of the BIM, and may go with it if some of the above questions are answered. But it seems like a DC-DC might have some intelligence that is missing in the BIM. OTOH, Battleborn Batteries seem to promote the Precision BIM a lot for their recommended lithium solutions.

BTW, and maybe others know this, battery isolators (some even called BIM) have been around for years in vans and motor coaches where the primary charging has been from the engine alternator. So, not new technology in concept, but to me the question is how much more intelligence has been added into these newer Precision BIMs.

I'm following here to see if Mike, or others, can find additional information.

Brad

MAWilsonPE · 02-10-2021, 11:44 AM

Hello Creeker,

Again, this is the BIM data sheet which explains it better than I can:

http://precisioncircuitsinc.com/wp-c...i-BIM-Rev1.pdf

It is a "smart" isolator. No battery buck or boost, current will ultimately be limited by the recommended 80 amp breakers, but I would hope they would not break during normal operation. It is specifically made for lithium house batteries and lead-acid truck battery, no other profiles available.

Best, Mike

Creeker · 02-10-2021, 11:53 AM

Brad

Yes, battery isolators have been around for decades but we didn't have to worry about a Lithium battery bank pulling 200+ amps from an alternator.

I'll be very interested in the info you receive about this particular BIM device. I'm sticking with the Renogy DC to DC charger as it perfectly suits my needs but its always great to have options.

Now if winter ever ends, I'll get this Charger and two Micro Air Easy Starts installed. We're heading south for two weeks on Friday weather permitting. Hopefully by the time we get back, this extreme cold snap is gone.

You may also like: