SquirrellCook
Forum Member
Four days waiting for the results 
AC Fridge In Campervan -.Power Consumption Test
- Thread starter wildebus
- Start date
wildebus
Forum Member
Not seen any effect on mine, but my van does spend a lot more time on the Driveways than yours I suspect
SquirrellCook
Forum Member
Don't unplug it!
st3v3
Forum Member
Lol. I suspect you're joking but it's to do with all the refrigerant getting shaken up.
SquirrellCook
Forum Member
I've had 3 fridges now in Murky and never unplugged one due to problems. Each sold on working. Don't ask
wildebus
Forum Member
There could be a lot more shaking around when transported from Depot to Customer I would guess? Should be ok if yout milk hasn't been churned into cheese at the end of your journey?
I think with "proper" ( ) caravan 3-way fridges, you are meant to invert them for a while before fitting to help redistribute the chemicals inside? That is probably like the "leave to settle" recommendation for a home fridge? but it should be a one-off?
I think with "proper" (
) caravan 3-way fridges, you are meant to invert them for a while before fitting to help redistribute the chemicals inside? That is probably like the "leave to settle" recommendation for a home fridge? but it should be a one-off?
wildebus
Forum Member
Completed the first part of the Battery-Fridge test now. Got some more tests to do before I make any of my own conclusions I think.
So recap.... Two Batteries tested, an Relion RB100 100Ah LiFePO4 Lithium and a Northstar NSB210FT Blue+ 215Ah PbC AGM Lead Carbon.
The Lithium can be safely take down to 100% DoD and the AGM is safe down to 50% DoD (actually more for this battery, but we will go with the standard Lead Acid 'norm'.
Neil make a prediction ..... How close was he (sounds like an episode of "The Price is Right")
So Neil, what was your estimate?
I think Nabsim wins a prize! Estimated 60 Hours; Expected time extrapolating from 24 hours is 61.5 Hours
As you would expect, the AGM Battery had a similar Ahs used in 24 Hours
If I had to guess, I would say the difference in Ahs of under 2 Hours is probably due to a slightly lower ambient temperature which meant the fridge came on slightly less frequently.
The Northstar AGM battery has a longer run time before it hits the 50% SOC, which will be due to its higher usable capacity (107.5Ah vs 100Ah).
Of course, those numbers are based on ONLY having the Inverter and Fridge on, nothing else. In the real world, other loads would shorten that run time.
Those 24 Hour Ah numbers are a fair bit higher than I would have expected as well, which is interesting, I think my previous testing was in the cooler months from memory? Maybe this difference is due to a season thing?
What I do know from the numbers is that the solar installation will more than keep up with the Fridges Power use in the summer months (and in fact from around March)
So recap.... Two Batteries tested, an Relion RB100 100Ah LiFePO4 Lithium and a Northstar NSB210FT Blue+ 215Ah PbC AGM Lead Carbon.
The Lithium can be safely take down to 100% DoD and the AGM is safe down to 50% DoD (actually more for this battery, but we will go with the standard Lead Acid 'norm'.
Neil make a prediction ..... How close was he (sounds like an episode of "The Price is Right")
So Neil, what was your estimate?
Bring on the Yodeller ......
I think Nabsim wins a prize! Estimated 60 Hours; Expected time extrapolating from 24 hours is 61.5 Hours
As you would expect, the AGM Battery had a similar Ahs used in 24 Hours
If I had to guess, I would say the difference in Ahs of under 2 Hours is probably due to a slightly lower ambient temperature which meant the fridge came on slightly less frequently.
The Northstar AGM battery has a longer run time before it hits the 50% SOC, which will be due to its higher usable capacity (107.5Ah vs 100Ah).
Of course, those numbers are based on ONLY having the Inverter and Fridge on, nothing else. In the real world, other loads would shorten that run time.
Those 24 Hour Ah numbers are a fair bit higher than I would have expected as well, which is interesting, I think my previous testing was in the cooler months from memory? Maybe this difference is due to a season thing?
What I do know from the numbers is that the solar installation will more than keep up with the Fridges Power use in the summer months (and in fact from around March)
SquirrellCook
Forum Member
Just a thought Dave, do you know what temperature your fridge is set at?
wildebus
Forum Member
I do.
Generally at 0C but with the occasional rise to 2C. Same for both battery tests.
It is a bit lower than it should be actually, but when we had that high heat a few weeks ago, I turned down the thermostat and haven't adjusted it back up again since. If it was set correctly, it would have run a little less I guess.
wildebus
Forum Member
If you look at this chart with for the Lead Acid test, you can see the effect of ambient temp I think?
Over the nighttime, the fridge temp stays at 0C and the times between the fridge coming on (each dip in voltage) slightly increases.
Fridge temp is at its peak (if you could call it the peak?) at the height of the afternoon.
Over the nighttime, the fridge temp stays at 0C and the times between the fridge coming on (each dip in voltage) slightly increases.
Fridge temp is at its peak (if you could call it the peak?) at the height of the afternoon.
Nabsim
Forum Member
My usage is fairly constant Dave, doesn’t matter if it’s summer or winter, hot or cold, fridge that is or seems to be anyway. Overall daily use can vary a bit, if we have some bad weather and I stay in with heating on it goes up a bit but not that much as I usually don’t have heating in at night or if I do I turn it down to 10 degrees.
wildebus
Forum Member
I am quite a bit different in that respect
I like it nice and warm and will have the heating on a fair bit - and unless it is a very warm night I will often have the electric blanket running for quite a bit of time over night 
wildebus
Forum Member
I was in my van this morning and checked the Fridge dial setting .... quite a bit higher than the usual position (marked with a sharpie ), which I think would partly explain the higher power useage than expected.
I thought I would look back and see how it changed. This is quite interesting I think. These times would have been when the van was not being used so the living area temp would have been around the same as the external temp, but I still think it is a factor in power use (for example, if you look at the specs for something like a Waeco CRX-50 12V Compressor Fridge, they quote the average power consumption as 1.29A at 25C, but rises to 2.0A at 40C). The plus point is that if when the Temperature rises that results in the fridge using more power, it is very likely if you have solar installed, that will be harvesting more energy.
But onto the comparisions ... Not showing the power, but the actual pattern of the Fridge compressor on - both for duration and duty cycle.
We have Winter (Feb 4th), Spring (Mar 25th) and Summer (Jun 9th). At any time the compressor is on, there is around a 5A draw in total for Fridge + Inverter
), which I think would partly explain the higher power useage than expected.I thought I would look back and see how it changed. This is quite interesting I think. These times would have been when the van was not being used so the living area temp would have been around the same as the external temp, but I still think it is a factor in power use (for example, if you look at the specs for something like a Waeco CRX-50 12V Compressor Fridge, they quote the average power consumption as 1.29A at 25C, but rises to 2.0A at 40C). The plus point is that if when the Temperature rises that results in the fridge using more power, it is very likely if you have solar installed, that will be harvesting more energy.
But onto the comparisions ... Not showing the power, but the actual pattern of the Fridge compressor on - both for duration and duty cycle.
We have Winter (Feb 4th), Spring (Mar 25th) and Summer (Jun 9th). At any time the compressor is on, there is around a 5A draw in total for Fridge + Inverter
SquirrellCook
Forum Member
That's what I would expect to see Dave.
wildebus
Forum Member
Decided to run the same test one after the other to get a "in-service" comparision of Lithium versus Lead batteries.
The actual battery power used was near enough identical when the non-laboratory environment was taken into account, but that is just part of the story. What about the other aspects that should be considered?
Power Capacity & Delivery.
Well, if you size the batteries appropriately (i.e. get a Lead Acid twice the Ah capacity of the Lithium) then the usable capacity is pretty well the same for most people. Where Lithium batteries definately have an edge is the way the voltage stays at a higher more consistant level.
Applying Ohms Law, where P = IV, or Power (W) = Current (A) x Voltage (V), the lower the voltage, the greater the current needs to be to deliver the same power.
So as a Lead Acid battery starts to drop in charge, the voltage reduces and when the same power is demanded (e.g. from a fridge), the current is higher and the power drawn is higher. This means that a lead acid batteries efficiency is constantly (albeit slowly) reduces immediately from the point it gets used, even from100% full, whereas a Lithium batteries efficiency reduction is not really noticable until you get to a pretty low SOC.
NOTE: I have seen a few claims on Battery Specs and quite a few YouTubers saying that Lithium Batteries are perfect with inverters because the voltage doesn't drop. Yes, they are good - and often better - with Inverters, but NO, the voltage still drops under load.
A couple of graphs to illustrate this difference (note the differences in scale when comparing) ...
The LiFePO4 Battery in the last half of the Fridge test
You can see how the voltage dips as the current increases, but generally the voltage is sitting in excess of 13V even when the battery is at this stage getting below 50% SOC
The same time period for the Lead Acid
In the same time period the voltage has dropped pretty well twice as much from start to end, and is noticably lower (13.2V vs 12.70, and 13.1V vs 12.5V), so each time the fridge comes on, calling for its 50W of power or whatever, the current draw will be higher on the Lead Acid and so the power taken out the battery will be greater.
Recharging
Once you have the power consumed, you need to replenish of course. So let's compare the two....
Couple of comments first.
Lithium - I set the charger to the recommended limits by Relion - so 50A maximum for the RB100 (a C2 charge rate)
Lead Acid - Usually there is a maximum charge limit of around 25% for a good AGM Lead Acid Battery, and often lower. My Lead Acid Batteries are Lead Carbon AGM and have no charge current limitation so I set the charger to its maximum (120A) as I was also interested in how my own specific setup would compare with the Lithium, but most Lead Acid Batteries will not (and should not) charge at this level!
First I took the Lithium to 100% DOD - to the point where its internal BMS shut it down ... 0 Volts out; Plus I took the Lead Acid battery down below 50% (actually ended up being 45% SOC). So each battery needed 100Ah+ put back into it.
The question is how long would it take to get the batteries back up to 100% charge, as that is the critical thing when using Lesiure Batteries.
Plugging in the RB100 LiFePO4 Lithium first.
Pretty well two hours of bulk charging at around 48 Amps into the battery got it near enough full (the charger was set to 50A limit, so the 48A represents the efficiency loss of 4% in the charger - I guess I could have set it at 53A limit so it would be 50A at the battery).
So 96Ah in the first 2 hours and the remaining 45 minutes or so was the small 10% or so top up (the RB100 100Ah battery actually gave 104.2Ah at the point it switched off)
The Lead Acid profile was quite a bit different (showing the SOC and the Voltage/Current info here)
The 215Ah PbC (Lead Carbon AGM Battery) took in up to 110Ah and that started to drop quite soon, but it is still a high current coming in. The charger switched to float prematurely (the Multiplus Charger tends to do this with these batteries when they are getting a charge from a lowish SOC, and I have not sussed out why yet), but did a quick reprogram to get the voltage back up to carry on as required.
Interestingly this lead acid battery accepted in the two hours near enough the same amount of Ahs back into the battery as the Lithium battery did, which was a bit of a surprise TBH, but to finish the job took longer (as as you can see, nearly 4 hours in and still not quite back to 100%)
If this were a 'normal' Lead Acid battery, I think the difference would have been a fair bit bigger.
What if you had a smaller charger? well, the Lithium would take all it could get (upto 50A per battery in the case of the RB100), and the lead acid would sit there for longer in bulk mode. But generally whilst the Lithium battery requires a charge it would use all that the charging system could give I would say, so if using say a Generator, the chances are you could run it for less time, which would make everyone happier I am sure.
So that kind of concludes this test
I think I will do another post just with my thoughts and possible conclusions for my own setup and which way I would go in terms of battery bank technology if starting fresh.
The actual battery power used was near enough identical when the non-laboratory environment was taken into account, but that is just part of the story. What about the other aspects that should be considered?
Power Capacity & Delivery.
Well, if you size the batteries appropriately (i.e. get a Lead Acid twice the Ah capacity of the Lithium) then the usable capacity is pretty well the same for most people. Where Lithium batteries definately have an edge is the way the voltage stays at a higher more consistant level.
Applying Ohms Law, where P = IV, or Power (W) = Current (A) x Voltage (V), the lower the voltage, the greater the current needs to be to deliver the same power.
So as a Lead Acid battery starts to drop in charge, the voltage reduces and when the same power is demanded (e.g. from a fridge), the current is higher and the power drawn is higher. This means that a lead acid batteries efficiency is constantly (albeit slowly) reduces immediately from the point it gets used, even from100% full, whereas a Lithium batteries efficiency reduction is not really noticable until you get to a pretty low SOC.
NOTE: I have seen a few claims on Battery Specs and quite a few YouTubers saying that Lithium Batteries are perfect with inverters because the voltage doesn't drop. Yes, they are good - and often better - with Inverters, but NO, the voltage still drops under load.
A couple of graphs to illustrate this difference (note the differences in scale when comparing) ...
The LiFePO4 Battery in the last half of the Fridge test
You can see how the voltage dips as the current increases, but generally the voltage is sitting in excess of 13V even when the battery is at this stage getting below 50% SOC
The same time period for the Lead Acid
In the same time period the voltage has dropped pretty well twice as much from start to end, and is noticably lower (13.2V vs 12.70, and 13.1V vs 12.5V), so each time the fridge comes on, calling for its 50W of power or whatever, the current draw will be higher on the Lead Acid and so the power taken out the battery will be greater.
Recharging
Once you have the power consumed, you need to replenish of course. So let's compare the two....
Couple of comments first.
Lithium - I set the charger to the recommended limits by Relion - so 50A maximum for the RB100 (a C2 charge rate)
Lead Acid - Usually there is a maximum charge limit of around 25% for a good AGM Lead Acid Battery, and often lower. My Lead Acid Batteries are Lead Carbon AGM and have no charge current limitation so I set the charger to its maximum (120A) as I was also interested in how my own specific setup would compare with the Lithium, but most Lead Acid Batteries will not (and should not) charge at this level!
First I took the Lithium to 100% DOD - to the point where its internal BMS shut it down ... 0 Volts out; Plus I took the Lead Acid battery down below 50% (actually ended up being 45% SOC). So each battery needed 100Ah+ put back into it.
The question is how long would it take to get the batteries back up to 100% charge, as that is the critical thing when using Lesiure Batteries.
Plugging in the RB100 LiFePO4 Lithium first.
Pretty well two hours of bulk charging at around 48 Amps into the battery got it near enough full (the charger was set to 50A limit, so the 48A represents the efficiency loss of 4% in the charger - I guess I could have set it at 53A limit so it would be 50A at the battery).
So 96Ah in the first 2 hours and the remaining 45 minutes or so was the small 10% or so top up (the RB100 100Ah battery actually gave 104.2Ah at the point it switched off)
The Lead Acid profile was quite a bit different (showing the SOC and the Voltage/Current info here)
The 215Ah PbC (Lead Carbon AGM Battery) took in up to 110Ah and that started to drop quite soon, but it is still a high current coming in. The charger switched to float prematurely (the Multiplus Charger tends to do this with these batteries when they are getting a charge from a lowish SOC, and I have not sussed out why yet), but did a quick reprogram to get the voltage back up to carry on as required.
Interestingly this lead acid battery accepted in the two hours near enough the same amount of Ahs back into the battery as the Lithium battery did, which was a bit of a surprise TBH, but to finish the job took longer (as as you can see, nearly 4 hours in and still not quite back to 100%)
If this were a 'normal' Lead Acid battery, I think the difference would have been a fair bit bigger.
What if you had a smaller charger? well, the Lithium would take all it could get (upto 50A per battery in the case of the RB100), and the lead acid would sit there for longer in bulk mode. But generally whilst the Lithium battery requires a charge it would use all that the charging system could give I would say, so if using say a Generator, the chances are you could run it for less time, which would make everyone happier I am sure.
So that kind of concludes this test
I think I will do another post just with my thoughts and possible conclusions for my own setup and which way I would go in terms of battery bank technology if starting fresh.
Nabsim
Forum Member
I wouldn’t expect it to be any different amps used, should be the same for any battery type shouldn’t it? Just how long you can run it without damaging your battery’s.
of course while twice the amount of lead acid will give you a similar capacity it will need twice the space with 4 times the weight. My two 100ah Lifepo4 come in at the same weight as a single Bosch/Varta 90ah PowerFrame they replaced.
of course much more expensive and you need suitable cable and ancillary items. Nothing is simple huh
of course while twice the amount of lead acid will give you a similar capacity it will need twice the space with 4 times the weight. My two 100ah Lifepo4 come in at the same weight as a single Bosch/Varta 90ah PowerFrame they replaced.
of course much more expensive and you need suitable cable and ancillary items. Nothing is simple huh
wildebus
Forum Member
Actually no. My point on the voltage ...I wouldn’t expect it to be any different amps used, should be the same for any battery type shouldn’t it? Just how long you can run it without damaging your battery’s.
of course while twice the amount of lead acid will give you a similar capacity it will need twice the space with 4 times the weight. My two 100ah Lifepo4 come in at the same weight as a single Bosch/Varta 90ah PowerFrame they replaced.
of course much more expensive and you need suitable cable and ancillary items. Nothing is simple huh
You have a device that uses 100 watts.
if the battery is sitting at 13.0V - a fairly typical Lithium Battery Voltage - the current draw will be 100W / 13V = 7.69A (Ohms Law ==> I = P/V )
if the battery is sitting at 12.5V - a fairly typical Lead Acid Voltage - the current draw will be 8V - 4% higher.
This is why the use of Amp-Hours (Ah) as a storage rating is not really that good and Watt-Hours is more useful.
Weight and storage space (as well as cost of course) are separate - but important things. Power Delivery is equally important. All these points will lead me to what I would choose if I were buying again ....
xsilvergs
Forum Member
David, interesting results, I'm not surprised but most of your results.Decided to run the same test one after the other to get a "in-service" comparision of Lithium versus Lead batteries.
The actual battery power used was near enough identical when the non-laboratory environment was taken into account, but that is just part of the story. What about the other aspects that should be considered?
Power Capacity & Delivery.
Well, if you size the batteries appropriately (i.e. get a Lead Acid twice the Ah capacity of the Lithium) then the usable capacity is pretty well the same for most people. Where Lithium batteries definately have an edge is the way the voltage stays at a higher more consistant level.
Applying Ohms Law, where P = IV, or Power (W) = Current (A) x Voltage (V), the lower the voltage, the greater the current needs to be to deliver the same power.
So as a Lead Acid battery starts to drop in charge, the voltage reduces and when the same power is demanded (e.g. from a fridge), the current is higher and the power drawn is higher. This means that a lead acid batteries efficiency is constantly (albeit slowly) reduces immediately from the point it gets used, even from100% full, whereas a Lithium batteries efficiency reduction is not really noticable until you get to a pretty low SOC.
NOTE: I have seen a few claims on Battery Specs and quite a few YouTubers saying that Lithium Batteries are perfect with inverters because the voltage doesn't drop. Yes, they are good - and often better - with Inverters, but NO, the voltage still drops under load.
A couple of graphs to illustrate this difference (note the differences in scale when comparing) ...
The LiFePO4 Battery in the last half of the Fridge test
View attachment 2616
You can see how the voltage dips as the current increases, but generally the voltage is sitting in excess of 13V even when the battery is at this stage getting below 50% SOC
The same time period for the Lead Acid
View attachment 2617
In the same time period the voltage has dropped pretty well twice as much from start to end, and is noticably lower (13.2V vs 12.70, and 13.1V vs 12.5V), so each time the fridge comes on, calling for its 50W of power or whatever, the current draw will be higher on the Lead Acid and so the power taken out the battery will be greater.
Recharging
Once you have the power consumed, you need to replenish of course. So let's compare the two....
Couple of comments first.
Lithium - I set the charger to the recommended limits by Relion - so 50A maximum for the RB100 (a C2 charge rate)
Lead Acid - Usually there is a maximum charge limit of around 25% for a good AGM Lead Acid Battery, and often lower. My Lead Acid Batteries are Lead Carbon AGM and have no charge current limitation so I set the charger to its maximum (120A) as I was also interested in how my own specific setup would compare with the Lithium, but most Lead Acid Batteries will not (and should not) charge at this level!
First I took the Lithium to 100% DOD - to the point where its internal BMS shut it down ... 0 Volts out; Plus I took the Lead Acid battery down below 50% (actually ended up being 45% SOC). So each battery needed 100Ah+ put back into it.
The question is how long would it take to get the batteries back up to 100% charge, as that is the critical thing when using Lesiure Batteries.
Plugging in the RB100 LiFePO4 Lithium first.
View attachment 2618
Pretty well two hours of bulk charging at around 48 Amps into the battery got it near enough full (the charger was set to 50A limit, so the 48A represents the efficiency loss of 4% in the charger - I guess I could have set it at 53A limit so it would be 50A at the battery).
So 96Ah in the first 2 hours and the remaining 45 minutes or so was the small 10% or so top up (the RB100 100Ah battery actually gave 104.2Ah at the point it switched off)
The Lead Acid profile was quite a bit different (showing the SOC and the Voltage/Current info here)
View attachment 2619
The 215Ah PbC (Lead Carbon AGM Battery) took in up to 110Ah and that started to drop quite soon, but it is still a high current coming in. The charger switched to float prematurely (the Multiplus Charger tends to do this with these batteries when they are getting a charge from a lowish SOC, and I have not sussed out why yet), but did a quick reprogram to get the voltage back up to carry on as required.
Interestingly this lead acid battery accepted in the two hours near enough the same amount of Ahs back into the battery as the Lithium battery did, which was a bit of a surprise TBH, but to finish the job took longer (as as you can see, nearly 4 hours in and still not quite back to 100%)
If this were a 'normal' Lead Acid battery, I think the difference would have been a fair bit bigger.
What if you had a smaller charger? well, the Lithium would take all it could get (upto 50A per battery in the case of the RB100), and the lead acid would sit there for longer in bulk mode. But generally whilst the Lithium battery requires a charge it would use all that the charging system could give I would say, so if using say a Generator, the chances are you could run it for less time, which would make everyone happier I am sure.
So that kind of concludes this test
I think I will do another post just with my thoughts and possible conclusions for my own setup and which way I would go in terms of battery bank technology if starting fresh.
I didn't know the RB100 had a maximum recommended charge current of 50 Amps.
So does this take us back to the B2B thread?
Without some form of charge current limit a Religion LiFePo4 battery could accept damaging charge current levels. True or False?
wildebus
Forum Member
Damaging to what? the Battery or the Source (Alternator?)
The RB100 has a maximum charge rate of 100A, but 50A is recommended. Also that is per battery and I think it is likely someone might have multiple batteries - so if you had a pair, that would be 100A recommended.
So I guess the alternator could be a potential weak link IF the B2B was rated above the Alternator output?
I suppose the answer is you don't have a B2B that can deliver more than the Alternator can provide? Same as you wouldn't plug a 240V device into an inverter that is rated below the power of the Inverter?
Now I am not a automotive electrician so Alternators are not my forté, but I would also think an Alternator would not put out more than it can put out? so if the battery can take 100A but the alternator can output only 50A, then that is all it will deliver - same as a mains charger rated at 30A will not deliver more than 30A, or a solar controller with a max of 20A will not provide more that that (and likely less)?
You would expect the Alternator would have some kind of protection against "overload", no?