This youtube video states that the ctek does boost the voltage that the alternator puts out.
wfscot, where did you find this for $170?
wfscot, where did you find this for $170?
DC-DC Battery Charger
- Thread starter wfscot
- Start date
wfscot
Member
ski3pin, thanks for pointing out that video! At this point, I'm super confused. Both a reseller and CTEK U.S. have said that it does not boost. Then you have stuff like this that claims it does. Honestly, boosting that kind of power is a big deal in terms of hardware. Given the low cost and the lack of heat dissipating fins, I'm inclined to think that it is just a passthrough. There's also an interesting comment in response to that video that says the solar efficiency is quite bad compared to (just) PWM. If that's truly the case, that's a deal breaker for sure.
Here's a link for the $170 deal, though:
http://www.techbatterysolutions.com/CTEK-D250S-Dual-Battery-Charger-p/c008.htm
FWIW, I hooked up a TriMetric battery monitor. I ran a quick test with the truck running and the camper batteries depleted to 80% or so. In that test, the camper pulled about 15A. Very interestingly, the while the truck was outputting 14.4V, the camper was only receiving 13.7V. Thus it seems I'm losing quite a lot in my wiring. I'm going to look into that first before doing anything else.
I had an additional idea, too. Since I have the IOTA convertor with the IQ4 smart-charger built in, I'm thinking I could also just run an inverter off the truck while running and then run 110V to the convertor to charge the batteries. I'm sure there would be some efficiency loss, but it shouldn't be huge (I'm guessing 10% or so with a good inverter). However, with a 130A alternator, I have a bit or room to spare. Assuming the IQ4 is good at what it does, it should really optimize the charge in the camper batteries, too.
Here's a link for the $170 deal, though:
http://www.techbatterysolutions.com/CTEK-D250S-Dual-Battery-Charger-p/c008.htm
FWIW, I hooked up a TriMetric battery monitor. I ran a quick test with the truck running and the camper batteries depleted to 80% or so. In that test, the camper pulled about 15A. Very interestingly, the while the truck was outputting 14.4V, the camper was only receiving 13.7V. Thus it seems I'm losing quite a lot in my wiring. I'm going to look into that first before doing anything else.
I had an additional idea, too. Since I have the IOTA convertor with the IQ4 smart-charger built in, I'm thinking I could also just run an inverter off the truck while running and then run 110V to the convertor to charge the batteries. I'm sure there would be some efficiency loss, but it shouldn't be huge (I'm guessing 10% or so with a good inverter). However, with a 130A alternator, I have a bit or room to spare. Assuming the IQ4 is good at what it does, it should really optimize the charge in the camper batteries, too.
ntsqd
Custom User Title
The inverter-charger combo has a slightly rabid supporter on the tiny trailers forum. It just rubs me wrong. wasteful and inefficient even if it does work.
I used 6ga. for both the power and the ground between the camper and the truck. I fear the day that I need cables that large to power something in the camper. I went that large for the lack of voltage drop.
I used 6ga. for both the power and the ground between the camper and the truck. I fear the day that I need cables that large to power something in the camper. I went that large for the lack of voltage drop.
wfscot
Member
ntsqd, I feel you on the wasteful sentiment regarding the inverter-charger approach. It does feel wrong. That said, there don't seem to be a lot of options for good charging off of the truck alternator.
I'm going to redo my wiring to at least 8ga to see if that doesn't do something about the voltage drop from the truck to the camper. With that plus solar, I may be satisfied. We'll see...
I'm going to redo my wiring to at least 8ga to see if that doesn't do something about the voltage drop from the truck to the camper. With that plus solar, I may be satisfied. We'll see...
Ethergore
Senior Member
I'm glad I saw this thread. It's got some overlap with my thread in the truck moods section. I'm glad to hear I'm not the only one to have my separator cycling when my battery gets too low. I'm still trying to pinpoint at what point it does this but it was a huge problem for me on my last trip.
After making sure my starting battery and alt are fine I have been thinking about the ctek too. What would be the point of the product if it doesn't increase the voltage? I thought it's purpose was to make your power source into a 3 stage charger? I'm really considering it so let me know if you get it or what you find out. Heck the thing is even supposed to compensate for temperature which our iq4 doesn't even do.
One thing I do know about the ctek is that it contains it's own voltage sensing relay just like the one we are both having problems. The only difference is it's supposed to turn off at 12.7 instead of 12.8 v. What I decided on my setup is that I shouldn't be running my battery this low anyways and increased the size of my bank. Now in the much less likely event that I run my battery low I will do what I did on my last trip and bypass the separator or ctek to recharge. If you do that bypass the separator after you start the vehicle so you don't send a current overload through your tiny wire.
As far as your voltage drop maybe you can help me understand. Did you measure with our without a load? On my system I get the same voltage from where my camper plugs in as I do on the starting battery. However, when I hook up to charge the battery I get a much different reading from my aux battery then I do from the starting battery. I thought this was normal??? Basically the closer you get in the circuit to the higher voltage battery the higher the voltage. Is this something I need to avoid or is this normal?
After making sure my starting battery and alt are fine I have been thinking about the ctek too. What would be the point of the product if it doesn't increase the voltage? I thought it's purpose was to make your power source into a 3 stage charger? I'm really considering it so let me know if you get it or what you find out. Heck the thing is even supposed to compensate for temperature which our iq4 doesn't even do.
One thing I do know about the ctek is that it contains it's own voltage sensing relay just like the one we are both having problems. The only difference is it's supposed to turn off at 12.7 instead of 12.8 v. What I decided on my setup is that I shouldn't be running my battery this low anyways and increased the size of my bank. Now in the much less likely event that I run my battery low I will do what I did on my last trip and bypass the separator or ctek to recharge. If you do that bypass the separator after you start the vehicle so you don't send a current overload through your tiny wire.
As far as your voltage drop maybe you can help me understand. Did you measure with our without a load? On my system I get the same voltage from where my camper plugs in as I do on the starting battery. However, when I hook up to charge the battery I get a much different reading from my aux battery then I do from the starting battery. I thought this was normal??? Basically the closer you get in the circuit to the higher voltage battery the higher the voltage. Is this something I need to avoid or is this normal?
Ethergore
Senior Member
One other thing. You were worried about not being able to support more than one solar panel. You just have to make sure you connect the panels in parallel and not in series. Ie positive to positive and negative to negative. This will keep the panels under the required voltage as long as they are 12 v panels of course.
camelracer
Contributors
This will depend on your solar controller. Some will allow 24v input which is more efficient since there is less current for the same power. Less current means less power loss due to wire resistance.Ethergore said:
Ethergore
Senior Member
Camelracer- this comment was specifically for the ctek which does not allow for the 24volts that 2 panels wire in series would create.camelracer said:
wfscot
Member
It's been quite a while, but I figured I'd update this for the benefit of others asking similar questions.
Following this thread, I ended up pulling the trigger on a solar system. I have a 100W panel permanently mounted on the roof and a second folding 100W that we can deploy if we really need to stretch it. All this is connected through a SunSaver MPPT controller to our battery bank.
Most of the time, the rooftop 100W alone is enough to keep us at 100% or very close. If it's very hot (i.e. the compressor fridge is working overtime) and we're looking to stay out for a week or more, I'll bust out the 2nd 100W and that does the trick, especially if I adjust it towards the sun a few times a day.
So now I don't really care about truck-to-camper charging. Problem solved!
Ethergore, I still don't think the CTEK boosts the voltage. That said, you asked "what's the point if it doesn't boost?" and I believe it will at least bring the batteries back more quickly from very low SoC vs the VSR. This is due to the fact that the CTEK should stay on deliver a maximum current (assuming proper bulk absorption behavior) regardless of the SoC, while the VSR will cycle when the SoC is very low. Even if it doesn't boost past the alternator voltage, that should still get you very close to 100% during the bulk absorption phase with the added advantage of ramping up the voltage slowly in order to keep you camper batts healthy.
As for your observation that under load, the voltage increases the closer you get to the source battery, that's totally expected. It's basically DC line loss. The further you get from the source battery, the more resistance you have due to longer wire, etc. Per Ohms law, that higher resistance translates to a bigger voltage drop.
My issue is that the voltage drop seems quite high (0.7V), which is likely due to the small-ish wiring used by FWC (12g, I believe). If I were really concerned about maximizing the efficiency of charging off the truck, it would probably make sense to redo that with larger wire.
And yeah, I understand that you can do parallel solar panels to keep the voltage under the CTEK max. That said, a real controller (such as my SunSaver) gives you the flexibility to do either parallel or series, which is nice. Again, it doesn't sound like the CTEK is a very good solar controller.
Following this thread, I ended up pulling the trigger on a solar system. I have a 100W panel permanently mounted on the roof and a second folding 100W that we can deploy if we really need to stretch it. All this is connected through a SunSaver MPPT controller to our battery bank.
Most of the time, the rooftop 100W alone is enough to keep us at 100% or very close. If it's very hot (i.e. the compressor fridge is working overtime) and we're looking to stay out for a week or more, I'll bust out the 2nd 100W and that does the trick, especially if I adjust it towards the sun a few times a day.
So now I don't really care about truck-to-camper charging. Problem solved!
Ethergore, I still don't think the CTEK boosts the voltage. That said, you asked "what's the point if it doesn't boost?" and I believe it will at least bring the batteries back more quickly from very low SoC vs the VSR. This is due to the fact that the CTEK should stay on deliver a maximum current (assuming proper bulk absorption behavior) regardless of the SoC, while the VSR will cycle when the SoC is very low. Even if it doesn't boost past the alternator voltage, that should still get you very close to 100% during the bulk absorption phase with the added advantage of ramping up the voltage slowly in order to keep you camper batts healthy.
As for your observation that under load, the voltage increases the closer you get to the source battery, that's totally expected. It's basically DC line loss. The further you get from the source battery, the more resistance you have due to longer wire, etc. Per Ohms law, that higher resistance translates to a bigger voltage drop.
My issue is that the voltage drop seems quite high (0.7V), which is likely due to the small-ish wiring used by FWC (12g, I believe). If I were really concerned about maximizing the efficiency of charging off the truck, it would probably make sense to redo that with larger wire.
And yeah, I understand that you can do parallel solar panels to keep the voltage under the CTEK max. That said, a real controller (such as my SunSaver) gives you the flexibility to do either parallel or series, which is nice. Again, it doesn't sound like the CTEK is a very good solar controller.
I have the ds250 dual paired with the optional unit I believe is called the bypass.
It works great. I have 6 volt golf cart batteries that I purposely discharged to 50% to see the effects. It was charging at over 60A and continually adjusted the output as batteries reached the full charge. It will also boost or drop voltage dependent on the state of charge.
The reason for me to by the pair was to quickly charge the batteries and not have to bring a generator. Before installing this combo, I did a test on the camper 40A charger. At 50% I was only receiving about 25A which adjusted as I got close to charge. I would have to run the generator for several hour to get to get close to fully charged.
I have a DC fridge and a cpap machine running off these batteries. So quickly charging these batteries is important. I run to the store and when I return battery capacity is much higher, if not fully charged.
I have not found the need for a solar panel yet. The good thing with the solar input is that it will recharge your truck batteries after house batteries are fully charged. Great for longterm boondocking without generator.
It works great. I have 6 volt golf cart batteries that I purposely discharged to 50% to see the effects. It was charging at over 60A and continually adjusted the output as batteries reached the full charge. It will also boost or drop voltage dependent on the state of charge.
The reason for me to by the pair was to quickly charge the batteries and not have to bring a generator. Before installing this combo, I did a test on the camper 40A charger. At 50% I was only receiving about 25A which adjusted as I got close to charge. I would have to run the generator for several hour to get to get close to fully charged.
I have a DC fridge and a cpap machine running off these batteries. So quickly charging these batteries is important. I run to the store and when I return battery capacity is much higher, if not fully charged.
I have not found the need for a solar panel yet. The good thing with the solar input is that it will recharge your truck batteries after house batteries are fully charged. Great for longterm boondocking without generator.
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