144 replies to this topic

[Casa Escarlata Robles Too]

I started this camping season,to shut the 3/way off about an hour out from the nights camp. That way all the trucks and solar charging will go into the camper battery.

Not by any means an expert,but it seems to work. Now that I have upped my solar to 100w I feel better about a good battery charge for the night time hours.

I have a watt meter to place in the system maybe it will give me more useful info.

Frank

[Ethergore]

With only having the built in FWC meter currently I can only present ancillary evidence based on my experience but since I put in my Isotherm 65 a 2-3 hour drive with the fridge running only brings the charge up to 4 lights most of the time.  If I drive 5 hours with the fridge running it will bring the batteries to all the way full.  Doesn't seem to matter what level the batteries were at when I started.
 
Hopefully this is all going to change soon as 200W of solar is scheduled to be delivered next week!

Mine does that too but the meter on our campers are very optimistic. At 12.5 my meter will say charged but that's not close to the 12.8 my battery sits at when charged with my iota/iq4. What's 12.5 like 80% charged?

[DrJ]

Here is a link for the percentage of charge based on battery voltage:
http://modernsurviva...harge-chart.pdf

The problem is always that the voltage is always based on a resting battery. So if there are loads on the battery it is not always accurate.

Then the battery monitors are always very optimistic. It may show a full battery at 13-13.5 volts when it wouldn't even be close to charged at that point. The trimetric won't show 100% until the amp hours are all restored or the voltage and amps meet the criteria you set.

It's very frustrating trying to make a decision on your power use if you don't really know what's happening.

[Ethergore]

Here is a link for the percentage of charge based on battery voltage:
http://modernsurviva...harge-chart.pdf
The problem is always that the voltage is always based on a resting battery. So if there are loads on the battery it is not always accurate.
Then the battery monitors are always very optimistic. It may show a full battery at 13-13.5 volts when it wouldn't even be close to charged at that point. The trimetric won't show 100% until the amp hours are all restored or the voltage and amps meet the criteria you set.
It's very frustrating trying to make a decision on your power use if you don't really know what's happening.

That's the exact thing I have learned by adding a refrigerator to my camper. That's why I'd be so interested to see what the trimetric says about the charge it gets from an alternator.

I drive a lot when I go on vacation so if the alternator is charging my batteries to 90% I'm OK with cycling them that way for a few weeks before they get a good charge. However, if the alt is only charging to 80% that's too low for my taste and it would confirm my need for a solar panel permanently mounted to top off my batteries more often.

[PaulT]

Since float voltage is typically about 13.6 volts for lead acid batteries, 13.5v would not be optimal.

From what I understand about the voltage sensing battery isolator that FWC installs, the truck alternator will not be allowed to provide charging power if the camper battery voltage drops below a certain level. That would mean running the engine earlier if the sun doesn't cooperate or your alternate charging source can't work.

I guess in a pinch, you could use an inverter to produce AC from the running truck and plug that into the camper AC input although that seems risky as the camper chassis is electrically tied to the truck chassis and who knows what is the electrical potential of the inverter case.

That Trimetric and careful note keeping while camping is becoming more attractive. Great thread even if there are more questions than answers.

Paul

[Mic]

Boy that is some great information!!! I am 85 days out from picking up my new Eagle!!! can't wait!

[craig333]

I just wish they weren't so pricey. I could add another battery for that price. 

[DrJ]

After hearing so many requests about truck charging, I've started an experiment this week to test it out.
I'm disconnecting the solar panel system. This is really easy to do - just unplug it at the roof.
I'll continue to run the compressor fridge until I get the battery to 50% of charge. Then the only charging method will be from the truck.
Later this week I have a several hour drive to make. We'll see just how much power gets restored per hour of driving and if I can get back to 100%. Total drive time is about 6 hours so if the system works that should be a reasonable time to try it out. I'll also look at the FWC battery charging lights and see what they tell me along the way. I will try it running the compressor fridge along the way as that would be the most common way I traveled. Should be interesting to see how much battery power is restored. I would think 80-90% of recharge in 6 hours of driving.
Any other guesses for how much battery can be recharged?

Edited by DrJ, 31 August 2014 - 09:23 PM.

[Ethergore]

I'm guessing closer to the 80% but I'm pessimistic at times. Do you think you can also tell me what voltage you get at your aux battery with the truck running, solar disconnected, fridge running and battery at 50% charge? This should give me an idea of your voltage drop compared to mine.

Thanks in advance for your willingness to experiment. This is helping me refine my setup until I can blow some cash on a trimetric myself.

[RC Pilot Jim]

Smoke, we are currently using the truck engine on idle when off the grid for two days when we don't take the portable 60 watt panel. Idling the truck for 1 hour increases voltage from 12.3 to 12.9 volts. ....Bottom reading slowly drops point one volt every 12-14 hours running the comp refer and lights couple hours in evening.

We use a what meter to check the amp draw of the refer ...Range 2.5 down to 1,5

As I read this I wonder if a "Trimetric" would be overkill for just 4 circuits??

Ether I get 13.6 volts engine running and refer cycling on - off

Edited by RC Pilot Jim, 31 August 2014 - 10:18 PM.