Electrical System Debacle

[mikracer]

I bought this portable solar kit and it works great. It would fully charge the batteries in my old trailer (2x group 31 batteries) after running the heater and/or heated mattresses throughout the night.

https://www.amazon.com/Renogy-Monocr...8-2&ref=sr_1_2

[Flipperfla]

I agree with Flux, look at it as time instead of volts, your taking more time out of the battery than you are putting time back in with your short drive to work. I used to work in a Marine store and saw this issue all the time with the Bass Boaters fishing for hours with their trolling motors and then the 20 min blast across the lake back to the boat ramp not putting the time back in the battery. This will eventually damage the battery not charging it up to 100%. A charger on the house batteries when at home would solve your issue.

[PulseofdaNation]

@mikracer - Thanks for the link. As I'm currently living in the van with my fiancee and 2 dogs, I'm worried that a portable solar kit is going to take up more room than I have available, so I'm inclined to focus on doing a more permanent solar solution I can mount to my roof. Where did you end up storing your setup when on the road?

@Flipperfla - The thing that I'm not 100% on regarding the time/volts debate is how to evaluate the time of use vs. time of charging based on a quantifiable metric besides minutes, because even if the time I'm charging is less than the time I'm using, if the charging power is significantly higher than the usage power, then it doesn't seem like it should be a 1:1 comparison... does that make sense? Like I mentioned previously, I think I'm drawing less than 1 amp of power for 12 hours or less at a time before driving again when using my lights, espar d2 heater and maxxair fan.
I would LOVE to have the luxury of charging my battery with a charger, but I have yet to find any electrical hookups out in the National Forest around Bend

Update: Scheduling an inspection with Bend Battery to have them look through my setup and see if/where i'm having voltage loss.

[mikracer]

My van is pretty empty (not a camper conversion) so I have plenty of room to just throw it in. With that said, it does fold up pretty compact and comes with a carrying/stowing case. I just figured it might be a quick and simple temporary solution until you get a permanent system installed. You can always sell the portable system once you get a hard mounted system in place.

[Twoxentrix]

Unless you intentionally park in the sun, majority seek out shade so the fixed top-mount arrangement becomes compromised. A suitcase allows the opportunity to park in the shade and just place the panels in sunlight. I have both, and the suitcase provides more effective charging when parked (if electric outlet isnt an option), coupled to a 75ft cord.
I purposely purchased very thin flexible panels suitcase (very thin & light compared to others) - and have been very pleased with the results.
The only drawback is you have to tend the panels periodically to keep them facing the sun, but the convenience of being in the shade outweighs the effort.

https://www.amazon.com/Lensun-Foldab...r=8-5-fkmrnull

[carringb]

Originally Posted by arctictraveller

I wonder if the alternator is sensing the voltage of just the start battery, and thinks it's fully charged, so it reduces the output?

This is almost certainly a factor, especially if the wiring through the isolator circuit is undersized (preventing the aux battery from pulling down the start batt voltage when connected).

[Scalf77]

In general you need to have each a cell above 2.25 volts to supply a charge (2.25 x 6 = 13.5 Volts) this would be a slow charge, typically 13.8 is considered the low point for a alternator.

Alternator charging is relatively slow, and the charge rate drops pretty quickly, so as it gets charged the rate slow down. A larger alternator doesn't necessarily help unless, you you have to much load on the system. At Idle you get about half your rated output. You also have to put more into the battery than you take out to fully charge

Since, you really haven't probably ever completely charged your battery in a while, you have most likely lost some of your capacity. This will cause you to see 12.2 volts a lot earlier than you were used to, also the cold temperatures in Bend will a a profound effect on the battery capacity.

I would recommend a good battery monitor , such as the Balmar SG-200 This will help you understand the power going in and power going out of your battery.

Even with solar, you have the problem with time, once you get 80% to 90% (depends on controller) you go into absorption phase, which holds the voltage and decreases current until charged, this can be the longest part of the cycle.

greg

[arctictraveller]

Originally Posted by PulseofdaNation

@Flipperfla - The thing that I'm not 100% on regarding the time/volts debate is how to evaluate the time of use vs. time of charging based on a quantifiable metric besides minutes, because even if the time I'm charging is less than the time I'm using, if the charging power is significantly higher than the usage power, then it doesn't seem like it should be a 1:1 comparison... does that make sense? Like I mentioned previously, I think I'm drawing less than 1 amp of power for 12 hours or less at a time before driving again when using my lights, espar d2 heater and maxxair fan.

What your talking about are "amp hours". A draw of 10 amps for one hour equals 10 amp hours. The trouble is, it's pretty easy to calculate amps out of the battery by adding up all your loads and the time they draw on the battery. It's harder to quantify re-charge time because there are so many variables. Time, temperature, charging sources, battery acceptance rate, depth of discharge and more, all factor into how long it will take to fully recharge a battery. In general, it takes much longer to fully recharge than it did to discharge the battery. I wonder what your true amp hour usage is, and I doubt your only drawing 1 amp while running lights, heater and the Maxxair. I suspect your usage is more than you think, but the only way to know for sure is to install a battery monitor. A monitor will allow you to analyse your system performance. In my case, I have 3, 100W solar panels, and run my refer 24/7, a couple lights and the heater for a couple hours a night. In full direct sunlight, I only see about 14amps, and as the sun moves it drops quickly. The end result is that on solar alone, I never get over about 80% of a full charge, and on cloudy days it's far less. I'd say average current is about 8amps over a full day. A few hours of driving helps, but the batteries (two 6v golf cart's for a total of 225Ah at 12V) never fully recover until I plug in overnight.

[moorefc]

As described earlier, examine where your sense line to the alternator goes and if it has voltage drops....If sensing on the alternator side of the isolator and not at the start battery for instance, any voltage drops are not seen by the alternator so the output is lower....

[HK33FAN]

It looks like a few members have hit on the meat and potatoes of this topic. You must, must, must get a good quality battery monitor, one that will show voltage, amp hours in, amp hours out and state % of charge.

I see a few major issues with your current set up.

1. Based on your list of power users I would say that your battery is undersized for full-time use. My CO2 and gas detector draw about 1Ah and my Diesel Air heater draws 1.2-1.7Ah (on low after glow plug warm up). These small draws, when added up, can easily be 50-75AHs in a 24-hour period. Are you and you're girlfriend charging cell phones or using laptops at night when the Van is off, the amp hours add up fast.

2. At 12.2VDC your battery is considered dead and is at 50% discharge. This is the lowest you ever want to deep discharge a battery and will greatly reduce the life of the battery. Adding another battery or a larger one will not help unless you upgrade the charging system, you will be left with two half charged batteries. With lead acid batteries you only safely get 50% of the rated amp hours, 175ah = 87.5 and for longer battery life you should try and keep it above 75% so only 44AH discharge before fully recharging your battery.

3. Charging from just the alternator probably wont ever be enough, your alternator charges a battery that in normal use, is 90-95% charged and it only has to recover from the starter Ah loss and provide steady power for life support. Another issue is that the charging system is designed for long life and safety. Your battery should not be charged faster than 1/5 its amp-hour capacity 35amh in your case and this number tapers off to as high as 1/20c above 80% charge. In my experience, anything over 1/10c 17.5Ah in your case will boil off the electrolyte in the battery. Without a battery monitor, it’s hard to say what your recovery charge is, but I doubt you’re getting more than 30Ah back in the battery on your dialing drive if it's 2 hours or more. I Have a 220Ah battery with 200 watts of aux solar. The Solar was added because even after driving 4 hours or more my house batter with a 50Ah discharge would never get back up past 85-90%. This is because the alternator output is tapered off drastically as the battery is charged. You have to add solar, shore power and or a generator to supplement your charging needs and extend your battery life.