Battery Tutorial and Discussion

[W0AAT]

Xantrex, Morningstar are 2 sources of charge controllers. If you need to maximize your charge go MPPT (maximum power point tracking). It can gain 15% greater charge over a PWM controller. I went with the Morningstar TS-45 MPPT controller. It costs considerably more but with soon to be 1100 watts of panels it will pay for itself.

[KA1MDA]

I'm not sure if Xantrex even makes solar chargers any more. I checked their web site and couldn't find any in their current product line up. I would definitely avoid them on the used market as well. They had an issue with MPPT in their grid tie inverters, where the inverters didn't put out anything close to the rated output (as reported in an in-depth review in Solar Power magazine a number of years ago). MPPT technology itself, if correctly implemented, is well worth the extra expense, though. Not only will it maximize PV panel output (actually delivering rated panel wattage), it can also significantly cut down on resistive cabling losses by allowing PV panels to be run in series with string voltages as high as 300 or more volts!

Xantrex, Morningstar are 2 sources of charge controllers. If you need to maximize your charge go MPPT (maximum power point tracking). It can gain 15% greater charge over a PWM controller. I went with the Morningstar TS-45 MPPT controller. It costs considerably more but with soon to be 1100 watts of panels it will pay for itself.

[KF5LJW]

Do you recommend that the charger have temperature compensation for change in temperature

Ned sorry for the delay in responding, I lost track of the thread. If you are going to be using AGM batteries, or outdoors exposed to the environment then yes. AGM's are prone to Thermal Runaway. If using a flooded battery indoors with stable room temperatures it is not needed.

who do you recommend for charge controllers to be used with solar panels?

Charge controllers fall into two types of PWM and MPPT. PWM is the least expensive but the efficiency is very poor at 67% best case if using standard battery panels with a Vmp of 18 volts for the simple fact of CURRENT INPUT = CURRENT OUTPUT For example if you use a 100 watt, 18 Vmp, 5.5 amps Imp, at best the output is 5.5 amps x 12 volts = 66 watts.

MPPT controllers are much more expensive but have up around 95% efficiency so that same 100 watt panel above outputs up to 7.9 amps @ 12 volts. In addition you are not forced to use battery panels, you can use less expensive grid tied panels that run on higher voltages which means greater efficiency because you incur less voltage drop on the cable between the panels and charge controller. In addition GT panels come in much higher wattage than their battery bothers. However like I said MPPT controllers are much more expensive, and until you get to 200 watt panel and above input wattage, PWM wil give you more bang for the buck. Once you get above the 200 to 300 watt level MPPT blows away PWM in both performance and cost because you can use less expensive GT panels and not need as high of a wattage.

Example in my area the winter insolation is about 3.5 Sun Hours, and if I wanted to run a minimum 1 Kwh/day with PWM I would need a 600 watt battery panels and a 40 amp charge controller for a total cost of about $1300 for the panels and charge controller. To get the same amount of daily energy with a MPPT controller I need 400 watt panel and 40 amp controller for a total of about $1000.

OK to answer you directly look at MorningStar PWM controllers as they are quite good quality and value for smaller less demanding systems under 200 watts. Other notables are Bluesky and Steca. You can get a 15 amp PWM charge controllers for under $100. For larger systems using MPPT Outback and the best there is is Midnight Solar, but I am talking serious money for 60 and 80 amp MPPT controllers like $600 to $1000.

[KF5LJW]

I'm not sure if Xantrex even makes solar chargers any more.

You are correct. Xantrex is now Schneider Electric and they still make charge controllers but I would never recommend them. They just have way too many complaints.

[KK4BBG]

question for using solar power and batteries for "ham in a can" applications for vhf uhf radios.

is it neccesary to get a voltage "stepper" like on grumpy's website, or the mfj version to boost 12v - 13.8?

i know rigs work at 12 but they are "happier" with 13.8. just wondering if i need to add another $65 item to my project.

[KF5LJW]

question for using solar power and batteries for "ham in a can" applications for vhf uhf radios.

is it neccesary to get a voltage "stepper" like on grumpy's website, or the mfj version to boost 12v - 13.8?

i know rigs work at 12 but they are "happier" with 13.8. just wondering if i need to add another $65 item to my project.

Not sure what you mean by ham in a can?

When we talk about 12 volt batteries encompasses quite a broad term. 12 volts is just a nominal term. The actual voltage depends on the battery chemistry like lead acid, NiCd, or NiMh.
Sense this topic is tailored to the lead acid family lets stick with that. In the lead acid family (Gel excluded because they are even lower voltages) assuming you never discharged them more than 50% DOD the voltages encountered are going to range from 12.2 volts at 50% DOD up to 15.6 volts during and Equalization charge.

But here is kind of the low down with respect to normal day to day solar applications. During the daylight hours the battery terminal voltage will likely start out around 12.7 volts at sun rise. As soon as th epanels receive direct sunlight will start to charge up and the voltage will jump up to 13 volts or more depending on how deeply they were discharged during the night. As they charge will climb up to around 15 volts after they cycle through the Bulk and Absorb charge sequence. Once fully charged the controller switches to Float charge of 13.6 to 13.8 volts and holds there until the sun sets. Once the batteries set there and bleed off the surface charge will settle at 12.6 volts 100% state of charge. If you use them at night the voltage will gradually decrease and assuming you do not go below 50% will remain above 12.2 volts. The cycle repeats itself the next day.

If you are like me Solar is just there to look cool and not actually ever do anything. Only there if by some chance the power is off more than a week which has never happened yet. I float my batteries off my DC power supply set to exactly 13.6 volts and never turn it off. If I get a brief power outage when operating I just keep on talking and the batteries take over. I have a set of Trojan T-105RE or 12 volts @ 225 AH and can talk a full week several hours a day before they hit 50% DOD @ 12.2 volts. Only reason I know that is I tried it a couple of times. Works great. When power is restored my DC supply recharges the batteries with up to 30 amps which is perfect charge current for my batteries. It was designed that way.

[K7ELP]

Dereck KF5LJW,
Thanks for all the information. I really appreciate it.
Ned K7ELP

[KK4BBG]

i thought "ham in a can" was a universally accepted term, you tube it.

its portable amatuer radio in some type of container. (ammo cans, gator boxes, pelican cases etc.)

im building one in an ammo can of sorts. ill be using

12v 22AH Rechargeable maintenance-free SLA/AGM

batteries. Its kinda like what HF backpackers do. take batteries and their radio somewhere high and do dx. This case will be used for relays. events, and occasional power outages where all i have to do is open the case turn on the radio and if neccesary throw up some solar panels connect it to the box and the coax with antenna and be set up to go.

if the power fluctuates to 15v doesnt that mess up a normal uhf vhf radio? i know they are supposed to operate on 138.v for their preffered voltage for max watts output, but they will run off of 12v.

[K0BG]

As a whole, there is a lot of good information here. Unfortunately, there is a lot of misinformation too.

Common battery terms are either misused, misconstrued, or assumed. Charge cycle life isn't discussed. The impression is that some specific LA (lead acid) battery can be discharged further than another without affecting charge cycle life. Any LA will have drastically reduced capacity as the temperature drops below about 10°F, including AGMs and LFPs (LiFePO4, lithium Iron phosphate).

If you want to know what all of the terms really mean, go to the Battery Counsel's web site.

[KB4QAA]

'Ham in a can" ?

*shakes head* [edit] Or as it has been known for the last 100 years..."Portable Operations/Operating Portable".