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Father's Day-CA

Charge 2 AGM Batteries & A Power Station With Solar Panels

Question

This is a great question about finding a simple way to charge a portable power station like the Goal Zero Yeti 1000 (click to view on Amazon) and multiple 12 volt AGM batteries with the same solar panels.

Is a common setup for not only RVers and travelers but homeowners who want to have a reliable backup power source.

Here’s the comment from our Goal Zero Vs Jackery – The Ultimate Power Station Battle article.

I decided to keep things as simple as possible with a GZ yeti 1000 and 1500 with GZ Boulder 200 briefcase solar panel

What I need your help with is that I want to purchase one or two RV 12V AGM type batteries. I want to use solar panels to charge the 12 volt batteries, which I then plan to use for backup power on no sun days to charge/power the yeti 1000 and/or 1500. I installed the MPPT optimization unit (charge controller) you recommended on the 1000 yeti. The1500 yeti has the MPPT kit already installed (like the 30 am external kit you recommend for the 1000 yeti). Because I live in a state that is cold in winter and hot in summer, I will most likely go the AGM battery route, but am open to suggestions on that subject. My other concern is the probability of discharging them under 50% unintentionally. A quick read of your blog indicates the batteries would need to be connected in parallel.

Would you detail what connections I need to use the boulder 200 solar panel to charge the 12 v battery. What connections I would then need to connect the 12 v to the 1500 yeti and separately to the 1000 yeti (I assume they will differ based on the 1000 not having the external MPPT kit installed) ?

I am also considering purchasing another Bolder 200 briefcase solar panel. Is that overkill for charging both the Yeti units in one day? Also, when connecting the 200 panels to each other is that technically considered 2 or 4 panels? These panels are Anderson power pole connections. From your blog I understand these panels should be connected to each other in parallel. I like the Renolgy you recommend, but trying to keep things simple and uncomplicated for ease of use.

I have read and understand the blog postings you have on each of these subjects. These units will be used for emg needs as opposed to camping or RVing. – K

Answer

(click links to see products on Amazon)

Let’s see. Someone else might have something to add to this conversation, but here are some thoughts.

1. Based on the recent tests I have read on AGM batteries, they’re ok to discharge below 50% but not below 20%.

You’re still going to shorten the lifecycles by doing this, as with any battery, but as long as you don’t bring it below 20% you’re ok.

I would still try to keep it as charged as possible at all times, but going below 50% a couple of times won’t make a huge difference.

2. Yes, if the batteries are 12V AGM batteries they should be connected in parallel to increase the amperage but not the voltage.

Just connect the positive terminals together, then the negatives together separately from the positive.

3. The Boulder 200 doesn’t have a charge controller built-in, since the Yeti 1000 and 1500X has one built-in.

If you want to charge a 12V battery with a solar panel you need to put a charge controller between the two.

The charge controller regulates the voltage and makes sure that the battery isn’t overcharged.

Goal Zero used to sell a product to connect a Boulder panel to a 12V battery, the Guardian 12V Plus, but it has been discontinued.

This makes it much trickier to charge your external 12V battery with a Boulder panel. It would take some rewiring.

4. To add to the above, what I would recommend instead of getting another Boulder panel is to get a portable solar panel that has a charge controller with a built-in quick disconnect.

That way you can disconnect the charge controller to charge the Yeti batteries, then connect the charge controller when you want to charge the AGM batteries.

A panel like the Acopower 100W portable solar panel which can charge both a power station and a 12V battery at the same time would work great for that purpose.

All you would have to add to the Acopower panel is the MC4 to 8mm adapter.

5. To monitor the battery voltage, I recommend connecting a battery monitor like this.

6. To charge your Yeti batteries with the AGM batteries, I would actually recommend a typical car inverter, like the Bestek 500W inverter.

Hook it up to your batteries, then plug the Yeti chargers into the inverter.

7. Another 200W of solar wouldn’t be overkill at all, although it depends on what you need to power during emergencies and for how long.

The Yeti 1000 and 1500X have a 2561Wh (watt-hour) battery capacity combined.

A total of 400W of solar will generate about 250-300Wh per hour in good sunshine, so in the best-case scenario, it would take 9-12 hours to recharge both.

8. It would be four panels connected in parallel.

Hope I didn’t make it too confusing, let me know how I can help out further.

I wish it was easier than this to deal with Goal Zero lithium batteries and external batteries that don’t come from Goal Zero!

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Have any questions about this Q&A? Leave a comment below.

by Jenni
Jenni grew up in a small town in Idaho. With a family that loves camping, she has been towing trailers since a very young age.

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