Good Sam Club Open Roads Forum: Tech Issues: Solar panels and lithium batteries
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prstlk

Post Falls ID

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Posted: 07/06/22 10:19am Link  |  Quote  |  Print  |  Notify Moderator

We are thinking of installing 2 solar panels and replacing our deep cycle batteries with lithium batteries. Big cost but if it gets us where we don't run out of power with our current set up it might be worth it.

What we have right now is a Owen 5500 generator, inverter/charger and 4 deep cycle 6v batteries, which are 5 years old and we know they are close to needing replaced.

We are boondocking and run the generator until the panel shows full but we run out of power in the middle of the night. Both of us have to use CPAP machines so this is not a good thing. We make sure that everything else is shut off even unplugging the coffee pot and TV.

Has anyone switched to the lithium batteries? Will installing just the solar panels be enough with 4 new golf cart batteries?

Any feedback would be appreciated.


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Lwiddis

Cambria, California area

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Posted: 07/06/22 10:47am Link  |  Quote  |  Print  |  Notify Moderator

My solar system works well with my 200 amp hour Lithium battery but the panels, battery and controller are properly sized to my usual electrical use. Start with your average daily amp use then multiple it by 1.5. Size the three from that number. Done right, you’ll be able to camp without generator noise and maintenance.


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TechWriter

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Posted: 07/06/22 01:40pm Link  |  Quote  |  Print  |  Notify Moderator

prstlk wrote:

Has anyone switched to the lithium batteries?

Not yet, but when I do, I’ll install at least two of these 206 Ah SOK batteries.

Remember, your charger will need to have adjustable Absorbtion and Float battery voltages.


prstlk wrote:

Will installing just the solar panels be enough with 4 new golf cart.

Probably not since you are draining fully charged batteries each night.

I’d replace your lead-acid with lithium batteries first.


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time2roll

Southern California

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Posted: 07/06/22 03:15pm Link  |  Quote  |  Print  |  Notify Moderator

Please don't tell us the four light panel is saying full and the generator is turned off. Need to get these batteries up in the 14.4 to 14.8 voltage range and hold for an hour minimum to be about 95% while camping.

Going to need to get this right for lithium & solar anyway so dig into the inverter/charger specs and verify with a voltmeter what is going on. Post your findings.

And yes I have solar and lithium. Huge improvement over GC2.


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wa8yxm

Davison Michigan (East of Flint)

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Posted: 07/06/22 03:34pm Link  |  Quote  |  Print  |  Notify Moderator

The panel will show full long before a hydrometer will show full (A temperature compensated hydrometer is the only way to be 100% sure of full on flooded wet cells) you might want to test using one of those.. Resting voltage is also a good indicator but you must DISCONNECT the battery for a while before measuring. Else you see only "Surface charge" or the converter output.

I'd recommend the hydrometer. Auto stores still have 'em in many cases.

The major advantage of LI is that you can run 'em down near zero before they reduce voltage.. Just make sure you have the proper solar controller.
Also you need to do a bunch of math to decide

How many watts do we use per day
How many watts will the panels actually produce (Figure half their rating)

and the loss in the charging cycle. MPPT controllers Maximum Power Point Transfer) will charge fastest .


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valhalla360

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Posted: 07/06/22 03:50pm Link  |  Quote  |  Print  |  Notify Moderator

wa8yxm wrote:

T
How many watts do we use per day


This should really be figured out first.

Also, as someone else suggested, you may not be fully charged. While hydrometer is the gold standard, turn off the generator and let the batteries rest for an hours. If they aren't up around 12.7v, you didn't fully charge them. What you likely saw was the charging voltage which tends to be up over 13v.


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FrayJo

Latham

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Posted: 07/06/22 11:38pm Link  |  Quote  |  Print  |  Notify Moderator

I also installed a couple of like this

Microlite Mike

NW Washington State

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Posted: 07/07/22 09:19am Link  |  Quote  |  Print  |  Notify Moderator

prstlk wrote:


We are boondocking and run the generator until the panel shows full but we run out of power in the middle of the night. Both of us have to use CPAP machines so this is not a good thing. We make sure that everything else is shut off even unplugging the coffee pot and TV.



This is a very common practice and also the biggest mistake many make when charging their Lead/Acid batteries. Generally a converter (powered by generator or shore power) can charge a discharged battery to about 90% in a few hours. The catch is that the last 10% can take the same amount of charging time (or more) to finish replenishing that last 10%.

The LED indicators supplied by most RV manufacturers are responsible for more battery deaths because they lull people into thinking the battery is charged.

A good battery monitor like those from Victron or a Trimetric will prevent a lot of early battery deaths from partial charging and the resulting sulfation that eats away at the battery's capacity.

If changing to LiFePo4 batteries one of these monitors is almost essential as the LED gauges will show a fully charged battery until the LiFePo4 battery is almost dead. All due to the battery voltage curve during discharge.

Yes, the mentioned Battery Monitors are more expensive than the LED "gauges" and some of the cheaper monitors on the market but they give a far more accurate display of battery State of Charge. Properly set up (which is easy) one can see with great accuracy when it's time to shut off the generator.

As for Lithium batteries, I have two of them I charge with a portable 240 watt solar kit (self built) that has cut my generator run time to only days when it's too overcast and raining to get a full charge. My last week long trip resulted in NO generator time at all, even with watching movies in the evening and using the microwave several times per day.

BTW, 5 year old Lead/Acid batteries are pretty much at end of life. Fact they won't last the night is a good indication.


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ReneeG

Meridian, Idaho

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Posted: 07/07/22 01:34pm Link  |  Quote  |  Print  |  Notify Moderator

We checked into getting lithium, but they're cost prohibitive and with our current 4 bank of deep cycle batteries and two solar panels, 300 watt, it gives us enough to never have to run the generator and we watch TV off our satellite daily along with using the computer. Hubby has a CPAP, but we have a Jackery he uses for that and we recharge it off their own set of solar panels. So far this year we've only been out twice for a week at a time and have not had to recharge the Jackery during the trip.


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Skibane

San Antonio, TX

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Posted: 07/07/22 03:43pm Link  |  Quote  |  Print  |  Notify Moderator

prstlk wrote:

Both of us have to use CPAP machines so this is not a good thing. We make sure that everything else is shut off even unplugging the coffee pot and TV.


There is a huge variation in the power consumption among various CPAP machines.

Switching to a different model might be the only change you need to make.

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