Electrical 100ah Gel Battery | SOC charge levels | 2 years old | Is it still in good condition

Jared01

Active Member
Oct 28, 2016
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Sydney
Hello,

I have a 100ah Ritar GEL battery which has been in my caravan/in use for about 2 years 2 months.

Not including powered sites, we have done a total of approximately 60 free camping nights.

I have taken the battery out 3-4 times over the above period, to give it a charge on my Ctek MXS5.0.


We are planning a 4 night free camping ski trip in Threbo in about 2 months time (using our 2.2Kw diesel heater) and I have taken the battery out of the caravan, on the bench, to give it a run by connecting a 50w halogen light bulb (which uses 50w/12v=4.17amps/hour)

The last time it had a good charge, was the a 5 night powered site in April, then a 1 night un-powered site 2 weeks ago.

I have been searching the internet for Stage Of Charge graphs for Gel batteries with mixed results. It seems as though the battery is about 50% SOC. Would you agree 12.35v is about 50% SOC?

I ran the Halogen for 1 hour, another 1 hour, another 1 hour then 2 hours as shown by the below image, and the voltage when rested, was 12.36v.



I will now charge the battery with my Ctek charger and give it a constant run with the halogen bulb (maybe for 5 hours straight / 20ah) and check the voltage and see how the life of the battery is going.


My main reason for this thread is advice on the battery life and that I need to run my diesel heater whilst in the snow for approx 9 hours per night (5pm-8am) and hope the battery has good enough life and enough solar power during the day, to put charge back in the battery

- I have a standard 120w solar panel on my Jayco Starcraft 17-58-3 OB
- I believe the max it can product is 12a per hour (in perfect conditions)
- I plan to run the diesel heater on setting 2 of 4 which consumes 12w/hour which is 1 amp
- Not sure what is the lowest level voltage I should take this battery down to
- I need to check which Setec Jayco charger is in the van and how much of a charge it would give if I ran the car for 1 hour to charge the caravan battery as a worst case

My calculations are therefore using 9 amps for 9 hours of diesel heating per night (excluding lights etc). I hope I can therefore get enough charge back into the battery for 4 nights, if there are no constant overcast days.

I'm just after any feedback from others including how long your Jayco supplied batteries lasted.
It looks like my battery is still in good condition. If not I may consider buying a new Gel and take it with me charged up ready to swap out. Also considering lithium as an option if I need to buy a new one.
 

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Boots in Action

Well-Known Member
Mar 13, 2017
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Ferny Grove, Queensland
Hi @Jared01 , I have just come across your thread about your Ritar Gel battery and your other questions on its ability to provide the power you want whilst in the colder snow conditions.
1. If the battery is only 2 years old and has been discharged and properly charged promptly, one can be pretty sure it will be still suitable for full use.
2.It is not the number of times you have free camped using battery power, but rather how low you let the voltage get and how promptly it was FULLY charged again.
3. Your Ctek MXS5.0 is a sophisticated "smart" charger and should do a better job than the charger in the van, provided the charge settings were correct - GEL.
4. The attachment below is a proper SOC for a Gel battery. Using that chart an open circuit voltage after charging, I would think it was closer to 70% than 50%.
5. There is NO WAY that your 120w solar panel on roof will generate 12A per hour!! More like 6A with a PWM controller. You also have to consider that with the panel flat on the roof, your best generating power will be for about 4 hours between 10.00am and 2.00pm when the sun is mostly overhead. After that generation will drop off considerably. One good thing is that the panel will not get too hot in the cold weather and if the air is clear, you can get more.
6. A Ritar 100ah battery is designed to deliver just that if it starts fully charged (technically that is at 25C) and so it will deliver less than that in colder conditions.
7. Working on you having available 90ah, you will have to make sure that you do not discharge the battery below 50% which limits you to only 45ah. Now you have to consider how much your solar will be able to recover during the day. I estimate 30ah at best if conditions are good, but probably much less. So as long as you only use 10A per night on heating plus say 8 to 10A for other uses per day, you should be okay. But the big unknown is the weather! Cloudy days are the norm during the snow season and clear blue skies are rare. You really only have 45ah available if no charge is able to be generated to keep battery topped up.
8. Careful surveillance of voltage and amps used each day will be necessary. If you have a voltmeter and a method of seeing amps in against amps out, you are at least in a position to control your battery usage. If you have records of what you have used/generated from previous trips, that will be the best information.

Hope all this info is useful to you. The lowest voltage i would let battery go down to would be 11.80 volts. Below that, the battery goes into a steep dive from which you may not be able to recover FULL STORAGE CAPACITY.

Good luck and safe travelling.
 

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mikerezny

Well-Known Member
Sep 11, 2016
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Mount Waverley, VIC
Hi,
I am unclear about how you arrive at 9 hours of operation from 5pm to 8am, that is 15 hours by my reckoning. If that is the case then the heater will consume 15Ah per night.

A 120W panel will usually deliver it maximum power at about 20V giving a maximum current of about 6A. That is the maximum current that will be given from a standard PWM solar regulator.

As @Boots in Action stated you would be barely able to get 4 hours of effective sunshine on a good clear day in winter onto a roof panel. We just did 12 days camping in around Victoria and got less than three days of barely reasonable sunshine in that time.
A reasonable estimate would be to budget for 2 hours per day at 6A which would provide 12Ah per day.

So you are likely to be in deficit of 3Ah per day not including any other 12V usage.

If you start with a fully charged Ritar (actually only a 95Ah battery), over 2 years old and in cold weather, more likely to be about 80Ah, then it would be prudent to not discharge below 50%. So you have an effective supply of 40Ah.

If you only use the heater, then you could budget on a maximum span of about 13 days, but obviously less than this if you use much other 12V power.

One other consideration is you fridge. If it is a three-way AES fridge then it will also be consuming power to run its electronics. This may not be negligible.

cheers
Mike
 
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