24 replies to this topic

[PaulT]

If you find you have two GC type batteries & want to go to LiFePO4 batteries, Battleborn makes the 100 Ah batteries in the GC2 size.

I replaced my factory AGM GROUP 24 batteries with a pair of them and while it was a tight fit in my front dinette Hawk, they did fit.

 

It is nice to have 200 Ah to draw down rather than just effectively 75 Ah.

 

Paul

[ckent323]

RallyRock,

 

Welcome to the WTW forums.

Determining the state of charge (SOC) of your batteries using a voltage monitor is not accurate.  

As previously suggested by others above, I strongly recommend installing a good shunt type battery monitor such as a Victron BVM-712 or equivalent.

I also recommend that you do not routinely draw your AGM batteries down below 50% SOC and always fully recharge them before drawing them down again (routinely under charging AGM and Lead Acid batteries before discharging is one of the causes of sulfation which reduces battery life). 

For more on batteries here is a great resource:

https://batteryuniversity.com/articles

 

 

Also, in case you are not familiar with Solar Panels, if you get any shade on any part of your solar panel the output from your system can be seriously reduced (depending on the panels as well as how they are connected).  So beware of shade from roof top racks, trees, power poles, etc.

If you have an Overland Solar or Victron MPPT Solar Controller with bluetooth you should be able to monitor your solar power production from a smart phone (or laptop).


P.S. The battery monitor also serves as a diagnostic device. You can turn the various items drawing electricity on (or off) individually and see what they actually draw. If you have a device pulling more than expected you may be able to isolate it and then trace down the problem - bad connection or whatever.


I hope this is helpful.

Craig

Edited by ckent323, 23 October 2022 - 10:00 PM.

[RallyRock]

Welcome to the cult,also.

I have had issues with the heater at times.

There are times it takes a few tries to get it to throw out the heat.

Sometimes it's just easier to run the stove for a few minutes.

Frank

This is the kind of cult I can get used to!  What impressed me was that I was in 30 degree weather recently and the insulation pad kept us nice and warm. No need for a furnace at all. When I was tenting it I was always either cold or too hot in the mummy bags when it got down to those temps. What an upgrade this is. 

[NRVhawk]

RallyRock,

 

Found the post by rando on the tradeoff between depth of discharge and battery lifetime.  It's post #217 in this thread:

 

https://www.wanderth...ime#entry171105

 

Unfortunately, it looks like the link to the graph that he posted illustrating the tradeoff is broken.   That whole thread has a lot of useful info, but it's long and can quickly lead you down a rabbit hole.

 

As you can read, rando was comfortable drawing down to 30% SOC because he concluded that the resulting decrease in battery life was acceptable to him.  Craig, on the other hand in the post above, recommends not going below 50% routinely.   When I used AGM batteries, I never went below 50% and usually not below 70%.  I was hoping to make my battery last as long as possible, so I was pretty conservative.  Not too difficult in my case because I didn't have a 12V fridge, so my only big current draw was the furnace. 

 

As it turned out, I replaced the AGM battery after 5 years of use, but not because of decreased performance.  Instead, I was tired of the unreliability of my 3-way fridge, so I put in a compressor fridge along with a lithium battery for more capacity (and lower weight).

 

- Rusty

[RallyRock]

If you find you have two GC type batteries & want to go to LiFePO4 batteries, Battleborn makes the 100 Ah batteries in the GC2 size.

I replaced my factory AGM GROUP 24 batteries with a pair of them and while it was a tight fit in my front dinette Hawk, they did fit.

 

It is nice to have 200 Ah to draw down rather than just effectively 75 Ah.

 

Paul

Ok so finally got into my battery compartment today. I’ve got two USAgm 2224 deep cycle 6 volts. 
 

https://www.usbatter...es/us-agm-2224/

 

Does this mean I’ve got 224 AHs of use available to me assuming I don’t go below 50% and I’m not charging the battery at all?

[RallyRock]

Thanks for the post ckent323.  I think it’s a good idea to invest in a battery monitor like you pointed out. It’s too bad that isn’t available from the factory, just seems like an option I would have picked right off the bat!  However, do not mind installing my own either and saving a few bucks;)

 

And thanks NRV, here I was thinking I’m going to ruin the battery but dropping below 50%. It’s reassuring to read. However, everybody really seems to like these LiFePO4 batteries so one day when it’s time to consider an upgrade I’ll give them a look!  Maybe something will come out that’s better by that time!

[RallyRock]

Also ckent323 appreciate the battery link. Already reading through just to understand this stuff more. 

[PaulT]

As 6 volt batteries, they are wired in series to get 12 volts at 224 Ah. If you read the referenced pdf file, you will see that you should discharge only to 50% meaning you have 112 Ah to use.

 

Paul

[Mighty Dodge Ram]

My comment about 6V GC batteries designed to be drawn down was not to suggest that you can “empty the bank”, but rather that these batteries are designed and built for longer and lower discharge compared to starting batteries. The 50% threshold is still good advice. Your typical 12v lead acid “deep cycle” batteries (most are marketed as marine) have anywhere from 90 to 120 amp hours, at least the ones I’ve seen. That gives you 45-60 useable ah. Your 6v GC batteries combined to make 12v give you approx 225 total ah, around 112 usable ah. Even though they’re much heavier and bulkier than one 12v unit, you’re way ahead of the game in terms of available power. And they’re typically serviceable which can increase the lifespan. I need to replace the GC batteries in my motorhome soon. My local Costco has them for $100/ea. I don’t service them at all, my bad. But I get 4-5 years of moderate use out of them which makes them a relative bargain.

 

All of those considerations make them a viable choice for your unit, especially if your camper originally came equipped with them. Get yourself a good battery monitor, as suggested, and then go ahead and use them with confidence. 

[RallyRock]

As 6 volt batteries, they are wired in series to get 12 volts at 224 Ah. If you read the referenced pdf file, you will see that you should discharge only to 50% meaning you have 112 Ah to use.

 

Paul

Ah ok got it thanks.