Lwwilltravel
Senior Member
We have a 2008 2808 C and need batteries in the spring. we have 2 in there and want to replace them both. i am thinking Marine but unsure of what I should get. Any Suggestions?
batteries required
- Thread starter Lwwilltravel
- Start date
Yup, you need Marine/Deep Cycle (M/DC) batteries. These are different from the starting batteries you see in the engine compartment of a vehicle. The M/DC battery is designed to withstand a steady drain over a somewhat prolonged period before being recharged. A starting battery is designed for a short burst engine starting drain (generally very high current) and then it is immediately recharged by the car's alternator. But, neither battery wants to be deeply discharged. If you can keep the discharge level above 70%, it prolongs battery life.
In my opinion, there's no reason to get an expensive battery design such as AGM or Gel Sealed. A simple flooded lead acid battery will give you the best bang for your bucks. I always got Kirkland batteries from Costco before my recent switch to LiFePO4 batteries and was happy with them.
I'm also happy with my LiFePO4 setup, but it requires charging circuits that are designed for Lithium batteries, and that means a considerable up-front cost. My trailer's new converter is designed for Lithium batteries, as is my new solar controller, a house powered charger and a DC-DC converter that prevents excessive Amperage pull from my tow vehicle when traveling.
- Jack
In my opinion, there's no reason to get an expensive battery design such as AGM or Gel Sealed. A simple flooded lead acid battery will give you the best bang for your bucks. I always got Kirkland batteries from Costco before my recent switch to LiFePO4 batteries and was happy with them.
I'm also happy with my LiFePO4 setup, but it requires charging circuits that are designed for Lithium batteries, and that means a considerable up-front cost. My trailer's new converter is designed for Lithium batteries, as is my new solar controller, a house powered charger and a DC-DC converter that prevents excessive Amperage pull from my tow vehicle when traveling.
- Jack
sam-HILO
Senior Member
Battery, I have had several Intrerstate batteries over the course of owning four TT. One time we got a new one under warranty with no hassle.
Shaihulud2090
Advanced Member
Before I upgraded to LifePO4, I looked at several types of batteries. If you're settled on lead acid technology, Jack is right. Marine is the way to go. AGM is useful if you want to keep your battery in an unventilated compartment, but it's not needed since we have the battery box in the a-frame of the trailer. AGM can also be discharged more than your standard deep cycle. Steer clear of dual purpose batteries. They aren't true deep cycle batteries.
A novel approach to lead acid is using golf cart batteries. They're typically 6 volts so you'll have to wire two of them in series to get 12 volts, but they're designed to discharge and recharge frequently. Some people swear by them, though I don't know anyone personally.
However, LifePO4 batteries are cheap enough now that you may find it worth the investment. Lead acid has a short life in comparison to LifePO4 and cannot be discharged as deeply. It is recommended to discharge a lead acid no more than 50% while LifePO4 can typically be discharged 80% and some brands even lower.
For the a little more than the cost of two 100AH lead acid batteries, you can replace the factory power converter with a newer model capable of charging LifePO4 batteries and purchase an economical 100AH LifePO4. LifePO4s are stated to have a much longer life than lead acid batteries. Another advantage is you'll cut your battery weight by 2/3's since they're much lighter. My 100AH LifePO4 is about 25lbs, versus two 50lbs lead acid batteries. So, for me, it made sense to upgrade the trailer's stock power converter to a newer model and install a LifePO4.
If you upgrade to LifePO4, you're eventually going to run into posts about needing a DC-DC converter. I'm not sure it's "needed". Might be desireable. The typical concerns touted are: 1) It'll over work your alternator because a discharged LifePO4 will draw much more amperage due to lower resistence, 2) Because the alternator can't always provide the higher charge voltage the built in BMS will shutdown the battery, 3) the alternator will over charge the battery. I found none of this to be true. I have a smart gauge on my truck and I can see the voltage coming from the alternator. I never saw long periods of high voltage. My battery never shut itself down. As for potential of over charging, the battery's BMS module will keep that from happening. I went on a 5400 mile trip without a DC-DC charger and had no issues I can attribute to not having one. Whether my truck's alternator really charged the LifePO4 while mobile, IDK. If you're concerned about it, you can disconnect the pin on the 7 blade connector that provides auxillary power to the trailer.
A novel approach to lead acid is using golf cart batteries. They're typically 6 volts so you'll have to wire two of them in series to get 12 volts, but they're designed to discharge and recharge frequently. Some people swear by them, though I don't know anyone personally.
However, LifePO4 batteries are cheap enough now that you may find it worth the investment. Lead acid has a short life in comparison to LifePO4 and cannot be discharged as deeply. It is recommended to discharge a lead acid no more than 50% while LifePO4 can typically be discharged 80% and some brands even lower.
For the a little more than the cost of two 100AH lead acid batteries, you can replace the factory power converter with a newer model capable of charging LifePO4 batteries and purchase an economical 100AH LifePO4. LifePO4s are stated to have a much longer life than lead acid batteries. Another advantage is you'll cut your battery weight by 2/3's since they're much lighter. My 100AH LifePO4 is about 25lbs, versus two 50lbs lead acid batteries. So, for me, it made sense to upgrade the trailer's stock power converter to a newer model and install a LifePO4.
If you upgrade to LifePO4, you're eventually going to run into posts about needing a DC-DC converter. I'm not sure it's "needed". Might be desireable. The typical concerns touted are: 1) It'll over work your alternator because a discharged LifePO4 will draw much more amperage due to lower resistence, 2) Because the alternator can't always provide the higher charge voltage the built in BMS will shutdown the battery, 3) the alternator will over charge the battery. I found none of this to be true. I have a smart gauge on my truck and I can see the voltage coming from the alternator. I never saw long periods of high voltage. My battery never shut itself down. As for potential of over charging, the battery's BMS module will keep that from happening. I went on a 5400 mile trip without a DC-DC charger and had no issues I can attribute to not having one. Whether my truck's alternator really charged the LifePO4 while mobile, IDK. If you're concerned about it, you can disconnect the pin on the 7 blade connector that provides auxillary power to the trailer.
Interesting points about the DC-DC converter, Shaihulud, and you may well be right about not needing one. I was concerned because my truck (a hybrid), does not have an alternator, but charges its starting battery through it's own DC-DC converter from the High Voltage battery, and that charging algorithm is provided by the Power Control Module (PCM) in the truck. All those electronic gadgets are expensive and I didn't know how well they'd manage the unique requirements of the LiFePO4 batteries I put in my trailer. So, I simply installed a DC-DC (current limiting) converter in the tongue of the trailer. It cost in the neighborhood of $100 as I recall and seemed a reasonable bit of insurance.
Interestingly, I found the truck was not charging the batteries at all when underway. And, I'm pretty sure it's because the solar panels on the trailer roof are supplying a high enough charging voltage that the truck "sees" a fully charged battery. I have a 7-pin tester, and it shows the plug is putting out +12V at the charging pins when the truck is running. I MAY have set the voltage output of the DC-DC converter below that of the solar panel controller, which is set at 14.6V. However, my batteries stayed charged during travel, even powering the refrigerator, so I'm not going to try to "fix" it.
You're right about the cost of LiFePO4 batteries being low now. One of them will provide the electrical capacity of two lead-acid batteries, and they ARE much lighter. Because I subscribe to the philosophy of "more is better", I installed two LiFePO4 batteries in my trailer.
- Jack
Interestingly, I found the truck was not charging the batteries at all when underway. And, I'm pretty sure it's because the solar panels on the trailer roof are supplying a high enough charging voltage that the truck "sees" a fully charged battery. I have a 7-pin tester, and it shows the plug is putting out +12V at the charging pins when the truck is running. I MAY have set the voltage output of the DC-DC converter below that of the solar panel controller, which is set at 14.6V. However, my batteries stayed charged during travel, even powering the refrigerator, so I'm not going to try to "fix" it.
You're right about the cost of LiFePO4 batteries being low now. One of them will provide the electrical capacity of two lead-acid batteries, and they ARE much lighter. Because I subscribe to the philosophy of "more is better", I installed two LiFePO4 batteries in my trailer.
- Jack
Shaihulud2090
Advanced Member
I've been considering adding a second.
Lwwilltravel
Senior Member
thanks to both and will look into this type battery. I know the one battery last year at the end of the season my mechanic said it was dead and the other one about have or from me 1 foot in the grave. They was new in 2021 so only lasted 3 1/2 years . I keep the camper plugged in the garaage all the time and that may been part of the problem as I failed to check the water in them.
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