Back in issue 29, we wrote about the latest technology in 12-volt batteries, Lithium Iron Phosphate or LiFePO4. In this feature, we look at what it is actually like to live with lithium batteries in the real world and how they compare with their lead acid ancestors.
THE DOWNSIDE OF LEAD ACID
In our case, we have a Roadstar Safari Tamer off-road caravan that was designed to be completely self-sufficient so we could free camp away from mains power for extended periods of time. To that end we had a 12-volt system that was based on two 120Ah Fullriver AGM batteries. Now anyone familiar with the 12V RV scene will know that Fullriver batteries are among the best you can buy. We were, for the most part, very happy with them, but like all lead acid batteries, they had a number of flaws.
First and foremost is the weight of these things. Each battery weighed in excess of 40kg. That’s over 80kg in batteries alone. In the battle to keep our caravan weight down, this was a big issue.
The second problem with lead acid batteries is they don’t like being discharged to below 40 percent state of charge. In other words, even though we had 240Ah of battery capacity, we could only use 140Ah before we started to damage the batteries.
THE LOWDOWN ON LITHIUM
Lithium batteries overcome both these issues. For a start they are much lighter. The 200Ah Pro Power lithium batteries we replaced our AGMs with weigh just 35kg. Immediately we saved 45kg. The second advantage lithium batteries have is they can be discharged to much lower levels without sustaining any damage to the cells. Pro Power recommends not to discharge them below 10 percent state of charge. In other words, you can run your caravan or camper electronics for longer between recharges for the equivalent amp hour rating.
If there are any disadvantages to lithium batteries, apart from the cost, it is that they do not like to be charged at higher than 13.8 volts. Lead acid batteries can cope with charge voltages as high as 14.3 volts. In the past this would have necessitated changing both the 240 mains charger and the solar charger to ones that have a lithium charging profile. Pro Power batteries get around this problem by having inbuilt battery management systems that limit the charge voltages regardless of the source charger. That said, it is still preferable to have a charger that can either have the maximum charge voltage limited to 13.8V or has a lithium charge profile.
We decided to fit a Redarc BMS1230 Battery Manager as part of our conversion. This was a wise move. It not only has a specific lithium charge setting but it also manages the 240V mains, 12V and solar charge sources to ensure our battery has the most efficient and effective charge regardless of the conditions. It’s an excellent system that is well worth the money regardless of what sort of batteries you have.
In use, the Pro Power lithium battery behaves exactly the same as the previous AGM batteries it replaced. Our fridge runs exactly as it did as do all our 12V appliances. We don’t discharge any slower or faster but we are not constantly monitoring the state of charge to ensure we don’t go below 40 percent. Whatever power we use overnight is quickly recharged the next day.
One difference we have noticed is that we get back to 100 percent state of charge much faster than the previous AGMs. Lead acid batteries recharge to 80-90 percent in reasonable time but that last 10 percent can take a long time depending on the charger. The other difference we’ve noticed is that the lithium battery sustains higher voltages for much longer.
Fully charged, our Pro Power battery measures at 13.3 volts. After running our compressor fridge and my CPAP machine overnight as well as recharging our phones and tablets, the voltage reading is still around 12.9 volts at 65 percent state of charge. It means there is no degradation in performance of any of our devices. Our lights stay bright, our fridge stays cold and our water pressure from our pumps stays strong.
If you ask me if lithium batteries are worth the extra expense, I would say a resounding yes. After six months living full-time on the road in our caravan, doing a lot of remote outback free camping, the Pro Power battery is living up to all expectations. And with a three-year warranty, we expect that to last for many years to come.