AGM can't handle Baja

[daveb]

You'll probably need more than a trickle charge to bring it back (if that's even possible). I'd think 12A for a few days at minimum. Just monitor the charge. If the charge tapers off quickly it could mean it's toast but you really needs to do a load test after the charge to see what it can hold. Then you can set to equalize the battery by following the battery manufactures instruction as a last resort. If the battery gets hot at any time, stop the charging session right away.


Highly recommend a good battery monitor so you're not in the dark about what's going on. Depth of discharge and the state of charge needs to be followed as best as possible. It also helps to know how much charge is actually getting into the battery when driving.



Always follow the manufacture instructions. Here is Lifeline's but the voltage points are usually similar to each other

[jonyjoe101]

I would highly recommend you get a 90 volt 30 amp combometer (you can find on ebay for 20 dollars) . You connect this between the controller and battery. This is a bright LED display that gives you battery voltage and amps going into battery. I been using these combo meter on my solar system for 8 years, you can see the important data in real time, the controllers blinking lights are useless for seeing if the battery is getting charged. You can leave these connected 24/7, I havent turned mine off in years. So at night time you can see if the battery is getting too low.
With a meter like this you will be able to find out quickly if the controller is fully charging the battery, on the picture it reads 14.1 volts and its charging at 4.7 amps, so its not fully charge yet. For lead acid it would have to reach 14.4 volts and stay there for a while (absorb).

Batteries that large need a good charge at high amps, high amps might even bring them back to full performance. Thats probably all they need a good charge and then monitor them daily to make sure they are reaching 14.4 volts during charging. If they are never reaching 14.4 volts then you have a problem.

As an example I have a 220ah lifepo4 (comparable to about 400ah lead acid) which I drained almost to zero percent about 2 summers ago running my swampcooler 24 hours a day on a hot week, the 240 watt solar panel wasnt keeping up with the swampcooler and 12 volt fridge. Little by little it went to zero percent and fridge stop working.
With the 240 watt panel and perfect sunshine it took over 2 weeks to get the battery back to 100 percent. Depending on your solar system it will probably take just as long (probably longer) to fully charge 400ah of lead acid. I since upgraded to a 365 watt panel and that can fully charge my 220ah battery in about 3 days. But with 365 watts the battery is always at 100 percent every day.

[b. rock]

Originally Posted by jonyjoe101

....
As an example I have a 220ah lifepo4 (comparable to about 400ah lead acid) which I drained almost to zero percent about 2 summers ago running my swampcooler 24 hours a day on a hot week, ....

Not to derail the thread, but any details on that swamp cooler?

[1der]

Sounds to me like one or both the connections to the battery terminals came loose or a disconnect master switch has failed or is switched off. Possible that the washboard caused the connections at the terminals, especially if tapered posts, to come off.

No voltage??, MPPT reads when panels are in the sun because there is voltage from the panels. MPPT should read from batteries when sun goes down, even for a 30 mins on a bad battery but does not. Implies no connection to battery this not charging the battery.

When you drop the battery take a voltage reading BEFORE charging. If you have voltage in the battery then your problem is elsewhere.

[jonyjoe101]

Not to derail the thread, but any details on that swamp cooler?

On this post I talk more about the swampcooler
https://vanlivingforum.com/threads/i...-cooler.40651/


During the tests I was doing I was running 2 swampcoolers and multiple fans due to the heat. And over a few days it drained my battery to about 10 percent were the voltage was too low to run the fridge compressor. A battery can drain quickly if your not keeping a close eye on the charging.
During the 2 weeks it took to recharge the battery back to 100 percent (with solar only) it took that long because I was still using minimal power. I was seriously considering getting a generator to charge the battery. After that happened I been watching my battery charging extremely close, and have kept my battery at 100 percent every night, the lowest its ever been in 2 years has been about 80 percent.

I always talk about voltage drop, because I encounter it so many times with 3 different solar controllers, they were all reading too high compared to what the actual battery terminal voltage was. The controllers reading high voltage (14.4 volts) consider the battery full and switch to float and trickle charge the batteries with 2 or 3 amps. If you do have voltage drop the only way to fix it is to raise the bulk voltage setting higher, until the battery terminals reach 14.4 volts. IF you have a .5 voltage drop you might have to raise it to 14.9 volts. I tried using larger gauge wire but that didnt work for me, I suspect the controllers are not calibrated properly.

[dokaman]

Unfortunately, I have seen more Renogy failures across the whole product line than any other brands I have used in the camper van world. I actually use one of their DC to DC chargers for a wheel chock at home.

Sorry for your issues and hopefully you find a good fix.

[palsing]

Originally Posted by jonyjoe101

I would highly recommend you get a 90 volt 30 amp combometer (you can find on ebay for 20 dollars) . You connect this between the controller and battery. This is a bright LED display that gives you battery voltage and amps going into battery. I been using these combo meter on my solar system for 8 years, you can see the important data in real time, the controllers blinking lights are useless for seeing if the battery is getting charged. You can leave these connected 24/7, I havent turned mine off in years. So at night time you can see if the battery is getting too low.
With a meter like this you will be able to find out quickly if the controller is fully charging the battery, on the picture it reads 14.1 volts and its charging at 4.7 amps, so its not fully charge yet. For lead acid it would have to reach 14.4 volts and stay there for a while (absorb).

How does this meter differ in function from my Victron BMV-712 battery monitor? Do I need both of them?

[Scalf77]

If you got the BMV-712 you would not need this other meter.

greg

[palsing]

Originally Posted by Scalf77

If you got the BMV-712 you would not need this other meter.

greg

Thanks Greg!

[jonyjoe101]

How does this meter differ in function from my Victron BMV-712 battery monitor? Do I need both of them?

The main difference is that it is bright and easily readable in the day from a distance. I also have an LCD meter (tk15) like the victron, but its not easily readable from a distance, I have to get up closed to see what its doing. The LCD I only check once in a long while, the LED I check constantly throughout the day and will find problems with the charging quickly. The combo meter has other functions like AH, percentage etc, but I never use those, I only have it for the bright display of volts/amps, thats its only purpose for me. I use the tk15 coulombmeter when I want to find the battery percentage/AH etc which I might check once a day.
During the day if I see the LED meter and its reading at least 14.1 volts or higher I know the system is charging (lifepo4) , if I was charging lead acid and it was reading 14.1 volts all day long charging at 2 or 3 amps (when the panel is capable of 10 amps output), I know I would have a problem.

The victron or tk15 coulombmeters are good for lifepo4 (which voltage remain constant during use and requires amp counting) and can also be used on a lead acid system that is new or batteries are good condition and have not lost too much capacity.

If I had to choose which is more important to me its the LED meter. Also its easy to install, since it only goes up to 30 amps no shunt is needed. If you need more than 30 amps, there are other LED volt/amp meters that can go up to 100 amps which are in the same price range but require shunts. I used both of them and would recommend either one as a good addition to a solar system.