Help troubleshooting my 12v system please
- Thread starter Johnboyy
- Start date
I believe you are likely to cook batteries if you have any high amp charge source without a high draw (mismatched) but I am an amateur and not an Electrical Engineer. I have found that my 200w solar and Victron MPPT does a decent job of limiting power when not needed, some days only producing a few dozen watt-hours and other days producing a kWh or more, seemingly dependent more on driving than sun. However, I still top off water 3-4x per year, but I also live in a desert where 115+ F ambient temperatures are common, and my battery is an under hood starter. I would not buy a “sealed” battery. I also average 3.5 years life, which seems pretty typical around here, but I buy cheap batteries.
I’ve matched the Jeep and Trailer battery. When the Jeep battery fails, I move the trailer battery up, and put the new one in the trailer.
I’ve matched the Jeep and Trailer battery. When the Jeep battery fails, I move the trailer battery up, and put the new one in the trailer.
Joe917
Explorer
A charge controller set to the correct voltage profile will not cook batteries.
While using the same battery in the trailer and as a starter might seem like a good idea, you have two opposite battery needs, starter and deep cycle. No matter what the salesman says there is no lead acid battery that does both. Use the right battery for the intended use and it will last far longer.
What if they're both being charged together?
When my engine is running both batteries can be charged by the alternator, which is setup to charge a starter battery. But they will also both be charged by the solar. If I shut off the ignition on a sunny day both batteries will contine to be linked and hence charged by the solar.
I'm thinking of sticking with two starter batteries (identical ones this time too) so that they will be charged in the same way as each other.
Does that make sense for someone that doesnt have a DC-DC charger for battery seperation?
I've had no problems using a Deep-Cycle marine battery as a starting battery, even with V8 gas engines. Gear-drive starters generally aren't very demanding.
Deep-Cycle batteries have removable caps to check electrolyte levels, and handy little threaded posts to attach wires. I use the largest group size to fit the battery box(es).
Deep-Cycle batteries have removable caps to check electrolyte levels, and handy little threaded posts to attach wires. I use the largest group size to fit the battery box(es).
Joe917
Explorer
It is not the charging that will damage the trailer battery (although you will have to address the voltage drop)
Using a starter battery as a house battery, depleting it and not immediately recharging it will shorten it's life dramatically. Get a true deep cycle for the trailer, a pair of 6V golf cart batteries work well. In the case of a starter battery failure a deep cycle will get you started in all but the most demanding conditions.
Some slightly crossed wires there, I don't have a trailer (well I have two, but neither have batteries or anything else camping related). That was NatersXJ6.
Anyway hopefully my story is concluded. I got a smoking deal on a pair of Yuasa starter batteries with 3 year warranty. matched batteries so should hopefully maximise their survival being used inappropriately.
Also decided to upgrade from the super cheap pwm charger to a renogy mppt. I'm hoping that the fact that it has a temp sensor which is now stuck to the side of the house battery should reduce chances of cooking the new house battery.
Thanks for the help folks
Anyway hopefully my story is concluded. I got a smoking deal on a pair of Yuasa starter batteries with 3 year warranty. matched batteries so should hopefully maximise their survival being used inappropriately.
Also decided to upgrade from the super cheap pwm charger to a renogy mppt. I'm hoping that the fact that it has a temp sensor which is now stuck to the side of the house battery should reduce chances of cooking the new house battery.
Thanks for the help folks
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Joe917
Explorer
Matching your batteries will do nothing to extend their life. You only match batteries when they are part of the same bank. You have a starter battery and a house battery. Your house battery should be deep cycle for long life, a starter battery will not stand up to long slow deep discharges as well as a deep cycle.
Are they not one bank whenever the engine is running and they both being charged by the alternator?
I've not flattened the single battery in two years on house duty so I'm not expecting to be discharging this one too deeply either.
Joe917
Explorer
No. they are two separate "banks" although there is only one battery in each bank. When they are not being charged the house bank is being drawn down while the starter is untouched.
Two years is not very long. How much you use the system determines how robust it needs to be. A weekend warrior and a fulltimer have different expectations.
Two years is not very long. How much you use the system determines how robust it needs to be. A weekend warrior and a fulltimer have different expectations.
That's the thing, we'd be very light users.
The only things running for any significant time would be the cooler which mostly runs when it's sunny, or the fan that runs when it's sunny and overnight.
When we're camping we'd never go more than 18 hours with the engine off.
The only things running for any significant time would be the cooler which mostly runs when it's sunny, or the fan that runs when it's sunny and overnight.
When we're camping we'd never go more than 18 hours with the engine off.
DaveInDenver
Middle Income Semi-Redneck
Absolutely true that it's important batteries put into banks be closely matched in type, age, condition when you're discharging. This is basically mandatory if you want the batteries to last without accelerated aging.
Understand that batteries have different characteristics when they are the load consuming current from the charger than they do when they are the source producing current to loads, fridges, lights, engine starter.
When charging differences in batteries can be tolerated to some extent. That's not to say you have free reign to pair wildly different batteries in parallel. Just that if you have multiple batteries or banks of batteries that are only combined during charging then you have more flexibility.
Generally once a battery is charged it just sits waiting for something to change. It's static situation where it's consumed all the current it needed to reverse the chemical reactions and, once done, stops taking more current. It doesn't care what any other batteries might be doing. It just is done and sits basically quietly as long as the voltage is still high enough that it doesn't start to discharge either. This is the literal float state. It's neither significantly charging nor discharging, so it's just floating along.
I say generally here because we're assuming lead-acid and that chemistry works this way while other, notably lithium, chemistries are a bit different. Lithium chemistries may keep charging as long as the voltage is high enough, which is a problem since pushing more into the battery after 100% charged is turned to heat and that's a serious risk. But that's primarily why you have a BMS in them, which negates any discussion of parallel banks since the internal controller deals with it.
Even so you can't get around some things, like batteries that do not share compatible voltage thresholds for absorption and float can't practically be charged in parallel. Setting your charger for one type risks over- or undercharging other types in the parallel circuit.
This is something you might encounter trying to mix gel and AGM and flooded lead-acid. And using lithium with a BMS doesn't necessarily mean it's inputs are guaranteed compatible. You have to read the manuals and spec sheets for all the batteries to make sure their values work together.
Understand that batteries have different characteristics when they are the load consuming current from the charger than they do when they are the source producing current to loads, fridges, lights, engine starter.
When charging differences in batteries can be tolerated to some extent. That's not to say you have free reign to pair wildly different batteries in parallel. Just that if you have multiple batteries or banks of batteries that are only combined during charging then you have more flexibility.
Generally once a battery is charged it just sits waiting for something to change. It's static situation where it's consumed all the current it needed to reverse the chemical reactions and, once done, stops taking more current. It doesn't care what any other batteries might be doing. It just is done and sits basically quietly as long as the voltage is still high enough that it doesn't start to discharge either. This is the literal float state. It's neither significantly charging nor discharging, so it's just floating along.
I say generally here because we're assuming lead-acid and that chemistry works this way while other, notably lithium, chemistries are a bit different. Lithium chemistries may keep charging as long as the voltage is high enough, which is a problem since pushing more into the battery after 100% charged is turned to heat and that's a serious risk. But that's primarily why you have a BMS in them, which negates any discussion of parallel banks since the internal controller deals with it.
Even so you can't get around some things, like batteries that do not share compatible voltage thresholds for absorption and float can't practically be charged in parallel. Setting your charger for one type risks over- or undercharging other types in the parallel circuit.
This is something you might encounter trying to mix gel and AGM and flooded lead-acid. And using lithium with a BMS doesn't necessarily mean it's inputs are guaranteed compatible. You have to read the manuals and spec sheets for all the batteries to make sure their values work together.
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Just when I thought I was done with this.......
everything seems to be charging just fine. but the charge controller is flashing the load led with signifies a current overload whenever I try to use the pump or the cooler. it's a 20A controller and the pump and cooler are both on 5A fuses.
I know there's startup current on a motor but it has no problems with the fan starting. I thought maybe it was my connections or something this morning so I checked them and switched the output mode from manual to always on and it ran the cooler, lights and fan all at once for over an hour. thinking it must have been a dodgy connection I changed the output mode back to manual and it failed again. Thinking ok it's the output mode I put it back to always on but it's flaking out each time with an over current warning.
I've logged a case with Renogy but getting concerned now because we hit the road for the continent in 10 days. (I live in Ireland, going on a european trip this summer)
everything seems to be charging just fine. but the charge controller is flashing the load led with signifies a current overload whenever I try to use the pump or the cooler. it's a 20A controller and the pump and cooler are both on 5A fuses.
I know there's startup current on a motor but it has no problems with the fan starting. I thought maybe it was my connections or something this morning so I checked them and switched the output mode from manual to always on and it ran the cooler, lights and fan all at once for over an hour. thinking it must have been a dodgy connection I changed the output mode back to manual and it failed again. Thinking ok it's the output mode I put it back to always on but it's flaking out each time with an over current warning.
I've logged a case with Renogy but getting concerned now because we hit the road for the continent in 10 days. (I live in Ireland, going on a european trip this summer)