Charging problems

[KYoung7434]

I have a 2006 Attitude 25 AK (purchased used) 30 amp system I recently replaced the original converter charger with an Iota 45 amp and installed two 100 AH AGM batteries I also installed a battery monitor. All this thinking I would get higher amperage going to the batteries when they were low which did occur for a very short time 22 amps then nothing. After my solar brought the batteries up some the system showed 6-8 amp charging. I suffered thru the winter months then decided to upgrade. I purchased 2 100 ah lithium batteries (not Battle Born too expensive)and replaced the converter charger with Progressive Dynamics 30 amp lithium converter charger and wouldn't you know it had the same problem intermittent charging usually with lower amperage. All 12v and 110v systems work fine with shore power, generator , and 12v when others are unplugged or shut down. Anyone have any ideas as to the cause ??

 

[Gary RV_Wizard]

Do you understand that the charger is limited by the battery's ability to accept current (amps)? When the battery charge state is low the charger may be able to deliver near its rated amperage, but as the charge stored in the battery increases, the rate of charge (amp rate) decreases. The exact rate at any point is determined by the charge profile (how much voltage is applied), but it's seldom the max rated amperage. It differs for lead-acid vs LiFePO4 and even for the subtypes within lead-acid, but not by a huge amount. This article may be instructive.

Could you please explain in more detail the "22 amps then nothing" comment? How long at what amps and what was the state of charge at that point. And does "nothing" mean the amps went to zero or ???

 

[JayArr]

First thing I would suspect is the battery monitor.

EDIT: Gary has a good point. Do you understand how a three or four stage charging system works? Do you know the difference between constant current and constant voltage charging? The difference between bulk, maintenance and float charges?

Maybe you just need to do some reading so you know what to expect?

 

[CharlesinGA]

I agree with suspecting the battery monitor. Also, if the original cables were reused, they were probably marginal (8 gauge probably) and especially with lithium, this will restrict the charging. However, same results with two different converters and battery setups points to the monitor. What monitor is it? Does it need to be set up with certain parameters before using?

Charles

 

[KYoung7434]

Do you understand that the charger is limited by the battery's ability to accept current (amps)? When the battery charge state is low the charger may be able to deliver near its rated amperage, but as the charge stored in the battery increases, the rate of charge (amp rate) decreases. The exact rate at any point is determined by the charge profile (how much voltage is applied), but it's seldom the max rated amperage. It differs for lead-acid vs LiFePO4 and even for the subtypes within lead-acid, but not by a huge amount. This article may be instructive.

Could you please explain in more detail the "22 amps then nothing" comment? How long at what amps and what was the state of charge at that point. And does "nothing" mean the amps went to zero or ???

Gary thanks for your interest when the batteries were showing 60% charged and I pluged into shore power the battery monitor showed 22 amps going into battery within a minute or two it went to negative 1.4 to 2.0 amps. I checked all connections, used a multimeter which showed 14.5 volts from converter charger to fuse panel and 14.5 volts leaving the fuse panel. Left shore power on all night and battery voltage actually went down. After a full day of sun on solar batteries were at 80% plugged into shore power the monitor showed 7.5 to 8 amps going into the battery and decreased slowly as the battery finished charging.

 

[JayArr]

used a multimeter which showed 14.5 volts from converter charger to fuse panel and 14.5 volts leaving the fuse panel. Left shore power on all night and battery voltage actually went down.

It could be a bad connection somewhere between the converter and battery that heats up as the 22Amps is going through it and then it opens up and the current (and the charging) stop. A splice? A bad fuse?

Try this:

Connect a multimeter directly to the battery terminals. When the monitor switches from 22 amps to -1.5-2.0Amps see if the voltage at the battery is still 14.5V.

I suspect it won't be, it'll be back down to battery voltage of 13.6 or so.

If that's the case you need to follow the battery cables from the converter to the batteries or run new ones. If there is no negative battery cable and the manufacturer used the chassis as ground then check the connections to the frame at the battery box and at the converter. A problem ground point can sometimes be found by the fact that it gets really warm. Wear a glove before touching it.

 

[HikerBob]

I had charging problems once. It was the solenoid

 

[Gary RV_Wizard]

when the batteries were showing 60% charged and I pluged into shore power the battery monitor showed 22 amps going into battery within a minute or two it went to negative 1.4 to 2.0 amps. I checked all connections, used a multimeter which showed 14.5 volts from converter charger to fuse panel and 14.5 volts leaving the fuse panel.

Either your monitor panel is whacky or there is a mistake in the measurements because it is physically impossible to have negative amps (battery is discharging) at the same time the charger is applying more than 12.6v to the battery terminals. Current (amps) must flow into the battery when the externally applied voltage exceeds the battery voltage.

Measuring voltage at the fuse panel doesn't tell anything about battery charging - that has to be measured at the battery terminals. However, it does show that the converter/charger is producing adequate voltage to provide charging.

Look at the wiring between charger and battery and also between the monitor and both charger & battery. Something is cutting out, stopping the flow of amps. A sketch or photo of the wiring would enable us toe make some guesses about what is happening.

 

[Kirk]

Look at the wiring between charger and battery and also between the monitor and both charger & battery.

And double check everything to be sure that it is properly installed. In my 40 years of electrical work I learned the hard way that everyone makes an occasional mistake.

 

[JayArr]

I assumed that the -1.5 to -2.0 Amps was just an error on the battery monitor from not being zeroed.