More Charging Current for FLA Batteries?

I've read a bit of Rolls info on equalizing and seems the obvious reason to equalize is when SG varies between cells, which mine do not, though probably worth trying. I bought these batteries from Sam's club so hoping I might be able to have them replaced.

Click to expand...

So SG is not a measure of capacity, just state of charge. It is possible to have a 'fully charged' battery that is still low on capacity because sulfation is covering a significant amount of surface area of the plates. An EQ attempt in that case would just be trying to break down / break off sulfation from the plates to get more Ah capacity out of the battery.

So it does have a purpose which is not JUST getting SGs to match. But you should ideally start from a fully charged battery before attempting EQ which is why i said "after fully charged (as verified by SG)," and Sunshine backed that up with his statement as well. In any case the EQ would come AFTER you've established that there is indeed a bunch of missing Ah capacity by doing some form of capacity test such as your 4a load comment. It's not something I'm pushing as the right/only course of action, just a likely next step to try to recover any lost capacity that resulted from the batteries existing in a less than fully charged state for so long due to charging issues from your converter/wiring.

hotcoldsummer said:

Yeah, or just hook them up to an automotive charger or use Solar to top them off over a couple days.

Reading that thread on these WFCO’s linked above, it seems they are more suited to basic 70amp hour lead acid batteries. I might eventually buy a 30amp Victron IP22 charger that I can use to charge and maintain with the battery disconnect switched off from the system. Plus, I’ll be set up for when I eventually make the jump to lithium.

Click to expand...

I hate to see a 55A charger go to waste.

hotcoldsummer said:

I also consulted my wiring schematic and realized the trailer chassis is used between the battery and converter to ground the system so there’s a lot of opportunities for resistance. Luckily, it’s just lights, small electronics and water pump on the WFCO so nothing pulling significant amps.

Click to expand...

So the Chassis is the (-) path from the converter to the battery? If so, that's very bad.

Vigo said:

So SG is not a measure of capacity, just state of charge. It is possible to have a 'fully charged' battery that is still low on capacity because sulfation is covering a significant amount of surface area of the plates. An EQ attempt in that case would just be trying to break down / break off sulfation from the plates to get more Ah capacity out of the battery.

So it does have a purpose which is not JUST getting SGs to match. But you should ideally start from a fully charged battery before attempting EQ which is why i said "after fully charged (as verified by SG)," and Sunshine backed that up with his statement as well. In any case the EQ would come AFTER you've established that there is indeed a bunch of missing Ah capacity by doing some form of capacity test such as your 4a load comment. It's not something I'm pushing as the right/only course of action, just a likely next step to try to recover any lost capacity that resulted from the batteries existing in a less than fully charged state for so long due to charging issues from your converter/wiring.

Click to expand...

Agreed. I think I'm going to buy a good Victron charger to get around any issues related to my power converter or resistance in the wiring. My plan is to make sure the batteries are as charged as they will get, then I'll re-test SG, then equalize, if necessary. Thanks for the help!

sunshine_eggo said:

I hate to see a 55A charger go to waste.



So the Chassis is the (-) path from the converter to the battery? If so, that's very bad.

Click to expand...

Yes, that appears to be the way it was wired from the factory. I crawled under to verify.

I did just test resistance on my multimeter after thoroughly cleaning the terminals and checking all the connections and I'm not showing any significant amount of resistance. Is there any reason this is bad aside from the resistance issues?

hotcoldsummer said:

Yes, that appears to be the way it was wired from the factory. I crawled under to verify.

I did just test resistance on my multimeter after thoroughly cleaning the terminals and checking all the connections and I'm not showing any significant amount of resistance. Is there any reason this is bad aside from the resistance issues?

Click to expand...

You must have resistance somewhere. It's clearly a problem, and it's going to remain a problem for any installed charger until you can deal with it. It's probably worth running a direct wire from the converter (-) to the battery (-).

The lowest amount of resistance most multimeters will show is ~0.2ohm, unless they have a zero'ing function in which case you could get it to read 0.0ohm, but in either case you are still measuring in tenths of ohms, not hundredths or thousandths.

It's an issue of scale. Batteries HAVE resistance, but it is TINY. If you think about a car battery that might be rated at 1000 cranking amps, ohm's law says 12.6v / 1000a = 0.0126 ohms. In other words, even if you hooked a battery to something with ZERO resistance (not possible), the only way you'd get 1000 amps to flow is if the battery itself had no more than 0.01ohm of resistance!

So with any battery circuit, the VAST MAJORITY of all the resistance of the circuit, is simply the wiring/conductors/connectors. That's why seemingly tiny changes in circuit resistance can result in huge changes in charging current, AND why a regular multimeter set to measure ohms is not very helpful in assessing what is good or bad. Making a tenth of an ohm difference on a circuit with a 100ohm 'load', would do practically nothing. Making a tenth of an ohm difference on a circuit where the 'load' (battery in this case) is in the hundredths or thousandths of an ohm, would give a huge result because that tenth of an ohm is a huge proportion of the total circuit resistance.

To get a good assessment of a resistance that tiny with a 'regular' multimeter, you need to make current flow in the circuit, and then measure voltage drop (aka difference) between both ends of the circuit, and do ohms law with those voltage and current numbers.

So just taking some numbers you posted and using them for sake of example, 13.7 - 13.35 = 0.35v 'drop'. 0.35v / 9amps you have seen (if these numbers were simultaneous or taken under identical conditions) would equal 0.038ohms. If you cut your voltage drop in half (aka cut your resistance in half) that would be .038ohms / 2 = 0.019ohms. That would be ~50% drop in the TOTAL resistance of the circuit, with a commensurate increase in charge current as the result. But also, if we reduce that 0.35v drop by half, that also means the charger is effectively 'pushing' ~0.17v harder! So you would get more of an increase then JUST the reduction in circuit resistance would have you think because doing so also increases the effective voltage differential you are working with to push current through the battery. So, huge increase in charge current by taking ~0.02ohms out of a circuit.

I would not say this is 'useful' math (too many approximations) except to build a mental framework of why things happen the way they do. You can improve your wiring, see no difference in ohms on a multimeter, yet get huge results. It's just that the scale of resistance that is determining these results, is much smaller than the layperson is used to thinking about, or a meter set to ohms will effectively measure.

Vigo said:

The lowest amount of resistance most multimeters will show is ~0.2ohm, unless they have a zero'ing function in which case you could get it to read 0.0ohm, but in either case you are still measuring in tenths of ohms, not hundredths or thousandths.

It's an issue of scale. Batteries HAVE resistance, but it is TINY. If you think about a car battery that might be rated at 1000 cranking amps, ohm's law says 12.6v / 1000a = 0.0126 ohms. In other words, even if you hooked a battery to something with ZERO resistance (not possible), the only way you'd get 1000 amps to flow is if the battery itself had no more than 0.01ohm of resistance!

So with any battery circuit, the VAST MAJORITY of all the resistance of the circuit, is simply the wiring/conductors/connectors. That's why seemingly tiny changes in circuit resistance can result in huge changes in charging current, AND why a regular multimeter set to measure ohms is not very helpful in assessing what is good or bad. Making a tenth of an ohm difference on a circuit with a 100ohm 'load', would do practically nothing. Making a tenth of an ohm difference on a circuit where the 'load' (battery in this case) is in the hundredths or thousandths of an ohm, would give a huge result because that tenth of an ohm is a huge proportion of the total circuit resistance.

To get a good assessment of a resistance that tiny with a 'regular' multimeter, you need to make current flow in the circuit, and then measure voltage drop (aka difference) between both ends of the circuit, and do ohms law with those voltage and current numbers.

So just taking some numbers you posted and using them for sake of example, 13.7 - 13.35 = 0.35v 'drop'. 0.35v / 9amps you have seen (if these numbers were simultaneous or taken under identical conditions) would equal 0.038ohms. If you cut your voltage drop in half (aka cut your resistance in half) that would be .038ohms / 2 = 0.019ohms. That would be ~50% drop in the TOTAL resistance of the circuit, with a commensurate increase in charge current as the result. But also, if we reduce that 0.35v drop by half, that also means the charger is effectively 'pushing' ~0.17v harder! So you would get more of an increase then JUST the reduction in circuit resistance would have you think because doing so also increases the effective voltage differential you are working with to push current through the battery. So, huge increase in charge current by taking ~0.02ohms out of a circuit.

I would not say this is 'useful' math (too many approximations) except to build a mental framework of why things happen the way they do. You can improve your wiring, see no difference in ohms on a multimeter, yet get huge results. It's just that the scale of resistance that is determining these results, is much smaller than the layperson is used to thinking about, or a meter set to ohms will effectively measure.

Click to expand...

sunshine_eggo said:

You must have resistance somewhere. It's clearly a problem, and it's going to remain a problem for any installed charger until you can deal with it. It's probably worth running a direct wire from the converter (-) to the battery (-).

Click to expand...

Great explanation. I figured it wouldn't be that simple, lol.

I re-tested for voltage drop between the battery box and the battery posts and after cleaning and tightening, I'm no longer showing any measurable drop. I'm currently charging on solar and getting 14.4v at both the MPPT and the battery.

When I install the new meter, I'm thinking I'll install it right next to the battery with 4 awg wire connected directly to the battery box. This will eliminate any resistance happening within the factory electrical system. I'll just flip the battery disconnect switch before plugging in the charger so its not getting confused from the power converter's voltage. I'll also replace the wiring within the battery box to 4awg.

Is that a good plan?

hotcoldsummer said:

Great explanation. I figured it wouldn't be that simple, lol.

I re-tested for voltage drop between the battery box and the battery posts and after cleaning and tightening, I'm no longer showing any measurable drop. I'm currently charging on solar and getting 14.4v at both the MPPT and the battery.

Click to expand...

You probably have a much better connection from the MPPT to the battery, and with only 100W available, you're likely not much over 7A at any time.

hotcoldsummer said:

When I install the new meter,

Click to expand...

Meter?

hotcoldsummer said:

I'm thinking I'll install it right next to the battery with 4 awg wire connected directly to the battery box. This will eliminate any resistance happening within the factory electrical system. I'll just flip the battery disconnect switch before plugging in the charger so its not getting confused from the power converter's voltage. I'll also replace the wiring within the battery box to 4awg.

Is that a good plan?

Click to expand...

Yep. 4awg sounds luscious.

I don't think the battery need to be cut off from the converter for any additional chargers. They can all work together.

Sorry, charger not meter.

Exactly, usually less than 7 amps parked in my driveway.

The victron charger will also do a proper equalization if it comes to that, once I charge and re-test.

Thanks again!

Your issue is common with the WFCO converters. They dont go into 14.4v mode. The only reason you are seeing a small 9amp charge, is because that is how many amps it takes for the converter to see 13.5v. If you drain your batteries further you will see a much higher amp charge. But i doubt you will see 14.4v from it. From the info in this thread maybe you have to really drain your batteries down low. More than the 50% drain we try to avoid getting passed.

Ive never seen my WFCO go into 14.4v mode, except when my batteries are disconnected. It happens every 3 or 5 days. Not at the exact hour. So pretend its something like every 40-50 hours. Do you by chance have a little USB port in the trailer that shows voltage? That will tell you what charging mode your converter is in. The USB voltage display (with no load) will tell you if/when you ever go to 14.4 mode. Mine sits at 13.5v with trailer plugged into shore power but batteries disconnected.

My advice would be to upgrade the battery and solar well before a new converter. Ive run it through my head for years because i have the same issue. When camping do you use a generator? If yes, then that is when you can benefit from a better converter/charger. Since you have solar, you dont really need the converter to go into 14.4v mode. Especially since you dont use much power.

In terms of equalizing you can use a 12v battery tender on the 6v battery. I use a 5a battery tender on a 210ah GC battery just like yours. Mine is the less desirable costco version. Like you, when they die im going lithium. Put the battery outside and loosen the caps. Make sure water is covering the plates. Monitor voltage. I forget exactly but its something like 8.0x volts at 70F. Your chart above must say. I think it might be 2.65v per cell from the trojan website.

Ive read there is a little device you can buy to help the WFCO converter go into 14.4v mode. I dont think its worth the money though. Some people claim the thin wire from converter to batt is to blame. Yes true, but the voltage drop is not enough in my opinion. The real issue is the factory setting, and the reason why aftermarket fix-it devices were sold years ago. My toyhauler is like yours. Chassis does the negative wire from battery to converter. I thought about investing in thicker wire, but then i remember when i go lithium i can move the batteries right next to the converter.

I also plan to invest in good Victron equipment. Just wanted to let you know your charger as it sits now will produce more than 9a if you drain your batteries further. It will never go into 14.4v mode and fully charge them is the major issue. Now that a lot of campers have solar that 14.4v problem gets solved. But......need to remember that flooded batteries like big strong charge amps. Your 100w of solar is not able to produce that. So for optimal battery life you would want to hit them with your converter when they are drained so that they see a nice big 30-50a charge.

Or if you feel comfortable to the hybrid style equalization charge with a battery tender. I have a super fancy charger and used to perform some crazy equalization charges where i adjust amps on the fly. When im lazy i just grab the 5a battery tender and hook it to a single 6v. Its an older version and just starts pumping about 4.8a according to my clamp meter.

wopachop said:

Your issue is common with the WFCO converters. They dont go into 14.4v mode. The only reason you are seeing a small 9amp charge, is because that is how many amps it takes for the converter to see 13.5v. If you drain your batteries further you will see a much higher amp charge. But i doubt you will see 14.4v from it. From the info in this thread maybe you have to really drain your batteries down low. More than the 50% drain we try to avoid getting passed.

Ive never seen my WFCO go into 14.4v mode, except when my batteries are disconnected. It happens every 3 or 5 days. Not at the exact hour. So pretend its something like every 40-50 hours. Do you by chance have a little USB port in the trailer that shows voltage? That will tell you what charging mode your converter is in. The USB voltage display (with no load) will tell you if/when you ever go to 14.4 mode. Mine sits at 13.5v with trailer plugged into shore power but batteries disconnected.

My advice would be to upgrade the battery and solar well before a new converter. Ive run it through my head for years because i have the same issue. When camping do you use a generator? If yes, then that is when you can benefit from a better converter/charger. Since you have solar, you dont really need the converter to go into 14.4v mode. Especially since you dont use much power.

In terms of equalizing you can use a 12v battery tender on the 6v battery. I use a 5a battery tender on a 210ah GC battery just like yours. Mine is the less desirable costco version. Like you, when they die im going lithium. Put the battery outside and loosen the caps. Make sure water is covering the plates. Monitor voltage. I forget exactly but its something like 8.0x volts at 70F. Your chart above must say. I think it might be 2.65v per cell from the trojan website.

Ive read there is a little device you can buy to help the WFCO converter go into 14.4v mode. I dont think its worth the money though. Some people claim the thin wire from converter to batt is to blame. Yes true, but the voltage drop is not enough in my opinion. The real issue is the factory setting, and the reason why aftermarket fix-it devices were sold years ago. My toyhauler is like yours. Chassis does the negative wire from battery to converter. I thought about investing in thicker wire, but then i remember when i go lithium i can move the batteries right next to the converter.

I also plan to invest in good Victron equipment. Just wanted to let you know your charger as it sits now will produce more than 9a if you drain your batteries further. It will never go into 14.4v mode and fully charge them is the major issue. Now that a lot of campers have solar that 14.4v problem gets solved. But......need to remember that flooded batteries like big strong charge amps. Your 100w of solar is not able to produce that. So for optimal battery life you would want to hit them with your converter when they are drained so that they see a nice big 30-50a charge.

Or if you feel comfortable to the hybrid style equalization charge with a battery tender. I have a super fancy charger and used to perform some crazy equalization charges where i adjust amps on the fly. When im lazy i just grab the 5a battery tender and hook it to a single 6v. Its an older version and just starts pumping about 4.8a according to my clamp meter.

Click to expand...

Yeah, there's a whole thread about these WFCO's never going to 14.4v here. I have a Victron Smartshunt that records voltage and don't recall ever seeing a voltage other than 13.6 or 13.7 but maybe I have resistance issues with the factory wiring.

I was gifted a 100/15 MPPT solar controller and 100w panel so I can only add another 100w panel before adding a second MPPT. If I go to lithium, the WFCO won't have sufficient voltage for charging anyway, so I'd rather spend $200 on a good Victron charger now than shell out for more solar or replace the WFCO.

hotcoldsummer said:

Yeah, there's a whole thread about these WFCO's never going to 14.4v here. I have a Victron Smartshunt that records voltage and don't recall ever seeing a voltage other than 13.6 or 13.7 but maybe I have resistance issues with the factory wiring.

I was gifted a 100/15 MPPT solar controller and 100w panel so I can only add another 100w panel before adding a second MPPT. If I go to lithium, the WFCO won't have sufficient voltage for charging anyway, so I'd rather spend $200 on a good Victron charger now than shell out for more solar or replace the WFCO.

Click to expand...

FWIW, you can over-panel the 100/15 and get 15A output for a longer period of time.


With a 15A input limit, you could easily put a 3S2P array of 100W 12V panels and get ~220W of charging most of the day.

Oddly enough, while still likely frustrating, the WFCO will do better with LFP than with lead acid given the documented behavior. Unlike lead acid, the vast majority of charging occurs below 13.8V. While you're still looking at extended charge times, they should be better than LFP due to lower resistance and the more efficient charging at lower voltages. Many choose to charge their LFP no higher than 13.8V to reduce stress and optimize cycle life.

sunshine_eggo said:

FWIW, you can over-panel the 100/15 and get 15A output for a longer period of time.

https://www.victronenergy.com/upload/documents/Datasheet-SmartSolar-charge-controller-MPPT-75-10,-75-15,-100-15,-100-20_48V-EN.pdf

With a 15A input limit, you could easily put a 3S2P array of 100W 12V panels and get ~220W of charging most of the day.

Oddly enough, while still likely frustrating, the WFCO will do better with LFP than with lead acid given the documented behavior. Unlike lead acid, the vast majority of charging occurs below 13.8V. While you're still looking at extended charge times, they should be better than LFP due to lower resistance and the more efficient charging at lower voltages. Many choose to charge their LFP no higher than 13.8V to reduce stress and optimize cycle life.

Click to expand...

Interesting! I assumed it wouldn't be safe to exceed 220w but just read this helpful doc about overpaneling and makes total sense.

My teardrop has a small curved roof so limited to 2 flexible panels but maybe I could add two more in a suitcase. Would it be ok to use the cheaper, non-flexible versions of the panel I have now? Specs are similar (see below).





MPPT Specs:
Max. PV open circuit voltage 100v
Nominal PV power, 12V 220w
Rated charge current 15a

My Panel: ​

HQST 100 Watt 12 Volt Waterproof Flexible Monocrystalline Solar Panel​

• Max Power at STC ( P max ): 100W
• Cell Efficiency: 22-23%
• Open-Circuit Voltage ( Voc ): 23.5V
• Optimum Operating Voltage ( Vmp ): 19.4V
• Optimum Operating Current ( Imp ): 5.2A
• Short-Circuit Current ( Isc ): 5.51A
• Operating Temperature: -40°F to 194°F
• Maximum Series Fuse Rating: 15A
• Max System Voltage: 600VDC ( UL )
• Weight: 5.3 lbs
• Dimensions: 43 x 23 x 0.8 in

Similar Suitcase Panel:

HQST 100 Watt 12 Volt Monocrystalline Solar Panel​

• Max Power at STC ( Pmax ): 100W
• Max System Voltage: 600VDC (UL)
• Optimum Operating Voltage (Vmp): 18.0 V
• Open-Circuit Voltage (Voc): 21.6V
• Optimum Operating Current (Imp): 5.56 A
• Short-Circuit Current (Isc): 6.5A
• Temp Coefficient of Pmax: -0.23%/ºC
• Temp Coefficient of Voc: -0.33%/ºC
• Temp Coefficient of Isc: 0.05%/ºC
• Weight: 13.2 lbs
• Dimensions: 32.5 x 26.4 x 1.18 in

hotcoldsummer said:

Interesting! I assumed it wouldn't be safe to exceed 220w but just read this helpful doc about overpaneling and makes total sense.

Click to expand...

Good doc.

Victron specific:


1) don't exceed Voc and allow temperature safety margin, and
2) don't exceed PV input current limits.

hotcoldsummer said:

My teardrop has a small curved roof so limited to 2 flexible panels but maybe I could add two more in a suitcase. Would it be ok to use the cheaper, non-flexible versions of the panel I have now? Specs are similar (see below).

Click to expand...

Worth noting that flexible panels mounted directly to a surface tend to run very hot, and it reduces their life.

hotcoldsummer said:

View attachment 167322


MPPT Specs:
Max. PV open circuit voltage 100v
Nominal PV power, 12V 220w
Rated charge current 15a

My Panel: ​

HQST 100 Watt 12 Volt Waterproof Flexible Monocrystalline Solar Panel​

• Max Power at STC ( P max ): 100W
• Cell Efficiency: 22-23%
• Open-Circuit Voltage ( Voc ): 23.5V
• Optimum Operating Voltage ( Vmp ): 19.4V
• Optimum Operating Current ( Imp ): 5.2A
• Short-Circuit Current ( Isc ): 5.51A
• Operating Temperature: -40°F to 194°F
• Maximum Series Fuse Rating: 15A
• Max System Voltage: 600VDC ( UL )
• Weight: 5.3 lbs
• Dimensions: 43 x 23 x 0.8 in

Similar Suitcase Panel:

HQST 100 Watt 12 Volt Monocrystalline Solar Panel​

• Max Power at STC ( Pmax ): 100W
• Max System Voltage: 600VDC (UL)
• Optimum Operating Voltage (Vmp): 18.0 V
• Open-Circuit Voltage (Voc): 21.6V
• Optimum Operating Current (Imp): 5.56 A
• Short-Circuit Current (Isc): 6.5A
• Temp Coefficient of Pmax: -0.23%/ºC
• Temp Coefficient of Voc: -0.33%/ºC
• Temp Coefficient of Isc: 0.05%/ºC
• Weight: 13.2 lbs
• Dimensions: 32.5 x 26.4 x 1.18 in

Click to expand...

Those two panels are close enough that they can be paralleled or in series with negligible penalty due to Vmp or Imp mismatch.

If you want to buy a good quality converter and wont have to eat ramen then go for it. But from what ive gathered in this thread you are focusing on the wrong problem. You kind of got tricked and dont realize yet that the converter is not as bad as you think.

Problem 1. WFCO doesnt go into 14.4v.
Since you have solar this problem somewhat gets solved. Check your solar controller manual to make sure its set for flooded batteries. You can get fully charged before a trip. During the trip im not sure a new Victron charger will change anything for your particular situation. Some campers are only allowed to run generators during certain hours. I remember reading about a guy who loved his new high power charger because he could pump a lot of juice in the small amount of charge time. If you are on shore power then a new charger wont help. Your high draw items like an electric heater or electric water heater will most likely be covered by the available 120v source. Or propane. Im trying to focus my trailer towards electric instead of propane. But wow how ive come to respect how much stored energy is inside a portable 5g propane tank!!

Problem 2. WFCO is only charging at 9a.
This is where you are getting tricked in a way. Its true a new converter will fix this problem, but is it a problem? There are thousands of trailers just like yours with people who dont have a clue their batteries are not fully charging. Because the silly WFCO only charges to 13.5v or whatever the exact number. Thin charge wire only makes it worse. Good news is the WFCO will push more power. Drain the batteries down lower. So that when the charge starts the batteries are still below 13v. You will most likely see a charge closer to 50 amps. Guessing you are using a clamp meter? Or maybe your battery monitor.

Its a trailer and you have solar to get you to 14.4v. I think it would be rare when you found yourself in a situation where your batteries were dead because the WFCO puts out 50a instead of a better charger at 100a. I agree not going to 14.4v is a problem. But you have that solved with solar. If i had a teardrop trailer i think i would put more focus towards stored battery power. I picture you out in the forest with tons of shade. Hiking in the rain. Would be cool to have peace of mind knowing you have a ton of battery powered stored. Dont need the sun or shore power or a genny. I think your GC batteries are new huh? Ok so screw that idea. I get the feeling you are going to take good care of them. One of the few guys who has tested SG.

If it was my trailer and brand new 6v i would probably figure out a way to do equalization. Maybe check your solar controller manual. Some do it automatically. Which to me would suck!!! What about all your other 12v items? Ive got a bunch of 12v Noctua fans that are already a very high RPM. Sending them 16v is just dumb. I hate when my trailer goes into 14.4v mode. Ive got unregulated LEDs. Its very bad for them to see 13.5v let alone 14.4v. To equalize you have a few options.

1. New high quality solar controller. Can add panels down the road. Will equalize hopefully i think 100w would be enough. Might look into a way to tilt the panel when the trailer is parked. I get 8a from a 150w panel flat on my roof when the sun is shining, and da weather is sweet. It honestly makes me want to move my dancing feet

2. Use a 12v car charger on a 6v single battery. Not safe and only a dum dum would do this. (waves) p.s. 5a is a good rough starting point. Takes hours to get to 8v if your batteries are healthy. If i remember right i think the last time i did that i never got to 8v.

3. Buy a new multi purpose charger that can do lithium, flooded, and most important has an equalization mode for 6v. Will come in handy down the road for cars or trailer batts.

One last thing dont be afraid to use those batteries. The trojan website had a graph that showed the capacity actually goes up during the first 100 cycles. Think about the majority of campers. They dont go camping for 100 days in the 6 or so years the batteries last. Kind of weird to think about. Best thing you can do is dont leave them on that solar float 24/7. Especially during summer temps. Also dont use solar for your main way to charge. The flooded batteries need a big strong charge to keep the plates happy.

Oh one other last thing. You want to disconnect the solar panel from the solar controller before you play around with the batteries. I didnt know that when i first got my trailer. I keep meaning to add a switch to the positive lead coming down from my panel. For the last 4 years ive just used a big blue wire nut and short piece of wire. I disconnect my solar panel from my 6v all the time because there is no need for it to get a 14.4v charge every morning if they are not being used. Even worse on hot summer days because my solar controller does not account for battery temp.

sunshine_eggo said:

Worth nothing that flexible panels mounted directly to a surface tend to run very hot, and it reduces their life.

Click to expand...

I know but it was the best option on the curved roof of the teardrop. Good news is I store it in a covered carport so it won't be subjected to daily doses of full sun.

Those two panels are close enough that they can be paralleled or in series with negligible penalty due to Vmp or Imp mismatch.

Click to expand...

Great!

After the second day of topping off the batteries with the MPPT, it completed the absorption phase and went into float. The SG is now higher, 1.250 up from 1.225, but still a little sub-optimal. I'll re-test tomorrow after the battery has rested 24hrs.

If the SG stays around 1.250, I guess it would be worth an equalization attempt, or an attempt to have Sam's club replace the batteries as they're under warranty (lol) but I imagine they aren't bad enough for them to read bad if they tested them in the store.

It would cost me about $360 to add three more 100w panels, 2S2P, with two on the roof and two in a suitcase on a 25' 8AWG extension. If I go that route, I may set it up so I can switch the roof-mounted panels to parallel when I'm not using the suitcase, as its a curved roof so the two panels would be on different angles and in series, the one getting less sun would always drag down the other's performance.

Or , $350 I could get one additional panel for the roof and an IP22 20 amp charger that will also do a proper equalization. I guess with the added panels and a sunny day I could equalize with the MPPT but I'd rather pull the batteries out of the camper and monitor them throughout the EQ charge.

Either way, I'd like to have a good charger that will recharge the batteries on an overnight at a campsite with hookups or in my carport, so I don't have to move the panels into the sun every time I want to fully recharge.

hotcoldsummer said:

After the second day of topping off the batteries with the MPPT, it completed the absorption phase and went into float. The SG is now higher, 1.250 up from 1.225, but still a little sub-optimal. I'll re-test tomorrow after the battery has rested 24hrs.

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1.250 is normal for some batteries. It's also an indication that they are not heavily sulfated.

hotcoldsummer said:

If the SG stays around 1.250, I guess it would be worth an equalization attempt, or an attempt to have Sam's club replace the batteries as they're under warranty (lol) but I imagine they aren't bad enough for them to read bad if they tested them in the store.

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You'd have to jump up and down screaming to get Sam's Club or anyone else to warranty batteries at 1.250.

hotcoldsummer said:

It would cost me about $360 to add three more 100w panels, 2S2P, with two on the roof and two in a suitcase on a 25' 8AWG extension. If I go that route, I may set it up so I can switch the roof-mounted panels to parallel when I'm not using the suitcase, as its a curved roof so the two panels would be on different angles and in series, the one getting less sun would always drag down the other's performance.

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Consider that flexible panels on a curved surface are their own worst enemy. The cells themselves all have different facings, so series vs parallel may not matter significantly.

hotcoldsummer said:

Or , $350 I could get one additional panel for the roof and an IP22 20 amp charger that will also do a proper equalization. I guess with the added panels and a sunny day I could equalize with the MPPT but I'd rather pull the batteries out of the camper and monitor them throughout the EQ charge.

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I'd go for this option... or get a Powermax PM3-??LK and mount it near the battery with short cables. Can operate as a 14.4/13.6/13.2 converter, OR you can set it for constant voltage. Both the 3 phase bulk and constant voltage levels are set with a pot. I know I've been able to set mine to over 16.2V - typical high end for EQ cycles.

I wonder how much capacity you would be losing in the campground situation. The battery will definitely take a charge. Just wont be to 100%.
At some point i will pull out my fancy charger and do a test. Let my WFCO do its normal charge to 13.5v. Then hook up my other charger and see how many amp hours it takes going from 13.5v to a proper 14.4v charge.

I did half the test. Was worse than i thought. Could be due to my batteries being from 02/19. Let the WFCO do its thing with my solar disconnected. It stuck around a 10a charge for awhile. Battery voltage at the batteries 13.36v. Checked it a few hours later and still taking 6amps. Let it sit overnight and was taking 0.86amps and voltage was up at 13.67v. My converter is a pain to reach so i didnt test output at the converter. I always thought it put out 13.5v so not sure how my batteries were at 13.67v.
Tested SG and it was down at 1.180-1.200 which the Trojan website says is 60% charge. Wow that is much lower than i expected!! I wonder what the OPs new batteries would test at after floating for a day or 2 at 13.5v?