Battery setup help

[EmpirE231]

Okay here is what fullriver wants for a charge profile

Which according to fullriver... a magnum inverter should be set to AGM 2 battery type (which both currently are)

from what I have read, each charger is capable of charging @ 100 amps. 



per the fullriver manual... total charging current can be:

All Models (excl. FSG): The recommended bulk current is 20-25% of the 20 Hr AH capacity or 0.20 x C20 (20 Hr. capacity in AH). The maximum allowable bulk current is 35% of the 20 Hr. AH capacity or 0.35 x C20 (20Hr. capacity in AH), unless specified.

So.... I have a total of 896 AH (if I did my math right), so according to their formula... I can push 180 amps to 224 amps 

and then what they recommend for absorption time is:

Absorption time varies per installation according to total bank size and total PV kW. Our maximum absorption time is 4 hours, however most installations need 2-3 hours on average. To estimate your rough absorption time, use the following formula: [(AH * DOD) / CHARGE AMPS * 0.85]

I have no idea what DOD means in that formula... so maybe someone can help there.  But currently both chargers were set at 3.5Hr absorption time... and they were set at 80%, most likely meaning only 80 amps per charger.... and the other thing to keep in mind, is both of those going while plugged into a regular 15amp outlet were tripping breakers.... so I have no idea if this was all the proper setting to get these batteries to 100% charge level.

with all this info given... what should my charge amps and absorption time be set at? and keep in mind there are 2 chargers... so do I split it between the two?

first thing I need to figure out before deciding if the batteries are bad, is if these are even being charged to 100%

 

[Lord of the Dunes]

Okay here is what fullriver wants for a charge profile

Which according to fullriver... a magnum inverter should be set to AGM 2 battery type (which both currently are)

from what I have read, each charger is capable of charging @ 100 amps. 

View attachment 21656

per the fullriver manual... total charging current can be:

All Models (excl. FSG): The recommended bulk current is 20-25% of the 20 Hr AH capacity or 0.20 x C20 (20 Hr. capacity in AH). The maximum allowable bulk current is 35% of the 20 Hr. AH capacity or 0.35 x C20 (20Hr. capacity in AH), unless specified.

So.... I have a total of 896 AH (if I did my math right), so according to their formula... I can push 180 amps to 224 amps 

and then what they recommend for absorption time is:

Absorption time varies per installation according to total bank size and total PV kW. Our maximum absorption time is 4 hours, however most installations need 2-3 hours on average. To estimate your rough absorption time, use the following formula: [(AH * DOD) / CHARGE AMPS * 0.85]

I have no idea what DOD means in that formula... so maybe someone can help there.  But currently both chargers were set at 3.5Hr absorption time... and they were set at 80%, most likely meaning only 80 amps per charger.... and the other thing to keep in mind, is both of those going while plugged into a regular 15amp outlet were tripping breakers.... so I have no idea if this was all the proper setting to get these batteries to 100% charge level.

with all this info given... what should my charge amps and absorption time be set at? and keep in mind there are 2 chargers... so do I split it between the two?

first thing I need to figure out before deciding if the batteries are bad, is if these are even being charged to 100%

DoD means Depth of Discharge, which is expressed as a percentage, like 80% DoD or 50% DoD. With both chargers set at 80%, you are correct, they could each provide 80A, if you were plugged into an outlet that could provide over 20A. You could just run 1 charger like you have, it would just take twice as long plugged into a 15A outlet as it would with both charging while plugged into a 30A outlet.

If the batteries reach 14.7V, the assumption is they are fully charged. Again, if you use an IR thermometer, you'll be able to see if any batteries are shorted or open. If none of them are open or shorted, then they are working to their capacity, which might not be anywhere near their rated cap. Even when new, they never produced the rated cap., they could be seriously degraded now.

The only way to tell for sure how many watts you put into them and how many watts they put out is to connect a Battery Monitoring System, which measures everything using a shunt. The Victron smartshunt I mentioned above is the best, especially for the money.

 

[r3meyer]

You have no idea what condition these batteries are in so it could be any number of issues.  I could never get more then 2-3 out of AMG or FLA and I kept them in perfect shape.  They just suck.

I would do a capacity test so you can tell what type of AH you have available and decide if its livable.  After that I would take them to the nearest recycler and get a minimum of (2) 300 LiFePo4 setups.  You can use every bit of the AH they provide.

600AH fits in the space of (4) 6V's.

 

[Dockmaster]

Okay here is what fullriver wants for a charge profile

Which according to fullriver... a magnum inverter should be set to AGM 2 battery type (which both currently are)

from what I have read, each charger is capable of charging @ 100 amps. 

View attachment 21656

per the fullriver manual... total charging current can be:

All Models (excl. FSG): The recommended bulk current is 20-25% of the 20 Hr AH capacity or 0.20 x C20 (20 Hr. capacity in AH). The maximum allowable bulk current is 35% of the 20 Hr. AH capacity or 0.35 x C20 (20Hr. capacity in AH), unless specified.

So.... I have a total of 896 AH (if I did my math right), so according to their formula... I can push 180 amps to 224 amps 

and then what they recommend for absorption time is:

Absorption time varies per installation according to total bank size and total PV kW. Our maximum absorption time is 4 hours, however most installations need 2-3 hours on average. To estimate your rough absorption time, use the following formula: [(AH * DOD) / CHARGE AMPS * 0.85]

I have no idea what DOD means in that formula... so maybe someone can help there.  But currently both chargers were set at 3.5Hr absorption time... and they were set at 80%, most likely meaning only 80 amps per charger.... and the other thing to keep in mind, is both of those going while plugged into a regular 15amp outlet were tripping breakers.... so I have no idea if this was all the proper setting to get these batteries to 100% charge level.

with all this info given... what should my charge amps and absorption time be set at? and keep in mind there are 2 chargers... so do I split it between the two?

first thing I need to figure out before deciding if the batteries are bad, is if these are even being charged to 100%

Do you have the Magnum remote panels? Once plugged in you should be able to see the chargers kick on and what amperage they are charging at. I have 24 (ea) Full River AGM batteries in my off grid cabin and they have been great. To really know what you have you need to disconnect each battery and do a load test on it as others have said. 

 

[EmpirE231]

DoD means Depth of Discharge, which is expressed as a percentage, like 80% DoD or 50% DoD. With both chargers set at 80%, you are correct, they could each provide 80A, if you were plugged into an outlet that could provide over 20A. You could just run 1 charger like you have, it would just take twice as long plugged into a 15A outlet as it would with both charging while plugged into a 30A outlet.

If the batteries reach 14.7V, the assumption is they are fully charged. Again, if you use an IR thermometer, you'll be able to see if any batteries are shorted or open. If none of them are open or shorted, then they are working to their capacity, which might not be anywhere near their rated cap. Even when new, they never produced the rated cap., they could be seriously degraded now.

The only way to tell for sure how many watts you put into them and how many watts they put out is to connect a Battery Monitoring System, which measures everything using a shunt. The Victron smartshunt I mentioned above is the best, especially for the money.

Got it... so based off that formula, and for proper charging... should I change the charge % to 100% on each charger... so that way I’m charging at 200 amps? 
 

and then how many hours absorption time? Fullriver says max 4 hours... so would 4 hours at 200 amps get this bank fully charged? Or would I be over charging at that point? 

 

[EmpirE231]

You have no idea what condition these batteries are in so it could be any number of issues.  I could never get more then 2-3 out of AMG or FLA and I kept them in perfect shape.  They just suck.

I would do a capacity test so you can tell what type of AH you have available and decide if its livable.  After that I would take them to the nearest recycler and get a minimum of (2) 300 LiFePo4 setups.  You can use every bit of the AH they provide.

600AH fits in the space of (4) 6V's.

View attachment 21658

View attachment 21659

How do you do an AH test?

 

[Lord of the Dunes]

Got it... so based off that formula, and for proper charging... should I change the charge % to 100% on each charger... so that way I’m charging at 200 amps? 
 

and then how many hours absorption time? Fullriver says max 4 hours... so would 4 hours at 200 amps get this bank fully charged? Or would I be over charging at that point? 

I would leave the chargers at 80%, that is plenty of power from 2 of them. Keep in mind, the batteries control the charge rate. As they approach fully charged, their voltage and internal resistance will decrease the current consumed - you'll see the amps slowly tapering down to just a couple of amps at 14.7V when fully charged. The charger doesn't force 80A into the batteries, the charger can provide up to 80A, but the batteries will take however much they want, tapering down until fully charged.

Mathematically, if you discharged the batteries down to 50%, that's 450Ah you need to put back in. AGM batteries (any lead-acid battery) loses something like 20% in recharging, so your total current it would take to fully charge the batteries from 50% would be 540A. Since the batteries taper down near the end, it's not a straight 160A/hr you can put into them. The bulk charge will get them to 80%  charged, 4 hrs of absorption will probably get them to as fully charged as they're going to get.

You really need a BMS to see what's going on, it's like a dyno for your engine, it tells you what's really coming in/out of those batteries.

 

[EmpirE231]

Thank you all for the feedback so far! I am going to move the RV to a spot where I can plug it into a 20 amp  outlet and try to let both chargers run to get these batteries fully topped off.... and then I will turn off all inverters etc... to make sure the batteries aren't having any draw, then check the voltage a day later just to see what they are getting down to.

I really would like the lithium ion setup... but as of now, I am hoping this system just hasn't been fully charged and is salvageable... or at least covered by a warranty somehow to limit the $ bleed FML

 

[wopachop]

get these batteries fully topped off.... and then I will turn off all inverters etc... to make sure the batteries aren't having any draw, then check the voltage a day later just to see what they are getting down to.

Get yourself a clamp meter. I have one of the Uni-T models and its ok. Sometimes battery voltage can give you bad information. Lets say you have a dead battery. Toss it on a battery tender and wow...the light is solid green and battery shows 12.7ish volts. That does not mean the battery absorbed energy and is now "charged". Dead batteries will trick people like that a lot. Might even seem like that battery charged up quickly and must be healthy. Its the opposite. The battery is so unhealthy that it cant even absorb energy without the voltage spiking and the charger shutting down, thinking the charge is complete.

These are easy to use. All you do is clamp the jaws around a wire and it tells you how many amps are flowing through. No risk of shock you never need to touch a bare wire. Just saw a $15 version at harbor freight yesterday. I see the Uni-T version i have in the link its $49. I consider it OK. (UT210E) I tested its accuracy down to 0.00 amps and was pleased. Its nice to be accurate testing a DC light bulb at 0.23a for example and then also seeing 40a of AC power with the same tool. 

No matter the brand get one that lets you click a button to Zero out the screen. When you get the meter close to a wire it will falsely show a number. You click zero, and then clamp the wire. Ends up giving a really accurate reading. Thats perfect for chasing down a small ghost draw on a trailer, car, anything. 

https://www.amazon.com/s?k=true+rms+clamp+meter&crid=1KQ0B0ZMD3OM5&sprefix=true+rms+clamp%2Caps%2C182&ref=nb_sb_ss_ts-doa-p_1_14

 

[Lord of the Dunes]

Here is the reality of this situation. Let's say you have 1 or 2 bad batteries and you identify which ones they are. What's next? You can't just replace 2 of them, if the rest of them are 2 yrs old, you're throwing good money after bad. You have to replace the entire bank. If they are 2 yrs old, I doubt they're still under warranty - if they are, it's probably pro-rated and won't offset much of the cost of an entirely new set of batteries.

For about what those cost new, possibly less, you could get 800Ah of LFP batteries for less than $3000. That would save a lot of weight and a lot of space and give you a battery bank superior in every way. Negligible self discharge, higher efficiency, much less voltage sag under high load, higher cap. under high load, 640Ah of usable power vs 450Ah, 15 yrs or more lifetime, etc. 

 

[EmpirE231]

Get yourself a clamp meter. I have one of the Uni-T models and its ok. Sometimes battery voltage can give you bad information. Lets say you have a dead battery. Toss it on a battery tender and wow...the light is solid green and battery shows 12.7ish volts. That does not mean the battery absorbed energy and is now "charged". Dead batteries will trick people like that a lot. Might even seem like that battery charged up quickly and must be healthy. Its the opposite. The battery is so unhealthy that it cant even absorb energy without the voltage spiking and the charger shutting down, thinking the charge is complete.

These are easy to use. All you do is clamp the jaws around a wire and it tells you how many amps are flowing through. No risk of shock you never need to touch a bare wire. Just saw a $15 version at harbor freight yesterday. I see the Uni-T version i have in the link its $49. I consider it OK. (UT210E) I tested its accuracy down to 0.00 amps and was pleased. Its nice to be accurate testing a DC light bulb at 0.23a for example and then also seeing 40a of AC power with the same tool. 

No matter the brand get one that lets you click a button to Zero out the screen. When you get the meter close to a wire it will falsely show a number. You click zero, and then clamp the wire. Ends up giving a really accurate reading. Thats perfect for chasing down a small ghost draw on a trailer, car, anything. 

https://www.amazon.com/s?k=true+rms+clamp+meter&crid=1KQ0B0ZMD3OM5&sprefix=true+rms+clamp%2Caps%2C182&ref=nb_sb_ss_ts-doa-p_1_14

I have one of these... but how would I use that to test my batteries? I've been using it to get the voltage readings 

 

[EmpirE231]

Here is the reality of this situation. Let's say you have 1 or 2 bad batteries and you identify which ones they are. What's next? You can't just replace 2 of them, if the rest of them are 2 yrs old, you're throwing good money after bad. You have to replace the entire bank. If they are 2 yrs old, I doubt they're still under warranty - if they are, it's probably pro-rated and won't offset much of the cost of an entirely new set of batteries.

For about what those cost new, possibly less, you could get 800Ah of LFP batteries for less than $3000. That would save a lot of weight and a lot of space and give you a battery bank superior in every way. Negligible self discharge, higher efficiency, much less voltage sag under high load, higher cap. under high load, 640Ah of usable power vs 450Ah, 15 yrs or more lifetime, etc. 

For me, I am just not sure if I am keeping this RV long term (2+ years) so I really don't want to invest 3k into LI setup.  If this was for sure a keeper... I would invest in the LI and a solar setup.

So if I can get by with replacing 1-2 batteries... that would be money saved, for something that would actually be more than sufficient for the way I use it.  My last rig only had 4 basic costso 6volts and they lasted me 5 years.  I would hope a decent set of AGM's could go longer than that.  I am pretty sure fullriver has a 5yr warranty, but I haven't dug into the nitty gritty of it all.  Step one... is finding what caused, or is causing the problem... step 2 would be to fix it.

but yes... if the warranty isn't gonna do me any good, and I need a whole ne bank... then I'd rather spend a little more and go with lithium ion.... right now I am just trying to avoid that if I can. 

 

[J Alper]

also, i am doing a separate inverter for just the fridge, but i am using a non charging inverter, i am using a inverter with a built in transfer switch,  i am also using an inverter that is only lager enough for the fridge, i can't imagine a 2000 for a fridge, run the numbers, two large is hard on the inverter, 

Also Sandrash tried the AGM and had no luck he went back to the standard battery,

 

[Lord of the Dunes]

For me, I am just not sure if I am keeping this RV long term (2+ years) so I really don't want to invest 3k into LI setup.  If this was for sure a keeper... I would invest in the LI and a solar setup.

So if I can get by with replacing 1-2 batteries... that would be money saved, for something that would actually be more than sufficient for the way I use it.  My last rig only had 4 basic costso 6volts and they lasted me 5 years.  I would hope a decent set of AGM's could go longer than that.  I am pretty sure fullriver has a 5yr warranty, but I haven't dug into the nitty gritty of it all.  Step one... is finding what caused, or is causing the problem... step 2 would be to fix it.

but yes... if the warranty isn't gonna do me any good, and I need a whole ne bank... then I'd rather spend a little more and go with lithium ion.... right now I am just trying to avoid that if I can. 

You could always remove the LFP batteries and put them in your next RV. Then put new Sam's Club 6v batteries in this one when you sell it, you can honestly tell the buyer he's getting brand new batteries. 8 Sam's club batteries should cost about $800.

Let's assume you have a couple of bad batteries and the rest of them are only storing 60% capacity or so. If you put 2 new batteries in there, they will only store 60% like the old batteries, the old batteries will "drag them down." Will that be good enough for you for the next 2 yrs? n other words, putting a few new batteries in might not make that dramatic a difference in performance.

 

[wopachop]

I have one of these... but how would I use that to test my batteries? I've been using it to get the voltage readings 

You can perform lots of tests with a clamp meter. I think you were wondering if there is a small ghost load sucking down the batteries. You could put your clamp meter onto the main battery lead and see how many amps are being consumed. With the trailer turned completely off you should see zero. 

Sometimes the Propane detectors or CO detectors will draw power. Ive heard of radios left in standby mode sucking down batteries.

To be extra accurate check the manual for your meter. Some want you to put the clamp meter next to the wire and then hit the ZERO button before clamping that wire. That helps to get better accuracy when measuring fractions of an amp.

 

[Dockmaster]

I have one of these... but how would I use that to test my batteries? I've been using it to get the voltage readings 

Have you at least used your multi-meter to test the voltage of each individual battery? This will take you about 5 mins and at least give you some indication if you might have a bad battery or two in the string. You don’t even have to disconnect anything. Just put your meter on the + and - of each individual battery and write them down. They should all be within +/- a tenth of each other. It’s not a foolproof test but may give you an indication if some are bad and not holding a charge and possibly pulling the others down. 

 

[matt86m]

also, i am doing a separate inverter for just the fridge, but i am using a non charging inverter, i am using a inverter with a built in transfer switch,  i am also using an inverter that is only lager enough for the fridge, i can't imagine a 2000 for a fridge, run the numbers, two large is hard on the inverter, 

Also Sandrash tried the AGM and had no luck he went back to the standard battery,

I bought a Renogy 1000 to do just this. I like the idea of being able to shut off everything else (attached to the inverter) and leave just the fridge on. I plan to ditch the 12v fridge for a res fridge

 

[EmpirE231]

Have you at least used your multi-meter to test the voltage of each individual battery? This will take you about 5 mins and at least give you some indication if you might have a bad battery or two in the string. You don’t even have to disconnect anything. Just put your meter on the + and - of each individual battery and write them down. They should all be within +/- a tenth of each other. It’s not a foolproof test but may give you an indication if some are bad and not holding a charge and possibly pulling the others down. 

yep I have checked them all individually... and the reading are all very close.  Does it effect the reading since they are all tied together currently? as in, would I see different reading if I disconnected all the batteries?

One strange thing I am noticing is a constant buzzing sound coming from the battery area... even after I unplug from any shore power, and turn off the inverters / chargers.... This makes me think something is still drawing some juice... in order to make that buzzing sound.  There are all sorts of huge buss fuses and relays in this battery area... couldn't find my stethoscope to try and nail it down... but that is on the list of things to figure out.

I did find a fan that was constantly on in the holding tank area.... that kept running even if I turned everything off.  after some searching, turns out it is the basement heating unit for the aquahot, and it has a adjustable thermostat that I found tucked up in the wet bay area behind some panels.  I adjusted it down and the fan immediately shut off.  This makes me think it has been running non stop, which is another piece to this puzzle that I was able to solve so far. 

 

[Jtmoney714]

If your batteries are all tied together each one will read the same voltage. You have to disconnect all of them to verify what batteries are low or not. 

 

[r3meyer]

yep I have checked them all individually... and the reading are all very close.  Does it effect the reading since they are all tied together currently? as in, would I see different reading if I disconnected all the batteries?

One strange thing I am noticing is a constant buzzing sound coming from the battery area... even after I unplug from any shore power, and turn off the inverters / chargers.... This makes me think something is still drawing some juice... in order to make that buzzing sound.  There are all sorts of huge buss fuses and relays in this battery area... couldn't find my stethoscope to try and nail it down... but that is on the list of things to figure out.

I did find a fan that was constantly on in the holding tank area.... that kept running even if I turned everything off.  after some searching, turns out it is the basement heating unit for the aquahot, and it has a adjustable thermostat that I found tucked up in the wet bay area behind some panels.  I adjusted it down and the fan immediately shut off.  This makes me think it has been running non stop, which is another piece to this puzzle that I was able to solve so far. 

Oh for sure that aqua hot is your main issue.  Was the aqua hot left on?  I cant remember if the fan and pump will turn on independent of the main system being powered on.  I have my basement thermostat off since it never gets cold enough to cause problems.

Like others have said you can still get LiFePo4 and just move them to your next coach.  Just not having to maintain the cables alone is worth the price of them. Take these boat anchors out and stick them on a trickle charger in the back 40. When its time to sell swap them back in.  My current bus came with new Golf cart 6 volts.  I swapped them out into my old bus that I sold and moved my LiFePo4 setup over.

2 year of shitty batteries does not sound like fun to me.