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Old 09-09-2021, 07:15 PM   #1
hemiallen
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Update recharging 400Ah BB Lifepo4 attempt / test

Sorry for all the questions, but I don't have other resources for asking this, so far.

I did another draw down test, dropping my now 400Ah BB lithiums down to 75% -13.43v.

PD 4575A charger, factory Montana 4 gauge wire. Stared using my generator and finished with shore power, no difference seen in charging rate.

Started Charging at 51.59Amps as measured on Victron smart shunt and tapered down as batteries recharged.

I have 400Ah of Battleborn Lifepo4 that I need to recharge using my Honda 2000I generator. The trailer has a PD4575A converter, and I ran my battery bank down to 75 percent / 13.43V. Recharging the bank started with 51.59A at 13.43v ( total loss was -102.6 Ah) and gradually reduced Amps while increasing volts using my victron smart shunt measuring battery status. After 2 hours it was 13.62V and 39.38A ( -12.7Ah) and after 2 hours 45 minutes it was fully recharged at 14.55V, 0.76A and 0.0Ah loss.

This seems longer to top off than the advantage of Li batteries should take, all I want is to maximize recharging times when boondocking. It seems AC recharging isn't a readily found component for a decent price , and my 300W solar isn't as useful as my generator for where we camp.



Is there any way to get a faster recharge out of my 2000I generator, which running puts out an advertised 1800w? I wish to maximize my recharge time with this generator, but am willing to get a higher output generator if I can find an AC-DC charging system for times when I want a fast recharge, knowing this reduces the life of the batteries. BB states a suggested 50A / per battery so I could go as high as 200A, but realize that probably needs more AC watts than I care to take with me when boondocking. The largest I have found is a Victron 120A inverter-charger, but I only need the charging system.


My current thoughts are: plan to drop my batteries to a lower state of charge than I did in this test, and just run the generator a few hours a day to recharge some of the loss, and when I get the bank low enough either recharge longer, go find shore power for a day to recharge to 100%, then continue boondocking.

I am used to boondocking with L-A batteries, so maybe I just need to learn it's ok to drop to ~20% capacity before recharging them some? It is hard for an old dog to learn new ways , maybe the above is the route I should take....?


Thank you very much



Allen
 
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Old 09-09-2021, 08:37 PM   #2
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Since it appears that you are basing quite a bit on the data from the smart shunt are you certain it is synchronized? I suppose a better way to ask the question would be has it recently been synchronized at a known 100% SOC. If your measurements are all based upon the pack being in bulk charge without the pack ever making it through the absorption phase then the accuracy of the shunt is in question the more time the pack is in this state.
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Old 09-09-2021, 08:40 PM   #3
hemiallen
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Well

I placed the rig on shore power for 2 days after installing the 4th battery and reconfiguring them with the shortest 1/0 wires I could make, all equalized as much as possible, and the charge showed 14.66 for those 2 days. My belief is, that allowed them to synchronize, but am not 100% sure if that is correct.

All are BB-GC2 w/o heaters. 2 side by side, and the other 2 face to face for the shortest wiring lengths.

Thank you very much

Allen
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Old 09-09-2021, 08:49 PM   #4
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After the 2 days did you sync the shunt to 100%?
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Old 09-09-2021, 08:52 PM   #5
hemiallen
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Sorry, yes I did syn them to 100% on the app.

When the recharge test got to 14.01v , 20.43A, and -2.3Ah readings it said 100%, and I allowed the rechaqrging to go another 20 minutes until the readings were 14.55v , 0.76A ( charging) , 0.0Ah used.

Allen
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Old 09-09-2021, 09:09 PM   #6
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Ok so your shunt drift appears to have been accounted for. So is the expectation that your factory converter powered with a 30A gen should provide a higher charge rate possibly aligned with the .5C you noted for the 4 BB’s? I may be missing something but I think that initial 60A is in line with the 4575 converters. 60 A continuous output rating.
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Old 09-09-2021, 09:27 PM   #7
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Thank you,

Thanks for the confirmation, if the 52A is all I should expect out of the 75A converter, then atleast that is working.

Yes, I am hoping to optimize recharging using my generator with whatever Amp charger can be purchased. The highest Ac-dc converter I have found is this unit

Victron Energy MultiPlus 3000VA 12-Volt Pure Sine Wave Inverter 120 amp Battery Charger. I asked BB for help, and this is what they recommended.

Allen
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Old 09-09-2021, 09:48 PM   #8
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The MP will definitely provide you with a higher charge capability. Not to overstate the obvious but you will want to address your input source to take advantage of that rated 120 max charging amperage of the MP 3k. Good luck with your system.
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Old 09-09-2021, 09:55 PM   #9
hemiallen
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Thank you

Ok, I see it requires a 30A/ 120v input. Missed that .

I am still surprised this 120A seems to be the highest A unit I can find, there must be a higher output charger but I guess it defeats the off the grid part if you need a large generator to recharge the bank.

Do most folks run their bank down below 50% before attempting to recharge it. Still trying to learn how to use the Li system vs my old LA systems I have used in the past 20 years.

Allen
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Old 09-09-2021, 10:47 PM   #10
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I routinely run my bank down to 15% but I have 2600 watts of PV array to replenish. I will most likely add a 7k gen set as a backup means when there is little to no sun.

Not to rehash but perhaps are you running other loads off of the generator when you were charging?
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Old 09-09-2021, 10:54 PM   #11
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Thank you.

I ran the bank down using the DVD-Tv and main interior lights, but turned everything off for recharging. It was under 1 A draw for the inverter, I should have isolated the bank but forgot to. I will be sure to only use the TV while the gen is running, which is what I used to do for my lead acid's to drown out the generator while recharging.

And I am inside the shop, so I am not yet sure what the solar does for recharging. I put her away before getting the App to work so I could see the solarflex system with the Victron MPPT charge system my unit came with.

Thank you again

Allen
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Old 09-10-2021, 04:58 AM   #12
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For those short boondocking times I donít want to carry a generator, I installed a 60A DC-DC charger.
Here the write up and test results.

https://www.montanaowners.com/forums...hlight=charger
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Old 09-10-2021, 06:58 AM   #13
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You can add a secondary charger that only works when on shore or add truck charging fairly easily. The victron multiplus will be great but you'll need to make sure your current charger isn't on the inverted leg. I'd personally disconnect the converter and let the Victron do all the work.
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Old 09-10-2021, 04:42 PM   #14
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Hey Hemi,

Are you tracking how many watts are left over while charging? You could easily add another charger and directly plug it into the generator. Something like this:

https://www.amazon.com/Progressive-D...1313502&sr=8-5

Ray from Love Your Rv does something similar here:

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Old 09-10-2021, 05:02 PM   #15
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Thanks Carl.

Yes, great idea. I'll see if my Generator will support a second charger like that.

I was hoping to locate a single, larger Amp unit, but this will work also and his video is where I planned to add the larger single unit.

It seems the price of a charger isn't a linear $ / A, it isn't much more on a 90A unit vs a 60A unit, hence my hope to find a single large charger and just eliminate the factory one with the long 4 gauge wire.

Thanks for the idea and video.

Looking back over my spreadsheet at the 2 hr mark my system got the bank to about 95% / 13.6v, maybe I should just accept that as ok to top out at until I get to shore power to top them off.

Thanks again for all of your help, my friends

Allen
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Old 09-15-2021, 01:51 PM   #16
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Quote:
Originally Posted by hemiallen View Post
Sorry for all the questions, but I don't have other resources for asking this, so far.

I did another draw down test, dropping my now 400Ah BB lithiums down to 75% -13.43v.

PD 4575A charger, factory Montana 4 gauge wire. Stared using my generator and finished with shore power, no difference seen in charging rate.

Started Charging at 51.59Amps as measured on Victron smart shunt and tapered down as batteries recharged.

I have 400Ah of Battleborn Lifepo4 that I need to recharge using my Honda 2000I generator. The trailer has a PD4575A converter, and I ran my battery bank down to 75 percent / 13.43V. Recharging the bank started with 51.59A at 13.43v ( total loss was -102.6 Ah) and gradually reduced Amps while increasing volts using my victron smart shunt measuring battery status. After 2 hours it was 13.62V and 39.38A ( -12.7Ah) and after 2 hours 45 minutes it was fully recharged at 14.55V, 0.76A and 0.0Ah loss.

This seems longer to top off than the advantage of Li batteries should take, all I want is to maximize recharging times when boondocking. It seems AC recharging isn't a readily found component for a decent price , and my 300W solar isn't as useful as my generator for where we camp.



Is there any way to get a faster recharge out of my 2000I generator, which running puts out an advertised 1800w? I wish to maximize my recharge time with this generator, but am willing to get a higher output generator if I can find an AC-DC charging system for times when I want a fast recharge, knowing this reduces the life of the batteries. BB states a suggested 50A / per battery so I could go as high as 200A, but realize that probably needs more AC watts than I care to take with me when boondocking. The largest I have found is a Victron 120A inverter-charger, but I only need the charging system.


My current thoughts are: plan to drop my batteries to a lower state of charge than I did in this test, and just run the generator a few hours a day to recharge some of the loss, and when I get the bank low enough either recharge longer, go find shore power for a day to recharge to 100%, then continue boondocking.

I am used to boondocking with L-A batteries, so maybe I just need to learn it's ok to drop to ~20% capacity before recharging them some? It is hard for an old dog to learn new ways , maybe the above is the route I should take....?


Thank you very much



Allen
I have 600AH of BB LiFePO4 and 6x180W solar panels. I also carry a pair of Honda EU2000I's hooked up in parallel with the factory cable. This gives me close to a 30A service. My inverter charger is a 3,000W 120A charger. The gennys have no problem charging at full power since 120A at 12V is roughly 12A at 120V. One genny would work but just in case I want to run 2 AC units I bought the pair. One of the things I did different from you is remove/disconnect the built in converter. It is a POS. You say you don't need an inverter, so just buy a Victron charger. I don't see any that come close to 120A but maybe I missed something. I don't understand why you need 400AH of Lithium if you don't use an inverter.
I have my Victron 3,000W inverter charger set to charge at 180A (120 shore/genny plus 60 from solar) I have never let the batteries get that low, but in theory I could recharge from almost 0 to 100% on genny alone in 5 hours, 3.5 hrs with full sun at a high angle.
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Old 09-15-2021, 03:15 PM   #17
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Quote:
Originally Posted by hemiallen View Post
Thanks Carl.

Yes, great idea. I'll see if my Generator will support a second charger like that.

I was hoping to locate a single, larger Amp unit, but this will work also and his video is where I planned to add the larger single unit.

It seems the price of a charger isn't a linear $ / A, it isn't much more on a 90A unit vs a 60A unit, hence my hope to find a single large charger and just eliminate the factory one with the long 4 gauge wire.

Thanks for the idea and video.

Looking back over my spreadsheet at the 2 hr mark my system got the bank to about 95% / 13.6v, maybe I should just accept that as ok to top out at until I get to shore power to top them off.

Thanks again for all of your help, my friends

Allen
Before you go out and spend a bunch of money on chargers... You might want to call a company named 'Iota'. They make a variety of various electronic devices and are mostly known for their chargers and power supplies. They are very friendly and I recommend that you call their engineering department and tell them what you want to achieve. I have 2 Iota DLS 55 amp chargers with Lithium firmware for my LiFEP04 batteries. I was told that when using multiple chargers you can run into a problem where the 1st charger affects the 2nd charger and neither charger is sure of the battery capacity or SOC. You can end up damaging things. Give them a call and speak to engineering before you spend. My 1400 watts of solar can charge my 400AH bank from 20% to 100% in 3 hours with good sun.
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Old 09-15-2021, 04:03 PM   #18
bcrvman
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Quote:
Originally Posted by hemiallen View Post
Sorry for all the questions, but I don't have other resources for asking this, so far.

I did another draw down test, dropping my now 400Ah BB lithiums down to 75% -13.43v.

PD 4575A charger, factory Montana 4 gauge wire. Stared using my generator and finished with shore power, no difference seen in charging rate.

Started Charging at 51.59Amps as measured on Victron smart shunt and tapered down as batteries recharged.

I have 400Ah of Battleborn Lifepo4 that I need to recharge using my Honda 2000I generator. The trailer has a PD4575A converter, and I ran my battery bank down to 75 percent / 13.43V. Recharging the bank started with 51.59A at 13.43v ( total loss was -102.6 Ah) and gradually reduced Amps while increasing volts using my victron smart shunt measuring battery status. After 2 hours it was 13.62V and 39.38A ( -12.7Ah) and after 2 hours 45 minutes it was fully recharged at 14.55V, 0.76A and 0.0Ah loss.

This seems longer to top off than the advantage of Li batteries should take, all I want is to maximize recharging times when boondocking. It seems AC recharging isn't a readily found component for a decent price , and my 300W solar isn't as useful as my generator for where we camp.



Is there any way to get a faster recharge out of my 2000I generator, which running puts out an advertised 1800w? I wish to maximize my recharge time with this generator, but am willing to get a higher output generator if I can find an AC-DC charging system for times when I want a fast recharge, knowing this reduces the life of the batteries. BB states a suggested 50A / per battery so I could go as high as 200A, but realize that probably needs more AC watts than I care to take with me when boondocking. The largest I have found is a Victron 120A inverter-charger, but I only need the charging system.


My current thoughts are: plan to drop my batteries to a lower state of charge than I did in this test, and just run the generator a few hours a day to recharge some of the loss, and when I get the bank low enough either recharge longer, go find shore power for a day to recharge to 100%, then continue boondocking.

I am used to boondocking with L-A batteries, so maybe I just need to learn it's ok to drop to ~20% capacity before recharging them some? It is hard for an old dog to learn new ways , maybe the above is the route I should take....?


Thank you very much



Allen
It doesn't matter what generator you are using, the converter is never going to put out more than it's designed to and probably not even that much. Use Watts when doing these calcs as it eliminates the need to convert and avoids the risk of a conversion error. Here are some salient measurements.
The gennie c an put out 1,600W steady
The Converter puts out 75A if I remember the model number code correctly but I think the max you saw was about 52. That maybe caused by converter inefficiencies or wiring. I use 4/0 wires for the battery interconnects and from my inverter/charger to the batteries. My converter is totally disconnected freeing up a breaker!
At roughly 60A you should have no problem re-charging 102.6AH in under 2 hours but the last little bit does take a little longer by design. How is your Battery Monitor set up, that might make a difference. My batteries just reached full charge about an hour ago, here is the chart. You can see there is still some charging happening after it reaches 100%. I also included a calculation for 4AWG wire, I use 4/0 and the result for 10 ft is 0.5% but my run is less than 3ft so it's 0.15%
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Old 09-15-2021, 11:05 PM   #19
hemiallen
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Thanks for your reply with your system. Sorry, I didn't mean to imply I don't USE an inverter, I have the 2000 factory, so I am looking for a 120A charger without an inverter. I suspect yours is a Victron multiplus like I am looking at, I hate to pay over $1k for just the charger as I don't need an additional inverter.

Thanks

Allen
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Old 09-15-2021, 11:30 PM   #20
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Quote:
Originally Posted by hemiallen View Post
Thanks for your reply with your system. Sorry, I didn't mean to imply I don't USE an inverter, I have the 2000 factory, so I am looking for a 120A charger without an inverter. I suspect yours is a Victron multiplus like I am looking at, I hate to pay over $1k for just the charger as I don't need an additional inverter.

Thanks

Allen
I understand, but you may not be aware of the capabilities of the Multiplus. It can do more than the factory 2,000. The new model of Multiplus is even more capable. Sell the factory 2,000 and get the Victron, you will never regret it. BTW, if you do not boondock a lot none of this is cost effective but if you do it's a game changer. My plan is to boondock 5 out of 7 days then 2 days at Harvest Hosts and Boondockers Welcome with a monthly stay at a KOA or similar. Do your research.
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