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DIY 280Amp LifePo4 With BMS voltage problem.

larrylwill said:
I bought then In Aug
Supplier name LiitokalaVariCoreFlagship Store 4PCS VariCore 3.2V 280Ah lifepo4 battery DIY 12V 280AH
Click to expand...
That name does not inspire confidence.
Charging B grade cells at high amperage to 14.8 volts is not awesome.
 
At the time they were advertised as new, upon arrival, they looked new. No swelling and clean terminals.
 
Voltage measured with MM incoming 14.8v outgoing 14.6v. This Alternator was supposed to be for Lifepo4 batteries on this MH. Called Ecotrek modules.
 
C- B-, You ask questions I answer. you make wrong assumptions.
You insist in a dc to dc, So yes in that regard Im not going to do that but I will make it right, one way or another weather you personally approve or not. Sorry.
 
This product is brand new and original, and the battery pack can be DIY if the voltage is normal.
H3db1a6945c994f489d8a28b932b8289fe.jpg
 
Charge current （CC-CV ） Max Charge Current 1C The maximum charge current of the battery does not exceed 1C Cut-off under 0℃～45℃.
 
If you want your cells to last you are going to have to control charging some how.
 
Is this what you mean when you say your alternator may have a Balmer? https://balmar.net/?product=regulator-mc-614-h

It looks very configurable. I wasn't aware that such a system existed to control alternator output directly. It appears that the ones intended for LiFePo4 are able to have the charge curve programmed into them and then the alternator output is controlled by varying the magnetic field in the alternator.

I learn something new every day.
 
Yes that's it. When I bought the MH there was paperwork in the kitchen that said with EchoTrek which is the Roadtrek Lithium module. However it only came with AGM batteries. I ordered it with a UHG Roadtreks name for the 2nd alternator. It has a system called Voltstart that starts the engine to recharge the batteries when they get low and your boondocking. The first time I used it it came on at the wrong voltage. I checked and it a Lithium module which caused it to start at too low a voltage for the AGM. I called them and it was verified. I bought a buck converter to up the voltage to it to make it for AGM, So I'm hoping that the Balmar is on the alternator. This all happened about the same time Roadtrek was sold and they found that the company was insolvent and they went bankrupt. Eventually a French company bought it and brought the name back Erin Hymler. I just have to crawl around under it to see if its there.
 
It looks like I do not have a balmer, at least I cant find one.

The more I read the more negative things I find on charging Lifepo4 with an alternator. My original problem was trying to charge a 12v 280A Lifepo4 battery and 150A BMS with a 2nd alternator that puts out 280Amps. Solutions so far.
DC to DC converter, High cost low amps.

Smaller alternator may burn it out by sourcing high current too long.

Paralling 2 150A BMS's People disagree on this, and same possible problem with the Alternator sourcing high current too long. Also I read that the BMS turning off the charge can damage the alternator.

Adding a Balmar Best solution, High cost.

New Potential solution Since the high current is for usually less than 5 minuets before it settles to 120A or less I could use a relay (starter solenoid) to short the B- and C- until the Battery voltage reaches 13.5V or some value that reduces the current below 150A.
 
Sorry, I didn’t think the “Danger Will Robinson” gif would be an obscure reference.

I am thinking that anytime you bypass the BMS, especially for high amp charging, it creates a dangerous scenario. In this case, dangerous to your cells, unless you became the BMS and constantly monitor cell voltages and overall battery charging amps. It’s possible, I was a BMS for many months but it’s easy to destroy cells as it gets out of hand in just a couple minutes. Implementing this as a final solution, in my mind anyway, will eventually end in calamity.

There is no free lunch in alternator charging. Good solutions are expensive because the handle a lot of amps and protect your other expensive equipment intelligently and reliably. Like an SCC, money spent on a quality DC-DC charger is a good investment.

If there was another cheaper and easier shortcut, I am sure we would have heard about it.
 
It wasn't, very cleaver but without any information to accompany it, I have no idea what the danger was.
A 125 Amp dc to dc is 660 euros. Whatever that is in $ is even more. That's more than I spent on the batteries and BMS.
I would be monitoring the pack voltage with a module that would open the circuit when the battery voltage reaches a specific voltage.
I can still try 2 BMS in parallel for another $100
 
You can get two Renogy 60A DC-DC @ 260$ each and parallel them. Are you wanting the max charge amps to reduce the engine run time?

I didn't go back thru the thread but I recall you had some high current loads you needed to make up for with the charging. Alternative would be a portable generator to power the onboard shore power charger and just take longer to charge up. The chassis engine won't be very efficient for charging batteries unless you are using it for driving anyway
 
shadowsteve said:
You can get two Renogy 60A DC-DC @ 260$ each and parallel them. Are you wanting the max charge amps to reduce the engine run time?

I didn't go back thru the thread but I recall you had some high current loads you needed to make up for with the charging. Alternative would be a portable generator to power the onboard shore power charger and just take longer to charge up. The chassis engine won't be very efficient for charging batteries unless you are using it for driving anyway
Click to expand...
I just picked up that Renogy 60A DC-DC on Canadian Amazon site for $229 Cdn (approx. $200 USD). It's still available there: https://www.amazon.ca/Renogy-Batter...8383591&sprefix=renogy+dc,aps,267&sr=8-6&th=1
 
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