question

Micah Quinn avatar image

Charging Battle Born (LiFePO4) batteries from a Delco Remy 50dn (24v 270amp) alternator

Hello Victron Community,

For a few weeks now I've been struggling to find the right solution to charge my LiFePO4 batteries from my bus alternator. Here are the relevant technical details:

  • Delco Remy 50dn heavy duty alternator (24v 270amps); oil cooled, belt driven, externally regulated
  • 2x3 Battle Born batteries (12v 100ah) in seriesxparallel for 300ah at 24v (internal BMS)
  • Cyrix-li-ct relay connecting start batteries (2x group8 lead acid)

I consulted Battle Born and a few others in the industry and was told that this setup should work. The alternator is rated for heavy continous use and the Battle Born batteries can take charge from the alternator with the normal caveats (i.e. the alternator voltage will not be able to take the batteries to full SoC, etc.)

In practice, however, what I'm seeing is unworkable and I'm concerned I may actually damage my alternator/system. With the engine on and the relay engaged (solid blue light), I see a cycle that lasts 3-4 seconds and repeats ad infinitum. For a few seconds there is no current flow. Then, for a split second, a large in-rush of current (160+ amps) and a voltage spike of over 30 volts. Followed by no current and a return to 28 volts.

I've recorded the behaviour on video here:

https://www.dropbox.com/s/oo50xs8mdvwo9bz/delco50dn_bb12100_24v.mp4?dl=0

Does anyone at Victron or in the community have an idea as to why this is happening? In the video you can hear the relay making a noise that is a bit disturbing as well.

Thanks in advance for any advice.


Cyrix Battery Combineralternator
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3 Answers
Kevin Windrem avatar image
Kevin Windrem answered ·

My guess would be that the battery's internal BMS is disconnecting due to too much charging current. You probably are not seeing the peak current on the BMV.

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Micah Quinn avatar image
Micah Quinn answered ·

That's a good guess and I think you might be on to something. I've reveiwed the BMS features in the Battle Born manual and I think I may indeed be exceeding the charge voltage and/or amperage. I've got a message into Battle Born, so I'll wait and see what they say. The timing of the cycle is a bit longer than the 5 second disconnect time cited in the manual, but it's hard to know when to start counting.


Thanks Kevin!

4 comments
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Have you fully charged and balanced your 6 batteries before putting then in series/parallel?

Yes. I checked them prior to connecting them up and they were all at the same voltage. I double checked them recently and they were still at the same voltage.

Having the same voltage does not mean the batteries are all at the same Soc.

You're right. I'll look into equalizing them with a 12v charger when I get a chance.

randy-putnam avatar image
randy-putnam answered ·

Almost sure the internal BMS in the Battle Borns is restricting the voltage and amperage of your alternator. That restriction may also be saving your alternator. I think you should call BB and detail your issue again

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