Xantrex external regulator bulk charge

[gscriba]

Regarding a Xantrex XAR external alternator, the manual states the minimum time setting for the bulk charge is 30 minutes. If my battery bank (Lifepo)reaches the predetermined voltage setting, let's say 14.2, 15 minutes into the bulk phase, does the Xantrex regulator limit/change the alternator output, or does the output continue the same for the remaining 15 minutes? Thank you!

[smac999]

Only 2 things can happen when voltage is met in bulk. The current starts to go down. Or the voltage continues to climb. I’m going to assume it will just hold the 14.2v and currevt will drop. Instead of voltage going to ~18v. So it’s really in absorb at that point.

At that point. The timer has no effect unless bulk and absorb voltages can be set different. Which they can on a balmar.

[gscriba]

Thanks for that. The voltage definitely does not go up.
We spent some time in Mexico this past year. Our batteries were being topped up by our solar and on our last passage, it suddenly occurred to me that there was a 30 minute bulk charge as we set off from the marina under power. Our alternator was pumping out the amps with a full/near full charge. I turned on our AC and kept a close eye to ensure we did not overcharge. We didn't, but it has had me thinking and searching for a better understanding.
We have a Balmar 100 amp alt, Winston cells, Victron MPPTs x 4 and Victron inverter/charger. Victron are all slave to the REC. Super happy with the set up, which we have had for about 5+ years. Now interested in further tweaking the system with a REC wifi module, Balmar XT 170 and a Wakespeed WS500. Or not. :-)
In the mean time, I think I'll dial back the Xantrex regulator.
Thanks!

[witzgall]

Hi, Chris from Balmar here. Balmar made that regulator for Xantrex, I believe it is a rebadged ARS-4. It does not have the granular control needed to properly charge lithium batteries. I would suggest moving to a MC-618. With this you will get much better temperature control of the alternator, precise battery voltage measurement as it has a dedicated voltage sense wire, and the ability to monitor and control as part of the SmartLink network, if you so choose. I think that regulator is over 20 years old!!!

Chris

[gscriba]

Looks like that Balmar product's minimum bulk was 36 minutes compared to the Xantrex model's 30 minutes. Good to know, but didn't really answer the question I asked. If I proceed with the upgrades, I'll likely go with a product that will be slave to my BMS as previously stated. Pretty amazing really, that the currently used regulator still does the job, not optimally, but is adjustable enough and still working after 20 some years. Good product!

[lmxr]

Like Chris wrote, there has been some evolution in external regulators. Some regulators can also limit current, which is a very effective way to limit the alternator temperature while still maximizing the power output.

Would it be possible to do an integration with the REC by letting the REC enable/disable the Xantrex? It still wouldn't result in optimal charging, but the REC should avoid the extended durations of unnecessary high voltage.

[gscriba]

I spoke with a tech at Xantrex. The Xantrex does stop the current output mid-bulk phase charge once the pre-set (which is adjustable) voltage is reached. Turns out it's just fine for what I need it to do. Not slave to the REC BMS, but it (the regulator) will prevent overcharging, which is all I really needed to ensure. Thanks for the responses.