4.2 Charge voltage
- Recommended charge voltage: 14V-14,4V per battery (14,2V recommended),
- Absorption time: 2 hrs for a 100% charge, or a few minutes for a 98% charge.
- Maximum charge voltage: 14,4V resp
- Recommended storage/float voltage: 13,5V
- Batteries must be regularly (at least once every month) charged to 14V (max. 14,4V) in order to fully balance the cells.
There is quite a difference between the two. So by applying the Victron recommendations to the Balmar program this is what I came up with:
- Start delay is the same
- High Voltage limit: I would make it 14.2 (even though 14.4 is allowed why push the limit if 14.2 is recommended)
- Compensation limit: 14.2 (There should be no temperature compensation, see last line above)
- Bulk voltage 14.2
- Absorption voltage 14.2
- Absorption time * see note below but keep as is for now
- Float voltage 13.5
- Max Bat temp leave as is
- Max alt temp leave as is
- Batt temp compensation leave as is (zero)
*You can only define the minimum absorption time, not the
max absorption time. You may have to tweak this a bit. The purpose
of the absorption time is to equalize the cells. You just have to do that
from time to time, so if you go to a dock the MultiPlus does it for you and you
don’t necessarily have to do it on the water. If you never go to the dock
you might have to monitor it a few times to see what happens when you leave it set
to 18 minutes
If you have batteries (such as the Victron Smart Lithium) that have an external BMS then you can have the BMS control the regulator and stop charging when any cell in the battery gets to full. This is done using the Victron SolidSwitch as an ON-OFF switch for the regulator.
3 Comments
Ed
I’ve read that lithium batteries should not have any float time. So having the mc614 - shouldn’t we change the minimum float time To 0 and the maximum float time to 0 as well ?
Peter Kennedy
Andre
Thanks for the valuable information. With the new Smart BMS we now have two different battery chemistry interconnected on the same alternator (suppose its a Balmar). Suppose the start batteries are Victron AGM. Does your recommandation for charging profile would change in this context ? How to make sure the Lithium are charged and the AGM not overcharged ?
Peter Kennedy
Since Lithium and AGM are quite different it is more normal to use a Battery to Battery charger to charge one bank from the other. That way each bank gets the charge it needs.
If you try to charge them both from the same source at the same time the lithium battery tends to decide the outcome. Its voltage doesn't vary much throughout the charge cycle and only rises significantly at the end. That would cause the AGM battery to be undercharged for most of its charge cycle.
Kent
I'm installing a Victron Smart LIthium house bank, keeping AGM for engine start batteries. I have the VE.Bus BMS ver 2, and two Smart Battery Protect 220s, one each for load and charge disconnect. The example Victron system schematics for a similar setup have the Orion DC-DC set up to charge the Lithium bank, with the alternator charging the start battery. My local ABYC Marine Electrician suggested the opposite, to charge the Li bank with the alternator and use the Orion to charge the engine start battery. To me, this makes sense, and the Balmar 60 series alternator with MC614 will charge the Li bank pretty quickly, while conversely I'd have to run three Orions to come close to the alternator max output. Quite happy that I found this article, and the suggestion of using the Solid Switch to turn off the regulator. Question 1, does this make sense, and 2, wouldn't switching the MC614 off disable the Tach signal?
Peter Kennedy
It definitely makes sense to have the alternator directly charge your lithium battery. There are two things you have to do to make this work. Firstly there has to be a way for the BMS to stop the alternator. Secondly the alternator regulator must be set up to prevent the alternator from overheating. That means there needs to be a temperature sensor fitted that can reduce charging if the alternator gets too hot. It might also involve some permanent de-rating of the alternator because it was not designed to work flat out all the time. We do not expect the BMS to shut down charging every day, in fact in a normal system where the battery cells are properly balanced it should never happen. So yes, if it does happen and the alternator stops working so will the tachometer. It is a small price to pay to preserve your batteries.
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