diy solar

diy solar

Boat Batteries – Help me Make a Final Decision

You will really appreciate cell level monitoring when you have issues beyond just overall battery voltage.
The shunt options are great for tracking the status of the bank, and triggering actions like disabling charging when the temperature is too low, activating a charger when the voltage is low, etc.
The cell level monitoring is ideal when you are trying to understand the state of health, cell imbalances, IR, etc.
Ideally, you would have access to both, even if you don't use them all the time.
I don't doubt this though I can also see having access to all this information leading one to needlessly obsess over that which they can't control. Particularly when it's a sealed box battery, all you can really do when these numbers start to go off the rails is hope that you can file a warranty claim. If you're out of warranty or the company won't play ball on the claim, I don't see the info as being all that valuable.
 
Also, the more you dig into the issue it seems charging at <0.05C in temperatures down to about 10 deg F is unlikely to have any negative effects, especially if it only happens occasionally.

Huh, that's interesting to hear, I did not know that. You probably don't really need to charge it much at all if any during winter anyways, unless the BMS has a strong parasitic draw.
 
Jberger hit the nail on the head, shunt level may be nice if you have a bunch of batts and want overall SOC but they don't tell you nearly enough, not when it comes to lithium.

E.g. when I had 8S packs (using grade B cells, and overkill solar 8s bms) had I not had a way to see my cells I would have never found out that I had 2 junky cells that drop in voltage under heavy loads and also would peak during charging before the others. Because of this the best I could charge my pack up to was about 78% or so even though the BMS would reset to 100% as soon as 1 of the junky cells said its full.

These types of issue you want a proper BMS with individual cell monitoring.

I was able to subdue most of the issue using an 8s active balancer but it wasn't a perfect solution by any means, would have never known if I just looked at the voltage of the battery (which would read as 14.01v due to the 2 junky cells peaking prematurely).
 
When faced with this decision, we went the DIY route, also doing a 460Ahr 2p4s (ie two 230Ah batteries in parallel) but we went with a REC ABMS. Why? Because I wanted my BMS to fully integrate into my system.

I’m all in on the Victron Ecosystem, and having my battery integrate with my inverter/charger, my alternator, and solar MPPTs is absolutely glorious.

Plus, I can remote in and check on everything from anywhere in the world. It’s a very very nice system.
 
When faced with this decision, we went the DIY route, also doing a 460Ahr 2p4s (ie two 230Ah batteries in parallel) but we went with a REC ABMS. Why? Because I wanted my BMS to fully integrate into my system.

I’m all in on the Victron Ecosystem, and having my battery integrate with my inverter/charger, my alternator, and solar MPPTs is absolutely glorious.

Plus, I can remote in and check on everything from anywhere in the world. It’s a very very nice system.
Your nice system cost you way more than my nice system. Since we live aboard we don't need to check our system from anywhere in the world.
I love Victron kit but we have had to deal with failures on mppt regulators 3 times now. Its not all plain sailing
 
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