I was starting to highjack CND's thread with the LC200, so here's a new one. Kind of a continuation from my winching with Lithium thread, which concludes that winching with Lithium is somewhat new territory. At least when I set up my winch wiring, I made the leads long enough to reach both my house and start battery. It's a fair amount of work and material to redo the cables. But back to lithium. From the manufacturers, it seems that most lithium batteries would be ok running directly from an alternator, as their BMS would shut down the battery if voltage were too high or too low. What was not clear was which situations would damage the alternator itself, and why. I have one alternator that feeds the start battery, and an identical second one that was feeding the house battery. No relays or DC/DC chargers or any connection at all between the two systems, unless I used jumper cables. This was mostly done to preserve the starting battery from being dead, especially in the winter. I am often away from the truck for days at a time, and often the only vehicle at a trailhead. The second alternator can also be swapped into the start system, so extra redundancy there. From my searches, it appears that my old alternator may not even charge the Lithiums fully, and would need a boost from another form of charger, like a 120v or a DC/DC charger. Anyone have any experience with this? My plan is to add solar within a few months, but for now, I need to replace my defunct AGM battery.
Direct connecting a LiFePo4 battery to a 60 amp alternator. (1 Viewer)
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I forgot to add - my house system on its own alternator has its own fusing. The smoking alternator in the Victron video did not seem to be protected by fusing. My house system mirrors the Toyota start system. There is a fusible link next to the battery, and then two AMD? (big flat 80 and 40 amp fuses from Blue Sea) fuses on two of the wires in the alternator circuit. Would the fuses not protect both the battery and the alternator if the draw got too high? Or would the damage be done before the fuses blew?
Here's some 'food for thought': Many here say that an alternator should not be connected to LiFePO4 and that one should use DC-DC Charger - https://diysolarforum.com/threads/many-here-say-that-an-alternator-should-not-be-connected-to-lifepo4-and-that-one-should-use-dc-dc-charger.53318/
I have a drop in type LFP I bought from ElectricCarPartsCompany.com 7-years ago and its been in the bed of my '07 HD2500 directly connected to the alternator for the past 6-years w/o issue (the first year this LFP was installed in my former TrailTailor trailer). I assumed since it was labeled and sold as a "drop in battery" the BMS was designed to handle the wide range of battery temperature extremes for most/all 4-season climates, alternator protection, etc. So far so good.
But, for the 7500Wh LFP I put together using Prismatic cells in our little Escape 15A, I (as you already know from the previous linked thread) utilize solar + a Sterling BB1260 for charging. If I connected this LFP directly to the alternator (HD2500 or UZJ100) I'm sure it would kill either alternator.
Whether to use a condom
(DC-2-DC charger) or not...is directly related to what type of perimeters the BMS is designed to manage, alternator output voltage & amperage, etc.
The biggest challenge for adding a suitable DC-2-DC charger(s) inside an LC is where to put it/them. I assume this is the main motivator to determining how to charge directly from the alternator.
I have a drop in type LFP I bought from ElectricCarPartsCompany.com 7-years ago and its been in the bed of my '07 HD2500 directly connected to the alternator for the past 6-years w/o issue (the first year this LFP was installed in my former TrailTailor trailer). I assumed since it was labeled and sold as a "drop in battery" the BMS was designed to handle the wide range of battery temperature extremes for most/all 4-season climates, alternator protection, etc. So far so good.
But, for the 7500Wh LFP I put together using Prismatic cells in our little Escape 15A, I (as you already know from the previous linked thread) utilize solar + a Sterling BB1260 for charging. If I connected this LFP directly to the alternator (HD2500 or UZJ100) I'm sure it would kill either alternator.
Whether to use a condom
(DC-2-DC charger) or not...is directly related to what type of perimeters the BMS is designed to manage, alternator output voltage & amperage, etc.The biggest challenge for adding a suitable DC-2-DC charger(s) inside an LC is where to put it/them. I assume this is the main motivator to determining how to charge directly from the alternator.
the impression I got over time is that it's not going to damage an LFP battery if it's not charged to the full (max) 14.6V and that on the contrary, it will likely extend its life. (Correct me if wrong please.) If so, having an OEM alternator charge it to 14.2-14.4V or so should not be an issue, I would think (aside from other possible problems).
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Yes, if I go with a DC/DC charger, I have no idea where it will fit. This is a very compact truck (1990 Pickup), and the engine bay is already very full. The Victron units seem fairly compact, which is helpful. I can put solar on the roof of the canopy, and have a portable panel. I will have to figure out a location for an MPPT controller and a DC/DC charger. I can also upgrade my stock alternator to a 150 amp unit. Just more $$$$. I can also do short trips this fall, and charge the battery on a 120v when I am home. Looks like my possible risk is frying one of my old alternators.
I would get a Lipo with a good BMS with some perf data, not familiar with differences in Lipo's are and which ones if any have better BMS ? I get from the posts the diff effects of Lipo batt size but are the bms's widely different ? Kinda like an egnel fridge vs. an aspenora fridge. They both do the same thing just fine, however when you really break it down one is more suited to the use and is more expensive, dont know if this exists between diff Lipo batts ?
Cool setup. Like the redundancy.
Wish there was a(n affordable) dual alt setup for an 80 series
Wish there was a(n affordable) dual alt setup for an 80 series
Keep in mind there are drawbacks to putting the DC-DC and/or MPPT in the engine bay also. Not only is the high temperature potentially not good for the unit, but some of them will derate at higher temps, IOW not deliver as much power.
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Engine bay is way too full regardless. Tends to get way too dusty for electronics as well. Somewhere in the cab cubbies or back wall is possible, but would require moving or altering a few things. I have a Blue Sea switch panel mounted on the passenger side C pillar, which is out of the way enough that it does not get bumped on or off. I will have to get creative to minimize the wire runs between alternators, panels, batteries, and so on.
As for battery choice, I can't tell so far if any of them have better management systems than their competitors. I will try to look into that a bit, given the cost. The heated versions are pretty easy to separate.
I did just run across a blurb in a Victron DC-DC manual -something similar to what was mentioned above IIRC- where they were saying that an issue with connecting a LFP battery directly to the alternator is the low battery impedance and therefore possible overload of the alternator. Now, TBF, they are also trying to sell DC-DC chargers so I'd take this with a grain of salt, and as I mentioned, if the max current allowed by the BMS is lower than the alternator's capacity, that does not seem to be a big problem for the alternator. (Although if the BMS is the type that would fully disconnect repeatedly if the battery pulls more than the max, it may not recharge then, that would be a problem.) Not an expert, though. They were also talking about how the modern smart alternators could shut down when not needed (battery full?) and how the house battery could then discharge the starter battery if the 2 are connected together, but the logic of that escapes me, since I assume the alternator would simply kick back in.
It is true, also, that a DC-DC charger will have a better handle on optimizing the charging process for the connected battery than the OEM alternator, I would think, and that may pay off in the long run. Some DC-DC chargers may also serve as isolators.
So, all in all, while I'm not seeing huge red flags about connecting the LFP directly to the alternator in a pinch, unless $$ are a serious challenge, I would get a DC-DC and do this right.
It is true, also, that a DC-DC charger will have a better handle on optimizing the charging process for the connected battery than the OEM alternator, I would think, and that may pay off in the long run. Some DC-DC chargers may also serve as isolators.
So, all in all, while I'm not seeing huge red flags about connecting the LFP directly to the alternator in a pinch, unless $$ are a serious challenge, I would get a DC-DC and do this right.
The RedArc units are pretty much bullet proof for use under the hood. There isn't another make I would remotely trust in the same spot. It's one reason they cost so much.
