Any experience charging a lithium battery off a truck alternator

[dwh]

A couple of technicality nits to pick...

-- For years, automotive charging circuits limited their voltage to avoid overcharging open flooded lead acid batteries. (FLA) Call this the 13v era.)

I don't accept this as a given. I've noted before, how my old 60's VW Beetle, with a *generator* had a factory voltage regulator setting of 14.5v. My current camper, a 1976 Ford van, with a factory regulator (almost certainly the original 1976 part) also runs at 14.5v.

Some vehicles set to the 13v range...okay, that I can accept. But from my experience, those were the exception, not the rule.

Also AGM batteries, a form of FLA with sealed vents.

Oh no, not at all. AGM (and GEL) are not "flooded" and thus *not* FLA (flooded lead-acid).

Also, the first sealed batteries were all flooded - and many, perhaps even most, sealed batteries still are flooded - despite the prevalence of other types of sealed batteries such as AGM and GEL.





No nits to pick with the rest of the post though - all good stuff.

For me, the Holy Grail will be a BMS that automagically makes a Lithium bank look like an FLA bank and I'm not sure that anyone has such a beast on the market.

Well, I've seen a few "drop-in replacements" with on-board BMS that basically cuts the incoming power to prevent over-charge (and hey, that's exactly what a solar charge controller does as well so it's not a "bad" way to go), so I think there are already some lithium drop-in replacements on the market that are more or less "transparent" to the charging system. The StarkPower mentioned above is one of them.

 

[DiploStrat]

I don't accept this as a given. I've noted before, how my old 60's VW Beetle, with a *generator* had a factory voltage regulator setting of 14.5v. My current camper, a 1976 Ford van, with a factory regulator (almost certainly the original 1976 part) also runs at 14.5v.

Some vehicles set to the 13v range...okay, that I can accept. But from my experience, those were the exception, not the rule.

I don't have enough information to argue. I know that my '77 Blazer ran a 13v voltmeter. (Never tested to see what voltage it actually reached.) Ignored my '95 Isuzu, don't even remember whether it had a voltmeter, ammeter, or neither. Similarly, I have heard enough chatter to know that this was an issue with some Mercedes Benz owners. (The worst case that I have ever heard of was a Unimog owner who bought a very expensive camper equipped with a diode isolator. !3v -0.5v = you can drive all day and not charge a thing. It was he, in fact, who first put me in touch with Sterling Power.)

I think we are in agreement (along with Chris Gibson) that if your charging system runs between 14v and 14.5v, then you have very little reason to spend money on a secondary regulation system (A2B or B2B, etc.) if you are running any form of conventional lead acid battery.

Oh no, not at all. AGM (and GEL) are not "flooded" and thus *not* FLA (flooded lead-acid).

Also, the first sealed batteries were all flooded - and many, perhaps even most, sealed batteries still are flooded - despite the prevalence of other types of sealed batteries such as AGM and GEL.

I have heard this argued this way: "What do you think is absorbed into the glass mats between the lead plates?" However we describe them, lead acid batteries, whether open or sealed or absorbed glass mat, are similar in that they want a voltage over 14v and they also want multi stage charging. A key difference is that if you overcook an open battery, you can simply top up the liquid whereas if you overcharge a sealed battery enough to pop the vent, you may have a paper weight.

 

[dwh]

I have heard this argued this way: "What do you think is absorbed into the glass mats between the lead plates?"

To which I would reply, "Well...just because it has acid, doesn't mean it's flooded. If it doesn't slosh, it isn't flooded."

AGMs are a.k.a. "starved electrolyte". "Starved" and "flooded" have pretty much opposite meanings.

 

[DiploStrat]

I think we can achieve violent agreement on these points:

-- AGM and open FLA batteries want voltages in the 14-15v range, depending on temperature and type of construction.

-- The Delco Lead Calcium battery, used in recent GM products MAY have the hottest voltage requirements and thus, by extension, GM products may have the highest charging voltages on the market, at this time. (I would love to get real numbers from recent Ford, RAM, and other vehicles.)

-- All of these batteries want a multistage charge profile of bulk/boost, absorb/acceptance, and float.

-- Too high a voltage and amperage and you risk overcharge which will result in the loss of electrolyte. This may be catastrophic in the case of a sealed battery where the liquid cannot be replaced.

-- Too low a voltage and amperage or too short a charge time and you risk undercharging which can lead to reduced battery capacity over time.

Lithium batteries are different, offer many advantages for their increased cost, but require a different charging regime. Scholars differ on the exact nature of that regime.

 

[dwh]

Scholars differ on the exact nature of that regime.

Aye. And I'm not so sure at this point that I'm buying that whole, "3000 cycles" line. I've worn out about a metric ton of lithium ion laptop batteries over the years, and never seen 3000 cycles out of one yet (300 is more like it). Lithium iron phosphate may be enough different that it can actually do that many cycles, but I'm still on a vertical learning curve with them, so I can't say for sure other than, "not sure I quite buy it".

Halfway decent primer on the difference here (be advised, it's yet another typical "slow as dogsh*t painfully overloaded with totally useless crap" modern-day web site...):

http://www.brighthubengineering.com...rison-of-lithium-ion-to-lithium-iron-battery/

 

[LeishaShannon]

Ron,

LFP batteries are significantly easier to charge than lead based technology like AGM or GEL. They'll accept any charge rate that you'd find in a typical expo vehicle over the full 0-100% SoC and don't need an absorption or equalisation charge. Personally I charge to 3.45vpc (13.8v for a 12v system or 27.6v for ours) as this is where the cell voltages are likely to diverge from each other. At this voltage they are somewhere around 96% full and to safely charge any further you would require complicated cell monitoring/balancing and I don't see the point for RV use.

Our 3500W alternator (130A @ 27.4v) is told to stop charging once the batteries reach 3.45vpc, or manually via a switch in the cab if we're approaching a big hill (Our 6ton 4WD truck had 115hp from the factory and quite a few of those ponies have bolted over the years so the ~6hp alternator load is quite noticeable now

If you can automagically control the truck -> camper relay @ 13.8volts i'd say go for it.

 

[rrliljedahl]

The solution from the retailer selling lithium batteries is to install a second battery monitoring gauge in the cab of the vehicle as well as a battery isolator with in cab switch. When the voltage in the lithium batteries reach roughly reaches 14 volts when charging off my truck alternator output of 14.6 volts. , manually disconnect them from the alternator with a battery isolater and then let my solar controller take over to optimally top the rv batteries off.

I am not an electrical guru but the retailer claims to have put over 100 of these lithium systems in motor homes and RVs using the vehicle alternator to charge the lithium batteries.

I was considering using Blue sea systems ml-ACR-7622 with inside car switch for the battery disconnect as it seems to allow me to start the truck using the camper lithium batteries if my truck batteries were dead.

Thoughts??

Thanks for such a good discussion!

 

[LeishaShannon]

I was considering using Blue sea systems ml-ACR-7622 with inside car switch for the battery disconnect as it seems to allow me to start the truck using the camper lithium batteries if my truck batteries were dead.

Thats what we used when we still had start batteries (now we just use the house batteries) and it worked well.

 

[DiploStrat]

This Might Work

With the caveat that I have not tried this with lithium, I use a Magnum Smart Battery Combiner to control a large Blue Sea relay. http://magnumenergy.com/smart-battery-combiner-me-sbc/

The high voltage cut off can be adjusted between 14v and 15v. This might do what you want automatically. (I also use a dash switch for manual override.)

 

[Kiomon]

I don't like any system that you have to manually constantly watch, and then switch it off to prevent over charging. You are going to be busy driving one day and forget it. If you go the switch method for the alternator, be sure you have a BMS still there to protect the batteries.

I have some experience with Smart Battery (www.smartbattery.com) and I like their solution more and more vs the separate cells and separate BMS. You may want to check them out. We have a 50ah battery for them that we have been using for two years and it's been flawless and a heck of a lot easier to wire!

 

[damienperu]

Will I damage my lithium battery with voltage of 14.6?

My MK2 270amp alternator can output at up to 15V, so I too have been reading all i can about the subject before jumping into lithium. After reading a lot of conflicting information, i noticed that the smart battery site (http://www.lithiumion-batteries.com/lithium-rv-deep-cycle.php) shows a charge voltage of 14.4v to 14.6V and under 'Features' mentions that their over-voltage protection cuts in at 16V, so while a higher charge might not be as ideal, the fact they set it at 16V and not a lot lower leads me to think we won't damage them charging up to 15V.

 

[damienperu]

and for what it's worth, smart battery and starkpower both got back to me, smart battery simply said that it wouldn't be a problem, "..., so if you'd like to order just.... ". starkpower actually went to the trouble to mention specificially that their built-in battery cutout protection would cut-in at 15V, so that my high output alternator wouldn't be a problem.

 

[damienperu]

We have a 50ah battery for them that we have been using for two years and it's been flawless and a heck of a lot easier to wire!

Hi, would you be so kind as to describe which battery and what application you gave it? I'm considering getting some of the smart battery line for crank (100ah) and auxiliary (150ah) batteries, but not sure if their range is suitable for both. Starkpower actually markets separate batteries for both starting and auxiliary deep cycle uses, so it makes me wonder whether the smart battery single line of batteries will be optimum for both uses. Cheers,

 

[casmith32]

I don't like any system that you have to manually constantly watch, and then switch it off to prevent over charging. You are going to be busy driving one day and forget it. If you go the switch method for the alternator, be sure you have a BMS still there to protect the batteries.

I have some experience with Smart Battery and I like their solution more and more vs the separate cells and separate BMS. You may want to check them out. We have a 50ah battery for them that we have been using for two years and it's been flawless and a heck of a lot easier to wire!

Hi - I just bought (4) 50Ah batts from smart battery - trying to determine best configuration to charge these puppies via the alternator - do you use a simple battery isolator like the blue sea ACR and just rely on the battery's internal bms to cut off voltages ? how do you handle the issue of float charging ? which you are not supposed to do with these batteries ?

thanks!

 

[damienperu]

i haven't got my lithiums yet, but in preparation i bought some new 120 amp DC-DC chargers from Sterling that now have a lithium charging profile, which can also be customised with a remote interface. they also work as an isolator.