Lithium Batteries with direct alternator connection

[geoffr]

I'm currently planning out our move to Lithium. Are there any batteries from Kilovault, Battle Born (or similar price points) that can send a shutdown signal to an alternator controller?

At the moment I'm thinking that I'll need to go with Victron batteries and BMS so I can directly connect my 125A alternator (derated with Balmar MC-614 so won't burn up) to the lithium bank. (I just don't like the idea of needing to install multiple DC-DC chargers (just seems wrong and more $$ when I already am doing this with my lead-acid house bank).

[K1MGY]

From what I have learned about these systems with alternators, it is STRONGLY recommended that you include a DC-DC converter between the alternator and the battery buss. Your BMS will not protect the alternator from the load, which in the case of LiFePo, will be full bore.

I use a DC-DC converter from Victron. If you need more current than what they individually supply, you can put these in parallel.. a nice feature.

[wholybee]

Epoch has batteries with CANBUS communication that should work with a wakespeed, but you would need to check with their tech support to confirm. The balmar doesn't support CANBUS, so your options if you stay will balmar are exceptionally limited.
https://www.epochbatteries.com/produ...-victron-comms

However, the need is overstated. Your BMS should NEVER disconnect the battery, and should not control charging. It is a last effort failsafe when everything else goes wrong. There is certainly a non-zero chance of it happening, but you shouldn't obsess over it. For that tiny non-zero chance of it happening, either a Sterling or Balmar APD will protect the battery without needing any BMS communications.

[wholybee]

Originally Posted by K1MGY

From what I have learned about these systems with alternators, it is STRONGLY recommended that you include a DC-DC converter between the alternator and the battery buss. Your BMS will not protect the alternator from the load, which in the case of LiFePo, will be full bore.

I use a DC-DC converter from Victron. If you need more current than what they individually supply, you can put these in parallel.. a nice feature.

With a regulator like a Balmar or a Wakespeed that support LFP and have a temperature probe this is not necessary. The regulator will back off the current and keep the alternator withing safe temperature. So you can get as much power from your alternator as it can safely make, instead of limiting it to what the DCDC can produce. In the OP case, he might get 125A for 15 minutes before it backs down to 80A or 90A. Compared to only having 30A or 60A from a DCDC. It's significantly better.

The DCDC is a great option if you have a stock alternator without an external regulator.

[K1MGY]

Originally Posted by wholybee

Your BMS should NEVER disconnect the battery

I took note of this as my BMS (two, one for each bank of 2p x 6s for a total of 1300 AHr) will disconnect the charge and independently the discharge path should charging or discharging overloads (and other anomalies) occur.

So curious as to whether my BMS's are doing something that is not generally recommended.

[wholybee]

Originally Posted by K1MGY

I took note of this as my BMS (two, one for each bank of 2p x 6s for a total of 1300 AHr) will disconnect the charge and independently the discharge path should charging or discharging overloads (and other anomalies) occur.

So curious as to whether my BMS's are doing something that is not generally recommended.

Are you noting that your BMS actually is disconnecting either the charge or discharge paths? Or just noting that the manual says that they are disconnected separately?

[K1MGY]

Originally Posted by wholybee

Are you noting that your BMS actually is disconnecting either the charge or discharge paths? Or just noting that the manual says that they are disconnected separately?

Sorry for my lack of clarity there.

The charge and discharge functions are shut down by the BMS as its protection settings demand.

For example, I had a cell out of balance which triggered a pack overvolt error. The charge path was shut off by the BMS.

[GreenWave]

Next week I plan to install new balmar 170 amp alternator with wakespeed connected to by lynx smart BMS/cerbo. Using a 30 amp dc/dc charger is like buying a Ferrari and only driving in school zones.

[SOLAR SUPPORT]

Drop-in concept batteries are mostly used in vehicles such as caravans, boats and cars. All of these vehicles definitely have an alternator. Why don't drop-in Lifepo4 batteries produced by hundreds of different brands have a low-cost, simple communication port that sends a warning signal before the "Bms Hvcutoff" action?

Although some expensive brands have this feature, this simple hardware is not available in most Lifepo4 batteries. When the LA batteries in these vehicles are replaced with drop-in Lifepo4 batteries, the minimum necessary equipment must be available to ensure safe operation.

Doesn't the safety of people using these vehicles pose a problem for Lifepo4 battery manufacturers, who constitute the majority and do not have this simple equipment? The safety of users in the same region is also important for alternator manufacturers. New generation alternators must have a simple switch to turn off this device safely. In addition, new generation alternators should not self-destruct by overheating.

[wholybee]

Originally Posted by K1MGY

Sorry for my lack of clarity there.

The charge and discharge functions are shut down by the BMS as its protection settings demand.

For example, I had a cell out of balance which triggered a pack overvolt error. The charge path was shut off by the BMS.

That is proper function of the BMS. The question then is why was a cell out of balance. That should not happen. Obviously it can and does, but it should be investigated to prevent it from happening again, as it is not a normal thing.

I am several years into my installation. I have never had a cell go out of balance, and never had a HVC. I did have a LVC when I was off the boat for a few weeks and lots of rain and solar didn't keep up. I came back to a dead battery, but but everything was otherwise undamaged.

[SOLAR SUPPORT]

Originally Posted by K1MGY

I took note of this as my BMS (two, one for each bank of 2p x 6s for a total of 1300 AHr) will disconnect the charge and independently the discharge path should charging or discharging overloads (and other anomalies) occur.

So curious as to whether my BMS's are doing something that is not generally recommended in this case.

Consider two 12.8V Lifepo4 batteries connected in series being charged by a 24 volt alternator. One of the batteries reached full charge voltage and BMS isolated the battery from the system. I think that BMS is doing something that is not generally recommended in this case.

[smac999]

Or just Take the risk and connect the alt to the batteries. With the balmar reg well wired and setup the voltage should never go high to trigger the bms. If one battery has a cell unbalance only one battery will shut down. The others will still be taking the alt current. The chances off all the batteries all shuting down at the same time and taking out the alt would be very very small.

Ironically a bunch of batteries with internal bms that don’t talk to anything Actully has advantages over a big bank with a single bms. That will shut the whole bank off of a single battery has an issue.

Add a balmar apm to help if a shut down ever happened.

A bms does not shut down unless there is a serious issue. And every single battery would need to have an issue

If super worried , and a long ways from help. carry a spare alt. Which if you don’t have a gen or lots of solar. You should be carrying anyways. Even without lithuim.

[Letterkenny]

I just finished my install. Went with Balmar 618 and LiTime 100ah mini batteries (4 of them). So far, so good. Fit my battery compartment fine on my boat and protecting my altenator with significantly more output than a DC to DC allows. I already have a battery isolator for the start so didn’t need to get a DC to DC. I find it hard to justify the Battle Born/Dakota/Relion brands. They aren’t keeping up with the densities that these other brands are doing and price is just outrageous.

[CarlF]

I currently use Kilovault batteries with the alternator directly connected to the house bank. Works great.

As already discussed, there are two reasons people don’t do this 1) An internally regulated alternator can’t connect to lithium batteries because they have no temp sensor to manage temperature and they are prone to exceeding the BMS cutoff voltage. The OP has an externally regulated alternator so this doesn’t apply. 2) The other problem is the possible damage to the alternator from a surge due to a BMS shutdown.

Communication is one way to handle the second problem but it isn't the only way. This is what I did:

1) set the alternator regulator absorption voltage to 14.0V - well below the 14.4v usually used. This means that the alternator stops charging when the batteries are about 95% full making a BMS shutdown much less likely. In two years I’ve never had a BMS shutdown.. Lithium batteries will also last longer if not pushed all the way to 100%. But if you must get the last few percent, set your solar panel regulator voltage higher.

2) I let a LA battery absorb the surge from a BMS shutdown if one should still happen. I use a DC-DC charger to charge the LA start battery from the house bank. In the event of a BMS shutdown, this will still provide a load to the alternator absorbing any surge into the start battery

3) For belts and suspenders I installed a Balmar alternator protector on the alternator.

One reason I chose the Kilovaults is that they start balancing the batteries at 14.0v while most brands don’t balance until 14.4. So I never need to push the voltage up where BMS shutdowns become a worry. And Kilovault specs charge voltage at 14.1v — so I still get 100% rated AH while using a lower and safer voltage.

[krid2000]

Originally Posted by CarlF

2) I let a LA battery absorb the surge from a BMS shutdown if one should still happen. I use a DC-DC charger to charge the LA start battery from the house bank. In the event of a BMS shutdown, this will still provide a load to the alternator absorbing any surge into the start battery

CarlF,

you keep stating that the DCDC charger to your start battery would absorb any surge in case of a BMS shutdown. Can you please show where you find that in the Victron documentation or elsewhere. If true, it would solve a lot of the concerns for folks wishing to make the change to LiFePo4.

Thanks
Dirk