LiFePo battery upgrade question

[Teleman]

I ordered a 200AH LifePo battery to replace my two 100AH lead acid batteries and also a compatabile converter which takes care of charging the battery with shore or generator power but what about charging the battery with the alternator? Does the battery's BMS take care of everything and therefore no need to change or upgrade the alternator? Sorry if this is a dumb question!

[pianotuna]

Hi Teleman,

I was able to mount the three I use near the drivers seat in the wall. It makes it quite convenient for switching while I'm trundling down the road.

[Teleman]

Teleman wrote:

pianotuna wrote:

Teleman wrote:

pianotuna wrote:
Teleman,

Another reason to have a bypass circuit is for a "poor mans" boost switch. If the chassis batteries are dead, you would be able to get some amps into them from the "house" bank. Don't have it "active" when starting. The Li bms will NOT like it.

If the alternator did fail, then that bypass circuit could be used to keep the engine running a lot longer while getting to a service center. Of course the Redarc ought to be turned off to do this.

What kind of switch do you use? I take it using the house battery boost switch as is isn't recommended? I carry a jump start battery pack too.

Hi Teleman,

I use this type:

https://www.napaonline.com/en/p/NW_786125?impressionRank=3

I like it because I store it with the "key" hanging on a string. It would be nearly impossible to turn it on by accident. Maximum load up to 300 Amp @ 24 Volt DC.

OK thanks.

Do you place it between the staring battery and the charger or the charger and house battery? How did you mount it?

[Teleman]

pianotuna wrote:

Teleman wrote:

pianotuna wrote:
Teleman,

Another reason to have a bypass circuit is for a "poor mans" boost switch. If the chassis batteries are dead, you would be able to get some amps into them from the "house" bank. Don't have it "active" when starting. The Li bms will NOT like it.

If the alternator did fail, then that bypass circuit could be used to keep the engine running a lot longer while getting to a service center. Of course the Redarc ought to be turned off to do this.

What kind of switch do you use? I take it using the house battery boost switch as is isn't recommended? I carry a jump start battery pack too.

Hi Teleman,

I use this type:

https://www.napaonline.com/en/p/NW_786125?impressionRank=3

I like it because I store it with the "key" hanging on a string. It would be nearly impossible to turn it on by accident. Maximum load up to 300 Amp @ 24 Volt DC.

OK thanks.

[pianotuna]

Teleman wrote:

pianotuna wrote:
Teleman,

Another reason to have a bypass circuit is for a "poor mans" boost switch. If the chassis batteries are dead, you would be able to get some amps into them from the "house" bank. Don't have it "active" when starting. The Li bms will NOT like it.

If the alternator did fail, then that bypass circuit could be used to keep the engine running a lot longer while getting to a service center. Of course the Redarc ought to be turned off to do this.

What kind of switch do you use? I take it using the house battery boost switch as is isn't recommended? I carry a jump start battery pack too.

Hi Teleman,

I use this type:

https://www.napaonline.com/en/p/NW_786125?impressionRank=3

I like it because I store it with the "key" hanging on a string. It would be nearly impossible to turn it on by accident. Maximum load up to 300 Amp @ 24 Volt DC.

[Teleman]

pianotuna wrote:

Teleman wrote:

otrfun wrote:

pianotuna wrote:
. . . Can it be limited to 20 amps if need be? . . .

This could potentially be an important feature consideration. It'll be interesting to see if the 124a alternator has the headroom to handle the additional ~40a load for the long haul.

I'll have to look into it. I was originally looking at a 25A unit but that would have been inadequate for 400 watts of solo panels, which I plan to install next spring.

That would not be a switch. It would be a feature on the dc to DC charger.

Sorry that wasn't meant for you. Since edited.

[pianotuna]

Teleman wrote:

otrfun wrote:

pianotuna wrote:
. . . Can it be limited to 20 amps if need be? . . .

This could potentially be an important feature consideration. It'll be interesting to see if the 124a alternator has the headroom to handle the additional ~40a load for the long haul.

I'll have to look into it. I was originally looking at a 25A unit but that would have been inadequate for 400 watts of solo panels, which I plan to install next spring.

That would not be a switch. It would be a feature on the dc to DC charger.

[Teleman]

pianotuna wrote:
Teleman,

That is a good decision. Can it be limited to 20 amps if need be? It is a far superior make.

Another reason to have a bypass circuit is for a "poor mans" boost switch. If the chassis batteries are dead, you would be able to get some amps into them from the "house" bank. Don't have it "active" when starting. The Li bms will NOT like it.

If the alternator did fail, then that bypass circuit could be used to keep the engine running a lot longer while getting to a service center. Of course the Redarc ought to be turned off to do this.

What kind of switch do you use? I take it using the house battery boost switch as is isn't recommended? I carry a jump start battery pack too.

[Teleman]

otrfun wrote:

pianotuna wrote:
. . . Can it be limited to 20 amps if need be? . . .

This could potentially be an important feature consideration. It'll be interesting to see if the 124a alternator has the headroom to handle the additional ~40a load for the long haul.

I'll have to look into it. I was originally looking at a 25A unit but that would have been inadequate for 400 watts of solo panels, which I plan to install next spring.

[otrfun]

pianotuna wrote:
. . . Can it be limited to 20 amps if need be? . . .

This could potentially be an important feature consideration. It'll be interesting to see if the 124a alternator has the headroom to handle the additional ~40a load for the long haul.

[pianotuna]

Teleman,

That is a good decision. Can it be limited to 20 amps if need be? It is a far superior make.

Another reason to have a bypass circuit is for a "poor mans" boost switch. If the chassis batteries are dead, you would be able to get some amps into them from the "house" bank. Don't have it "active" when starting. The Li bms will NOT like it.

If the alternator did fail, then that bypass circuit could be used to keep the engine running a lot longer while getting to a service center. Of course the Redarc ought to be turned off to do this.

[Teleman]

After having the chance to investigate further I decided to return the Renogy unit and bite the bullet and get a Redarc 40A waterproof charger. It's $320 more but it's really the best solution. Trying to figure out a way to keep the Renogy dry was pretty much impossible without moving it to a basement. This way I can place it right next to the house battery and only a few feet from the starting battery. It also has a solar input with an MPPT regulator so when I add solar panels eventually I won't have the added expense of one.

[pianotuna]

I did not use the above--my cousin had 50 amp ones available.

[pianotuna]

Teleman wrote:

Can you recommend or share links to the circuit breakers? I need a 60a and 50a. Thanks!

https://www.amazon.ca/MASO-Waterproof-Circuit-Breaker-Suitable/dp/B07JYWD852/ref=asc_df_B07JYWD852/?...

https://www.walmart.ca/en/ip/Circuit-Breaker-Reset-Fuseholder-50Amp-100Amp-12-24V-Reset-Fuseholder-f...

[Teleman]

pianotuna wrote:

Teleman wrote:
If I can mount it in a plastic box safely I can keep the wires really short, 12-18", as the starter and house batteries are located very close to each other under the hood. Renogy recommendso 6ga from the starter battery up to 8' and a 60a fuse, and 8ga and a 50a fuse to the house battery.

If there is room--use a plastic battery box to hold the renogy. Make sure there is plenty of ventilation. dc to DC are not wonderfully efficient so the unit may need to dissipate over 250 watts of heat.

One minor concern. Is the starter battery flooded? If so the renogy should not be in the same compartment (corrosion will eat the renogy up). If the starter is AGM, then that's ok for the renogy to be in the same compartment.

I use auto reset circuit breakers rather than fuses.

I have dual 50amp charging paths (an attempt to improve charging before dc to DC devices were available). I've seen 70 amps--back in the old days when I had flooded house batteries (975 amp hours). I would use my inverter while running down the road and turn on the water heater. I used a duty cycle of 20 minutes on and 40 minutes off. I have manual control over the isolation solenoids.

Can you recommend or share links to the circuit breakers? I need a 60a and 50a. Thanks!