Battery to Battery charger as best solution- reality check

[sv Libby]

Hi everyone,
I've done some research and would like to know if I am doing the right thing going with a B2B charger in my situation.

We have a beta 65 A alternator - internally/poorly regulated. Most of our charging is from solar - we'll have 650W of panels soon.

We don't have a modern smart alternator controller.
We don't need more alternator output, but I need to feed the batteries properly and I don't now.

We just ordered 3x 134Ah AGMs for the new house bank. When they die I want to consider LiFePO4 but I don't have the money right now.

So I could
1/ mod my alternator to remove the regulator and add a mc 614 or something.
2/ buy a new alternator and regulator.
3/ leave it the same and buy a B2B charger
4/ leave it the same and buy an A2B charger
5/ leave the battery switch on the start bank when motoring

I am thinking that a B2B charger will both future-proof me for LiFePO4 down the track, be an easy install, and give my new batteries the care they need.

Any thoughts?

cheers,
John

[sv Libby]

When we are using our motor we are usually on our way somewhere

[donradcliffe]

I had a 100 amp ISKRA alternator on my Beta 50hp. Modifying the alternator for external regulation was a simple as removing the internal regulator and replacing it with a brush block, grounding one lead and using the other lead as the field wire. I think I got the brush block from Beta.

[john61ct]

That sounds like a perfect application for a Sterling BB series charger. The 60A can be derated to 30A I believe, or save a little money by getting a lower rated one to start with.

Work with a good supporting dealer like Maine Sail, PKSYS or Alan at Bay-Marine.

[smac999]

What for? Charge the agms from the internal reg. You are overthinking.

The external reg will charge better. But if you are not looking for more alternator charge. It will be just fine.

[Dockhead]

Charging via the start batt, or direct from alternator?

If the former, then B2B is good (solves both regulation and splitting), If the latter, then Sterling Alternator to Battery is what you need. More expensive but easier to install than an external regulator. I would go with the regulator myself. Sterling if you don't like the Balmar.

Originally Posted by sv Libby

Hi everyone,
I've done some research and would like to know if I am doing the right thing going with a B2B charger in my situation.

We have a beta 65 A alternator - internally/poorly regulated. Most of our charging is from solar - we'll have 650W of panels soon.

We don't have a modern smart alternator controller.
We don't need more alternator output, but I need to feed the batteries properly and I don't now.

We just ordered 3x 134Ah AGMs for the new house bank. When they die I want to consider LiFePO4 but I don't have the money right now.

So I could
1/ mod my alternator to remove the regulator and add a mc 614 or something.
2/ buy a new alternator and regulator.
3/ leave it the same and buy a B2B charger
4/ leave it the same and buy an A2B charger
5/ leave the battery switch on the start bank when motoring

I am thinking that a B2B charger will both future-proof me for LiFePO4 down the track, be an easy install, and give my new batteries the care they need.

Any thoughts?

cheers,
John

[sv Libby]

Originally Posted by smac999

What for? Charge the agms from the internal reg. You are overthinking.

The external reg will charge better. But if you are not looking for more alternator charge. It will be just fine.

Unfortunately the 14.2V output cooked my last set on a long motor.

The new ones want 13.4 float in the tropics

[Q Xopa]

Previous couple of posters are on the money.

Im not sure why a B2B is being suggested as 'ideal' as no reasons are given.

I like them and have one on my boat, but not for regulation of my alternator.

As said above most people use Balmar 614s or if you prefer Sterling their AB charger or Regulator series.

Future proofing with LFPs etc. A B2B is actually a limiting future factor. At 60A that will max out charging a practical bank size at less than 180AH at a 0.3C rate.

Aside from listening to forum posters like me. If you email Sterling and ask them Im pretty sure I know what he will recommend. Obviously I cant speak for them but my guess it will be AB Charger or Alternator Regulator products.

[john61ct]

The whole **point** - besides getting the bank input voltage properly controlled - is limiting the current demanded.

If the future LFP bank is 600Ah that issue becomes **more** critical, and there is nothing wrong with a 0.1C rate.

If a higher current source becomes available in future, can just add another B2B, perfectly modular and not in any way limited to just this one source, remains useful with any, on the next boat, whatever.

Originally Posted by sv Libby

We don't need more alternator output, but I need to feed the batteries properly
…
I am thinking that a B2B charger will both future-proof me for LiFePO4 down the track, be an easy install, and give my new batteries the care they need.

Yes, of course modifying the alt/vr setup is another solution, but it's not the only one, and IMO in this case the B2B is a better one, more flexible, longer term thinking.

[sv Libby]

Originally Posted by Q Xopa

Previous couple of posters are on the money.



Aside from listening to forum posters like me. If you email Sterling and ask them Im pretty sure I know what he will recommend. Obviously I cant speak for them but my guess it will be AB Charger or Alternator Regulator products.

Message sent

[mikedefieslife]

Alternator and external regulator seems the best method, but a B2B charger is probably the most simple in the interim.

I'm not a fan of the sterling one though. Have you read through the manual and seen the process you need to go through to set your custom profiles. It's some ridiculous button tapping dance to flashing lights.

Victron have just released their Orion-TR Smart DC-DC chargers that now include battery to battery charging features. Max output at 12v though is around 20-30amps so you may need a couple.

I found this B2B charger that seems to be customisable. Not seen any feedback on it yet though.

https://www.donrowe.com/KISAE-DMT125...-p/dmt1250.htm

[Q Xopa]

Ok yes, agreed there is nothing fundementally wrong with 0.1C charging.

Im not sure what is the desire to 'limit' current? To save the alternator, I assume. The 614 and Sterling external regulators save your Alternator. That's their job, along with charging your battery. Especially with temp sensors fitted, which the B2B hasnt got.

To me this is akin to kinking a garden hose to reduce the flow instead of just closing the tap some more.

However from 80% DOD, that would be 8 hours of motoring to get your house bank topped off, assuming no other current loads.

Sure thats fine if you wanted to motor for 8 hours anyway.

If you could charge at 0.3C you could do the same in 2 hrs 40 mins. This is obviously a fair bit of savings in engine run, diesel used and 5 hr 20 mins less noise. You could only do 0.3C with one B2B with less than a 180AH bank. This is a smallish cruisers house bank.

If you need to buy another one to stack later, it doesnt really sound future proofed.

I realise some people do things differently.

I cant see why you would want to myself.

[Dockhead]

The Sterling A2B charger has an alternator temp sensor and is capable of using the full power of the alternator if you want.

But as I said, I would prefer to regulate the alternator directly. The Balmar allows you to regulate down the current ; could be that the Sterling regulator does too.

Originally Posted by Q Xopa

Ok yes, agreed there is nothing fundementally wrong with 0.1C charging.

Im not sure what is the desire to 'limit' current? To save the alternator, I assume. The 614 and Sterling external regulators save your Alternator. That's their job, along with charging your battery. Especially with temp sensors fitted, which the B2B hasnt got.

To me this is akin to kinking a garden hose to reduce the flow instead of just closing the tap some more.

However from 80% DOD, that would be 8 hours of motoring to get your house bank topped off, assuming no other current loads.

Sure thats fine if you wanted to motor for 8 hours anyway.

If you could charge at 0.3C you could do the same in 2 hrs 40 mins. This is obviously a fair bit of savings in engine run, diesel used and 5 hr 20 mins less noise. You could only do 0.3C with one B2B with less than a 180AH bank. This is a smallish cruisers house bank.

If you need to buy another one to stack later, it doesnt really sound future proofed.

I realise some people do things differently.

I cant see why you would want to myself.

[Q Xopa]

Originally Posted by Dockhead

The Sterling A2B charger has an alternator temp sensor and is capable of using the full power of the alternator if you want.

But as I said, I would prefer to regulate the alternator directly. The Balmar allows you to regulate down the current ; could be that the Sterling regulator does too.

Exactly, agree entirely. Sounds like we are saying the same thing.

[Pete7]

Originally Posted by Dockhead

The Balmar allows you to regulate down the current ; could be that the Sterling regulator does too.

I don't think it is a user option, but instead relies on the multi stage charging profile set to the battery type.

https://sterling-power.com/collectio...-bw-waterproof

However, if the long term goal is LFP, investing £140 now to ensure the alternator output matches the battery type, then that seems a sensible option. Sterling have been making these little widgets for decades in one form or another and they achieve surprisingly high prices second hand.

Pete