Two Battery Chargers

[sgtdipper]

I install a inverter charger on our Mainship 390. I turned off the charger on the inverter because the boat already had a Sentry 12v 60amp 3 output charger that charges my house bank 2 8D AGM, Start battery 8D flooded and Generator start battery. My question is would it hurt to have both the inverter charger and the Sentry charger on at the same time to help the batteries recover quicker at anchor when using the generator?

I also have a Blue Sea SI-ACR automatic charge relay with start isolation install for charging when underway.


David
M/V Godspeed

 

[Wood]

Won't hurt anything. They will work together. Confirm the chargin profiles match your battery type and are at least similar.


My inverter/charger is a 1990ish Heart Freedom 25 130amp. It drops to float at 21 amps which is way too high. The batteries would never get fully charged.


I also have Promariner charger that drops to float at about 3amps. They work fine together.

 

[sgtdipper]

Thanks Wood

The inverter has 2 different AGM settings but the Sentry charger which was install in the boat when I bought it does not have a adjustment that I can find. Look like the Sentry charger floats at 13.5 v so I’ll set the inverter for the same and see what happens.

Thanks again
David
M/V Godspeed

 

[syjos]

I have used two identical chargers to get higher output with no problems.

I believe that the larger charger will cause the smaller charger to reduce or end charging. The small charger sees the voltage output from the larger charger, assumes battery is charged and reduces or stop charging.

 

[Xlantic]

It is what I do.

When I added an inverter-charger I kept my older charger.

On the hook I will run my 14 Kw Onan which has plenty of power for the two chargers working in parallel on the house batteries.

 

[syjos]

It is what I do.

When I added an inverter-charger I kept my older charger.

On the hook I will run my 14 Kw Onan which has plenty of power for the two chargers working in parallel on the house batteries.

Are the chargers the same output?

Have you measured output of the chargers while running parallel?

What I found was both chargers may run parallel initially but the larger one will overwhelm the smaller charger as the batteries come up.

It may be brand specific.

 

[Xlantic]

Are the chargers the same output?

Have you measured output of the chargers while running parallel?

What I found was both chargers may run parallel initially but the larger one will overwhelm the smaller charger as the batteries come up.

It may be brand specific.

Until the bank is fairly charged-up it accepts all the current the two chargers can throw at it.

 

[dhays]

Until the bank is fairly charged-up it accepts all the current the two chargers can throw at it.

I would think each charger would send its max configured current until they sensed that the absorb voltage had been reached.

 

[FlyWright]

I do the same, running both my Balmar alternator (120A) and my Honda powered shore charger (55A) to maximize my charge when needed. They play together very well.

 

[syjos]

Well that debased knowledge I picked up somewhere.

This is why this forum is so useful, sort the fact from fake advice.

 

[koliver]

Similarly, Solar charge controllers don't ask the charger for permission to add charging amps, they just do it. The charger doesn't complain. The batteries benefit.

 

[FF]

Most chargers monitor the voltage to decide on output to add.

If the batts are way down and the voltage is low the chargers will work together to boost the charge.

When the 85% charge (or so) is reached the charger with the highest voltage will do the charging the other will simply watch.

Using one charger for one bank and the other for a different bank can sometimes speed the last 15% of charge a bit.

Todays practice of a massive house bank works great for discharging , but a rotary switch to split the house bank in two may be a faster way to charge that last bit to get to the required (for long life) 100% charged.

 

[Maerin]

Add me to the dual charger club. My Freedom30 inverter side went TU, and I wanted a reason to go to a Full Sine inverter anyway, so rather than deep six the Freedom30, I relocated it next to the new Magnum, and wired a smaller set of conductors to the battery buss. I set up the profile for maximum absorb voltage. Both chargers work together happily in absorb, when the bank is down around 65% SoC they both crank up to near max, so I'll sometimes see 230A going into the bank. It's AGM, so it's happy to take all I can throw at it.

The result is faster charging, and with the solar to top off the bank during the day, I'm getting to 100% SoC almost daily. The bank performs much better, higher capacity, and I'm pretty confident this bank will outlive the predecessor Lifelines that I effectively murdered through chronic undercharging. 90% SoC and done will do that.

 

[jointcustody]

I know this is an old thread, but I wanted to ask-
I have 4, 6v costco deep cycles as my house bank wired series/parallel for 416ah.
I have an outback inverter that has a 40A battery charger and I have an older auxillary 50A charger that I can also turn on with my genset at anchor.
I have read that you shouldnt charge a flooded lead acid with more than 10% of the total bank AH?
That would mean like 41A....

Would you guys run both for 90A? thoughts?

Thanks

 

[fryedaze]

I know this is an old thread, but I wanted to ask-
I have 4, 6v costco deep cycles as my house bank wired series/parallel for 416ah.
I have an outback inverter that has a 40A battery charger and I have an older auxillary 50A charger that I can also turn on with my genset at anchor.
I have read that you shouldnt charge a flooded lead acid with more than 10% of the total bank AH?
That would mean like 41A....

Would you guys run both for 90A? thoughts?

Thanks

I would do it. I have a 940amphr bank and charge it with two 150 amp alts. They charge at 200 amps at peak. Charge rate drops off very rapidly. One of those chargers will dominate the other by having higher voltage.

 

[Comodave]

I always thought the maximum recommended charge percentage was 25%.

 

[BruceK]

...I have read that you shouldn`t charge a flooded lead acid with more than 10% of the total bank AH?

Thanks

It`s the other way round. The amp charge rate should be at least 10% of amp capacity being charged.

 

[jointcustody]

Awesome. Thanks for the quick replies.

 

[Delfin]

I install a inverter charger on our Mainship 390. I turned off the charger on the inverter because the boat already had a Sentry 12v 60amp 3 output charger that charges my house bank 2 8D AGM, Start battery 8D flooded and Generator start battery. My question is would it hurt to have both the inverter charger and the Sentry charger on at the same time to help the batteries recover quicker at anchor when using the generator?

I also have a Blue Sea SI-ACR automatic charge relay with start isolation install for charging when underway.


David
M/V Godspeed

No problem, but kind of pointless. AGMs or FLA will accept higher input very briefly before the charge acceptance rate drops below the 60 amp output of the Sentry, at which point it doesn't how many chargers you have pointed at the batteries.