AGM battery to sealed battery charging (1 Viewer)

[Jimbohorlicks]

Can anyone competent/knowledgeable in battery connections/ usage advise if this is an acceptable set of connections.
Connecting a battery master from a 100AH agm leisure battery that is charged from a 100 Watt solar to a 110Ah sealed battery ( none agm) in order to top up the 110 ah sealed battery to run a microwave or similar appliance through an inverter connected to the 110ah battery for short periods.
Additionally would it also be possible to fit a further battery master from the 110AH sealed battery to the engine start battery which would then charge up when both leisure batteries are full.

thanks

 

[eddie]

No it wont work, or rather it would work but would take forever. Battery Master will only allow a trickle charge of 1.1Ah

So a short burst from the microwave would take ages for the system to recover, and diddly squat left to trickle charge the engine battery

AGM - Engine Via the Battery Master would be fine.

 

[pappajohn]

I would simply link the two batteries with 16mmsq or 25mmsq cable depending on run length and fit the battery master to either battery and starter battery.
Don't know the current capacity of the battery master but the microwave draw well over 100 amps on start up.
Not sure if it could cope with that current.

^{_{Subscribers  do not see these advertisements}}

 

[funflair]

I don't think 110ah is enough for inverter to microwave I would want at least two of those.

Battery master from AGM to sealed should be OK but only gives a couple of amps charge I believe so 5 minutes in the microwave could take minimum 5 or 6 hours to put back and in reality most likely a lot longer depending on the charge level of the leisure battery.

Another battery master to the engine from the sealed battery would most likely do nothing as the sealed battery would never get a high enough level of charge to help the engine battery. I believe you need a 0.7 volt differential before the battery master kicks in, it would kick in OK on the sealed inverter battery as it would run very low on volts with the microwave running.

I would go for one decent sized leisure bank feeding habitation and inverter and as much solar as you can fit.

Martin

EDIT ok even longer than 5 or 6 hours at the 1.1 amps quoted by Eddie, and he should know.

 

[pappajohn]

700w microwave may draw 4 or 5 amps from the battery in 5 minutes use.
Around 5 hrs to recharge via the master if everything else turned off.

 

[Jimbohorlicks]

Thanks guys-useful info

^{_{Subscribers  do not see these advertisements}}

 

[eddie]

And it is fundamentally a different use to that I designed it for

A trickle charger lol

 

[Jaws]

Well I make the current draw approx 55 amps ( doing this in my head ) ( 700 / 12.5 )
So percentage of 100aH battery use over a 5 minute period would be about 20 % or so.. or about ( spookily ) 20 amps
Being as this is a head calculation I do stand to be corrected

 

[funflair]

Well I make the current draw approx 55 amps ( doing this in my head ) ( 700 / 12.5 )
So percentage of 100aH battery use over a 5 minute period would be about 20 % or so.. or about ( spookily ) 20 amps
Being as this is a head calculation I do stand to be corrected

I think your sums are about right, it's the voltage level that is the problem as it will often trip an inverter out, I wouldn't be surprised at less than 11 volts at the terminals with this use.

Martin

^{_{Subscribers  do not see these advertisements}}

 

[pappajohn]

700w /12v = 58ah
58amps / 5mins(8.62% of 1hr) = 11.6amps

8.62%....not 20%
11.6amps....not 20amps.

Haven't used a pocket calculator since the abacus went out of fashion so probably also wrong....and if it is right then we were both wrong.

 

[andy63]

I'll have a go as well
700w appliance through an inverter will draw 58 odd amps let's say 60 with some losses..
60 amp load for 5min equates to a 5amp hour drain on the battery
Ie 60 amps for 1 hour =60 amp hours
60 amps for 5 min =5 amp hour
Andy.

 

[funflair]

700w /12v = 58ah
58amps / 5mins(8.62% of 1hr) = 11.6amps

8.62%....not 20%
11.6amps....not 20amps.

Haven't used a pocket calculator since the abacus went out of fashion so probably also wrong....and if it is right then we were both wrong.

I think we are all wrong 58x5/60=4.8 ah

I still think one battery will crash through the floor

Martin

EDIT ok Andy I have been sat looking at it for 12 minutes

^{_{Subscribers  do not see these advertisements}}

 

[Jimbohorlicks]

so what's the concensus gents? to running a microwave for up to 5 mins max?

 

[funflair]

so what's the concensus gents? to running a microwave for up to 5 mins max?

I think the volts will drop too low and trip the inverter.

Any advance guys.

Martin

 

[andy63]

I think we are all wrong 58x5/60=4.8 ah

I still think one battery will crash through the floor

Martin

EDIT ok Andy I have been sat looking at it for 12 minutes

Lol... that it were that simple Martin. ..
I'll not split hairs but that load will amount to a 5ah drain...approx i agree that the current draw on a single battery is excessive and a fellow called Mr puket would point out that if the battery is discharged at a higher rate than its rated at ie usually the 20 hr rate ie 5 amps the battery will not last as long as it's rating suggests and it will take more than 5ahrs of charge to restore it to fully charged if that's where it started from...
Andy.

^{_{Subscribers  do not see these advertisements}}

 

[andy63]

so what's the concensus gents? to running a microwave for up to 5 mins max?

I'm suggesting that you can do it but don't expect the battery to last as long as it would if the loads were lighter by adding additional batteries which as Martin is saying will lighten the load on each battery if they are wired correctly...
I'm saying all that but I have no experience with inverters...
Not having a wife means I don't need one