Battery sizing question.

scotjimland

Free Member
Jul 25, 2007
32,020
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Funster No
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At present I have 4 x 85 ah house batteries and a Victron 70 amp charger, I plan to replace the batteries with larger capacity bank.

Question:
Is there an ideal opitmum battery bank size for this size of charger that I should use or should I just buy as big as I can physically fit .. I'm aware of charging times increasing with battery size, is there a 'rule of thumb' ?

thanks in anticipation

Jim
 
G

GeorgeTelford

Deleted User
Hi Jim

Yes for fastest charging, charger should be 20% of amp hour rating

ie with 70 amp charger 350 Ah bank would be ideal (for fastest charging)

However you could easily charge up a 700 ah bank with that charger, it would just take longer (way faster and better than any standard motorhome charger)
 
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scotjimland

Free Member
Jul 25, 2007
32,020
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Funster No
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Hi Jim

Yes for fastest charging, charger should be 20% of amp hour rating

ie with 70 amp charger 350 Ah bank would be ideal (for fastest charging)

However you could easily charge up a 700 ah bank with that charger, it would just take longer (way faster and better than any standard motorhome charger)
Thanks George, it was as I thought but always worth getting a second opinion ..

I was thinking on getting 6 volt Trojan deep cycle batteries.. possible four of these http://www.barden-ukshop.com/t605-532-p.asp

any thoughts ?

Cheers
Jim
 
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scotjimland

Free Member
Jul 25, 2007
32,020
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70 Amp!! - that's quite a charger

Was that fitted in the RV already or did you acquire it later?
Hi

I retro fitted earlier this year, the original charger was a standard RV unit..
As George said, it's a Victron 70 amp / 1600 watt inverter .. brilliant bit of kit,
works as a UPS supply, it 'tops up' a low amp EHU, you set the supply limit , say 6 amps, if you exceed that it pulls power from the batteries then recharges when the demand falls off ..

Full Description here
Multi Compact -functional (Multi Compact / MultiPlus Compact only)
The Multi Compact gets its name from the multiple functions it can perform. It is a powerful
true sine wave inverter, a sophisticated battery charger that features adaptive charge
technology and a high-speed AC transfer switch in a single compact enclosure. Beside these
primary functions, however, the Multi Compact has several advanced features that provide a
range of new applications as outlined below.
Uninterrupted AC power (Multi Compact / MultiPlus Compact only)
In the event of a grid failure, or shore or generator power being disconnected, the inverter
within the Multi Compact is automatically activated and takes over supply to the connected
loads. This happens so fast (less than 20 milliseconds) that computers and other electronic
equipment will continue to operate without disruption.
PowerControl – Dealing with limited generator or shore side power (Multi Compact/
MultiPlus Compact only)
The Multi Compact is a very powerful battery charger. It will therefore draw a lot of current
from the generator or shore side supply (nearly 5 A per Multi Compact at 230 VAC). With the
Phoenix Multi Control (PMV) a maximum generator or shore current can be set. The Multi
Compact will then take account of other AC loads and use whatever is extra for charging,
thus preventing the generator or shore supply from being overloaded.
PowerAssist – Boosting the capacity of shore or generator power
The feature that distinguishes the Phoenix MultiPlus Compact from the standard Multi
Compact is PowerAssist. This feature takes the principle of PowerControl to a further
dimension allowing the MultiPlus Compact to supplement the capacity of the alternative
source. Where peak power is so often required only for a limited period, it is possible to
reduce the size of generator needed or conversely enable more to be achieved from the
typically limited shore connection. When the load reduces, the spare power is used to
recharge the battery.
 

eddievanbitz

Trader - Funster
Oct 4, 2007
5,353
16,979
Taunton Somerset
Funster No
540
MH
RV
Exp
since 1989
Hi Digger

Did you mean twice as good? or twice as expensive? I agree that they are twice as expensive if not three times, but can't see why they would be twice as good.

I personally would always go for a wet battery, with caps, so that I can check the levels and use a hydrometer. I have got battery testers costing hundreds of pounds, but I always trust my trusty hydrometer!

Cheers

Eddie
 

Digger Driver

Free Member
Oct 4, 2007
578
2
Lancashire
Funster No
541
MH
C Class
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Hi Eddie!
After reading from the link George put up i am a bit suspect now!
I know a lot of people who swear by them but i think they are more of a gimmick than anything else after reading up on them!
Personally i have two Dumper batteries in mine (there free) and i have no trouble with them but i was thinking of getting gel batteries!
George has just changed my mind!
 
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scotjimland

Free Member
Jul 25, 2007
32,020
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serious piece of kit but i couldn't warrant £800 for a battery charger and /or invertor. :Eeek:
I was fortunate, I purchased it from a member on MHFacts, (he was upgrading to the next size up),
I thought it well worth it as it cost little more than a new 40amp inteli charger.. :winky:
 
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scotjimland

Free Member
Jul 25, 2007
32,020
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Funster No
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MH
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Exp
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jeez........whats he done, ditched the engine and fitted dc motors to the wheels.:Eeek::ROFLMAO::ROFLMAO:
Well, you should have seen his battery bank, not sure of ah size but it filled the void in the double floor of his Euromobile, he also had two 130 watt solar panels..
He was planning on full timing in France and runs an internet hosting company depending on a Datastorm for communication, the wardrobe in the van was full of electronic kit..
I don't believe he is a member here yet but if he joins I'm sure he will be more than happy to explain all .. :winky:
 
Jul 29, 2007
4,775
9,156
Ipswich
Funster No
32
MH
RV
Exp
30 years
Hi jim I believe it was around 800ah. During the summer he was getting 16amps out of his solar panels around midday, and even running all his gear never seemed to have any trouble keeping his batteries topped up.

That datastorm was a lot of trouble though, I just assumed you connected up and away you went, but he had quite a few problems that even with his programming knowledge he couldn't fix.

Met him once at a rally, nice guy.

Olley
 
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scotjimland

Free Member
Jul 25, 2007
32,020
29,505
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Funster No
15
MH
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Exp
.
That datastorm was a lot of trouble though, I just assumed you connected up and away you went, but he had quite a few problems that even with his programming knowledge he couldn't fix.

Met him once at a rally, nice guy.
Hi Olley

He spent about a week at the pub prior to going to France and assisted me to instal and configure the Victron. The Datastorm was giving him a lot of grief then and I believe he cut his France trip short due to problems with it..

As you say, nice guy, haven't seen him on the facts for a while though ..
 
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