Another Battery Question

Submitted: Monday, Oct 05, 2015 at 09:31
ThreadID: 130509 Views:1650 Replies:3 FollowUps:5
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When I bought the caravan it had two x 200 a/h 6v batteries fitted wired in series. Not useable. Replaced with a 100 a/h 12v. Now it is time to repower. Is there any advantage to using the two 6v batteries beside the obvious increase in amp hours? Space is limited to a little more than an N70 size battery. Bill
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Reply By: Bigfish - Monday, Oct 05, 2015 at 09:51

Monday, Oct 05, 2015 at 09:51
Not really. Increased weight and if one of your batteries dies your system is kaput anyway, plus you may not know which 6v is crook. Keep it simple with the one 12 volt. Increase this to a 130 amp battery if you want a little more running time for accessories. Save your money as well.
AnswerID: 591187

Follow Up By: Battery Value - Monday, Oct 05, 2015 at 10:44

Monday, Oct 05, 2015 at 10:44
If I may add to this:

12V in the N70 size is 306L 170W 210H which takes a max of 105Ah AGM.

The next size up is 330L 170W 210H for a max 120Ah AGM.

Stay away from sellers stating 125Ah or even 130Ah in this size.

The battery weight says it all, there's 0.3kg/Ah.
E.g. AGM batteries advertised as 130Ah, these would hit the scales at 38~39kg if the capacity were true.
Plenty of cons around flogging "130Ah" ones only weighing 31.5kg in the 330mm container (which would be a lot closer to 105Ah or 110Ah).

FollowupID: 859251

Follow Up By: Bigfish - Monday, Oct 05, 2015 at 11:13

Monday, Oct 05, 2015 at 11:13
BATTERY VALUE...I purchased a 130 amp in the 330x212x173 configuration and 31.4kg. Are you saying that no manufacturer produces an agm in this size at 130 amps? If this is the case I will quite happily inform the seller(sellers) that they are fraudulently selling batteries and demand my money back. As will many others, I suppose.
FollowupID: 859253

Follow Up By: Battery Value - Monday, Oct 05, 2015 at 11:45

Monday, Oct 05, 2015 at 11:45
That's precisely what I'm saying.

You can start by asking the seller to produce a load test as by AS4029.2.

If you want to escalate the matter you need to add some beef to your demand.
A verifiable third party test result is something you can use when contacting Consumer Affairs.
In Qld, such a test costs 2~3 grand.
The seller knows this and is betting nobody will be willing to fork out this big in order to make him stop acting fraudulently.

FollowupID: 859256

Follow Up By: Bigfish - Monday, Oct 05, 2015 at 13:36

Monday, Oct 05, 2015 at 13:36
Trouble is that the manufacturers are the ones making the claim. Fullriver, SSB, Universal Power, and many more battery brands advertise these batteries as around the 20-130 amp mark.
FollowupID: 859268

Follow Up By: Battery Value - Monday, Oct 05, 2015 at 14:56

Monday, Oct 05, 2015 at 14:56
Generally, battery manufacturers do not fudge the performance data of their product for obvious reasons (litigation by competing manufacturers within the same jurisdiction).
But the importers and/or sellers abroad frequently do, in their quest for increased market share.
The importer can approach the manufacturer, in terms of what goes on the screen printed label in his country.
Complete specs sheets can be "re-designed" with fudged performance figures, and the manufacturer couldn't care less if done under another trademark in a foreign country.

But all is not lost, because battery weight remains the biggest giveaway, and it can't be changed unlike the screen printed label.

Here are some battery weight examples from the Fullriver specs sheet:

HGL100-12 328L 172W 214H, 30.4kg, 0.304kg/Ah
DC120-12 331L 175W 214H, 36.5kg, 0.304kg/Ah

If you compare this to 0.24kg/Ah of your battery, obviously something doesn't add up - or Fullriver and the likes don't know how to save lead in a given battery size.

FollowupID: 859276

Reply By: Les - PK Ranger - Monday, Oct 05, 2015 at 09:56

Monday, Oct 05, 2015 at 09:56
No increase in amp Hrs wiring up 2 x 6v in series, this doubles volts for 12v use but amps say same.
Wiring parallel, you double amps and volts stay same.
AnswerID: 591188

Reply By: HKB Electronics - Monday, Oct 05, 2015 at 10:45

Monday, Oct 05, 2015 at 10:45
The main reason I can see for using 6V batteries is that it is easier to get 6V batteries in high ampage ratings than 12V batteries. And if one battery fails then you only need to change one though as far as good pracitices go I would still change both for reliability unless one for instance was only a year old or so.

Also the cell count could be less, ie two 200Ah 6V batteries is 6 cells, two 100Ah 12V batteries in parallel cinfiguration is 12 cells and you have increased the possibilty of a cell failurer.

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